Rock and Soil Reinforcement

Rock & Soil Reinforcementthird edition www.rockreinforcement.com Talking Technically Case Studies Product Specifications a technical reference edition Contents Foreword 2 Foreword by Federico Scolari, Vice President Marketing, Atlas Copco Craelius. 99 104 109 113 115 119 124 127 129 131 135 Talking Technically 3 5 7 11 13 15 17 19 22 24 28 33 35 38 41 43 45 47 51 55 59 61 Innovative Solutions for Rock & Soil Reinforcement Investing in Rock Reinforcement Controllable Rock Reinforcement Swellex Manganese Offers Improved Work Index Swellex Premium Line Hollow-Core SDA System Atlas Copco MAI Self Drilling Anchors Symmetrix For Large Holes Sacrificial Drill Bits Mechanized Bolting Using Rocket Boomers to Install Rockbolts Connectable Swellex Rockbolt Corrosion in Mining and Tunnelling Grouting for Support in Tunnels Rock Mass Stability with Swellex Secoroc Uppercut – New Tapered Equipment Getting the Drift with Magnum SR Rock Mechanics and Rock Reinforcement Swellex in Shear Stress Using ROC Drillrigs to Install SDA 3-D Imaging for Rock Support Design Introducing Swellex Hybrid Front Stabilization Using MAI Rock Anchors: pre-reinforcement as a means of ground control in Germany, Italy and Taiwan. Boltec at Kemi Mine: integrated process control demands reliable and consistent mechanized rockbolting. Overcoming Squeezing Ground at Mitholz: supporting deformed strata while fresh support is installed. Mechanized Bolting at Zinkgruvan: better rock reinforcement improves production and safety. Seismic Tunnelling at Bolu: crucial motorway tunnels recover from earthquake using Self Drilling Anchors. SDA in the Baltic States: novel uses for grouted SDA as micropiles to support ancient buildings. Increasing Land Use: SDA applied to subsoil stabilization prior to housebuilding in UK. Soil Nailing UK Transport Routes: securing major road and rail infrastructure using SDA. Portal Support Using Swellex: stabilization of entrances to Porte tunnel in Italy. Driving From Budapest to Nürnberg: difficult tunnels using advanced rock reinforcement techniques. Systematic Grouting at Oslo Subway: Craelius Unigrout provides the perfect solution for water ingress. Product Specifications 139 144 145 148 149 150 152 164 166 172 174 175 178 180 188 189 190 204 Swellex Manganese Line Plasticoated Swellex Swellex Premium Line Swellex Hybrid Swellex Face Plates & Washers Swellex Pumps MAI SDA Tophammer Crawlers Boltec Rigs Rocket Boomer Drillrigs Hydraulic MAI Bolt Support Hydraulic Rock Drills Hydraulic Feeds Symmetrix Overburden Casing System Unigrout Grout Plant Pusherleg Drills Secoroc Threaded Equipment Secoroc Tapered Equipment Case Studies 63 69 73 75 77 81 87 91 97 Swellex in Mining: project reports from Canada, Portugal, Turkey and Peru. Removing Bottlenecks in Austria: upgrading the European highway system in Central Europe. Extreme Temperatures: rock reinforcement in permafrost in Northern Quebec and volcanic strata in Hokkaido. Coated Swellex at Kvarntorp: longlife installation of rockbolts in a corrosive environment. Nuclear Quality Assurance: long-term tunnel support for the Exploratory Studies Facility at Yucca Mountain, US. Versatility in Tunnelling: project reports from China, Germany, Madeira, Spain, and Switzerland. Rapid Support Close to the Face: reporting use of Swellex at three important Italian TBM tunnelling sites. Large Hydroelectric Projects: widely differing demands at sites in Austria, Bhutan, India, Philippines and Portugal. Top Combinations in Japan: reliable support in sedimentary and volcanic rock formations in railway and road tunnels. Front cover: Different applications involving rock reinforcement. Atlas Copco reserves the right to alter its specifications at any time. For latest updates contact our local Customer Centers or refer to www.rockreinforcement.com Produced by tunnelbuilder ltd for Atlas Copco Rock Drills AB, SE-701 91 Orebro, Sweden, tel +46 19 670-7000, fax -7393. Publisher Ulf Linder [email protected] Editor Mike Smith [email protected] Picture Editor Jan Hallgren [email protected] Contributors Anders Arvidsson, Claes Hillblom, Federico Scolari, Francois Charette, Gunnar Nord, Hans Fernberg, Juha Hyvaoja, Jukka Ahonen, Lorne Herron, Mario Bureau, Mark Bernthaler, Olle Karlsson, Per-Olof Einarsson, Sara Sjödin, Sten-Ake Peterson, all [email protected]. Adriana Potts, [email protected]. Maurice Jones, maurice@tunnelbuilder. com. Wulf Schubert, Markus Potsch, Andreas Gaich, all [email protected]. Designed and typeset by Sheldon Mann, Belvedere, Kent, UK Printed by db grafiska, Örebro, Sweden Copies of all reference editions are available in CD-ROM format from the publisher, address above. Reproduction of individual ROCK & SOIL REINFORCEMENT 1 Foreword ngoing development of faster, safer and more exotic tunnelling techniques places a constant pressure on manufacturers to provide more efficient rock support solutions which will help the shortening cycle time. The use of versatile drilling jumbos for mechanized installation of a variety of rock support systems is part of the leading practice used in modern tunnelling. As ground conditions get more and more demanding, emphasis is placed on flexible and intelligent support systems in which rock and soil reinforcement is expected to contribute to the productivity and safety of the operation. The trend has been to provide rock support/reinforcement systems that are easy to install, assure efficiency and provide safety, both during and after excavation. For the last 25 years, Atlas Copco has been offering the Swellex concept as a unique, safe and reliable system of rock support. As the market leader in underground rock excavation technology, Atlas Copco has also been developing safer and more efficient rock reinforcement products such as the Manganese Line rock bolts, which are manufactured from a special type of steel. Another development is the Swellex Premium Line of rock bolts, for use where high yield load and stiffness are expected from the reinforcement system. The recent acquisitions of MAI and Rotex have introduced a whole new range of products, which are now being developed for mechanized installation by both surface and underground drillrigs, creating fresh applications in rock and soil reinforcement. Atlas Copco’s Rock Reinforcement Competence Centre at Feistritz/Drau, Austria brings together the skills necessary for the development of superior rock reinforcement products to serve the tunnelling, mining and construction industries worldwide. In 2005, the centre became a part of Atlas Copco Craelius, which is active in ground engineering with Symmetrix and ODEX overburden casing drilling systems, and Unigrout and Logac grouting equipment, and produces multipurpose drilling rigs such as the Mustang. The combined product portfolio includes Swellex and MAI, bringing together all elements of the Atlas Copco rock and soil reinforcement strategy. As a result, market-driven product development at this new facility is already setting the scene for another quarter-century of development in rock reinforcement and ground engineering. O Federico Scolari Vice President Marketing Atlas Copco Craelius [email protected] 2 ROCK & SOIL REINFORCEMENT TALKING TECHNICALLY Innovative Solutions for Rock and Soil Reinforcement Twenty Five Years On Over the past 25 years, Atlas Copco has developed a constant stream of products that have provided innovative solutions to a multitude of rock support and reinforcement tasks, and solved many difficult challenges for miners and drilling contractors around the globe. Further developments are on the way with the recent inauguration of a dedicated competence and R&D centre for rock reinforcement in Feistritz/Drau, Austria. Located at the headquarters of Atlas Copco MAI, the centre is dedicated to developing cutting-edge products for rock reinforcement and ground engineering applications. Official opening of the new Atlas Copco rock and soil reinforcement competence centre at Feistritz/Drau, Austria. Leading the Way When Atlas Copco applied for patents for the Swellex rock bolt in 1979, it was a significant milestone in rock reinforcement technology. This inflatable bolt was extremely easy and quick to install in a 38 mm hole, and provided immediate support. The advantages proved to be so effective that over the next decade several million Swellex bolts were used in demanding ground conditions worldwide. In the years that followed, this success led to the development of several new versions including: • Coated Swellex with rust protection to withstand corrosive environments • Super Swellex for larger hole diameters and a 20-tonne load-bearing capacity • Connectable Swellex for tunnels where the length of the bolt required is more than the height of the tunnel • Swellex Hanger for suspending such facilities as conveyor belts and working platforms ROCK & SOIL REINFORCEMENT • Swellex Manganese for increased tensile strength and higher elongation capacity • Swellex Premium Line for improved yield characteristics and tensile strength with slightly less elongation. Specialized Rigs At the same time as applying for patents for Swellex, Atlas Copco launched the Boltec 500, a new rig for fully mechanized rock bolting, primarily to increase productivity and to improve safety when installing the bolts. Safety is an especially important consideration on sites with poor rock conditions. However, the extreme conditions of rock bolting, in which water and rock Atlas Copco Boltec LC is a highly productive machine developed specifically for rock bolting. 3 drilling holes for rock bolts as well as for the installation of pipe roofing systems and self-drilling anchors.TALKING TECHNICALLY stabilization. are designed for exceptionally poor ground conditions where holes collapse and conventional bolts cannot be used. the Boltec LC working in a Finnish mine recently installed more than 120 Swellex Manganese bolts in a single 8-hour shift. In addition. Boomer face drilling rigs also began to be used for tunnelling in poor ground. Their performance was affected even more when cement-grouted bolts were used. and customers around the world can expect to see many new and interesting products in this area coming from Atlas Copco in the years ahead. Competence Centre The recent opening of the dedicated competence centre at Feistritz/Drau. Innovative two boom cable bolting rig drills with one boom while feeding and grouting cable with the other. through the acquisition of SDA specialist MAI Ankertechnik of Austria. mining and construction industries worldwide. they are used in combination with crawler drillrigs for surface applications. Swellex remains supreme. coupling. fitted with sacrificial drill bits. Atlas Copco MAI SDA are now commonly used with modified Boomer drill rigs. anchor rod and a sacrificial drill bit. The scene is now set for another quarter-century of development in rock reinforcement and ground engineering. Austria heralds a new era for the development of superior rock reinforcement products to serve tunnelling. For example. and Atlas Copco remains firmly at the forefront of 4 ROCK & SOIL REINFORCEMENT . the drill rod and bit are replaced by an MAI adapter. Swellex Still Supreme As the Swellex patents have begun to expire. Atlas Copco continued to develop further generations of more rugged and reliable bolting rigs that had fewer moving parts. A considerable amount of marketdriven product development will now be possible. such as soil nailing in slope by Federico Scolari Twenty five years of innovative solutions to rock reinforcement problems. In 2002. On the following pages. cuttings pour down along the drill string and onto the rock drill. These fully-threaded anchors. but none have managed to achieve the same quality. The current fourth generation rigs are capable of impressive performances. and in ground engineering for foundation reinforcement. In this case. Atlas Copco presents some technical papers. continually setting new standards and breaking new ground. the company added self drilling anchors (SDAs) to its ever widening product range. due to cement spilling out of the hole onto the bolting unit. case studies and product specifications to demonstrate this technology in action. other producers have made repeated attempts to imitate the design and features of the Swellex bolts. this technology. feed and moving components. In response to these challenges. had a negative effect on the service life of these rigs. a sounder attitude to this work is emerging. to carry out the support and rock reinforcement in the right order. As contractors and miners have a reputation for looking after their money. In a linear situation. the drilling performance has improved dramatically. engineers. and working environment and safety aspects. Since the introduction of the original Swedish Method. there is an ongoing drive to create new or improved solutions to rock reinforcement problems. miners and contractors around the world. adequately proven performance of reinforcement. and looking into the time needed to excavate a round and how this has developed. and with 350 m overburden and significant water inflow. will indicate the direction in which tunnelling technology is going. and concentrate all efforts on excavating the greatest amount of rock. through a couple of major faults. the time taken will reduce by 50%. and a technology that has the capacity to meet modern quality demands. 100 men can do it in one day. we discuss the cost implications of the time taken for the round in tunnel excavation. The introduction of heavy pneumatic drifters mounted on articulated booms. that rock reinforcement was considered a burden. There may be only one face to work at. The round cycle is just as real today as it was then. and to evaluate the results of the rock reinforcement effort. new ideas are born on how to carry out the support and reinforcement work in cost efficient ways. Atlas Copco is right at the core of practical solutions for rock reinforcement. This topic is generally broached at an early stage of a project by the contractors. In tunnelling. by fast installation of rock support. the drilling phase has decreased from 40% of the total 5 . life is not that easy. and they are often presented as alternatives in their quotations on underground construction projects. By doubling the effort. There is now a wish to achieve the required demands on quality. as a supplier of rock drilling equipment as well as rock reinforcement tools and material. has further multiplied productivity. Improving Performance Going back 20 years or so. in tunnelling and mining. In this presentation of the Atlas Copco approach. Practical Solutions At Atlas Copco. followed by three generations of hydraulic drill rigs. The latest Atlas Copco Boltec offers a new dimension in rockbolting safety. for instance. As the awareness of the consequences of poor rock reinforcement becomes more widespread amongst clients. in the shortest time. there is continuous ongoing evaluation aimed at optimization of the excavation reinforcement method. and this has contributed to our approach. In mining. if it takes 100 days for one man to dig a defined dyke.TALKING TECHNICALLY Investing in Rock Reinforcement Safety and Economy Time was. The aim seemed to be to get around the support work in the easiest and cheapest way possible. The only remaining option for the tunnellers is to improve mechanization. If we consider a tunnel with 80 sq m cross-section being driven in fractured limestone with clays strata. and a necessary pain. a cost. and is brought up constantly by the mining industry. As a result. to properly monitor what has been carried out. and there is usually little space for increased efforts at that face. ROCK & SOIL REINFORCEMENT The Atlas Copco focus is on total economy. the quality of the Atlas Copco rock reinforcement programme. The leading process has been drilling at the face. with full column contact. where the manual job is more difficult. You have a modern ventilation system. if the work is carried out in half of the set time. while mucking has a less noticeable development. fully grouted rockbolts. the reduction in cost will be at least 25%. Assuming that you have done everything to optimize your face drilling. Conversely. installed with a jumbo or with an automatic bolting rig. it results in a reduction of the cost by €250. and that your detonators and explosives are the best available. drilling time 20 years ago.000. as well as trimming the profile of roof and sides to make safe. since heavy hydraulic breakers now play an important role in improving the pull of the blasted round by cleaning off the face.TALKING TECHNICALLY will be €500/h saved. Self Drilling Anchors (SDA) are replacing manual installation of rockbolts in collapsing holes. will be excavated over a time period of one year. and this has to be tackled in order to boost productivity. 6 ROCK & SOIL REINFORCEMENT . there is a good incentive for looking for cost saving measures. and pumps check the inflation pressure of the bolts.500/m. then the cost saving by Gunnar Nord Rocket Boomer L1 C-DH drilling rockbolt holes at Auersmacher in Germany. is a bottleneck in the excavation cycle. Development of face excavation over the last 25 years. Time is Money In tunnelling the time related cost is most likely in the range of 50. and the most efficient shotcrete robot. while Cabletec does the same for cable bolting. Shotcreting shows a positive trend on time reduction. Further. These figures would improve for a smaller cross section.2 km in length. The time related cost will then be at least €3 million. and in particular. if no work is carried out during the set construction time.000/m or €6 million in total. the most powerful mucking equipment. This is an average advance of 100 m/month. We hope that the articles in this brochure can explain how. or €2. If we consider traditional. Consequently. Rock reinforcement. Investing in Rock Reinforcement The Atlas Copco commitment is towards a safer and more ergonomic working environment.60% of the total cost. Scaling shows a large increase in time. assuming that the working time is 500 hours/month. Boltec offers a new dimension in rockbolting safety. the increase in productivity does not keep pace with the drilling. Not all the different phases in the cycle have the same development. Atlas Copco has taken this problem seriously. to just 20% today. showing the changes in time taken for various components of the round. There are no shortcuts in this process. This means that. Assume a tunnel of 1. And you still stay with the most conventional rockbolting system? Then it’s time to invest in rock reinforcement. with all resources mobilized and the staff taking home their salaries. This commitment is translated into ergonomic machines and reliable rockbolts. rockbolting. Swellex offers immediate support. Figure 1 illustrates the development of drilling and ancillary face operations over 25 years. Our approach is to provide machines. at an estimated cost of €5. If a reduction in construction time of one month can be achieved. In our reference tunnel we can register a poor saving of 10% in total time consumption. with a cross-section of 70 sq m. Figure 1. rockbolts and know-how to add value to your rock reinforcement. the cost will be at least half of the forecast cost. and rock reinforcement certainly is an area of interest. The primary objective in the design of the support system is to assist the rock mass to support itself. Independent surveys reveal that as many as 50% of cement. and levels of operator skill and care. and is equally unfavourable in terms of economy. The moment the Swellex bolt is expanded in the hole. By contrast. ROCK & SOIL REINFORCEMENT 7 . They confirm that. As the rock quality declines. in both mining and construction applications.and resingrouted rockbolts are so poorly installed that they are virtually non- High pressure water expands the Swellex bolt into contact with the strata. This is a highly unsatisfactory result in terms of worksite safety.TALKING TECHNICALLY Controllable Rock Reinforcement Helping Rock to Support Itself Modern computer-based geotechnical monitoring techniques indicate that the greatest relaxation or movement of the rock mass occurs immediately following excavation. cartridge damage during insertion. after a certain period. The basic underlying factors are: the inherent sensitivity of resin to heat. Control brings peace of mind at every step: 1) Swellex bolts are manufactured following a very strict quality control procedure using specific steels for which origin and composition are known and controlled. the greater the degree of support required. quality and time are the two main parameters which must be taken into account when determining the type of rockbolt to be used for rock reinforcement. parameters during installation. Poorly consolidated and friable rock conditions have required the use of expensive external support. Sequence of installation of a Swellex bolt. injection nozzle alignment. and it becomes increasingly crucial to install reinforcement as quickly and as close to the face as possible after excavation. it interacts with the rock to maintain its integrity. age and improper storage. but their anchorage capacity is too low to keep stress concentration at distance from the rock face. the use of rockbolts has been limited to reinforcing reasonably solid rock. Split-set type bolts may be quick to install. functional. support requirements increase proportionally. the rock will establish a new equilibrium based on its own inherent self-supporting capacity. the Swellex concept entails that the rock is secured by immediate and full support action from the Swellex bolts. presence of cracks and flowing water. Controllability means safety. hole annulus. The poorer the quality of the rock. Accordingly. The quality of the bolt installation is automatically confirmed when the pump stops. and is independent of rock mass conditions or operator experience. Controllability Means Safety Traditionally. The best quality rock will remain self-supporting for extensive periods of time without the need for extra support. Engineers involved in the design of rock reinforcement systems must satisfy ever increasing demands to optimize the design to gain maximum safety and economy. independently of the operator. Reinforcement is unaffected by the presence of water. Immediate Support Modern drilling and excavation equipment used in civil engineering and mining applications has led to major increases in efficiency and productivity. at the same time. 8 Swellex rockbolts reinforce and improve the condition of the interfacing rock. and/or deform its profile to match the irregularities of the rock. since each installed Swellex bolt provides full support. so the bolting operation matches the required safety levels as planned by the engineers. it is possible to control their load bearing and yielding capacity. greatly reducing support costs. permit rock reinforcement where expensive external support is normally required. the New Austrian Tunnelling Method. 3) Pull-tests can be performed at any time on Swellex bolts. will only stop when the set pressure is reached. Swellex rockbolts have been used successfully to complete many tunnels in difficult rock conditions while. limit machine downtime. increasing its load-bearing capacity. Timing of the rock reinforcement measures is of particular importance in NATM. Developments in the speed and ease with which rock reinforcement can be applied to improve equipment utilization. or joints in the rock mass. The Swellex concept has kept pace with these advances. NATM can be expressed as a sequence of activities for tunnel development: drilling and Plasticoated Swellex with cap and without cap. and increase productivity. In brief. All the manufacturing parameters are filed and linked to a number on the Swellex bolt bushing for traceability. the same bolting effort using the Swellex system can result in increased safety. the pressure exerted during installation may compact the rock surrounding the borehole.TALKING TECHNICALLY arch or beam. The resulting high anchorage capacity makes Swellex bolts an integral part of the supporting Mn24H hanger rockbolts for suspending utilities while reinforcing the rock. providing a combination of strong mechanical interlocking and high friction. while simultaneously complying with safety requirements. or 10 years ago in a dry area. ROCK & SOIL REINFORCEMENT . and the quality assured installation procedure. is of interest to all those involved in tunnelling and mining. 2) Installation of Swellex bolts is controlled by sturdy Atlas Copco pumps to assure a perfect installation. with a single operator installing 50 to 100 bolts/shift. once started. compared to other rock support. The Swellex concept is designed to optimize the effectiveness of each bolt. Swellex rockbolts. Alternatively. Expertise has also been developed for examining the bolts with a fibre optic camera to control internal corrosion or shearing. The new patented HC1 pump. In fact. increasing the friction along the bolt. Whether they were installed a year ago in a corrosive environment. Depending on the rock mass strength. development has been so rapid that conventional rockbolting methods frequently act as production bottlenecks. the radial stresses enhance the contact forces between blocks of rock surrounding the bolt. As only 50-70% of resin coated and grouted bolts are properly installed. A real level of safety is achieved with Swellex. and the time required to fulfil the mission.TALKING TECHNICALLY blasting. or for use in a corrosive environment. leading to an increase in rock mass strength. Also. an exceptionally high figure. The cost of the rockbolt itself. in reality. Unfortunately. and the bolt can be controlled using pull test or internal visual inspection over time. may be unknown. Swellex bolts can accommodate up to 90-100% of their tensile strength under shear loading. as the corrosion is assessed. the rock mass properties such as water. and immediate initial rock mass support by systematic rockbolting and shotcreting. The decisive factors are the resulting safety. mucking and scaling. the total cost. Shear tests performed by several international institutes have shown that. To help choose the right alternative. As more bolts were installed per working shift. A strong anchorage capacity will help to distribute the stress around the excavation and avoid stress concentration close to the surface that can lead to rock falls or strain burst. In soils. The permanent lining is installed when the rock has reached a state of equilibrium. thereby maintaining the inherent strength of the rock mass. Mn24E Extendable Swellex offers fast installation of up to 12 mlong bolts. In situations where very long bolts are required. resulting in increased metres of advance/shift with improved safety. Conventional types of rockbolts made from carbon steel are susceptible to corrosion. or where there are demands for long life. The Right Protection When it comes to choosing the right product for longevity. see article in this issue. Swellex bolts provide consolidation immediately around the bolt. Swellex Mn16 and Pm16 are a cost-effective solution when 43-52 mm drilling is preferred. Swellex Mn12 and Pm12 are perfect for regular daily support in mining and tunnelling. depending on rock compressive strength. leaving a reduced corrosion potential to the external side only. they do not represent a reliable solution against corrosion. In the case of Swellex. and deformation has ceased. If shotcrete or sealant are used. and improved anchoring capacity of the rockbolt. by Mario Bureau 9 . or such properties as tensile strength. fixed costs for manpower and rigs were diluted. showing that Swellex bolts accommodate the same amount of shear displacement as the diameter of the drill hole. In highly corrosive conditions. Recent years have seen the development of the Mn24H. This is the essential idea behind NATM. or in confined space. It has been established that. are seldom of primary interest. rock movement. Swellex Mn24 or Pm24 is the answer. it will seal and protect the inside of the bolt. For similar reasons. In hard rock. Atlas Copco is using reputable corrosion institutes around the world to assess the corrosion potential of ROCK & SOIL REINFORCEMENT ground water around the rockbolt and inflation water within the rockbolt. Total System Approach The cost and time involved in rock reinforcement compels project engineers to evaluate a total system approach. joints. Hybrid bolt for long anchorage in rock. the bitumen coating is best.5 m of anchored Swellex rockbolt gives a pullout resistance equal to the breaking load of the bolt. caps can be used to seal the bolt internally. and even more in softer rock. leading to an increase in the strength of the material. When high loading capacity is needed. as well as the ability to accommodate large ground movements at maximum load-bearing capacity. a type of Swellex that is part of the rock support and is also used to hang heavy loads without inducing unfavourable stress in the bolt’s head bushing. Swellex has became a standard in most European countries and in Japan. The initial support system restricts ground movements after excavation. independently of the rock mass parameter. There are many products that offer what appears to be lifetime protection. it is advisable to proceed with caution. Swellex rockbolts provide immediate support. There are Swellex rockbolts for almost any environment and purpose. compared to the Swellex solution. plasticoated Swellex offers longterm corrosion protection. Coated or Plasticoated Swellex may be the choice. 0. A productivity study comparing Swellex to other bolts in a gold mine in Canada has proved that Swellex boosted metres of advance by 10% and reduced bolting costs by 10%. If there is no shotcrete or sealant applied after bolt installation. the threat from atmospheric corrosion diminishes. there is extra delay and cost associated with these bolts. and the quality of rockbolt installation may be unquantifiable. for medium term corrosion protection. To summarize. Joint shear displacement at bolt failure can be up to 35 mm/56 mm at a 90 degree angle between the bolt and the surface of the joint. However. Atlas Copco is also proud of its latest patented hybrid system of rock reinforcement. when the Swellex bolt is installed in heavily fissured rock. . Well-established co-operation with a leading steel supplier and with a pipe mill allowed a tailored technical specification to be developed for materials. marketed as Swellex Manganese. Wi Wi New Tool Atlas Copco research and development has engineered a new generation of Swellex bolt. The latest range of frictional bolts. The steel used in Swellex is already a special type. Standard Swellex is a 100 kN bolt. doublefolded. Search For Excellence The Swellex range is based on several hole sizes. strain concentration areas. performance and reliability of Swellex pumps. high-quality steel tubes. it did not make sense to modify its well-accepted and fit-toapplication dimensions. will dramatically increase performance. The excellent performance of the Super Swellex rockbolt is further improved by Swellex Mn24. or losing its function. At the same time. while Super Swellex is in the 190 kN category. Loading capacity normally defines a class of rock bolt. while both Super and Midi Swellex work in the 43 mm to 52 mm range. progressive ROCK & SOIL REINFORCEMENT Figure 1. and especially its contribution to safety. In deep mines. A possible solution to increase the Work Index was to increase the geometrical feature of the bolts. For example. with few impurities. deformation and squeezing ground are all cases in which a bolt with a superior capacity to follow the rock deformation can play an important role in balancing and re-adjusting the strain field towards stability. The expansion of the tube generates both contact friction and mechanical interlock between the steel and surrounding rock. and a new parameter capable of combining capacity and elongation. By these means. But elongation without tensile strength is simply out of the question. Experience in mining and tunnelling operations has shown that elongation is a very important parameter in judging the performance of a bolt. a quantum leap forward in safety and performance has been achieved. thanks to a new steel composition and an innovative heat treatment. But other parameters can influence the final performance of a rockbolt. which will better suit the rock mechanical requirements. Atlas Copco needed a new tool to measure the total performance of rockbolts. It was more logical to work on material properties and production methods. Standard Swellex is used in combination with holes from 32 mm to 39 mm-diameter. The Work Index (Wi) gives a truthful picture of the total energy absorbed by the bolt before breaking down. Considering the Swellex position as an established worldwide commercial success. giving immediate and full-column rock reinforcement in a simple and rapid way. Swellex rockbolts are watertight.TALKING TECHNICALLY Swellex Manganese Offers Improved Work Index Tough Newcomer Atlas Copco’s Swellex rockbolts have a long and successful history based on two simple advantages for the customer: safety and productivity. it was decided to further increase the productivity. which are expanded by a highpressure water pump through a pre-drilled hole. uneven load. As the deformation is expressed in percent (%) in the classical load deformation graph Atlas Copco is introducing the Work Index (Wi). the corresponding bolt in the new Manganese Line. 11 . The Work Index (Wi) as real work is defined by the integral of load in function of the deformation also represented by the area beneath the curve in Figure 1. In particular. a heattreated Manganese steel was chosen. the profile breaks down. representative for millions of rockbolts. The curve continues to point upwards until a 10% elongation is achieved. q Total Reliability The heat treatment used during the production of the new Swellex Manganese Line further improves repeatability of the performance obtainable by the bolts. through the entire process from manufacturing to installation. A postproduction heat treatment is then used to produce the extraordinary elongation properties needed for the Swellex profile. and weldability to assure perfect watertight contacts at the bushings. the manganese steel increases the load capacity due to the hardening process. with a higher manganese content. Only a limited number of options can handle the severe requirement of Swellex rockbolts with respect to radial deformation during expansion. enhanced elongation. q and a series of alloys and high tensile steels were considered. A large number of pull tests. show very little variation in the results. Beyond the yielding point (200 kN). beyond yielding point.TALKING TECHNICALLY Figure 2. miners. and very little training is required to use the equipment. engineers. The quick and easy installation. but with slightly lower strength. q 12 ROCK & SOIL REINFORCEMENT . This extraordinary behaviour gives the capacity to absorb a substantially higher quantity of energy. As a result. and the assurance that every bolt provides immediate full load-bearing capacity. but unsatisfactory elongation. Summary of Swellex® user benefits q Swellex provides costeffective rock reinforcement in most rock types and conditions. makes Swellex the most cost-effective rock reinforcement. When a 20% elongation is reached. It was decided to use a better quality steel. then a long horizontal segment goes above the 30% level before the profile breaks up. Swellex rock bolts are quickly installed. the steel reaches a very high tensile strength and high loading capacity. Swellex rock bolts provide full column interlock with the surrounding rock. the profile accepts a large amount of deformation. rockmechanics and consultants can rely on safe and quality controlled rockbolts. high-strength and fully annealed Manganese Line now offers q q by Federico Scolari Work Index for various types of bolts. the regular Swellex steel profile shows a classical behaviour for carbon steel. Figure 1 shows that. Produced in a cold forming mill. After a series of experiments. The new. Swellex installation procedure ensures that every bolt installed will provide optimum reinforcement. Swellex requires no environmentally harmful chemical grouts to anchor the bolt in the rock. as indicated in the 80% increase in the Work Index shown in Figure 2. This table shows the results of the design efforts with respect to tensile tests of the profile after expansion to simulate real conditions. without the need for mechanical locking devices or grouting agents. a higher loading capacity and. at the same time. Improved Behaviour Figure 1 compares typical load/ deformation curves for Super Swellex and the new Swellex Mn24. profiled. Elongation % Working index Yield Load kN (Rp02) Min. welded and heat-treated to survive extensive deformation at maximum strength for high-energy consumption before reaching failure. a progressive debonding. the best way to predict how the rock support will interact with the rock mass is to look at the steel load-deformation graph. Elongation % Working index Comparison tables for Mn and Pm bolts. and has striven over the years to develop support systems using the best available steel for each application. The rock mass stresses surrounding underground excavations have to be tamed using energy rather than strength. Competence Centre The Rock Reinforcement Competence Centre team at Atlas Copco understands the requirements of different rock reinforcement situations. while in other instances stiffness is preferable. Breaking Load kN Min. Yield Load kN (Rp02) Min. stress field evolution. excavation size. Sometimes. it is better to bend with the stress. corrosion and longevity required. geology. has recently launched the Premium Pm Line. Rock engineers are extremely conscious that the behaviour and efficiency of rock bolts can be dictated by the properties of the steel from which they are made. It all depends on the type of rock. Atlas Copco. as the manufacturing process will modify the property of the steel and the way the support will behave under load. Once the anchorage mechanism is understood. Elongation % Working index Mn12 75 100 20 2000 Mn16 105 140 20 2800 Mn24 150 200 20 4000 Pm12 100 120 15 1800 Pm16 130 160 15 2400 Pm24 200 240 15 3600 Yield Load kN (Rp02) Min. when the bolt is installed in rock. seismicity. Accordingly. Furthermore. It is preferable to assess graphs from manufactured product instead of the virgin steel. rock bolts are no longer judged simply by their maximum tensile strength. Mn Line Mn Line bolts are made out of high strength steel. Breaking Load kN Min. which introduced the Manganese Mn Line of Swellex rock bolts a couple of years ago. the plastic zone is characterized by a continuous progression of the load that allows. 300 250 200 150 Pm24 Mn24 LOAD(kN) 100 50 0 0 5 10 15 20 25 30 35 STRAIN (%) ROCK & SOIL REINFORCEMENT 13 . As the diameter of the loaded section reduces Typical load/strain graphs for Pm24 and Mn24 bolts. Breaking Load kN Min.TALKING TECHNICALLY Manganese and Premium Lines Continuous Improvement Atlas Copco has. over the years. improved considerably the Swellex system. TALKING TECHNICALLY under plastic deformation, a succession of new sections are progressively released to work and stretch, providing extra energy absorbency and avoiding rapid failure. Mn Line bolts are therefore best suited to an environment where rock mass stress is high and unstable, requiring good energy absorbency capacity. Typical applications for the Mn Line are where deformation/stress of the rock mass is unstable in time. These situations occur in mining stopes, deep mining, mining in a high stress environment caused by poor geology or faulting, and mining in zones where movement is expected in the walls or roof resulting in stress increase with time. Premium Line The Pm Line is also made of high strength steel but having different properties than the steel used for the Mn Line. No heat treatment is given to the Pm bolts, resulting in a very stiff behaviour at high load, because the yielding strength is very close to the maximum tensile strength. Pm Line bolts are used where maximum control of the rock mass convergence is targeted, and a high yielding load capacity (Rp02) and stiffness are required, as in civil tunnelling projects. Choice of Reinforcement Type Conditions Properties of reinforcement High Stiffness Preferred Reinforcement/ Support Types Swellex Pm Line Checking nut and plate on Swellex Premium bolt. Typical applications for the Pm Line are where deformation/stress of the rock mass is stable in time and high stiffness is required. These situations occur in tunneling, beam consolidation of strata in mining, mining where the rock mass stress and movement are low or stable in time, and the yielding load will never be reached, and mining and tunnelling in soft rock. Atlas Copco is continuously investing in research and development to offer the market the best rock reinforcement products with safety and productivity in mind. The right steel for the application adds safety and productivity! by Mario Bureau Soft Rock and low to medium stresses Soft Rock and high Stresses Weathered hard rock or laminated/ schistose rock and high stresses Hard Rock and low to medium stresses Hard Rock and high Stresses Yielding and high anchorage Swellex Mn Line + Connectable and Hybrid High Stiffness Swellex Pm Line + Swellex Hybrid cemented Swellex Mn Line + Swellex Hybrid non-cemented for rock burst (seismicity & strain bursting) Yielding and retention capacity 14 ROCK & SOIL REINFORCEMENT TALKING TECHNICALLY Hollow-Core Self Drilling Anchoring Systems Support Without Casing The Atlas Copco MAI Self Drilling Anchoring System is a fully threaded steel bar which can be drilled and grouted into loose or collapsing soils without the use of a casing. The bar, or SDA, features a hollow bore for flushing, or simultaneous drilling and grouting, and has a left-hand rope thread for connection to standard drill tooling. The Atlas Copco MAI SDA can be installed in a variety of different soils and ground conditions ranging from sand and gravel to inconsistent fill, boulders, rubble and weathered rock, as well as through footings and base slabs. Applications associated with underground works include: radial anchoring for stabilization of tunnel circumference during NATM-style excavation; as forepoles, spiles or umbrella for advance protection of the excavation; as root piles for reaction load of steel support arches; and for slope stabilization of the tunnel portal. MAI SDA Functional Parts The system elements of the Atlas Copco MAI Self Drilling Anchor (SDA) are as follows: The Atlas Copco MAI bar, which is manufactured from API standard heavy walling steel tubing, cold rolled to form a standard ISO rope thread profile. The rolling process refines the grain structure of the steel, increasing the yield strength, and producing a durable drill rod suitable for a range of applications. The standard rope thread of the Atlas Copco MAI bar produces an excellent bond between the bar and grout, as well as enabling connection to all Atlas Copco Boomer and surface drill rigs, and use with a wide range of drill steel accessories. ROCK & SOIL REINFORCEMENT The MAI bar is produced in 12 m lengths and then cut to size depending on customer requirements. Standard delivery lengths are 1 m, 2 m, 3 m, 4 m and 6 m. Recommended maximum bar lengths depend on diameter and can be up to 6.0 m. Additional lengths up to 12.0 m are available on request. The Atlas Copco MAI coupler, which features a patented design that enables direct end-to-end bearing between each bar, reducing energy loss and ensuring maximum percussive energy at the drill bit. The coupler design has a thread arrangement in which the top half of the thread is rotated against that of the lower half, providing a centre stop for each bar. All couplers exceed the ultimate strength of the bar by 20%. To enable the correct seating of each bar within the coupler, all bars have a precision cut at right angles to enable end to end bearing. A quarter turn back of the coupler on the lower bar will ensure optimum seating of the upper bar within the coupler. The Atlas Copco MAI hexagonal nut, which is machined with chamfered edges on both ends from high precision steel, and tempered to meet any stringent demands of the anchor specifications and the daily operations of underground works. All nuts exceed the ultimate strength of the bar by 20%. The Atlas Copco MAI bearing plate, which is a formed steel plate with a centre hole, allowing articulation of seven degrees in all directions. All functional parts are constantly tested, in line with the company’s rigorous quality assurance policy. The sacrificial Atlas Copco MAI drill bit is the most crucial part of the anchor system, and is responsible for the productivity of the installation. Atlas Copco MAI maintains a large range of drill bits to suit the changing demands of geology encountered on different projects. In order to improve on performance and cost efficiency, MAI SDA arrangement, showing threaded bar, coupler, nut, plate and bit. 15 TALKING TECHNICALLY Installation sequence of MAI SDA. data is collected from projects around the world, and incorporated into the design with the aim to improve penetration rate and bit quality, and to reduce manufacturing costs. Overall Advantages of MAI SDA Advantages of the Atlas Copco MAI SDA system are that it is particularly suitable for very difficult and unstable ground conditions, such as broken, fissured and fractured rock formations, or unconsolidated sands and gravels. Re-drilling time due to collapsing boreholes is avoided, and speed of installation is high, with no primary drilling required. The drilling, placing and grouting of the anchor is performed in one single operation, reducing the drill labour compared to cased boreholes. Since conventional rotary-percussion drilling equipment is used, the method of installation is very similar for all ground conditions, and the bolts can be installed in all directions, including upwards. There is an option to use simultaneous drilling and grouting techniques during installation, to consolidate any surrounding loose ground. The anchor bar consists of a full length left hand rope thread, which gives the flexibility to adjust the bar length to the actual requirement. This is especially useful if anchoring has to be performed in a confined workspace. Method of Installation Self Drilling Anchors are installed with air driven or hydraulic rotary percussion drilling equipment, using a 16 borehole flush medium suitable for the specific ground conditions. There are three types of borehole flush: 1) water flush for long boreholes in dense sand, gravel formation or rock conditions, for a better transportation of large cuttings and cooling of the drill bit; 2) air flush for short boreholes in soft soil, such as chalk and clay, where water spillage is to be avoided; 3) simultaneous drilling and grouting (SDG), for all lengths of boreholes in all unconsolidated soil conditions. Using SDG, the grout stabilizes the borehole during installation, providing a better grout cover along the nail shaft. The grout has good penetration into the surrounding soil, so higher external friction values are reached, and the installation is completed in a single drilling operation, saving time. By utilizing a sacrificial drill bit, the MAI SDA is drilled continuously forward without extraction, until the design depth is reached. To reach a required nail length of 12-15 m, the 3 to 4 m standard rod lengths are easily coupled together. When using the first two flushing media for the drilling operation, the soil/steel interface has to be created by grouting through the hollow stem of the anchor rockbolt. The grout exits through the flush holes of the drill bit, and backfills the annulus around the anchor that has been cut by the larger diameter of the drill bit. For simultaneous operation, the flushing medium is already a grout mix, which has the ability to harden after the installation process is completed. MAI PUMP The One and Only by Mark Bernthaler ROCK & SOIL REINFORCEMENT TALKING TECHNICALLY Atlas Copco MAI Self Drilling Anchors Productivity and Problem Solving The Atlas Copco MAI SDA is a unique bolting solution for unstable ground conditions such as sand, gravel, silt, and clays, and in soft to medium fractured rock formations. When discussing productivity, only projects facing such ground conditions should be considered. Conventional rockbolts, or soil nails, generally have the disadvantage that, when being installed in poor ground conditions, unproductive time is spent on measures such as: retrieving expensive drill tools from collapsed boreholes; repositioning the drill feed to clean collapsed boreholes; introducing the grout hose to the borehole bottom, and grouting the borehole; and inserting the nail or rockbolt with the assistance of the feed system of the drilling unit. The Atlas Copco MAI SDA system is designed to avoid most such time losses. With an optimized installation method, tailored to the project’s needs, the ultimate aim should be to limit the installation time to the actual drilling time of the borehole. Integrated Rotary Injection Adapter (Ceminject) mounted on a Boomer. Atlas Copco MAI SDA Techniques Post installation grouting A number of Atlas Copco MAI SDA bolts are installed in one phase to limit the working time of the drilling equipment and make it available for other drilling operations within the excavation cycle. The grouting is performed as an independent operation from a separate support vehicle. Installation and successive grouting In order to utilize this system, an Integrated Rotary Injection Adapter (Ceminject) is mounted between the ROCK & SOIL REINFORCEMENT COP hammer and the anchor bar. Drilling is carried out using water or air flushing, but, upon reaching the planned borehole depth, a suitable cement mix is immediately injected. By slow rotation while applying backwards and forwards movement of the SDA, the grout is pushed under pressure from the bottom of the borehole towards the borehole mouth. It mixes in the borehole to provide optimum backfilling of the borehole annulus contact to the soil. The advantage of this system is the reduction of cement consumption in horizontal boreholes. Simultaneous drilling and grouting Similar to the successive grouting method, this system also requires the use of a Integrated Rotary Injection Adapter (Ceminject). However, instead of drilling with air or water flush, a suitable grout mix is introduced. The following advantages are achieved: stabilization of the borehole and optimum filling of the annulus; improved protection against corrosion; and consolidation of gravel, fissures, fractures or voids surrounding the borehole. Time Saving Atlas Copco envisages full mechanization of the Atlas Copco MAI SDA to reduce the installation time and increase its productivity. The company is also interested in resolving particular site problems, and in advancing tunnel technology for typical applications of Self Drilling Anchors. These are, in particular: radial nailing of the tunnel circumference; forepoling for cylindrical tunnel advance, using lengths of approximately 4 m with 1 m overlap and face stabilization using lengths up to 15 m, and root piles. Worldwide, underground projects are designed with geological expectations based on information received 17 allow an immediate intervention. Transport to site. and onward to the working area. Anchor bars with a continuous left hand thread are delivered to site in standard lengths of 2 m. This increasingly demands flexibility by the contractor. Prior planning by the site management to maintain sufficient quantities of Atlas Copco MAI SDA available for use can Delivery lengths of Atlas Copco MAI SDA. Construction sites today have the option to cater for every eventuality. reducing time wastage and increasing productivity. who may be forced to adjust at short notice to unpredicted changes in geological conditions. and can be assembled to the specific lengths required. and to maintain tools at site for every type of ground condition. 3 m. 4 m and 6 m. is simplified. The design of the Atlas Copco MAI SDA also favours productivity in terms of storage and handling.TALKING TECHNICALLY Time savings by using MAI SDA System. today’s need to satisfy the design requirements for infrastructure projects mostly doesn’t allow a route selection that follows only good rock conditions. by Mark Bernthaler 18 ROCK & SOIL REINFORCEMENT . due to the short lengths of the anchor elements and their accessories. Furthermore. from rather limited soil investigations. primarily due to the expansion of building and infrastructure growth in areas that are less than ideal for such development. boulders and solid rock. micropiling and other types of ground engineering work. such as ground settlement. the casing can become the conduit for bringing the debris to the surface. Symmetrix handles the installation of casings up to 1. to the concrete that forms the pile shaft. Symmetrix enables drillers to go larger and deeper than ever before. In addition to its well-proven ODEX equipment. a large hotel and congress center located in the old city of Turku on the south western coast of Finland. rock and other debris are removed within a protective steel tube and brought to the surface. provide sufficient combinations to meet most overburden challenges. or for protection of the pile. For foundations. Now. Ground conditions 19 . This is compounded by other problems. and foundation piling. tunnel forepoling. and is often difficult to estimate in terms of costs. to opening ‘ratholes’ for oil and gas wells. the casing may be left in place as additional structural support. soil compaction and lateral soil displacement. with the introduction of the Symmetrix system. small dimension holes. the speciallydesigned Mustang rigs for anchor drilling and micropiling. Case for Casings There is no doubt that the use of drilled casings in underground construction is becoming increasingly popular worldwide. which is gradually withdrawn. Whereas the ODEX method is ideal for drilling holes up to 273 mm in diameter. a unique system that enables drillers to drill deeper and larger holes than ever before.2 m in diameter. Finland. In addition. Atlas Copco has opened the door to an infinite number of applications where casing drilling is the preferred solution for forepoling. Likewise. The Secoroc DTH hammers for ROCK & SOIL REINFORCEMENT overburden drilling. More Applications The ODEX method of overburden drilling with an eccentric bit is well established amongst drillers. the Symmetrix system is a perfect complement to Atlas Copco’s extensive range of DTH (Down-The-Hole) equipment. and the DTH products provided by Atlas Copco Drilling Solutions in the US. For these reasons. soil. This unique capability gives contractors the power to tackle any type of casing advancing work. Symmetrix RC system used in Turku. from micropiling. Atlas Copco is now able to offer Symmetrix.TALKING TECHNICALLY Larger and Deeper Holes With Symmetrix New World of Construction When Atlas Copco acquired the Rotex company of Finland in 2004. Pile driving in dense urban conditions can disturb surrounding structures or utilities. as well as horizontal casing drilling. is going through a main renovation scheme. Part of the project is to enlarge the parking capacity by building an underground parking lot. For exploration and well drilling. Symmetrix in Sensitive Conditions The Marina Palace Hotel. designers and owners turn to drilled casings. particularly when it comes to shallow. and DTH drilling with Symmetrix is often the only method that can drill through all ground conditions. it represented a major step forward for contractors in the field of overburden drilling and related technologies. When using a drill casing. in holes of 100 m-deep (300 ft) and beyond. during the concreting process the support is transferred from the temporary drill casing. so a unique drilling system is required. In the Marina Palace Hotel parking garage project. Symmetrix RC is designed to give the straightness the consulting engineers require.TALKING TECHNICALLY ROTARY MOTOR Principle of the Symmetrix system 1) The casing tube is drilled to the required depth. This is followed by till containing very hard boulders typically sitting on steeply inclined non-weathered hard granite or diabase. all of which are thick walled to form load bearing members. Casing sizes are from 140 mm to 508 mm. These are being replaced by steel casings drilled all the way to bedrock. clay and till layers reach 35 m-deep in the northern corner of the site. but subcontractor Sotkamon Porakaivo reports 20 ROCK & SOIL REINFORCEMENT . Atlas Copco Rotex has developed reverse flushing drill bits in order to control the air flushing in sensitive conditions. Hard. Drilling work is being carried out by Skanska and their subcontractor. Turku. 3) The casing is left in the hole as a support for the pile. Sotkamon Porakaivo. 2) The pilot bit is withdrawn from the casing. control of flushing media needed under existing foundations. The Symmetrix RC system specified by the supervising design engineering company for the Marina Palace Hotel job is being used on all four drillrigs. For the garage foundation. and high productivity in virtually any ground condition. Completing a deep pile at Marina Palace Hotel. which means that longest casings are 67-68 m-long. and the till is 65 m- deep on the southern riverside. COMPRESSOR CUTTINGS CASING PIPE OVERBURDEN DUAL WALL DRILL PIPE INTERCHANGE 1 CASING SHOE SYMMETRIX BIT 2 3 in Turku are problematic. with mainly post glacier clays at surface overlaying sand layers containing high water pressure. rubber-like clays are normally expected to be problematic. for which several underpinning projects are underway on the northern banks of the Aura river. steel casings are being drilled 1 m or 2 m into the solid bed rock. The old town is built mainly on wooden driven piles. Most of these casings are in sensitive conditions very close to existing buildings and their foundations. Together they rotate clockwise and cut a hole sufficiently large to allow the casing shoe to pull down the casing pipe. the pilot bit is unlocked from the ring bit with a slight counter-clockwise motion. The system consists of three main components working together as a single unit – a pilot bit with large internal flushing holes and external flushing grooves. Symmetrix will have a major role to play. During drilling.TALKING TECHNICALLY the locking mechanism and flushing holes. and even into very hard bedrock. and returns immediately up wide grooves between the pilot bit and ring bit and the annulus between the casing and the drill string. where it is no longer possible to open up the streets for further drilling work without disturbing vital installations. The flushing air is ejected through the holes in the face of the pilot bit. quick setup and high production rates. sands. the secret lies in the patented design of What it means for the contractor Symmetrix systems come in a large number of versions and sizes to suit a wide range of applications. underpinning with grouted columns. with casings going in very straight and fast all the way through clays. Here. the casing does not rotate. no jamming and lost bits. and horizontal casing drilling. When the hole is complete. With Symmetrix on board. forepiling and micropiling using both temporary and permanent casing. and withdrawn up through the casing. convenient drilling at any angle. Future Development The technology of casing drilling is constantly developing. Casings can be added to the string as required. The ring bit rotates freely on the casing shoe. One of the biggest growth areas is in drilling in urban environments. easy to lock and relock. and many more besides. These include: piling. well drilling. that Symmetrix RC has made drilling very easy and productive. This ensures high flushing velocity with low hole degradation. which is welded to the casing. and the demand is increasing fast in many different applications. Symmetrix Secret So what makes the Symmetrix casing advancing method so unique? Basically. The casing can then be either left in place or retrieved from the hole. The pilot bit is attached to the ring bit with a bayonet coupling. can be used in all ground conditions and at any angle down to 100 m (300 ft) and beyond. For the overburden drilling contractor this means: straight holes without risk of deviation. boulders. a symmetrical ring bit (reamer) with internal bayonet coupling. Drilling close to existing structures. Large city subways are typical cases where tunnel roofs have to be pipe-drilled in order to connect one underpass to another. Atlas Copco is able to provide customers with state-of-the-art casing drilling technology that can meet these challenges. and a casing shoe for driving the casing. and significant economic savings. till. less torque required in all formations. by Jukka Ahonen Product Manager. Atlas Copco Rotex 21 ROCK & SOIL REINFORCEMENT . TALKING TECHNICALLY Sacrificial Drillbits 22 ROCK & SOIL REINFORCEMENT . TALKING TECHNICALLY ROCK & SOIL REINFORCEMENT 23 . Scaling. and today safety is given a place of prominence in the operational priorities of the mining industry. As there are normally only one or two faces available for work before blasting and mucking. it is difficult to obtain high utilization for specialized equipment such as mechanized bolting rigs. These phases of the work cycle have been successfully mechanized. there is equipment available to meet most of the current demands from miners and tunnellers. Manual methods are still used in small drifts and tunnels. and modern equipment provides a safe operator environment. bolting and screening. The development of mechanized scaling and bolting rigs has been slower. is often used in combination with rockbolting. By contrast. which is the most hazardous part of the work cycle. a single drillrig can accommodate drilling for face blasting. it is quite common to use the same equipment for all drilling requirements. mainly due to variations in safety rules and works procedure in specific rock conditions. the modern LHD rapidly cleans out the muck pile. The bolt holes are drilled with the same equipment. After only a short delay to provide for adequate removal of dust and smoke by high capacity ventilation systems. Screening. with or without grouting. Mechanization Stages Various methods of mechanized bolting are available. These days. which must be removed to prevent fall-ofground injuries. with the advent of high productivity hydraulic drill jumbos. equipment manufacturers have had difficulty in providing globally accepted solutions. especially in fractured ground conditions.TALKING TECHNICALLY Mechanized Bolting and Screening Utilization is the Key For civil engineering applications such as tunnelling. Similarly. manual drilling and bolting This method employs light hand held rock drills. To summarize. the most hazardous operations. and these can be listed under the following three headings. which is a time-consuming operation. there is a perception that equipment for full mechanization of rockbolting is expensive. or with stopers. have only enjoyed limited progress in terms of productivity improvements and degree of mechanization. Specializing for Safety There was a time when underground mining and safety were terms not commonly referred to in the same sentence. considerable effort has been spent on mechanizing underground operational activities. However. Nevertheless. especially where a number of working areas are accessible using methods such as room and pillar. thanks to the development of bulk charging trucks and easily configured detonation systems. and was in widespread use until the advent of hydraulic drilling in the 1970s. 24 is common practice in Canada and Australia. protection umbrellas. and a largescale consumer of parts and components. Bolts. and drainage. Freshly blasted openings leave considerable areas of loose rock. By contrast. Improvements in drilling and blasting techniques have helped to significantly reduce the amount of this loose rock. the drilling phase has become fully mechanized. are installed manually with impact ROCK & SOIL REINFORCEMENT . blasting has become an efficient process. bolt holes. in underground mining. where drilling is performed with handheld pneumatic rock drills. Screening or shotcreting. However. including the rock excavation cycle. Since the 1960s and 1970s. times have changed. high utilization of specialized equipment can be expected. scaling bars and bolt installation equipment. Within the drill-blast-muck cycle repeated for each round. such as scaling. Mechanized bolting underway using Boltec. is used to remove the visible loose rock. Subsequent blasting might result in additional rock falls. as a means of retention of this loose rock. Quality of Bolting In 1992. as a working platform. or cement from grouting.TALKING TECHNICALLY New generation Boltec LC rig installing screen. are commonly used. operator remotely located. and today. During the 1990s. performs the hazardous scaling job. where several faces are operated simultaneously. The more obvious positive safety aspects of mechanized rockbolting have been sidelined by considerations relating to the scale of operations and the type of equipment available. where the rate of advance is of prime importance. semi-mechanized drilling and bolting The drilling is mechanized. service trucks or cars. While mining companies and equipment manufacturers. and bolt installation can be automated. and all functions in the rock support process are performed at a safe distance from the rock to be supported. Mesh is tricky to handle. The man-basket. because they might fall out when blasting the round. around 15 % of all bolting in underground mines worldwide is carried out by fully mechanized bolting rigs. and this has hampered development of fully automated erection. Also. Hence the higher acceptance in mining. with the ROCK & SOIL REINFORCEMENT non-functional. away from rock falls. and more parts and components have to be replaced. which is especially important when using resin cartridges. with elevated platforms. the grout can be measured and adjusted to the hole size. equipped with boom mounted hydraulic breakers. some manual jobs may still be required. by using a mechanized installation procedure. using a hydraulic drill jumbo. the economic criteria might be different. In larger tunnels. both of which impact upon maintenance costs. it was reported that independent studies were indicating that as many as 20-40 % of cement and resin grouted bolts in current use were fully mechanized work cycle A special truck. 25 . To facilitate access to high roofs. as there are more functions incorporated into the average rockbolter when compared to a drill jumbo. and the industry has been slow to accept the principle. especially in Canada. Bolting units are exposed to falling rock. or on a separate vehicle. a large proportion of rockbolts were being installed for psychological reasons. maintenance takes longer. Tunnellers were reporting that they were not installing bolts close to the working face. evolution in Europe concentrated on fully automated bolting. focused their development on improving semi-mechanized roof support. limits both the practical working space and the retreat capability in the event of falling rock. It can be proved that mechanization and automation of the rockbolting process offers improved quality and safety. However. Obviously. The bolt can be installed directly after the hole has been drilled. because of its shape and weight. progress accelerated. However. where time and mixing speed are crucial. rather than for good face support and a safe working environment. wrenches. For tunnelling applications. Where installation of steel mesh is undertaken. The operator controls everything from a platform or cabin. the bolt holes are drilled with the face drilling jumbo. this level of acceptance is far from impressive. compared to mechanization of face drilling and production drilling. followed by manual installation of the bolts by operators working from a platform mounted on the drill rig. usually equipped with a protective roof. Blast holes are drilled in the face using a drill jumbo. the quality of installation improves. by controlling all functions from the cabin seat. Holes are easy to relocate. the new mechanized bolting unit. In general. and less sensitive to falling rock. Major re-engineering has resulted in 30% fewer parts. as well as resin and cement grouted rebars. primarily for large tunnelling projects having roof heights of up to 11 m. Also. Once the screen handling arm has picked up a screen section and fixed it in the correct position. the COP 1532. Since rock reinforcement is potentially one of the most dangerous operations in the work cycle. and the basis for logging. mechanized rockbolting has become more popular. and features a modern double dampening system which. and is installed in both roof and walls. the powerful COP 1432 hydraulic rock drill quickly completes the 35 mm diameter. Furthermore.5 ft. a wide range of radical improvements was incorporated. or wire mesh. The bolting unit remains firmly fixed in position after the hole is drilled.5-6. The most outstanding benefit. is the computer-based rig control system. installing screen with split-set bolts. has been in use for a couple of years at Creighton Mine. The completely redesigned drill steel support provides sufficient space for bolt plates passing through. Based on the unique single feed system with cradle indexing. down to floor level. In general. the screen is 3. Versatility and Ergonomics Modern bolting rigs can handle installation of most types of rockbolts. transmits maximum power through the drill string. equipped with screen handling arm.5-3. offers simplified fault detection. Typical spacing of bolts is 2. which is matched to the drill steel. The new Boltec family has two members: the Boltec MC. galvanized split-set are used for wall bolting. the operator copes easily with the more demanding cement grouting and resin cartridge shooting applications. and the cradles are indexed. and facilitates extension drilling. is considerably more robust. Up to 10 different preprogrammed cement-water ratios.TALKING TECHNICALLY Significant Improvements When Atlas Copco introduced its new series of mechanized rock bolting units in late 2001. to pick up and install the bulky mesh screens.3 m-long x 1. rugged roof conditions.5 m-wide. because meshing is often carried out in combination with bolting. however. with the exception of pre-bolting at the face. can be remotely controlled.5 m and roof heights up to 8 m. Using the new 26 Boltec series based on RCS. MBU. is commonly used for rock support. Up to 80 cartridges can be injected before the magazine needs refilling. The initial positive response from operators and mechanics confirms that the new generation of Boltec will pave the way for further acceptance of mechanized bolting. and Swellex in sandfill. operator interactivity. combined with the RCS. and various additives. powerful lights provide outstanding visibility of the entire drilling and bolting cycle. The Boltec is equipped with the new rock drill. permits high impact energy and long service life of all drilling consumables. Boltec MC equipped with screen handling arm. Low positioned. which guarantees even and strong feed force for the rock drill. while a stinger cylinder improves collaring and the ability to work under uneven roof conditions. which is short and compact. RCS. the chain feeds used in the new Boltec series feature an automatic tensioning device. The new generation rigs offer the operator a modern working environment in a safe position. while resin grouted rebar or mechanical bolts are used in the roof. and high availability has been recorded. an optional screen arm can be fitted parallel to the bolt installation arm. depending on rock conditions. ROCK & SOIL REINFORCEMENT . and the larger Boltec LC for bolt lengths of 1. for bolt lengths of 1. The long and slender shaped piston. This system. and all bolting must be done through the screen. 6 ft and 8 ft holes. Less maintenance and stock inventory are required. and the stinger cylinder improves collaring and the ability to install bolts under uneven. Three different types of bolts are used.0 m. than its predecessor. such as Swellex. A computerized Boltec MC. Screen Installation In Canadian mines the combination of rockbolts and screen. storing and transferring of bolt installation production and quality data. which has already been successfully incorporated on the latest Boomer and Simba series of drillrigs. while drilling of the next hole after collaring is performed automatically. for which the rig has grouted and installed cable at a rate of more than 40 m/h.700 kg and is readily refilled thanks to the fold-out cassette arm. Cabletec is equipped with the well proven COP 1838 ME hydraulic rock drill using reduced impact pressure with R32 drill string system for 51 mm hole diameter or R35 for 54 mm holes. the booms can reach up to 7. resulting in a unique quality assurance of the grouting process. into position. The bolt feed. the ROCK & SOIL REINFORCEMENT drill unit can rotate 360 degrees and tilt 10 and 90 degrees. by separating the drilling and bolting functions. To minimize water demand during drilling. screening.200 kg of dry cement. The Boltec MC can also be equipped with a portable operator’s panel connected by a 50 m-long cable. with plate. resin grouted rebar and Swellex.8 m roof height. The first unit is in operation at Outokumpu’s Kemi chromite mine in northern Finland. The cable cassette has a capacity of 1. water-mist flushing is used. with a second boom for grouting and cable insertion. The new rig is designed on proven components and technology featuring two booms . most holes have been drilled in the 6-11 m range. The fully mechanized bolting rig of today. the risk of cement entering the rock drill is eliminated.3 m 32 m.7 m 3. the COP 1638 rock drill can be used. The two boom concept has drastically reduced the entire drilling and bolting cycle time and.7 m of parallel holes from the same rig setup. he can inject two fast curing cartridges for the bottom of the hole. 51 mm-diameter holes. The cement silo capacity is adaptable for up to 20 m-long. including pulling the rods out of the hole. mechanical-anchors. Turning radius: 4. comprising a cement silo containing 1.one for drilling and the other for grouting and cable insertion.3m / 7. housed separately in the dual cartridge magazine. The cement mixing system is automated. any reduction in the time required to install the necessary support has a direct impact on the overall cycle time. and a second unit has gone to Chile. backwards and forwards respectively. and Simba drilling downwards. safety and operator environment. and cablebolting. incorporating all of the benefits of modern computer technology. Cabletec L for Cable Bolting Atlas Copco has developed a fully mechanized rig for drilling and cable bolting by a single operator. bolting. A unique feature is the possibility to use two different types of cartridges. Conclusion Rock support. The operator can select how many cartridges of each type to inject into any hole. The booms have an exceptionally long reach and can drill a line of up to 4. including scaling. Clearly. and up to 80 cartridges can be injected before refilling is needed. the drilling capacity can vary between 30 and 60 m/h. Furthermore. Cabletec Simba Boltec MC Flexibility The Boltec MC delivered to the Creighton mine is capable of handling several types of bolts: split-set.9 m 2. Maximum hole length is Cabletec main technical data Length: Width: Height: 13. combined with the impact power from a COP 1025 hammer. and follow up with slower-curing cartridges for the rest of the hole. with fast or slower curing times. Cabletec drilling upwards. The complete rock reinforcement job is finished in just a few minutes. and consequently the overall productivity and efficiency of the operations. all without leaving his operator’s panel! Stoping sequence at Kemi underground mine. is used for installing split-set bolts. constitutes a major leap towards improved productivity. The cement is mixed according to a pre-programmed formula. is still the bottleneck in the working cycle in underground mining and tunneling applications.TALKING TECHNICALLY moving the bolt. Alternatively. The operator is able to pay full attention to grouting and cable insertion. Cartridge shooting is remote controlled for the Boltec MC. It also features an on-board automatic cement system with WCR (Water Cement Ratio) control. allowing the Cabletec L to install up to 20 m-long cable bolt holes in underground mining applications such as cut and fill mining and sub level stoping. Likewise.5 m by Hans Fernberg 27 . All these features facilitate a true single operator control of the entire drilling and bolting process. To date. Depending on type of geology and hole diameter chosen. The switch of accessories between different bolt types takes 5-10 minutes. The Cabletec L is based on the long hole production drilling rig Simba M7. For instance. Atlas Copco Rocket Boomer. a Swellex handle 28 with Swellex chuck. this can make the difference between profit and loss. attach the Swellex chuck to the COP hammer. the Atlas Copco Rocket Boomer is the best possible unit to choose. and. a standard Atlas Copco Rocket Boomer can be modified to take care of most of this work. and to the full length. it is of utmost importance to have the most suitable equipment available. This affords the contractor the option of using a single drillrig to cover all face drilling and rockbolt installation operations. a Rod Adding System (RAS) can be mounted on the feed. It will insert the Swellex Pm24 or Mn24 into the hole. keep the feed at the drill hole. Top of the list of optional components is a service platform to assist with the high level holes. or. with its very capable BUT booms. For semimechanized installation. and for rockbolt drilling and installation. such as Swellex rock bolts and MAI Self Drilling Anchors (SDA). and recover the drill steel by the RAS grippers. the following cycle of operations can be used: select a drill steel length that is slightly longer than the length of the bolt to be installed.TALKING TECHNICALLY Using Rocket Boomers to Install Rockbolts Adaptability for Drilling and Installation When a contractor undertakes an underground drill/blast excavation project. For most situations. On some contracts. An onboard Swellex hydraulic pump is advisable. it can provide the margin for the contractor that swings the award. but also for its adaptability to semi-mechanized installation of some of the most frequently used rock bolt systems. For mechanized handling of the drill steel. is suitable for all kinds of rock reinforcement. for mechanized insertion. On bids. manually locate the Swellex bolt with faceplate in the drill steel support at the top. drill the bolt hole at the chosen spot. fully inflate it to optimal capacity. and even test it! Not only is it quick and easy. Swellex Rockbolts Regardless of manufacturing origin. both for blast hole drilling. insert the Swellex bolt into its final position in The new Atlas Copco Swellex Pm24C and Mn24C features improved work absorption capacity by way of elongation and load taking. The Swellex Pm24 or Mn24 rockbolt is no exception. This is true. by adding a few optional items. but also safer than the traditional manual method. However. for manual insertion. the new Swellex chuck mounted on the COP hammer. installation of rockbolts of lengths of 4 m and upwards is normally a heavy and troublesome operation. not only for its drilling capacity. ROCK & SOIL REINFORCEMENT . or by using a Swellex retainer to keep the connectable Swellex in place when tying in Swellex sections. connect the Swellex pump. the drill hole. and attach the bottom end section of the connectable Swellex. Recommended drill hole diameter is 45-48 mm. 1 2. feed it into place using the rock drill and Swellex chuck. recover the drill string. using R28 drifter rods with a coupling diameter of 44 mm. The first SPEEDROD is drilled into the rock. or using the COP rock drill. The first section is sealed at its top end and threaded at its bottom end. grip the bottom of the string with the BSH 110. 29 . with maximum 51 mm. the pre-tensioned support element is grouted for full protection and long lasting anchorage. tunnel or cavern. After inflating the Swellex bolt. When the pump stops. the rock mass between the face plate and the Swellex is pre-tensioned to the desired value. using its two gripper arms attached to the BMH feed. The RAS system can greatly assist handling of the Swellex Pm 24C or Mn 24C sections. The rock mass is then exposed to confinement pressure and the hole annulus grouted through the centre hole of the SDA. using the feed-force from the hammer. the RAS system uncouples and removes the rod. It will take a few seconds to fully expand the complete bolt. with faceplate. the solution can be the Swellex Pm or Mn 24C connectable rock bolt. In this way. Each of these three sections is characterized by its function. or the retainer. and remove it from the feed. either manually. Installing Swellex Pm or Mn 24C utilizes the same optional components as for the installation of long Swellex bolts. When the hole is finished. 3. 2 using the feed and the COP rock drill. The gripers lift the second rod into place and drilling continuous. the bolt is ready to take its full 24 t load. which are remotely controlled by the Boomer operator. thread in the required number of middle sections The Swellex® Hybrid consists of a Swellex bolt coupled with one or more MAI Self Drilling Anchors (MAI SDA®). and the bottom section is threaded at one end and designed to fit into the Swellex chuck at the other. The installation sequence is as follows: drill the bolt hole a little bit longer than the full bolt length. and inflate the bolt. and inflate the Swellex bolt using the on-board hydraulic Swellex pump. The sections are threaded together to form a tight connection. The bolt hole is drilled to full depth using extension ROCK & SOIL REINFORCEMENT drill rods. with the addition of either the BSH 110 Swellex version. and feed the bolt section into the drill hole. place the top-section of the Swellex Pm 24C or Mn 24C into the drill steel support. and ready for the next bolt! Connectable Swellex When there is a need for very long bolts to be installed in a narrow drift. Swellex Hybrid 3 Mechanized Road adding RAS. This system comprises three different types of bolt section that can be combined to practically any required length.TALKING TECHNICALLY 1. grip the bolt with the BSH 110. Installation sequence of the new Atlas Copco Swellex Hybrid. All done. A special connection coupling welded on to the Swellex bolt. enables it to be inflated and the SDA portion to be grouted. The middle sections are threaded at both ends. Utilities can New Swellex PM24 Hanger rockbolt. with all the advantages of Swellex. Cables can also be passed through the eyebolts to form lacing or trusses in rockburst prone ground. a forged eyebolt (M30/M36) is screwed on. Atlas Copco SDA system is built around the Boomer. civil engineering and mining applications where suspending utilities in an underground excavation is needed. The bolt has a static load carrying capacity of 200 kN and is designed for hanging services while reinforcing the rock. the pre-tensioned support element is grouted for full protection and long lasting anchorage. Composition of the Atlas Copco Self Drilling Anchor (SDA). or to reinforce friable or weak formations. with add-on standard options. with faceplate. and backed up by Atlas Copco worldwide presence. The system is ideal in weak ground and around structural discontinuities. Swellex Hybrid The Swellex ®Hybrid consists of a Swellex bolt coupled with one or more MAI Self Drilling Anchors (MAI SDA ®). It is also recommended as a problem solver for long anchorage requirements.The rock mass is then exposed to confinement pressure and the hole annulus grouted through the centre hole of the SDA. 30 ROCK & SOIL REINFORCEMENT . The bolts are designed as anchor points for hanging utility pipes. civil engineering and mining applications where active (pre-tensioned) support is required to preserve rock mass structure.the rock mass between the face plate and the Swellex is pre-tensioned to the desired value. In this way. know how and support. Swellex Hanger Swellex® Pm 24H is a versatile rockbolt having a flanged head which has a female M30 or M36 thread. Swellex® Pm 24H hanger rockbolts are recommended for rock support in tunnelling. A special connection coupling located between Swellex and SDA enables the Swellex bolt to be inflated and the SDA portion to be grouted. After the bolt has been installed by using an inflation adapter.After inflating the Swellex bolt.TALKING TECHNICALLY Swellex® Hybrid rock bolts are recommended for rock support in tunnelling. while at the same time reinforcing the rock. Self Drilling Anchors System In 2002. Swellex® Pm 24H can be installed using a standard Swellex pump combined with an inflation adapter. Products like MAI Self Drilling Anchors (SDA) can be used in ground formations that are so soft. and grouting is needed for long life expectancy. ventilation columns and rails. The bolt. becomes part of the rock support pattern. Atlas Copco incorporated the MAI series of rock bolts into its product range. then be suspended directly from the eyebolt. TALKING TECHNICALLY BSH 110 The BSH 110 is a hydraulic drill steel support providing gripping and guiding functions. and when extending the SDA bolt sections. when the operation is assisted by a Rocket Boomer. a suitable solution is to use a shank connector to simplify the handling of ROCK & SOIL REINFORCEMENT SDAs on a standard Boomer. gripping and drilling. the shank connector is removed and normal drilling can resume. This is used to guide the bolt when drilling. Atlas Copco has developed some components and functions for the Rocket Boomer to make it the perfect tool for installing SDA. For those worksites where a lot of SDA drilling will be done. Using the optional equipment available for the standard Boomer. The SDA system comprises standard items like the sacrificial bit. The BSH has to be equipped with the rubber bushing and steel bushing halves to match the SDA dimension. a typical SDA bolting semimechanized sequence will be as follows. 1) Modify the rock drill by attaching a suitable SDA shank adapter and Length of anchor protruding after installation. or weak that a normal drill hole will collapse before a standard rock bolt can be inserted. The SDA shank adapter has a female end to eliminate the need for a loose coupling sleeve. productivity and safety are greatly improved. Atlas Copco semi-mechanized MAI bolt installation from a Rocket Boomer. Most frequently used threads are R32 and R38. However. There is also a special version. and should be chosen to match the thread that is used on the SDA. The BSH 110 is fully compatible with any BMH 6000 feed. Installing SDA fractured. but also combinations for the R51 and T76 SDA systems are available. which minimizes the part of the bolt protruding from the rock and can fit SDA bars up to the dimension of T76. Once the SDA activity is finished. The standard BSH 110 will manage anchors up to size R51. The standard feed on the Boomer should be equipped with the new BSH 110 drill steel support. All versions of BSH 110 have to be equipped with special SDA bushing halves when handling SDA. thus utilizing the full length of the installed bolts. The BSH 110 has remote-controlled functions for guiding. The new BSH 110 is designed to leave a minimum of the bolt protruding from the rock face. the COP 1238 or COP 1838 rock drills can be fitted with a special SDA shank adapter and a conversion kit. The shank connector is added to the shank adapter on the hammer. couplings. saving time when unthreading the bolt. giving the operator full control of the bolting sequence from the drilling position. faceplate and spherical nut. This makes handling easier when extending the SDA bolts. boosting productivity and improving safety. At work sites where SDAs are not in daily use. Most current rockbolt installation methods are manual. SDA length outside tunnel face = 405 565 COP 1838 BSH 110B 256 SDA length outside tunnel face = 281 COP 1838 565 BSH 110SDA 301 31 . a variety of bolt sections. BSH 110 available for SDA installation. depending on BSH 110 used. and the Atlas Copco Craelius UNIGROUT E 22. especially for radial bolting. and make it difficult to remove excess grout mix used for flushing. the BSH 110-SDA should be fully opened. or any other service platform. When the last section of the MAI bolt is being drilled. the percussion pressure for SDA drilling is less than half. while maintaining a slow rotation mode of the bolt still fixed to the drifter. sometimes only one third. open the BSH and continue drilling.TALKING TECHNICALLY Two-man operation for simultaneous drilling and grouting of SDA using a Rocket Boomer and MAI m400NT grout pump. the drilled hole. The SDA shank adapter makes it possible to drill the bolt close to the tunnel wall. and to commence grouting only after reaching the design depth. and thread the bolt into the shank adapter female end. 4) Grip the bolt with the BSH. The alternative method offered by the Ceminject system is to flush the borehole with water while drilling the SDA. Suitable and flexible grouting units are the MAI M400 grout pump. by Olle Karlsson Installation of anchor system using a Rotary Injection Adapter. This ensures good in-situ mixing and penetration of the grout around the bolt. prepared with a suitable anchor coupling. This is carried out manually from the Boomer basket. 3) Start drilling. optimizes the friction contact with the rock/soil. and hold it in position while adding another MAI bolt section. by connecting a grouting unit to the protruding end of the MAI bolt. to allow the shank adapter to drill the MAI bolt deep enough to leave about 280 mm of the bolt protruding. and is distributed through the MAI drill bit into MAI m400NT grout pump.Ceminject. filling cavities and cracks along the bolt. Normally. MAI bolt installation can also be undertaken with continuous grouting. Once the grout has cured for 8-12 h. This completely fills the hole. There is usually a need to alternate between flushing with water and grout. 2) Place the MAI bolt section on the feed with the selected MAI bit. 5) Once the MAI bolt section is connected. 32 ROCK & SOIL REINFORCEMENT . The grout is pumped into the hollow MAI bolt. the cured grout. using a grout pump m400NT and the new integrated injection adapter . and the surrounding ground formation. In underground installation. an SDA COP kit that match the thread on the MAI SDA bolt. forming a strong adhesion between the MAI bolt. and adjust the pressure to match the chosen bolt type and the prevailing ground conditions. Grouting SDA The installation sequences described above use water flushing for drilling. the MAI bolt can be post-tensioned to the required torque. it may be inconvenient to do the grouting during drilling as this may create a mess of grout on the feed. However. The BSH 110-SDA should be in position to guide the bolt. of the hydraulic pressure set for blast hole drilling. and reduces wastage of grout mix. The commonly used method for MAI bolts is post grouting. The average total cost of drilling and installing the cable bolts was reported at C$23.000 m of cable bolts are installed every year in Canada’s hard rock mines. saving is sizeable with long cable bolts.000 t/day. However. Although manual installation does not appear attractive on a large scale. when Mn24C becomes a good alternative. Time is Money A comparison has been made for typical underground mining practices. a high standard deviation that can be explained by disparities in the costing systems across the sample mines. With a semi-mechanized installation. The most-used mining method reported was longhole stoping. The market for very long cable bolts is not targeted. the sections of Mn24C are coupled together with threaded connections that can support loads at least as high as the profile strength. Most mines using cable bolts range in output between 1. Connectable Swellex is very competitive. and is deemed profitable in both North America and South America. Through an ingenious assembly. Many mine operators already consider Connectable Swellex Mn24 to be the best solution to their ground control problems in stoping. while the time Installing Connectable Swellex into a pilot drive. the Mn24C combines the exceptional ease of installation of Swellex with the length capability of coupled bars or cable bolts. However. followed by Vertical Crater Retreat. Market Study The following conclusions resulted from a market study performed in 1995 in Canada on 71 responses from 109 underground mines. excluding potash and salt. Advantages of Mn24C rockbolts are ease and speed of installation. With a profile made of Mn24 tubing. some 68 of which are mining metal and industrial minerals.TALKING TECHNICALLY Connectable Swellex Alternative to Cable Bolts The Mn24C connectable rock bolt is a relatively new addition to the Swellex family. ROCK & SOIL REINFORCEMENT 33 . and quality assurance of installation and performance.000 t/day and 5. it is not appreciable with lengths of less than 8 m-10 m. Swellex Mn24C threaded connection was launched in 2003. Sub-Level Caving and Cut & Fill. as longer bolts are usually installed by mechanized means. An estimated 870. operators are extremely interested in replacing their time consuming cable bolting operations with the simpler and safer Swellex system.00 ± C$6.60/m. total cost ranged between C$13/m and C$35/m. 40/m Total: 2. and there was no wait for curing before tensioning. To summarize. barrel and wedge Drilling costs: $5. and training is very simple. barrel and wedge Drilling costs: $5. it also underpins a smooth mining operation.4 shifts x 1 man 50 mm diameter holes Installation: 1. Conclusion Productivity and costs analyses have also been carried out to assess the competitiveness of the Mn24C rockbolts with cable bolting.8 man-shifts Elapsed time: 5. plate and $0.6 man-shifts Elapsed time: 6.: $2.00/m Install. and is performed after all the holes are drilled.50/m for the bolts.: $1.40/m Install. and facilitating the timely extraction of ore and its delivery to the mill.00/m Install.6 shift x 2 men Calculation Base: 60 Connectables 6 m long Drilling (Long Hole): 1.4 shifts x 1 man 50 mm diameter holes Installation: 2. retainers.: $12.3 shift x 2 men Plate tensioning: 0. Comparison of typical installation performances for Cable bolts and Mn24C.50/m Plate tensioning: 0. retainers.25 shift x 2 men Calculation Base: 60 single Cable bolts 6 m long Drilling (Long Hole): 1. with immediate support over the entire length of the bolt.8 man-shifts Elapsed time: 2.30/m ($45/h) Total: $24.50/m for seals and pumps parts Drilling costs: $5. Field testing in Canadian mines demonstrated higher productivity in ore extraction and development. plate. Mn24C is not only a very efficient means of ground support. adding flexibility to mine planning.0 shifts Supplies: cables. Increase in productivity still has to be analyzed in term of costs saving. quality control is better.4 shifts x 1 man 50 mm diameter holes Installation: 3 shift x 2 men Grouting: 2. Mn24C Semi-Mechanized Installation Simultaneous Installation Calculation Base: 60 Connectables 6 m long Drilling (Long Hole): 1.40/m ($45/h) Total: $23. The increase in productivity can be utilized to accelerate development of stopes.80/m Supplies cost: $8.8 shifts Supplies: Connectables. Perfect installation by non-specialized crews. The cost analysis presented in Table 1 shows that.20/m ($45/h) Total: $23. the combined system would have an 34 operating marginal cost similar to cable bolts.7 shifts Supplies: Connectables.50/m for seals and pumps parts Drilling costs: $5.60/m ($45/h) Total: $26. using a 40 double strand cable bolts block or a 60 single strand cable bolts block. Calculation Base: 40 double Cable bolts 6 m long Drilling (Long Hole): 1. Quality of installation was not jeopardized by geological cracking and voids. It was assumed that the support capacity required by the designed pattern of double strand cable bolts would be met by an array of 60 Mn24C rockbolts. due to the flexibility of installation of the Mn24C bolts.50/m Install.00/m Supplies cost: $17.00/m Supplies cost: $17.4 shifts x 1 man 50 mm diameter holes Installation: 2. In addition. plate and $0.0 shifts Supplies: cables.4 shift x 1 man Details: installation time is 10 min. retainers. for an Mn24C price of C$16.: $11. using Mn24C rockbolts to replace short cable bolts of less than 8 m-long saves a good deal of time.60/m Total: 6. and can be performed between each hole drilled. plate.3 shift x 1 man Details: installation time is 10 min.: $4. in a semi-mechanized installation.00/m Supplies cost: $ 17.7 shifts Supplies: Connectables. grout.70/m Total: 3. by François Charette ROCK & SOIL REINFORCEMENT .5 shift x 2 men Total: 9.5 shift x 2 men Total: 13. grout. contributed to a higher efficiency.TALKING TECHNICALLY Table 1.3 shifts x 1 man 64 mm diameter holes Installation: 2 shift x 2 men Grouting: 1.0 man-shifts Elapsed time: 3.00/m Supplies cost: $6. Analysis of Table 1 shows also that. grout tube.7 man-shifts Elapsed time: 3. The added productivity would also mean less overtime and scheduling conflicts.20/m ($45/h) Total: $25.00/m Install.40/m installing manual or semi-mechanized cable bolts. or water.50/m for seals and pumps parts Drilling costs: $ 5. plate and $0. grout tube. Cable Bolts Manual Installation Cable Bolts Manual Installation Mn24C Manual Installation Mn24C Semi-Mechanized Installation Drilling – Installation Separate Calculation Base: 60 Connectables 6 m long Drilling (Long Hole): 1. and changes in ions concentration over time.TALKING TECHNICALLY Rockbolt Corrosion in Mining and Tunnelling Observing Corrosion The phenomenon of corrosion of rockbolts in an underground environment is a subject that is attracting more and more attention from engineers and project owners. or very localized. and on the means to alleviate its effect on ground support. Often. whereas an extremely high chloride and sulphate ions concentration is more typical of Australian mines. Under uniform corrosion. in some conditions. where the bolts are in contact with running water. are the most common factors that will impact on the corrosion rate of rockbolts. where aggressive airborne contaminants are deposited on rockbolts and any metallic surfaces. Galvanic corrosion is another type of corrosion where dissimilar metals are in contact in the presence of an electrolyte. water flow. In the main. Corrosion Underground Corrosion can be either uniform on the exposed steel surface. and atmospheric corrosion. are present in most metal mines. and renders the water more aggressive toward steel components. it was recognized that theoretical predictions of a rockbolt’s life could only be a first assessment of applicability of non-protected ground support. It has also been observed that. This can increase the effective life of the ground support. Iron sulphide minerals. Water inflow. extra protection is needed to isolate the rockbolt from an aggressive environment. Oxidation of pyrite produces sulphuric acid. or where certain types of rock minerals are in contact with the bolt. unprotected rockbolts corrode freely and rapidly. uniform and localized corrosion can occur simultaneously. Although water supply can be non-corrosive at source. Uniform corrosion is characterized by a regular loss of metal from the corroding surface. Crevice corrosion can occur with confined and closely spaced metal surfaces. Use of recirculated water increases the potential for corrosion problems. environmental factors will determine the type of corrosion and the mode of attack. Graphical representation of the types of corrosion likely to attack rockbolts is presented in Figure 2. A more appropriate description may be bimetallic corrosion. A closer look at the overall conditions at monitored sites highlights the difficulty in predicting the life of the bolts. Figure 1. The major blame for corrosion in water lies with chloride and sulphate ions. chemicals in water. Ultimately. Field observations have shown that. Pull testing to verify long term mechanical properties of Swellex rockbolt. From the point of view of mechanism of attack. in highly corrosive environments. 35 . Localized corrosion by pitting can be seen in areas where the bolt surface is ROCK & SOIL REINFORCEMENT metallurgically non-homogenous. microbial species. such as at the interface between bolt collar and face plate. or. Also. will affect passivation. all over the world. the process of recirculating water often gathers corrosive ions. Level of isolation from external agents will also determine the rate of corrosion. and mine waters with pH as low as 2 can be produced. either liquid water or vapour. there are two main modes of attack in underground environments: corrosion in water. At Atlas Copco. in the case of split tube stabilizers. while localized corrosion will produce metal loss in a very confined area of the exposed surface. Very high concentrations of these ions have been measured in both civil engineering and mine tunnels. and fumes from both diesel engine exhausts and explosive blasts. Observed field performance in known conditions can provide an extremely instructive insight of the global corrosion process. from both sides. modified after Dillon (1982). principally pyrite and chalcopyrite. a rockbolt will be radially thinned from the outside or the inside. and secure its long-term performance. water conditions are not taken into account. It has been observed with the borehole camera that corrosion is limited to the first 30 cm from the inflation bushing. Figure 2. Figures 4 and 5 show the interior profile for two Swellex bolts. to make a first decision on the need for corrosion protection. 36 ROCK & SOIL REINFORCEMENT . such as DIN 50 929. This paint has been tested by Figure 4. the use of a corrosion protected Coated Swellex is recommended. corroded and non-corroded. Fibre optics borehole endoscopic camera. consisting of three steps that allow a high level of control on the bolt’s performance. Snapshot of inside view of Swellex bolt with borehole camera – corrosion visible inside the Swellex profile. Table 1 presents theoretical corrosion rates calculated with the norm DIN 50 929 for underground sites in Sweden. if the tests showed that the environment is corrosive enough to reduce the effective life below that required by the customer. will provide an index of load capacity at the collar of the bolt. In relatively nonaggressive environments. non-coated Swellex bolts have proved to retain their minimum loading capacity for over 10 years. First. so the loading capacity of the bolt inside the rock mass is almost always kept above its rated value. Snapshot of inside view of Swellex bolt with borehole camera – no corrosion visible inside the Swellex profile. performed with the equipment shown in Figure 1. Pull tests. Japan. regular testing can be performed. A new approach was elaborated. Third. the need to know the expected life span in temporary bolting applications has stimulated research and development in the Rock Reinforcement group. Types of corrosion encountered on rockbolts (from Dillon 1992). While the only way to assure long-life performance under aggressive conditions is to coat the bolt to isolate it from the environment. Corrosion Protection Atlas Copco Coated bolts are covered with Corrolastic Expander Paint 839BX. preliminary analysis of corrosion potential is carried out. Corrosion Potential Queries about the life expectancy of rockbolts are frequently received by Atlas Copco from its customers. Figure 5. Canada and Australia. This first step allows the tunnel owner. in order to assess the real corrosion rate of the rock support.TALKING TECHNICALLY Figure 3. or mine operator. using field data and standards in the field of corrosion. Typical tests performed include water analysis. destructive pull tests and profile endoscopy with a fibre optics borehole camera (Figure 3). Next. during the operation of the tunnel or mine. 2 0. The attack will. followed by protective coating of the rockbolt where necessary.5 0.5 0. the sodium chloride content of the seawater increases dramatically to 1. This approach to corrosion of rockbolts has been developed by Atlas Copco to deal with the need for life expectancy assessment in the mining and construction industries. with full support over the entire length of the bolt. because of their high degree of versatility and quality of installation. In places where the layer is damaged. and 2. Tests performed by the Swedish Corrosion Institute for Swellex immersed in sulphuric acid have shown that. The most critical parameters in corrosion protection are the characteristic corrosion sensibility of the coating. rockbolts. be less significant for the strength of the bolt.1/0. The views of the project management were borne out by a study carried out by the Swedish Corrosion Institute to estimate the risk of corrosion of Swellex rock bolts used at Aspo laboratory. by François Charette 37 ROCK & SOIL REINFORCEMENT . however. predictive methods can be helpful to evaluate the need for corrosion protected rockbolts.4 6.9 3. Case Study at Aspo The 4 km-long subsea tunnel driven to access the site of the Aspo nuclear waste research laboratory at Oskarshamn. and proved not to be affected by high chloride or sulphuric acid levels for periods over 10 years. corrosion in unprotected areas would not migrate to a protected area. Corrosion Rate Assessment of Unprotected Steel for Underground Sites Using DIN 59 929 Sites Ca (mg/l) Cl (mg/l) SO4 (mg/l) HCO3 (mg/l) pH Assessed Corrosion Rate German DIN 50 929 for Uniform/Pitting (mm/year) 0.02/0. PULL TESTING.5 mm/year in the simulated environment.0 the Swedish Corrosion Institute in extremely aggressive environments. RE-ASSESSMENT OF ADEQUACY OF CORROSION RESISTANCE TOOLS: WATER ANALYSIS.1 for Coated Swellex 0.5 More than 0.5 for non-coated 0. Test drilling showed that rock reinforcement would get more difficult as the tunnel progressed. The corrosion protection on Coated Swellex met their demands for long duration use.95 6. be limited and. as such. FOLLOW UP OF PERFORMANCE OF ROCKBOLTS – CAPACITY MEASUREMENT – ENDOSCOPY – WATER ANALYSIS TO MONITOR CHANGES IN CONDITIONS 3.5 0. BOREHOLE CAMERA and corrosion resistance. extremely reassuring. However. The attack will. and rockbolts with wire mesh and steel fibre reinforced shotcrete were used. can be used to control corrosion. while the corrosion rate of unprotected Swellex would be 0. PRELIMINARY ANALYSIS USING DIN 50 929 2.4 m-long Swellex bolts were used for the main rock reinforcement duties. the coating minimizing corrosion and controlling its spread. In Table 1. and pitting at scratch locations stayed very localized. both in temporary and permanent rock reinforcement applications.7 N/A Mine C Australia Mine D Australia 140 350 1200 10 420 8300 100 38 7. Bolts with an intact corrosion protection layer are not attacked for many years. however. and they found the quick and simple installation. In these conditions. Sweden required some rock reinforcement.5 Mine A Canada Mine B Canada Kapuzineberg Sweden Ritto Japan Aspo Sweden 600 540 22 13 N/A 540 870 2661 2 N/A 1610 61700 1.5%.TALKING TECHNICALLY Table 1. Sydkraft Konsult chose Swellex for the job.1/0. despite high quality rock over most of its length. The time for fracture due to general corrosion for a 2 mm-thick bolt can be considerably longer than 20 years.1/0. and the physical state of the coating with reference to scratches and indentations. the Coated Swellex showed no traces of general corrosion. as such. the Swedish Corrosion Institute has assessed that the life span (at Aspo) of a Coated Swellex in a very aggressive environment would be of more than 20 years.1/0. from which the following conclusions were made. mainly due to low oxygen content in the water.1/0.05/0. less significant for the strength of the bolt. In areas requiring support. be limited and. there is a risk for general as well as local corrosion. rockbolts with wire mesh. Field observations. and corrosion rates are very hard to predict accurately. At a depth of 300 m.8 3. It has been demonstrated that corrosion is a very complex process.1/0. Short 90 cm Swellex bolts were used for net fixing. because fissure zones and saltwater leakage would place high demands on holding power CORROSION POTENTIAL ASSESSMENT STEPS 1.3 3 N/A NA NA NA 52 N/A 7. stable grout. It is generally accepted that high grouting pressure. or seal the ground or the structure. Bigger rod sizes are needed to ensure better stability compared to blast hole drilling. in order to intercept as many as possible. Drilling for Grouting in Tunnels Grouting is often considered as a hindrance in the progress of the tunnel advance. but also because grouting is classified as part of the support. by way of reduced drilling costs and a higher output of fresh. is designed to avoid further damage to the strata by cracking or widening existing cracks. In such ground it is also essential to place the grout where it is required. as well as in traditional surface grouting. and then using a rod adding system. and with a maximum deviation of 3-5% from the intended target. soil or artificial structures. especially when using microcements. grouting encompasses so much more than traditional ground injection in tunnels. Today. These generally occurred when entering poor. Grout holes for pregrouting in tunnels are 15-25 m-long. or flushing fluids were lost. Where possible. it is harder to drill the holes. The company originally started to develop and manufacture grouting equipment in an attempt to rescue expensive holes. When the ground is of poor quality. and the need to drill straight holes is much greater. strengthen. developed by the Americans for the sedimentary formations in the USA. Instead it should be seen as a tool for the next step. This is important when post-grouting in tunnels. Cycle of events in face excavation and support. Depending on the composition and mix of the injected material. it will react physically and chemically to stabilize. Later on. and then replace overbreak with concrete. and as one of the most important parts of the final rock support. This involves starting with guide rods. strengthen or seal the ground mass around the tunnel. The intention is to use the cement to stabilize. fractured rock. Low pressure grouting. ROCK & SOIL REINFORCEMENT 38 . increases the grouted volume and strengthens and seals planes of weakness. although it is still generally defined as an injection under pressure of fluid material into fractures and cavities in rock. in which the drill string showed signs of getting stuck. and by the British in the coalfields. In Scandinavia. The diameter is normally 51-64 mm. It is a waste of time and money to blast and excavate the rock far outside the required profile. grout holes should be drilled at right angles to the main fissures. and should end 3-4 m outside the theoretical contour. Better economy is expected using high pressures. developed primarily by the French for use in the Alps. grouting tools would accompany Atlas Copco Craelius diamond drilling equipment on large international tunnelling projects.TALKING TECHNICALLY Grouting for Support in Tunnels Eighty Years of Development Atlas Copco Craelius has been active within the area of grouting for over 80 years. the lower cost of tunnels compared to the rest of Europe is not only due to better rock quality. are usually lined. and an elevated sound-protected cabin for full view of the face. Here. and soft or weathered rock. drill all holes from a single set up. this cannot be undertaken immediately. This lining is often placed concurrently with the tunnelling process itself. Movement of the water table may result in subsidence and damage to existing surface structures. together with good working lights. there will be a slight annular gap between the outside of the lining and the inside of the bore. where spacing is reduced to ensure that fissure planes. to avoid sliding in cracks. the diameter of the drillhole has very limited influence on the grouting result. Strengthening grouting is done for reinforcing a tunnel permanently. loss of capacity of drinking water wells. Consequently the driller cannot easily pass his information and observations to the grouting technician. Grouting and pregrouting of tunnels have three different purposes: stabilization. strengthen and seal the strata. General requirements for drilling equipment in tunnelling work are as follows. Pregrouting The cost for pregrouting can be 5-10 % of the cost of postgrouting for reaching comparable and satisfactory results. will be grouted properly. Even in bored tunnels. In most cases it is less expensive to utilize and strengthen the existing rock structure compared to replacing it with a new construction of concrete. then significant problems will occur. and under widely varying geographic and geological conditions. The latter requirement may be necessary to avoid draining natural water into the tunnel. larger hole diameters in general result in straighter.TALKING TECHNICALLY contact grouting method also serves to seal the joints between the lining segments. strengthening and sealing of the ground. fissures or bedding planes. particularly in TBM bored tunnels where it is constructed of rings of prefabricated segments. 39 Grouting of the curtain cone. Tunnels that have to be watertight. Sealing grouting is divided into different sealing classes depending on permissible water inflow. for the next 50 metres or so. Pregrouting means that the rock is treated ahead of excavation. bolting or excavation. occurrence of water. often cracked up from blasting and excavation. as well as tunnels in weak ground that have to have a long service life. Investigation drilling is done during the actual tunnel work and parallel with the pregrouting in order to investigate the rock properties. and similar undesirable consequences. which could lead to a general lowering of the ground water table in a wide area above its alignment. holes. so that the lining will support the ground from the beginning. In other instances. Stabilization grouting creates a skeleton of grout in weak parts or areas of the rock. This demand is difficult to meet when pre-grouting in tunnels. These two operations are repeated until a satisfactory result is achieved. and with two different rod sizes and three different hole diameters for blast hole. grouting may be necessary to stabilize. A positioning control instrument is a necessity. In Scandinavia normal tunnels are said to present insignificant problems when the leakage is in the range of less than 5 lit/min per 100 m. ROCK & SOIL REINFORCEMENT Grouting in Tunnels Tunnels are constructed for many different purposes. and all tunnels should resist the inflow of water from the surrounding ground. Grouting is too often planned and carried out as an off time shift. If possible. High pressure cleaning equipment will be necessary for the grout holes and the drilling and grouting equipment. Sealing grouting is strengthening grouting developed to almost water tightness. where the excavated shape and diameter are controlled within narrow limits. The main reason is that both the grout pressure and the grout flow can be fully utilized in undisturbed rock whereas postgrouting always is done against a free surface. when the drilling equipment is elsewhere. like cracks. especially in unstable ground containing running material under pressure. without settlement. Tunnels carrying fluids. This . bearing in mind that one drill rig uses 200-300 lit/min of water. be it fresh water or sewage. fissures and fissure systems. when there is a need for additional grout hole drilling. with an unfavourable orientation to the grout holes. should not leak. Use a service platform and a rod adding system (RAS) with rod magazine: drilling for a grout round may involve handling some 5 t of drill steel. Grouting behind the lining serves the purpose of filling this gap. If it exceeds 10-20 lit/min per 100 m. cut hole and grout hole. albeit more expensive. Thus. The setting of packers is more expensive and difficult in large diameter holes. A stepless mix of flushwater and air is advisable. as is the grouting. Because of the stiffness of the drill string. This type of is grouting is to support a temporary construction or when a concrete casting is done at a later stage. or in karst formations. The pregrouted zone should always go beyond the area that is disturbed by blasting. These were drilled by an Atlas Copco Rocket Boomer 353S. the local agency of the Norwegian State Highways Authority. one for telling when logging is on. which was manually attached.5 kW. The standard pressure sensor covers a range of 0-100 bar. two sizes of grout cylinders: 110 mm and 150 mm diameter. and two diodes. water flushing of cement and hydraulic piston rods. flow. All parameters are shown in real time on the Logac 4000 recorder display. which included a large drain. The standard flow meter operates in a range of 0200 lit/min with a maximum pressure of 40 and 100 bar respectively. The Logac 4000 samples data six times per second. and the other for informing when the memory card is 90% full. 51 mmdiameter holes ahead of the face to test for water. The main contractor was Selmer. and 10 lit/min/100 m in the centre section. There are Container mounted grout mixing and injection system to be carried on a truck. Maintenance is easy. Pumping and Logging The Atlas Copco Craelius Pumpac System is based on a double acting pump principle. or all eight lines simultaneously.3 km-long tunnel with bi-directional traffic flow was required to relieve congestion on the north bank of the river. The Logac system is a computer based logging system for sampling and storing of data during the grouting operation. Each groutline shows time. A condition on the construction of the tunnel demanded that there be no interference with the water table. and two types of valves: ball valves for normal grouting applications. The logged parameters are flow. using threaded extension steel.5. The control panel consists of an on/off switch for the recorder. The recorder is housed in a cabinet with a Craelius Flow Pressure (CFP) meter unit equipped with cable and quick coupling for easy connection. a second single-tube 2. There is a button to show either one single line. a major operation for which Selmer invested in a sophisticated Atlas Copco Craelius truckmounted Unigrout E 400-100 WB. This comprised a containerized mixing and pumping plant with external cement feed and additive hoppers. One reason for Selmer’s success at Drammen was that they could continuously pump high volumes of stable grout at high pressures. integrated in the hydraulic cylinder.TALKING TECHNICALLY Drammen Case Study At the Norwegian port of Drammen. 15 kW and 22 kW. The water/cement ratio ranged from 1. Generally. The card can be kept as a permanent record for future references. independent and stepless variable pressure and flow. and stores it on the card every 10th second. and liquid additive tank. The contract envisaged injection of 2. and a 10-key keypad. The system features a hydraulic switch-over system. or reused over and over again. A normal pumping rate is 110-120 lit/min at 5060 bar. and environmentally friendly hydraulic fluid. pressure and volume. and two 400 lit/min Pumpac units. allowing 17 m advance between events. real time. a display. The tunnel is on a curved alignment beneath the Bragernes Ridge. The grouting sequence commenced with the drilling of 27 m-long.5 sq m. with a 10 m overlap. real time and hole number. and disc valves for when a smooth flow and minimal pressure drop are required. Then the whole life cost is kept to a minimum by system adaptability. easy and fast change of valve assembly units. but up to 66 t of cement was successfully injected into a particularly wet round over a 15 h period. volume. The maximum ingress of water allowed before grouting was 30 lit/min/100 m towards the tunnel ends. The CFP meter unit consists of an electromagnetic flow-meter and a pressure-meter. and the tunnel itself be kept dry. and only one 46 mm wrench for servicing the cement pump. for client Statens Vegvesen Buskerud. ten forward holes were drilled. time. Inside the container were two Cemag units. and they used 80 bar as stop criterion. with a single 400 litre Cemix WB weight batching mixer. The main face had an excavated arched cross-section of 70. and stored on a PCcard. by way of a self cleaning cement fluid end.370 t of grout to achieve the objective water flows. and a split cotter fast-locking system of the two piston rods for easy dismantling of the cylinder assembly. The system has been made simple and user-friendly by way of modularized parts. and sometimes even 90 bar.0 to 0. Three sizes of electric motors are available: 7. by Sten-Äke Pettersson 40 ROCK & SOIL REINFORCEMENT . an outcrop of igneous rock comprising 50% porphyry and 50% basalt. The unit’s nominal capacity is 4 t/h of dry cement. a separate button for each of the eight groutlines. pressure. Tests determined the bonding stiffness and bond strength of Swellex and 41 . particularly where the initial deformation speed of the rock is high. using a steel fibre mixture ratio of 0. and also has greater control effect of displacement and rock mass plasticity. However. the influence on support of the rockbolt installation method was investigated by means of numerical modelling. with negative effect on the long-term stability of the concrete. early strength would be required to give the necessary support. have also resulted in rock falls up to 0. because Swellex exhibits support faster. Unfortunately.5D behind the face.7%. Pull-out testing of rockbolts in the underground laboratory. Without early shotcrete strength. as well as displacement control. However. it can be said that the Swellex rockbolt is very suitable for support of a discontinuous rock mass. The risk of collapse in this area grows with increasing cross section of the tunnel. offering the possibility of shorter bolt lengths if Swellex is used. The Swellex rockbolt also has more control over the shear behaviour of joints compared to the grouted rockbolt. caused by joints in the harder igneous and metamorphic rocks. they don’t have much effect on the initial stability of the rock mass. rockbolts become the main support. especially in sedimentary rock. The 28-day strength of this shotcrete was 36N/mm2. the rock mass in a tunnel is unstable between the face and 0. No difference in support effect between the two lengths was found. attempts to increase the early strength of shotcrete may induce microcracking. It was found that the Swellex rockbolt exhibits more support effect right ROCK & SOIL REINFORCEMENT after installation.5D behind the face. Tomei Study In a study on the Tomei tunnel in Japan. As a result.TALKING TECHNICALLY Rock Mass Stability with Swellex Early Strength Means Early Support According to Konda and Itoh. Discontinuities.5D behind the face. Steel Fibre Reinforced Shotcrete (SFRS) was recommended to increase the rock stability in the Tomei tunnel. Numerical Modelling Face stabilization methods using Swellex at Tomei were also confirmed by means of numerical modelling. compared to grouted rockbolts. For stabilization of the region up to about 0. This is because Swellex completes the natural arch immediately after installation. regardless of rock types. Comparisons between 4 m and 6 m lengths of Swellex were also carried out. it contributes to the formation of the natural arch. Because one of the main roles of the rockbolt is to improve discontinuous rock mass to continuum. since standard rockbolt grouting materials require time to harden. the Swellex rockbolt is a more effective device than the grouted rockbolt. Collapses occur most often when the stress/strength ratio of rock mass is smaller than 5. by improving stress continuity around the tunnel. Where there is no support. since the continuity for ground stress of the arch section is greater than when using grouted rockbolts. rising to 38 kN. Except for right after installation. improving the stress continuity of the rock mass. the plastic region near the crown tends to decrease. and contributes to stabilization of the rock mass near to the face. Using Swellex. and exhibits excellent support. and 66 kN at the sidewall right by Federico Scolari Displacement contour. and is about 1. Swellex contributes more to the formation of the natural arch by controlling the shear behaviour of joints. In the case of the Swellex rockbolt. rising to 32 kN maximum. preserving its continuity for tangential stress. without the impediment of curing time for shotcrete and grouting materials.2 mm. a plastic region of about 4 m is generated from the crown to the sidewall section. Overall distribution of rockbolt axial force was measured at 1 m. and 4 m at the side wall section. In the case of Swellex. The rockbolt axial force generated at the tunnel crown in the case of grouted rockbolts was 1 kN immediately after installation. 1. shear displacement grouted rockbolts as input for numerical modelling. Swellex has a greater control effect over the plastic region. respectively. At 10 m (0. due to the time lapse for grout hardening. so the required bolt length is shorter than with grouted bolts. Because stabilization of the rock mass close to the face was a key point for the Tomei tunnel. Using grouted bolts. maximum bonding with the strata is achieved right after installation. and 30 m behind the face. 42 ROCK & SOIL REINFORCEMENT . Summary The excellent support effect of Swellex rockbolts can be summarized in four points as follows.5 times larger for Swellex than for grouted. it is possible to avoid rock instability. Swellex controls tunnel deformation better.6 times that of grouted rockbolts. extends to more than 4 m. 50 kN was generated at the crown and 131 kN at the sidewall. the axial force is more than 60% of the maximum value from the beginning. Laboratory testing has determined the relationship between curing time and load capacity for grouted rebars. In heavily jointed rock. almost no axial force was generated from crown to sidewall immediately behind the face. Displacement contour.0 m of the tunnel profile. 33 kN was generated at the crown. and the value is controlled at about 2 m. Swellex enables a tunnel structure to be stabilized by support. Using these values. Using grouted rockbolts. and this can be controlled immediately using a 4 m-long Swellex bolt. longitudinal. loads on rockbolts do not increase more than 1D behind the face. With grouted rockbolts. In the case of Swellex. and 20 m behind the face. Compared with grouted rockbolts. making it superior to the equivalent grouted rockbolt. For both cases. and 1. axial force generated is about 1. Swellex exhibits a much greater support effect right after installation. due to the convergence tendency of rock mass displacement. 20 m. 30 kN was generated immediately. Natural Arch The difference of crown settlements for grouted bolts and Swellex was 0. it is thought to have a major effect on tunnel stabilization.5 mm. For Swellex. using shorter Swellex rockbolts. for grouted rebars.5 mm at 1 m. 10 m. two-dimension and three-dimension models simulated pull-out tests.5D) behind the face. 30 kN was generated at the crown and 82 kN at the sidewall. 10 m. rockbolt axial force. The tunnel is stabilized by generating a natural arch of the surrounding rock mass. In a continuous rock mass. At 10 m behind the face. the value is 6 m at the crown. Swellex rockbolts were specified. Joint shear displacement is generated within 4. By installing Swellex bolts immediately after excavation. When using Swellex rock bolts.TALKING TECHNICALLY behind the face. Uppercut rods have surface hardened shank and tapered sections for high wear resistance on those parts exposed to severe stresses during drilling. These harsh facts have not only guided Atlas Copco Secoroc in its selection of steel quality. All in all. The result is a tapered rod that’s better suited to the stresses and strains of modern rock drills. Even the drifted flushing hole at the shank end is lined in the same way. A wide taper angle is normally used when drilling with high impact hydraulic rock drills in medium hard to hard and abrasive rock formations. not to mention corrosive water in the flushing hole.TALKING TECHNICALLY Secoroc Uppercut – High Quality Tapered Equipment Designed for Pressure Increasingly powerful pneumatic and hydraulic rock drills place great demands on rock drilling tools. a fact that is well known to drillers working in mining and dimensional stone applications. In addition. They’re also subjected to high bending stress. but also in their decision to have a rolled-in stainless lining throughout the entire length of the flushing hole. Taper angles of 11 degrees and 12 degrees are common on modern rigs. This is the reality that has guided Atlas Copco Secoroc in the design of its range of Uppercut tapered equipment. to prevent bits from spinning or becoming detached when using pneumatic or hydraulic rock drills. a 4 degrees 46 minutes angle is available for very soft rock. A narrow taper angle of 7 degrees is used for low impact rock drills and softer rock formations. and. This angle can also be used to counter spinning problems when using 11 degrees or 12 degrees equipment. The flushing hole is also protected by special anti-corrosion oil as standard. Secoroc tapered rods are already renowned for their superior fatigue strength and resistance to bending stress. have improved material properties still further. you won’t find longer lasting rods on the market today! Tough Rods for a Tough Life Rods have a tough life. The unique heat treatment process employed helps to release the internal stresses of the steel and give it greater bending resistance. At the heart of these innovative products there is a formidable steel grade and specialized manufacturing technique. Secoroc Uppercut rods are available with 22 mm hexagonal rod section and Features of Secoroc Uppercut tapered rod. to prevent corrosion and risk of rod breakage. with the Uppercut range. And for even greater protection. while retaining high durability. transferring the percussion energy from rock drill to bit. and then into the rock. manufacturing technique and heat treatment processes. Question of Degrees Different taper angles are used for different rock formations and rock drills. ROCK & SOIL REINFORCEMENT 43 . TALKING TECHNICALLY range comprises button and cross-type bits in an extensive selection of design configurations. 44 ROCK & SOIL REINFORCEMENT . there are two new models. especially in mining applications and the dimensional stone industry. 11 degree and 12 degree tapers. drilling costs. Uppercut rods with 25 mm hexagonal rod section and shank length 159 mm are available with 12 degree taper. and is taking market share from integrals. The Secoroc Uppercut q Special anti-corrosion oil to protect the flushing hole of the rod Surface hardened taper end for high wear resistance and a longer service life Stainless steel flushing tube lining to prevent corrosion and breakage Drifted flushing hole with stainless steel lining at the shank end prevents breakage and increases service life Surface hardened shank end for high wear resistance and a longer service life Z708 steel for superior fatigue and bending strength Range of Uppercut tapered rods and bits from Atlas Copco Secoroc. which first appeared on the scene in the 1960s. q shank length 108 mm for 4 degree 46 minute. a claim that has long been synonymous with Secoroc products. higher penetration rate and longer service life. Moreover. along with higher drilling productivity. Tapered products. tapered equipment is favoured for increased penetration rate. by Jan Lindkvist The Secoroc Uppercut Rod q q Prepared for the Future Secoroc Uppercut tapered equipment can be used in all types of applications and rock formations. q High Performance Bits Secoroc bit design and production processes are in a state of constant refinement. Nowadays. 7 degree. longer service life and lower q Uppercut tapered rod and button bit ready to drill. These designs can be used in a variety of rock formations for maximum productivity. The lowest cost/metre drilled. with an extra front button for improved hole straightness. while they are also ready to cope with the stronger rock drills currently on the drawing board. Furthermore. can readily handle the impact energy from modern pneumatic and hydraulic rock drills. the Secoroc range of ballistic button bits is in the process of being extended to meet ever more diverse demands. is now lower than ever with this range. which counters problems with breakage and offers performance to match that of the modern drill rig. saving time and equipment. and involved more than a half million metres of drilling over a period of one year. the bits should be easy to uncouple. This concept not only upped the fatigue resistance of the rods. And third. Thread of Innovation To solve the problem. delivers more and straighter holes per shift and has a considerably longer service life than any competing system. leading to costly downtime. the solution was deceptively simple. 45 . the new design was given a distinctive. First. Field Tests Worldwide Extensive field tests with the Magnum SR were carried out on four continents. As with all genuinely groundbreaking endeavours. the choice was easy. R28 and R32. Atlas Copco Secoroc faced two choices: either increase the dimensions of the rods and bits in the same way as everybody else. specially designed for the new generation of powerful drillrigs. Being notoriously stubborn innovators. It was high time for fresh ideas. Why? Because it’s the most vulnerable part of the rod. with the introduction of ever-more powerful hydraulic rigs. and resulting in more holes drilled. Second. Even worse. the hole sizes should remain as for drilling with standard equipment. reducing productivity.TALKING TECHNICALLY Speedy Rock Reinforcement Using Magnum SR Thread System for the Future The tried and tested thread systems. either just behind the skirt or on the last thread. The secret of the Magnum SR thread design is that the ROCK & SOIL REINFORCEMENT Magnum SR used in a bolting application. The Magnum SR thread design also has the added bonus that the bits are very easy to uncouple and change. During the creative process. Consequently. conical shape. but also reduced the tendency to deviate during collaring. these battle-worn solutions started to show weakness. three important insights emerged. Putting it bluntly. Rod breakage at the bit end. was becoming distressingly common. bits were lost. The new Magnum SR system for drifting and rockbolting. the old thread design had to be left behind. By adding considerably more steel at the end of the thread. diameter is larger at the end of the thread and smaller at its tip. However. or find a new way. Extensive development by Atlas Copco Secoroc came up with the new Magnum SR range. have served underground drillers well for many years. Magnum SR has proved a big hit with operators. drifting and rock bolting equipment was struggling to cope with the power of the new rigs. R25. holes often had to be redrilled. Magnum SR was designed to withstand the high pressures so typical of today’s underground drilling operations.TALKING TECHNICALLY products for hole diameters of 43-64 mm. and in a variety of tunnelling projects. Drillers using it are not only drilling more and straighter holes than before. Atlas Copco Secoroc is genuinely confident that Magnum SR heralds the dawn of a new era in drifting and tunnelling. together with Magnum SR28. All together. that means less downtime changing bits and rods. The next addition to the family was the Magnum SR28 range. The system was put through its paces in mines. and the rigs more powerful. as well as for rockbolting. and created very high operator acceptance due to easy 46 uncoupling of the drillbits. but can also be used for small hole drifting. This new line replaces the traditional R25 system in 33-35 mm drilling. The tests showed that the Magnum SR systems increased service life by 25-100% on the rods. Expanding Family The Magnum SR thread system was first introduced with the SR35. gave better service life of the bits. they’re also finding that Magnum SR lasts longer than any competing solution. thanks to easy collaring. straighter holes and better equipment availability during the drilling cycle. Although Magnum SR is relatively new to the market. and the performance that it delivers. The results were unequivocal: service life and rig availability both enjoyed sharp increases. and more time spent drilling. Tests have shown that SR28 is perfect for the rapid drilling of holes for rockbolts. the enthusiasm with which it has been received. Magnum SR bit ready to drill. facilitating rapid changes and more holes drilled. Dawn of a New Era The trend in drifting and tunnelling is clear: the rounds are getting longer. and as a result the drillstring is subjected to fewer damaging shockwaves. which is specially designed for hole diameters of 38-41 mm. This resulted in higher drilling productivity. the bits are easy to uncouple. are ultimately aimed at helping drillers advance their tunnel or drill rockbolt holes quicker than ever before. have given an indication of the direction in which the product is heading. Tests in rockbolting have shown convincing increases in service life for both SR28 rods and bits. As with all other Magnum SR products. The most recent member of the family is SR32. which has a comprehensive selection of by Anders Arvidsson ROCK & SOIL REINFORCEMENT . Magnum SR35. The success of this innovative system is beyond dispute. Figure 2. the evaluation of the mechanical parameters of the intact rock and structures. Balkema p215). ROCK & SOIL REINFORCEMENT 47 . This global process can be very detailed. Failure can propagate a long way into the rock mass if it is not controlled. shear zones. Structural failures and gravity Shear analysis of critical structures Evaluation of failure zones Calculation of “factor of safety” Calculation of reinforcement needs Influence of blasting Rock Mass Characterization Rock Mass classification and identification of failure modes Failure caused by overstressing Determination of in-situ stress Mechanical properties of rock masses Evaluation of zones of high stresses Calculation of reinforcement needs Influence of blast and dynamic events Reinforcement design Rock Engineering In the context of definitions. the identification and quantification of the failure modes based on stress and structural analysis. (above) General process encompassed by the general definition of rock mechanics application to the design of structures in rock. intensely schistose. but will also accumulate load and can fail violently under the right conditions (see figure 3). the influence of the excavation mode. subjected to low in situ stress conditions. and the design of the rock reinforcement itself. to the design of reinforcement and calculation of factors of safety. Bawden. 1995. rock mechanics provides the basis for the assessment of reinforcement needs. as components from geological. with relatively few discontinuities. and often deforms in a problematic manner (figure 4). depending upon the magnitude of the mining operation and the available resources. with relatively few discontinuities. Floor heave and sidewall closure are typical results of this type of failure. it is often more accurate to talk about rock engineering. Heavily jointed rock subjected to high in situ stress conditions. Differently formulated. fall or slide due to gravity loading. P. (below) Simplified description of rock mass conditions and rock failure (from Hoek E. The fundamentals include: the definition of the structural fabric of the rock mass including aspects such as joints. Failure occurs as a result of sliding on discontinuity surfaces and also by crushing and splitting of rock blocks.TALKING TECHNICALLY Rock Mechanics and Rock Reinforcement in Mining Behaviour of Rock Rock mechanics or geomechanics is a term often used to include all the steps that lead to define and control the behaviour of rock around excavations. civil. excavation shape. Rock stresses intensity can vary from very low to very high. Combination of various stresses regimes and fragmentation will dictate the behaviour of the excavation (see figure 2). From the geological and mechanical definitions.K.The opening surface fails as a result of unravelling of small interlocking blocks and wedges. Support of Underground Excavations in Hard Rock. and intensity of fragmentation from massive rock to sugar cube structure or Reinforcement design Figure 1. Linear elastic response with little or no rock failure.. or quite basic. Kaiser and W. Low stress levels High stress levels Massive rock Massive rock subjected to low in situ stress levels. Massive rock subjected to high in situ stress levels. Very fractured rock will tend to yield to stresses. slabbing and crushing initiates at high stress concentration points on the boundary and propagates into the surrounding rock mass. size and orientation also affect the response to the acting forces at play. Blocks or wedges released by intersecting discontinuities.The rock mass surrounding the opening fails by sliding on discontinuities and crushing of rock pieces. Although rock mechanics is a relatively new science that deals with the mechanical behaviour of rock material. Massive rock. Massive rock will draw most of the intact rock strength. it could be said that stresses and rock structures are the two most important factors affecting the stability of any excavation in natural strata material.F. faults. subjected to high in situ stress conditions. Obviously. through rock mass characterization. Jointed rock Massive rock. it Heavily jointed block Optimized Excavation Heavily jointed rock subjected to low in situ stress conditions. Spalling. mechanical and mining engineering are combined to create the process presented in figure 1. Using rock mechanics leads to a better understanding of the behaviour of the rock masses. Then. It is also a fact that. it is often a sign that the rock is overstressed and is rupturing in a brittle and uncontrolled way. as long as well-recognized brands of rock reinforcement are used. and not to low to create major structural instabilities. but can be used to plan with the right kind of conditions in mind. Stress regimes can be predicted and mining sequences optimized to keep the stress level at a comfortable level: not too high to create seismic events. fastened by rock bolts to support large area of roof led to the principle of “suspension roof supports”. This could be the precursor of seismic events and dynamic failure.TALKING TECHNICALLY This applies especially for the rock reinforcement and support aspects. which in turn leads to a more effective and safer operation. when hard and massive rock fails. as early as 1905. As an example. and results are easier to analyze thanks to the use of powerful desktop computers. The need for early support to secure the lower roof layer to avoid Figure 3. which most rock reinforcement would be unable to control. Ground conditions leading to yielding walls and roof. Rock Reinforcement Rock reinforcement devices and surface support are used to control the rock masses within a certain range. producing small fragments like those seen on figure 5. the support devices rarely fail as a result of poor material quality. typical roof support in mines was timber posts and beam. Numerical Modelling Long term excavation planning can benefit from detailed analysis like numerical modelling. before the 1900s. or will warn when in-situ conditions are close to exceeding the rating of the device. by providing room to manoeuvre free of conventional timber posts. systematic reinforcement of mine roofs was introduced to allow the use of mechanical full-revolving loading shovels. as field conditions will almost always change for the worse. Historically. Rubble created from a dynamic failure of a mine roof. For day-to-day operation. numerical analysis will give results that must be confirmed by field observation. It is critical that the correct assessment of failure mode is made. as this understanding will lead to proper reinforcement instead of using a long and arduous trial and error methodology. The design process should also be repeated at later stages of the mining operation. allowing safe and economical access to the excavated areas. and use rock reinforcement that will still be adequate when conditions change. Inclusion of channel irons. Stress analysis is also more commonly performed on site. In late 1920. Figure 4. Some rock reinforcement and support that can be perfect for static conditions may become quite inadequate when confronting seismic events or high stresses and deformations. is now regularly used to optimize the performance of mining excavations in rock. 48 ROCK & SOIL REINFORCEMENT . roof bolts were reportedly used in coal mine roofs in the United States. It is then important to be able to predict future conditions. but rather as a result of inadequate applications. 5 m 2.5 0.7 m shotc 1. and bolting 7) Fibre reinforced shotcrete. fully grouted untensioned deformed bars. provide a 100 Exceptionally poor Extremely poor Very poor Figure 5.4 10 4 Rock mass quality Q = RQD x Jr x Jw Jn Ja SRF 10 40 100 400 1000 REINFORCEMENT CATEGORIES 1) Unsupported 2) Spot bolting 3) Systematic bolting 4) Systematic bolting with 40-100 mm unreiforced shotcrete 5) Fibre reinforced shotcrete. recognizing the need for support in moving ground.90 mm. tested and marketed. Around 1945. Immediately active. more recently. Holland and US. Around the same time. 120 . good Exc. expansion shell anchors appeared in England.3 m 1. Figure 6. experiments were made with epoxy and polyester resins as bonding media. In Canada.5 m ing in 1. was introduced in the South African mines. Self Drilling Anchors that were first developed for ground engineering applications are slowly gaining ground as an alternative in extremely poor ground conditions.0 m 3 24 3.3 m 2. Atlas Copco introduced the Yielding Swellex. cable bolts. J. During the 1960s. and its application in other continents is still under development. provided a strong argument in favour of permanent reinforcement with rock bolting. a yielding rock bolt better adapted to rock burst events. Atlas ROCK & SOIL REINFORCEMENT 50 2. Estimated support categories based on the tunnelling quality index Q (after Grimstad and Barton. >150 mm.1 m area reted 1. an all around high performance yielding friction rock bolt.0 m 1. and by 1949 rock bolts began replacing timber supports in US mines at a rapid rate. large range of operational possibilities.0 m (9) (8) m 0 12 m m 10 7 5 Span or height in m ESR 20 (7) m (6) (5) (4) m m (3) (2) 4. In 1997. as well as the hollow core groutable expansion shell rock bolt.TALKING TECHNICALLY loosening the upper layers. By the end of the 1950s rock bolts were in use everywhere.5 m 2 1 1 0.01 lt Bo ed ret otc sh un in ing ac sp a are 40 2. and their use in combination with rock bolts provides a counter-effect to stresses.0 m 10 m 0m 25 0 15 m 50 90 m m m 5 1. By 1972. and in 1980 Swellex bolts were introduced by Atlas Copco. Between 1952 and 1962 the introduction of grouted slot and wedge bolts. created difficulties in installing the reinforcement system. and bolting 6) Fibre reinforced shotcrete. prepackaged polyester resin systems were developed.04 1 0. 90 .3 m spac Bolt 1. as well as the creation of roof beam action. In 2003. over 2 million rock bolts per month were being installed.004 0. Today. the cone bolt. connectable friction bolts (Swellex Connectable) and Self Drilling Anchors.0 m 0. water and time.120 mm. 1993). compared to timber sets. Scott introduced the splitset rock bolt. full-length reinforcement of rock masses became possible.J.2 m 1. laid the foundations of modern rock reinforcement principles. systematic bolting of roof in coal mines began in 1950. 50 .001 1. Surface retaining supports like shotcrete and reinforcing membranes are now adding another dimension to the reinforcement of underground excavations. Rapid installation. with reinforced ribs of shotcrete and bolting 9) Cast of concrete lining 49 . Atlas Copco and MAI joined their efforts and introduced the Swellex Pm Line and the mechanized installation of SDA anchors. Slabs created by the violent failure of a mine roof during a small rock burst. These two products started the use of friction anchored rock bolts in underground excavation. By end of 1952. and bolting 8) Fibre reinforced shotcrete. Quality of installation remained an issue. as well as resin quality and setting times. Poor Fair Good Very good Ext. good 20 Modern Rock Bolts By 1979. During the 1980s. and lengths of bars. Copco introduced the EXL Swellex.150 mm. coupled rebars and. For long reaching reinforcement. thanks to the systematic use of modern carbide tipped steels for fast hole drilling. was also compatible with mechanized mining methods. the better the productivity and working relations. Fast and reliable ground control practices can make the difference between a profitable extraction and a marginal one. Figure 6 presents a rock reinforcement design method based on the tunnelling index Q. and opening sizes and shapes are carefully designed and planned to fit both the equipment requirements and the stability limits. recognizing that ground conditions are going to change brings the need for easily adaptable design methods of rock reinforcement. As rock fall incidents are often fatal. but then the profitability of mining demands that knowledge and applications are at the forefront allowing the best overall performance . empirical methods can help rapid and sound decisions. by Francois Charette 50 ROCK & SOIL REINFORCEMENT . An objective of mining operations all over the world is to eliminate working injuries. Social costs are now considered as valuable. In order to get the full benefit of rock mechanics application and rock reinforcement systems. In this case. It has been recognized that the safer the environment. In fact. and improvements in dilution and stability go hand in hand. the practical application of rock mechanics in everyday mining is often considered a normal part of the extraction process. rock mechanics people are always pushing the limits of performance of excavations. and minimized. It is true that mining operations are often working at the limits of stability of excavations. and the very active transfer of knowledge and technology between research and mining operations. Rock mass classifications are used systematically in most mining operations in North America. During the past two decades. By developing local expertise and sharing it through conferences and publications. the two must be linked and interconnected in a way to provide feedback information and data for each other. the impact of accidents and damages has been better understood. Conclusion Rock mechanics in mining has evolved tremendously over the last 15 years with the availability of numerical models that run on desktop computers. However. Better long hole drilling equipment provides straighter boreholes that allow larger stopes with less development and better blasting control.TALKING TECHNICALLY Adaptable Design Rock reinforcement and rock mechanics applications are inter-related as the design of an excavation and its reinforcement is an implicit process in which most parameters are interdependent. The design of excavation also gets new “blood” with advances in technologies. they should be avoided by using integrated bolting systems to provide optimum reinforcement and support solutions. Testing apparatus with a) original configuration and b) modified configuration for distributed impact. or complete sliding of bolt inside tube. the Swellex bolts were inflated in two steel tubes. The rationale is that. 2) initiating the datalogging system (when used) to measure impact load. 4) if no failure. Failure of the bushing weld almost never occurs in the field. since no bolts are breaking at the bushing weld in field events. impact tube also generates some friction above the bushing and plate assembly. The friction inside the steel tube was not sufficient to create failure of the bolt profile. the rock reinforcement is more than often destroyed or at least mobilized in excess of its working range. The static weight of moving part was one metric tonne. To try to reproduce the failure pattern observed in the field. as well as retaining the rock adequately before and after the event. The load data was Figure 1. or 1000 kg. and c) completed test with modified configuration. resulting in caving or closed-in excavation contours. a Testing Procedures The basic test procedure was: 1) turning on the electro-magnet and lifting the weight at the appropriate height above the impact position on the bolt. this reduced friction demonstrated interesting behaviour that has led to a better understanding of anchorage requirements in dynamic loading.TALKING TECHNICALLY Performance of Swellex Rockbolts in Dynamic Loading Conditions Avoiding Dynamic Failure Dynamic failure of rock underground can generate high levels of kinetic energy and expulsion of rock from the opening surface. the weight is hooked up again and lifted up for the next drop. b Testing Configuration Figure 1 shows the testing apparatus used to simulate the action of seismic events on Swellex rock bolts. and this highlighted the need to better simulate steel/rock anchorage capacity. In order to assess the Swellex capability in dynamic failure conditions. In field failure. All impact tests were performed on 2. However. the Swellex bolts are usually broken at a distance varying from 10 cm to 50 cm from the head bushing. laboratory testing programmes have been undertaken to quantify the performance of Swellex rock bolts in dynamic loading conditions. Rock material reaches velocities of a few metres per second and in those conditions. Rock reinforcement used in those conditions must be able to sustain the energy burst. 51 . The second (see Figure 1) shorter. it must be that the bulking occurs at such a ROCK & SOIL REINFORCEMENT c distance from the head as to mobilize load from the anchorage and retaining force generated by the bushing-plate ensemble. which dampens the impact.1 mlong Swellex Mn12 bolts. with the top tube generating the anchorage. 3) turning of the electro-magnet to release the moving weight. TALKING TECHNICALLY A Load B A: Impact B: Sliding of bolt inside tube section C: Harmonic oscillation of weight after sliding has stopped.1 Slided Table 2.200 Energy Absorption (kJ) 1–4 2–6 2–4 4–8 4 – 10 2–4 5. Table 1 presents typical results from the laboratory testing programme.5 18 – 29 5 – 15 10 – 25 19 mm resin-grouted rebar 16 mm cable bolt 16 mm. i. the bolt starts to deform.55 Figure 2. 1995) ROCK & SOIL REINFORCEMENT . Typical signature of impact test on Swellex bolts: a) Typical phases of an impact test. or exceeds. As the weight slows down.35 1. 1 tonne) Time of sliding Time to failure (when it occurs) C maximum dynamic strength differs from maximum static strength.1 Failed in tension Test 4 18. the friction coefficient increases toward its static value.6 Failed in shear and tension Test 3 17. by a factor of about 1. Theoretical energy absorption capacity based on quasi-static load -strain properties Description Peak Load (kN) 100 – 170 160 -240 70 – 120 160 – 240 70 – 130 105 – 110 120 – 125 220 – 240 50 – 100 90 .4.00005 seconds. Typical Impact Tests Results Result Impact Load (T) K(kJ) Status of bolt Test 1 10. and the bolt is finally stopped.e.15 1. which acts as a stiff spring. frictional energy is dissipated according to the friction generated on the wall of the tube. the impact load is measured. Table 1. the weight accelerates until it reaches the impact point.25 time (s) 1. The typical measurements of the tests are: Impact load Sliding Load Final load on load cell (should be equal to the moving mass.4 – 12. intervals of Impact Tests Analysis Upon starting the test. the bolts showed only minimum yielding for loads exceeding Swellex Sample A1 Load (tonnes) 25 15 5 -5 0. but almost simultaneously. it also starts to slide inside the steel tube. Bolt 16 mm.1 Failed in shear Test 2 15. Measurements show that the impact load exceeds the ultimate static tensile strength by a factor of about 1. During sliding. However. if the transmitted load at the restricted location does not reach the ultimate strength of the steel. Static steel properties can be used to preliminary assess the theoretical energy absorption capacity. After being released. If the load reaches.3 8. A summary of impact testing is presented in Figure 2.45 1. Under the impact load. At this point.5. b) actual impact test with sliding of bolt inside steel tube. The momentum creates harmonic oscillations in the bolt.2 9. so that it does not fail if it is not pinned or restrained. From the tests performed during the spring of 2004.8 6. then the bolt simply breaks. measured at time 0. 52 according to the load level. based on the test results. the weight is elevated to a pre-determined height above the impact point.95 1. the bolt only deforms elastically and plastically. 2 m long mech. while when shearing was observed (Figure 3). and these are damped very rapidly.4 9.150 Displacement (mm) 10 – 30 20 – 40 20 – 50 30 – 50 50 – 100 25 – 35 45 – 100 80 – 120 80 – 200 100 . taken as 60% of tensile strength. 4 m debonded cable 16 mm grouted smooth bar Standard Swellex bolt Mn12 Swellex bolt Mn24 Swellex bolt Split Set bolt 16 mm cone bolt (Data from Kaiser. but it has been found that load and deformation are different from static tests. Time Analysis Of Energy Absorption Capacity Table 2 summarizes testing results on various types of rock reinforcement fixtures. including an impact test where the recording equipment was successful in picking up all of the information. The sliding reduces the load on the bolt. the impact load exceeded the ultimate shear strength. When the bolt is clamped or fixed so that it cannot start to slide at both ends.05 1. the ultimate strength. 5 kJ Swellex Mn12 2. when the bolt is able to slide slightly in order to avoid critical deformation.1 m 9 kJ ROCK & SOIL REINFORCEMENT 53 .1 – 5. These values exceed by far any strain energy accumulation mechanism. Swellex bolts elongated only 32 mm with a load of about 17 t on the test to failure. The impact was localized on the head only so the higher strength of the profile could not be mobilized. Table 2 gives some typical results from Kaiser (2. However. 4) and from Noranda Technology Center (5). absorbing about 5. loading was not accompanied by failure. which might be more with rougher tubes and longer bolts. in dynamic loading. These results take in consideration only the elasticplastic behaviour of the shank/body of the bolts when submitted to a static load: the dynamic capacity is inferred in considering that the same loaddeformation relationship would exist during dynamic events. It is important to understand that. in dynamic testing. on a single event. Energy absorption capacity from dynamic testing Figure 3. In fact. Failure of Swellex bolt in shear. results from dynamic testing are presented and. and about 22 kJ with the Cone bolt tested at NTC (Kaiser). the impact energy that can be accommodated is quite a bit higher. Single Event Variable with Max: 22 kJ 4. ultimate load and deformation are not the same as in Bolt Type Cone Bolt (NTC) from Kaiser and al. its energy absorption capability is enhanced. The mechanical properties of the bolts’ components can give instructive insights on the energy absorption capability of a given bolt type. which is similar to the energy absorption capacity calculated from static testing. Swellex Source Kaiser and al. when a reinforcement fixture dissipates Figure 4. outline the fact that most reinforcement fixtures have limited capacities of absorbing energy when using deformation/yielding properties. Profile deformation during the tests ranged from 42 to 55 mm when the bolts broke. The energy that a rock bolt can accept is smaller when the bolt is pinned inside the tube (Figure 4). When the rockbolt was not restrained.TALKING TECHNICALLY more than 50% of their maximum static strength. sliding is restrained. By contrast. energy through sliding. Results from NTC’s tests on Swellex (2003) and Cone bolts (1998) show that. (3) as well as from Ortlepp and Stacey (1).3 kJ of energy. stretches to failure at the first blow. Results from Kaiser et al. In Table 3. and values range from 1 to 25 kJ of energy at most. it is possible to dissipate over 9 kJ with a Standard size Mn12 Swellex. or when the Table 3.1 kJ Ortlepp and Stacey Ortlepp and Stacey Atlas Copco/ NTC Rebars 4.1 – 5. 3. from Ortlepp and Stacey (1). Swellex anchored in steel pipes could absorb 4 – 5 kJ of energy when sufficient anchorage is provided. Failure of bolt at pin location. but the deformational energy absorption seems to be quite similar. Kaiser. Stacey. June 1998. 3. Canadian Rockburst Design Handbook. It is also very interesting to consider what kind of energy dissipation could be achieved when using an Mn24 instead of an Mn12 bolt. by François Charette 54 ROCK & SOIL REINFORCEMENT . As the bolt itself is twice as strong. References 1. Johannesburg 2004. and. Drift Support in burst-prone ground. The conclusions obtained from these laboratory tests is being applied to the Hybrid Swellex bolt that combines the controllable sliding ability of the Swellex with the strength and reliability of MAI bars. Testing of tunnel support: Dynamic load testing of rock bolt elements to provide data for safer support design (GAP423). W.TALKING TECHNICALLY static loading. Support Against Rock Burst – Short Course 1995–2003. as long as the anchorage length is adequately coupled to the static anchorage capacity. When this right combination is reached. Tests results from NTC and Atlas Copco also demonstrated another important fact. Kaiser et al. Centre Technologie Noranda. 5. and repeat the same testing with Mn24 bolts. Mai 2003. V. 6. Performance of Swellex rock bolts under dynamic loading conditions. The next step is to increase the friction against the bolt in order to simulate an anchorage capacity of 130 to 180 k/m. equivalent to the rated capacity of the bolt. the energy absorption could certainly be in the order of +18 kJ per event. F. The South African Institute of Mining and Metallurgy. Kaiser. since the friction could be adjusted in order to provide the right anchorage capacity. the maximum load could be doubled. This allows maximum energy absorption without failure of the unit. Ortlepp. 1995. and provides a consistent energy absorption capacity. and still provide an adequate load capacity. Charette. Conclusion Dynamic testing at the laboratory has shown that Swellex bolts can accept and dissipate a reasonable amount of energy without failing.R. Falmagne. Second International Seminar on Deep and High Stress Mining. coupled with stable static load bearing capacity.. This is that maximum energy can be absorbed when the friction properties are tightly matched to the strength of the material. the bolt head will move just before the shank/bolt body enters the deformation phase. March 1996.D. Etude de faisabilité: tests d’impact sur Swellex. 4. This operation was successful with steel tubes instead of rock. T. CIM Bulletin. 2. These can be extended using couplings to allow installation of soil nails up to 15 m depth. the speed of installation has increased considerably. as construction proceeds. air flush for short boreholes in soft soil such as chalk and 55 . using a borehole flush medium suitable for the specific ground conditions. There are three types of borehole flush: water flush for long boreholes in dense to very dense sand. affording the flexibility to adjust the nail to the actual requirements on site. because of the commonly used rod length of 3 m or 4 m. To install conventional soil nails. Unstable slopes or excavations consist mostly of unconsolidated soils or deteriorated rock formations. gravel formation or rock conditions. meaning that it is not pre-tensioned. and the risk of re-drilling time spent cleaning collapsed boreholes has been eliminated. Advantages of Self Drilling Anchors Since the slow cased borehole drilling methods were superceded. a cased borehole drilling method is required to overcome such difficult and unstable ground conditions. Method of Installation Self Drilling Anchors are installed with air driven or hydraulic rotary percussion drilling equipment. thread. The fundamental concept of soil nailing is to effectively reinforce soil by installing closely spaced grouted steel bars into a slope or excavation. is strong in tension. up to 20-30 soil nails/day using MAI SDA. Transportation and handling of MAI SDA to and on site is safe and economical. without waste or delay. The selection of the drilling equipment for MAI SDA installation is also more flexible. There is also the option to use simultaneous drilling and grouting installation techniques. on the other hand. as construction proceeds from the top down. An alternative is the MAI Self Drilling Anchors (MAI SDA). which is specially designed for use in ground where the boreholes tend to collapse during the drilling process if casings are not used. A soil nail is therefore commonly referred to as a “passive” anchoring system. Switzerland.TALKING TECHNICALLY Slope Stabilization with Self Drilling Anchors Soil Nailing for Reinforcement Soil nailing is used to reinforce and strengthen ground which has questionable stability. MAI SDA rods are manufactured with a continuous ISO standard ROCK & SOIL REINFORCEMENT Installation of SDA R38 N with ROC D7 at Carriere d’Arvel. Steel. depending on the geology. for a better transportation of large cuttings and cooling of the drill bit. Soil is generally a poor structural material because it is weak in tension. especially for working in confined space. as is normal with ground anchors. The grout exits through the flush holes of the drillbit. which has the ability to harden after the installation process is completed. the 3 to 4 m standard rod lengths are easily coupled together. For the third operation. so higher external friction values are reached. until the design depth is reached. and the installation is completed in a single drilling operation. Kent. the flushing medium is already a grout mix. The rod handling system contains at least two sets of three 3. When using the first two flushing media for the drilling operation. facilitating installation of two complete 10 m-long Soil Nails without having to manually feed 56 ROCK & SOIL REINFORCEMENT . the MAI SDA is drilled continuously forward without extraction. By utilizing a sacrificial drillbit. the grout stabilizes the borehole during installation. The ROC D7 feed reaches to a height of 7 m. allowing installation of two rows of SDA from one position. UK. The grout has good penetration into the surrounding soil.5 m-long R 38 N SDA rods. saving time. Using SDG. a better grout cover along the nail shaft. and simultaneous drilling and grouting (SDG) for all lengths of boreholes in all unconsolidated soil conditions. where water spillage is to be avoided. Bromley. the soil/steel interface has to be created by grouting through the hollow stem of the anchor. and backfills the annulus around the nail that has been cut by the larger diameter of the drillbit. ROC D7 offers excellent reach with a folding boom.TALKING TECHNICALLY Galvanized MAI-SDA R 25 and R32 anchors installed into loose and collapsing ground using simultaneous drill and grout at the Shortlands Junction. A typical application of SDA is currently being carried out by the open cast mine Carriere d’Arvel in Switzerland. Here an Atlas Copco ROC D7 drillrig equipped with a Ceminject (integrated rotary injection) adapter and a rod handling system is being used for SDA installation. clay. To reach a required nail length of 12-15 m. providing Principle of the MAI Self Drilling Anchor. Field tests have shown that the Atlas Copco ROC D-series of drillrigs can be used to install self-drilling anchors (SDAs). For some. ROCK & SOIL REINFORCEMENT A simple conversion kit enables this rig to be converted to an SDA installation unit. Bromley. enabling SDAs to be used in very inaccessible places. The Shank Connector is a coupling sleeve locked to the shank adapter. where loose and collapsing ground was affecting operation of the railway. prior to uncoupling the last rod from the rock drill. swivel and brackets to replace the standard shank adapter. high-tech features. Installation Using ROC Drillrigs The use of self drilling anchors for stabilization and reinforcement work in soft rock is common both in the underground world of mines and tunnels and. and the sidewalls of cut-and-cover tunnelling are just a few examples. normally used on surface crawlers.TALKING TECHNICALLY Atlas Copco ROC D7 installing MAI SDA for soil reinforcement using MAIm400NT grout pump. BSH 110 is a hydraulic drill steel support providing gripping and guiding function. extension rods at these extreme working heights. This would be the final step in the installation sequence. or very low for horizontal toe-hole drilling. contractors who own one of these crawler rigs for quarrying operations are perfectlyequipped to take on stabilization jobs. Hence. To alternate between water and grout. Similar methods were used to stabilize the slope at Shortlands Junction. The beauty of being able to adapt the ROC D7 for such applications is that the contractor can make full use of the rig’s powerful and flexible hydraulic system. it is generally poor quality ground and soil that threaten the stability of installations or landscapes. first drilling to full depth with an air flush and then grouting the annulus of the borehole. or minimize spillage during collaring. The rock drill is fitted with a kit consisting of an Ceminject (integrated rotation injection) adapter. The SDA installation becomes a fast continuous mechanized process with high grouting quality in a safe working environment. A flushing head with inner diameter of 53 mm is needed. The SDAs. The system is equipped with SDA bushing halves in the gripping arms and the star wheels carrying the rods. The alternative is to flush with water when drilling-in the anchor. and one to handle the pump. The swivel is mounted on the rock drill with a bracket and has two separate inlets. UK. for example. various types of foundations and hills prone to landslide. The Rod Handling System RHS 52 is used for carrying bolts on surface crawlers. Connecting Grout Pump and Ceminject adapter Most of the time there is a need to alternate between flushing with water and grout. and the most. To drill SDA it is equipped with the rubber bushing and steel bushing halves to match the anchor size. either direct or by letting it run on the feed through the hose tree and over the hose drum. To provide the locking function a special male T38 shank is required. or as in this case. The newly developed integrated injection adapter (Ceminject) can be used for either simultaneous drilling and grouting. as this may contaminate the feed with the grout. In surface SDA installation. some contractors have 57 . When installing SDAs using a surface drillrig. because of the size of the female front part of the shank adapter. when installing R51 or T76 anchors and when alternation between bolting and blast hole drilling is required. It can also be positioned at extreme angles. available from Atlas Copco MAI. it requires a flushing head with inner diameter of 53 mm. it may open up whole new markets that they have previously not even considered. with their R threads and sacrificial bits. are installed and grouted in one operation. The folding boom. Embankments along roads and railways. Kent. as well as for blasthole drilling. without losing the advantages of the ROC D7 standard. it may be inconvenient to grout during drilling. for a wide variety of applications on the surface. The hose from the y-coupling is then connected to the Ceminject. Ceminject is a SDA shank adapter combined with a separate swivel providing flushing media and grout. is also recommended. This type of y-coupling requires manual switching between water and grout. On surface. This is an alternative to SDA-shank. connect the grout pump and water hose to a y-coupling equipped with two valves. Available for R32 and R38 anchors. Two-man Operation Only two people are needed – one to handle the drilling. can be positioned up to a height of 7 m beside a slope. so that water or grout may be selected. These easy adjustments will enable ROC D7 owners to get the best. out of their equipment. and then grout it through the Ceminject. The grout pump m400NT. The SDA shank adapter is a female shank having integrated coupling sleeve to ease uncoupling. commence grouting until the hole is full. then the installation cycle is now complete and the feed can move to the next anchor position. needing 58 only a single hose. then resume drilling.or water-flush modus. In air. It is possible to replace the hose for air flushing by the grout hose by attaching it to the hose tree and letting it run over the hose drum to the rock drill. 6. or by the pump operator on demand from the rig. If simultaneous drilling and grouting modus has been used. two hoses can be connected to the Ceminject. improving corrosion protection and external friction values of the rock–grout interface. The in-situ rotation mixing process of the grout guarantees a homogeneous filling of the annulus. and grout flow by starting and stopping the pump. Extend with next rod using the rod handling system. This makes the connection between the grout pump and the Ceminject straightforward. The two hoses can be put on the feed over the hose drum. The installation cycle is completed and the feed can move to the next anchor position. This has the advantage that. The water supply hose should be equipped with a nonreturn valve at the connection to the Ceminject. switch over to grouting mode and. Repeat rod-adding sequence until final design length of the anchor has been drilled. pump and the other to the water flushing system on the rig.TALKING TECHNICALLY COP 1832 rock drill with Ceminject adapter. 4. 2. it is fully grouted and ready to be attached to the face plate. chosen to drill and grout simultaneously. Uncouple before retracting the rock drill. in order to prevent grout from entering the water system. 5. stop the flush and loosen the rod end connection to the drifter by clamping the DSS and unscrewing the female shank adapter. This system makes it easier to control both water and grout flushing. Drill first SDA rod. SDA Installation Cycle The optimal SDA installation cycle comprises the following steps: 1. either with simultaneous drilling and grouting or with conventional air or water flush. To simplify the system further. guiding with the Drill Steel Support (DSS) in open position. open DSS and commence flushing. once the anchor is completely drilled into the ground. When the rod has fully penetrated into the soil/rock. and to reduce number of people needed to do the installation. while maintaining a slow rotation of the anchor. 7. using only grout as the flushing medium. one to the grout by Mark Bernthaler ROCK & SOIL REINFORCEMENT . Standard rod handling magazine with SDAs and couplings. with the water controlled by a valve on the rig. The grout pump can be controlled remotely by the rig operator. The special bushing halves prepared for firm gripping of the SDAs. In order to allow for measurements. Panoramic Line Scanner For very high-resolution images. a 3D imaging system has been developed consisting of an imaging device and 3D evaluation software components. Introduction Currently the assessment of potential for excessive overbreak and discontinuity controlled block falls or slides heavily relies on experience. In order to master these shortcomings with respect to efficiency and accuracy. Processing the images leads to 6 MPix 3D images with several hundred thousand 3D measurements. Data acquisition 59 SLR Camera A conventional SLR camera with a minimum 6 MPix sensor is used to . Named the JointMetriX3D® system. such as CAD ROCK & SOIL REINFORCEMENT Evaluated 3D image generated with JointMetriX3D®. and other geometrical properties • Link to other applications. Measurement of discontinuity pattern and orientations is done manually. recording the face column by column. The evaluation of the incomplete and inaccurate data with respect to block fall hazard is slow. if at all. Imaging at the Tunnel Site The major goal is to record the actual rock mass conditions comprehensively by producing images that allow reproducible assessments. the device head rotates. thus easing visual inspection of the rock mass. A 3D image combines a large number of three-dimensional surface measurements with a high-resolution colour image. The absolute position and orientation of the joints is directly determined. while the other uses a panoramic line scanner. persistence. A major advantage of the panoramic principle is that existing reflective targets in the tunnel can be used to establish a reference of the image to the tunnel. A recently developed imaging system and evaluation software assists in identifying unstable blocks and design of rock support. the panoramic line scanner should be applied. distances. The whole data acquisition process requires only about one minute. Efficient identification of potentially unstable blocks and instant design of appropriate rock reinforcement thus contributes to safer and more economical tunnel construction. The stereo-photogrammetric principle of JointMetriX3D® requires two images of the same area captured from different positions in order to obtain 3D information. it unites several features: • Data (image) recording at the face • 3D image generation and assessment • Metric and accurate measurement of discontinuity orientations. Joints are represented by traces and areas. The arrows indicate the orientation of an area by its normal vector while the spherical triangles indicate the orientation of the plane fitted through the trace. This scanner is capable of producing images of more than 100 Mpix. Scale and local orientation is introduced by locating a vertically levelled bar somewhere within the region of the images. the camera is calibrated. The first one uses conventional calibrated single lens reflex (SLR) cameras. take two free positioned images. besides generating additional costs.TALKING TECHNICALLY 3D Images for the Design of Rock Support Reducing Rock Fall Hazards in Tunnels Rock blocks falling from the roof or sliding into the tunnel can be a hazard for the miners and equipment. and usually does not allow for the determination of appropriate rock support in time. Currently. recording very fine details. two options for imaging are available. During scanning. • Lithological boundaries • Areas • Volume of overbreak JMX Analyst contains a tool to plot joint data in stereographic projection and the variation of orientations of joint sets (cone of confidence. and weight. Rock block support by bolting during tunnel excavation . by Wulf Schubert. such as JointMetriX3D® can be installed on a drilling jumbo. Prediction and final design is based on the rock mass structure derived from JointMetriX3D® measurements. Markus Pötsch and Andreas Gaich 3D imaging with SLR camera.jointmetrix. allowing an assessment of the conditions ahead of the face. etc. and can be exported directly into standard file formats. This enhances the quality of short-term prediction. assessments and measurements are taken from it using the 3D software JMX Analyst. giving a realistic impression of the actual conditions. using secure Internet connections. Recorded data are transferred to the office for evaluation. spherical aperture. This can be carried out by personnel on-site or off-site. 3D Image Generation and Measurements From a stereoscopic image pair a 3D image is reconstructed by purposebuilt software. This software allows the inspection of 3D images thoroughly. location and length of required bolts to stabilize the blocks is determined.TALKING TECHNICALLY on site typically takes in the region of ten minutes. etc). An imaging system. Using the acquired information on the rock mass structure. and the necessary information for the rock reinforcement transferred back to the drilling equipment within minutes. volume. Once a 3D image is ready. 60 ROCK & SOIL REINFORCEMENT . A free copy of JMX Analyst is available for download at www.com/. potentially unstable blocks are identified with respect to their location. leading to 3D images which are referenced to the tunnel coordinates. the quantity. Further processing of the existing data can be used to extrapolate the rock mass structure in a representative volume around the tunnel. Measurements are taken directly on the 3D image using the software. allowing for an instant imaging during work. Prediction of Block Failure Modes and Support Design The measurements derived from 3D images are used to establish a consistent and accurate ground model. thus reducing any surprises during excavation. All measurements are metric and referenced either to a relative or the tunnel coordinate system. orientations. Once the failure mode and the properties of the blocks are identified. such as: • Joint locations. persistence. spacing. A standard Swellex Connectable blind segment (2) is used when the hybrid is to be used for energy absorbancy. As only a short segment of Swellex is required. once equilibrium has been reached with no further movement of the rock mass expected.MAI Anchor Coupling 5 Pre-tensioning and Grouting The vast majority of grouted rebars and cable bolts are not pre-tensioned. the anchorage strength can be controlled.Nut for Swellex inflation and grouting 9 MAI Anchor Adaptors 9- * Notes The Grouting valve(3) is included with the special version of Swellex Connectable(2) when Hybrid bolt is to be grouted. real pretensioning is possible. higher Seismicity Most of the present generation of rock bolts. 6. The Swellex segment can then be inflated through the MAI SDA anchors.Swellex Connectable 2 (blind segment)* 3 3. . Furthermore.Face Plate 7 8 8. low-cost installation every time. Competence Centre The Atlas Copco Competence Centre team was looking for a type of rock bolt offering the following features: immediate and efficient support. long life expectancy and the level of safety and productivity characterizing Atlas Copco Rock Reinforcement products. fast and trouble-free installation. followed by as many MAI SDA rods as needed to reach the required length. A plate and nut are installed after inflation to provide immediate support and real pre-tensioning. the product may be installed in long holes by simply adding new MAI SDA segments. The Swellex segment and the grouting device are inserted first. with the insurance of a perfect.MAI Anchor Rod R32 (hollow bar) 5. became apparent that the solution was to combine the two. The new Swellex Hybrid provides immediate support. larger stress can be absorbed without rock failure. the system can be installed in very tight locations to virtually any hole length. grouted or use as a rock reinforcement system for seismicity. offering longevity while adding stiffness in shearing. Good anchorage capacity in any type of rock is another advantage of using a Swellex segment at the end of the bolt.Grouting valve* 4 4. the new rock bolt offers immediate anchorage.Retainer 2. as a plate and nut are fastened on the MAI rod side. that address the seismicity problem ROCK & SOIL REINFORCEMENT 61 . and the possibility to control the anchorage capacity and behaviour of the rock support to maintain the bolt integrity in case of seismicity. pre-tensioning capacity when requested.TALKING TECHNICALLY Introducing Swellex Hybrid New Versatile Rock Support By combining the benefits of Swellex bolts with those of the MAI Self Drilling Anchors (SDA) system. Installation sequence of Swellex Hybrid for pre-tensioning and grouting. adaptable to any hole lengths. mainly because this process is cumbersome and time consuming. it Hybrid bolt for long anchorage in rock.MAI Anchor Rod R32 6 7. By coupling MAI SDA bolt sections. longevity when required. As pre-tensioning creates an active support. immediate anchorage in any type of rock. Atlas Copco has developed a new versatile type of rock support that can be pre-tensioned. By limiting the length of the Swellex segment. Grouting can then be carried out immediately. Components 1 1. or later. Shortly after Atlas Copco acquired the reputable MAI SDA system. such as cone bolts and durabar. The grout then achieves strength and resistance. Sliding behaviour at high tensile load consumes energy without compromising the integrity of the bolt. A special coupling has been developed to connect the MAI rods and the Swellex segment for the purpose of grouting. Equipped with a Swellex end. The need for pre-tensioning is higher if ground movement is likely to occur during the cement curing period. and sliding distance calculated according to the energy to be dissipated. 6-Inflate Swellex through the SDA rods using a standard Swellex pump having 300 bars in water pressure. there is no access for corrosive elements.5 kJ of energy.TALKING TECHNICALLY use the same principle of having a part of the system that can disengage and absorb energy through friction or deformation. for long life expectancy Swellex Hybrid offers solutions to match the threat. 3-Thread the SDA rod all the way into the grouting valve on the Swellex. a sliding of 0. The efficiency of these systems depends on the quality of the installation. which varies significantly with the quality of grout and de-bonding agent. 2-Insert Swellex (the length can be determined from pull test – should be sufficiently short to generate pull out resistance lower to its yielding strength into the hole). and experience and training. rock mass condition. 4-Install plate and nut. 2-Insert Swellex (the length can be determined from pull test – should be sufficiently long to generate pull out resistance equal or higher to its yielding strength into the hole). or for long life expectancy. Life Expectancy When it comes to protecting the investment. A plug can be used to protect the inside of the Swellex in the long term. 9-Pre-tension the bolt. Installation Sequence For pre-tensioning and grouting: 1-Drill the hole to the required length using 48 to 51 mm bit. For seismicity: 1-Drill the hole to the required length using 48 to 51mm bit. efficiency of rock reinforcement for seismicity. 8-Detach the inflation coupling. above all. 8-Pre-tension the bolt. Site Testing The Hybrid bolt is now being tested at WASM facility in Australia to determine the optimal anchorage for maximal energy absorbancy of the system under dynamic loading conditions. always perfect. Extend with additional SDA rods and special Hybrid couplings (good for 300 bar) to match the hole depth. and Swellex in Plasticoated or coated versions. 10-Grout (MAI 400 NT Grout Pump is recommended). because of poor quality of installation. Installation sequence of the Atlas Copco Swellex Hybrid. The grout will then offer the first protection layer. This allows the Swellex Hybrid to be inflated. for example. and then grouted through the MAI SDA rods. it is easy to calculate the length of the Swellex required to reach the maximum sliding strength that would not damage the bolt under dynamic conditions. For full protection from a corrosive environment. Recent studies have shown that the quality of surface support is of paramount importance for ensuring the 62 by Mario Bureau ROCK & SOIL REINFORCEMENT . As the MAI bolts are grouted from inside out. 7-Open the grout valve (in the Grouting device) by rotating the MAI rods by a 1/2 turn anti-clockwise. The installed system can also be tested at any time to make sure it is working according to calculation. in order to make the system absorb the energy and preserve the rock mass between each bolt. Both the Hybrid bolt and its system of controlled energy absorbancy are patented. Swellex plasticoated and galvanized MAI SDA anchors are recommended for corrosion protection. 7-Detach the inflation coupling. as it is controlled by the Swellex pump. 4. The advantage with the Hybrid system is that. 3-Thread the SDA rod to the Swellex. By combining the merits of the Swellex and MAI SDA systems. a sliding pull test (on a short bolt segment inflated) performed on site will confirm the anchorage capacity. When used for seismicity.15 m would consume as much as 22. The installation is easy and.Install plate and nut 5-Attach inflation coupling to the last SDA rod. a 1 m Swellex Pm24C offering a 150 kN anchorage is proven to slide (yielding strength = 200 kN) under dynamic conditions without damaging the bolt. The length of the Swellex will then be chosen to match the maximum sliding strength. and the free sliding length needed to dissipate the energy. or the plasticoating on the Swellex. This system offers the facility to be tested at any time. Once sliding behaviour is tested and the system proven. MAI rods can be supplied galvanized. preserving the MAI rods from contact with the environment. once the anchorage capacity (kN/m) is deduced from onsite pull test of the short Swellex segment. 5-Attach inflation coupling to the last SDA rod 6-Inflate Swellex through the SDA rod using a standard Swellex pump having 300 bars in water pressure. pre-tensioned when required. When used for pre-tensioning and grouting: Atlas Copco has developed a special grouting device that is coupled between the Swellex segment and MAI rods. Atlas Copco has invented a completely new approach to rock bolting. If. The grout then protects the Hybrid bolt. Often. followed by the zinc layer. these systems have not achieved the expected success and efficiency underground. as well as providing a safer underground environment for miners and tunnellers alike. Second. But in multiple face development or ore extraction. In the tunnelling business. Bolt installation takes less than 30 seconds. which is inserted into a predrilled hole in the rock. and provides full and immediate support along the entire hole length. holding up the others and wasting time and money. Now they are ensuring higher advance rates. The mining industry is increasingly recognizing that Atlas Copco Swellex rockbolts. productivity and quicker access to orebodies in mines as well. fastest and most reliable ground reinforcement technology available. the rock mass is never without support. The Bieniawski diagram shows the relationship between the unsupported span and stand-up time of an excavation with reference to its rock mass quality. The Swellex bolt is a folded steel tube. Fourth. This means that operations must be synchronized so that one does not fall behind. over the years. for a given Bieniawski diagram showing stand-up times for different spans and rock classes. the support can be more active when installed early. high-speed rockbolting obviously cuts the time to completion. First. pre-reinforced ground will not deteriorate or collapse as rapidly as a totally unsupported excavation.MINING WORLDWIDE Swellex in Mining Safe and Speedy Support Rock support is often a bottleneck in the business of underground mining. as well as to advance the faces on ROCK & SOIL REINFORCEMENT schedule. is a common way of improving the rock quality before excavation takes place. the objective is to utilize manpower and equipment efficiently. the Swellex rockbolting system has become world famous as the simplest. pre-reinforcement increases rock strength prior to excavation. both by blasting and by the elastic and non-elastic stress redistribution of the excavation process. Drilling ahead of the tunnel face to install bolts or grout as pre-reinforcement. has built up an enviable reputation for saving time and money. Empirical observations have shown that. Forward Stabilization Using Swellex In single-face development. 63 . and an obvious solution is faster rockbolting. allowing a safe working period for installation of regular support. a pre-reinforced rock mass will be less damaged. Over the past two decades. Swellex bolts are already accepted as the key to better operational efficiency. adapting to every irregularity. which are quickly and safely installed to give immediate support. making Swellex the perfect partner to provide reinforcement quickly. Third. so that the next operation can start without delay. blowing out the fold and expanding the tube into the exact shape of the hole. The cost is negligible when compared to the higher profits that can be made by keeping equipment fully and economically employed to increase production. even at the split second following blasting of the round. rather than passive when installed later. The system speeds up rock reinforcement considerably and. Water is blasted into the tube at high pressure. are speeding up operations and boosting revenues. There are several benefits to this. Instead of relying on supporting the ground following excavation. in ground conditions ranging from the hardest rock to clay and even non-cohesive material. The development of Atlas Copco’s Rocket Boomer and Boltec rigs is constantly reducing drilling time. 500 t/day. and grouted at high pressure with high strength. productivity was compromised. 1991). Primary support could be installed during the normal cycle without safety problems. The rock mechanics engineer at Mine Doyon designed a pre-reinforcement method using cable bolts installed over the future roof of the access drifts. The Mine Doyon property is one of the most important gold-bearing orebodies in production in Canada. allowing three to four rounds to be taken before installing heavy support consisting of vertical cable bolts and shotcrete. Field observations show that cable bolts installed in stopes before the first blocks are blasted are more effective than cable bolts installed after the slot or cut has been excavated. The orebody is also oriented E-W. a linear reduction in Rock Mass Rating (Bieniawski. fine grained cement grout. located near Rouyn-Noranda. a linear increase in excavation span results in a logarithmic increase in instability potential. and from surface reaches a depth of over 1. Mining method: Longhole stoping with cemented rock fill. although the underlying concept could definitely be useful. an inverse shearing caused by a NW-SE compression. Through each cemented hole. Quebec. The No. The footwall of the No. Although stability was achieved. Rock reinforcement required: Protective umbrella in access drift. Rouyn-Noranda. Stope development in this ore zone was delayed due to repetitive caving in access drifts. ROCK & SOIL REINFORCEMENT . with Rock Mass Rating values between 0 and 30. the umbrella grouting method of pre-reinforcement is frequently used. This method pre-supports the planned roof area with steel rods. At least four major ore zones are found on the Doyon property. This is not always the case for cable bolts installed during stope exploitation. The cohesive effect of the cable is greater when added to undisturbed ground than when added to weakened and disturbed ground.000 m. Large holes are drilled in the future roof perimeter. and has an average width of 8 m at depth. Several tectonic events have been identified. Mill production is around 3. in northwestern Quebec. a smaller hole is then drilled. dips steeply south.1 Ore Zone is defined by a major quartz and sulphide vein system. Economic mineralization is found on a corridor that extends at least 2 km E-W. Rockbolt selected: Super Swellex. Hence. the time period available to install roof support is significantly lower than for small drifts. among them a N-S compression 64 followed by a N-S extension. 1 Zone is located in very poor quality sericitic schist. For cable bolts installed prior to stope exploitation.3 mspan tunnel driven through poor to very poor quality rock. travel time for the equipment and cable grouting crew was significant. since the bolter was tied up in stope preparation and rehabilitation work. It is surrounded by sericitic schist corresponding to the sub-unit 4b of the Blake River Group (Savoie et al. For large span drifts. Mining method is long hole stoping. the grout curing period is generally respected. The method was successful from a rock mechanics point of view. in which a highstrength reinforcement bar is grouted. Also. In the case of a 4. it may be logistically impossible to support the roof before it collapses. This alteration zone runs for about 100 m up to the ore body. In tunnelling. Rock: Quartz and sulphide veins surrounded by seritic schist. An array of nine 50 ft cable bolts was used to presupport the roof during drift development. Although highly effective for shallow tunnels driven in very adverse ground conditions. Project: Underground gold mine pre-reinforcement. Obviously. oriented E-W. Mine Doyon Experience A variation of the umbrella method was attempted at Mine Doyon. which is located in very weak chloritic schists. with cemented rock fill. it is easy to see that such a work-intensive operation would be deemed neither practical nor economic for mining applications. when production concerns may override ground support design concerns.MINING WORLDWIDE excavation size. Location: Mine Doyon. A better solution was needed. and a polyphased fracturing caused by an as-yet undetermined stress gradient. the operational and safety implications of such cases are important. since several levels were being developed concurrently. 1974) will lead to a logarithmic reduction in unsupported stand-up time. Midi and Super Swellex. and different types of bolts were field-tested. Pre-reinforcement using Super Swellex at Mine Doyon.600 Standard Swellex bolts/month are being installed at the mine. and the method became a standard at Mine Doyon for bad ground conditions. Presently. Prereinforcement holes are 50 to 60 cm longer than drifting length. in addition. Canada. to accommodate the 3. parallel and spaced 60 to 75 cm apart. Peru. Several variations of the method were used to secure pillars and cuts in stopes. installation before the next drift advance. Peru. for both permanent and temporary support in the five different types of rock at the mine. around 300 m of access drift and stope have been developed using this method. Super Swellex and Midi Swellex bolts are being used in areas where the metal content is high and recovery must be around 95% and. The experience was a total success. some 1. 65 . Rock: Variety of different rocks. was Swellex bolts from Atlas Copco. Since the few extra holes required for the spiling bolts are drilled at the same time as the blasting holes. nearly 2. is the main mineralized structure. but has contributed to an increased advance rate and improved economy. Rockbolt selected: Standard. and the bolts are installed in the short period between drilling and loading.000 m long and up to 200 m deep.MINING WORLDWIDE Requirements were: easy integration in the normal development cycle. are installed sub-horizontally over the perimeter holes. and to slightly reduce drifting length to about 3 m. the Swellex system has not only increased safety. Excavation method: Drifting. and reasonable cost.000 m above sea level. The design of drift support in the mine has been the subject of detailed research by its soil mechanics team. this pre-reinforcement method does not increase the excavation cycle time. Inflation pressure is 300 bars. it was decided to try pre-reinforcement using Super Swellex bolts instead of cables. Installing Swellex at Ares mine. In order to increase productivity and regain some flexibility.6 m-long bolts. With the Super Swellex bolts. Thanks to its special features. Holes are drilled using the development drillrig. ROCK & SOIL REINFORCEMENT Project: Underground gold and silver mine. The final choice. Detailed Research in Peru The Ares Gold and Silver Mine is located 275 km north-west of Arequipa. productivity actually increased to the same level as for ramp and drift development in fair to good quality rock. Close cooperation between the engineering and production departments made this success possible. It is a new ore deposit in which the Victoria vein. Location: North-west of Arequipa. nearly 5. Five to six Super Swellex. effective support. Rock reinforcement required: Permanent and temporary support. An efficient solution to this problem has been to use Super Swellex bolts as a prereinforcement method. The method can be applied to systematically support roof. Rock: Volcanogenic massive sulphide deposit. It is part of the Abitibi Greenstone Belt. on a 1. and can be easily integrated into development operations. Louvicourt Solution The Louvicourt Mine is a polymetallic orebody of copper. It is a volcanogenic massive sulphide deposit. and simplicity of the operation. The collaboration of the production department was crucial to developing the method. The orebody dips 70 degrees north and strikes E-N-E 66 with a plunge to the east. Rock reinforcement required: Support through fault zones. Mining method: Longhole stoping with paste backfilling. Location: Near Val d’Or.5 m x 1. improves safety. The holes are drilled 50 degrees upward.5 m below ground surface. Rockbolt selected: Super Swellex. starting 47. zinc. Project: Mine with copper. ROCK & SOIL REINFORCEMENT . The immediate support effect. zinc. Quebec. within the Precambrian Shield of eastern Canada. silver and gold. The gouge associated with the faults. 25 km east of Val d’Or in northwestern Quebec. and the bolts are inflated to 300 bars using a pneumatic Swellex pump. risk and lost time associated with rehabilitating a caved roof. or to prevent caving from a nearby fault zone. contribute to the formation of high roof and unstable ground conditions.6 m-long Super Swellex. silver and gold. as the experience of the miners and supervisors is a valuable asset in improving excavation methods. Gouge thickness can reach up to 90 cm. are definite advantages to using Swellex instead of cable bolts. Steel straps are sometimes used to increase support capacity and cohesion. the unfavourable dip of the two main joint sets. Such experience shows that Swellex bolts can be efficiently used as a prereinforcement system in order to improve productivity and safety while excavating tunnels in incompetent rock. The method is fast.MINING WORLDWIDE Super Swellex aids safe and cost effective development at Louvicourt mine in Canada. Three to four rings of 3.0 m x 2. Thickness varies from 20 m to 100 m.0 m pattern. Dimensions of the orebody are 300 m along strike and 500 m along dip. The method creates a small increase in normal cycle time. are installed in the roof of the drift before the next advance in the fault zone. Systematic stability problems are encountered while drifting through fault zones disseminated in the orebody. and the intense black chlorite alteration of the joints.5 m to 2. Cooperation of the underground department for testing is paramount to the success of the technique. The mining method is long hole stoping with paste backfilling. but the drilling and installation time are more than justified by the cost. with minimum handling. some 300 km north-east of the capital Ankara. For benching and mini-benching. Rockbolt selected: Swellex. At the Neves Corvo copper mine in Portugal. which means time is precious. The two fully-mechanized Boltec rigs are installing 2. Rock reinforcement required: Faster bolting to increase production. and Torres Marquez.4 m-long Standard Swellex bolts in the roof and walls of the orebodies. have been put into production. Project: Underground copper mine. the mine management and support crew agreed that the system also offers value for money. Rock: Seam roof.3 million t. Sven Buskqvist. and the remaining 10% from mining of the sill pillars. Although the unit cost of Swellex bolts might seem expensive compared to some other rockbolts. 20% from benching. After experiencing the speed and ease of the Swellex bolt installation. Wirsbo Stålrör AB.9 million t of copper and tin ore. The aim was to introduce the high load-carrying capacity and yielding characteristics of Swellex to the country’s coal industry. they have proved to be the best solution in terms of the total installation costs. and the time taken to install a Swellex bolt in a pre-drilled hole at the mine is now less than 30 seconds. Drift-and-fill mining is carried out by 13 face drilling rigs. s At Çeltek mine in Turkey. Atlas Copco Portugal. Rockbolt selected: Standard Swellex EXL. owned by Somincor. Reserves are around 30 million t of copper and 1. Antonio Rodrigues. Some 95% of the ore is being extracted using several mining methods: 60% of the tonnage comes from a modified drift-andfill method. the support system of a gate road has been changed from the traditional steel arches to systematic support with Atlas Copco Standard Swellex EXL bolts. The mine blasts 25 faces/day to meet production targets. Rock: Orebody roof and walls. equipped with the latest Swellex hydraulic pumps. of which nine are Atlas Copco Boomer units. resulting in an increased daily advance rate. safety and economy. A universal pull-tester developed by Professor Ünal’s team was used to show the superiority of the Swellex bolts in terms of speed. the mine is using three drill rigs. a Swellex bolt is installed to demonstrate its unique ability to provide safe and immediate support. Location: Southern Portugal. has recently increased annual production from 2. They are popular because they offer instant support with easy and fast installation. Systematic Support in Turkey At the Çeltek Coal Mine in Turkey. with an average spacing of 1 m. Somincor. Turkey.MINING WORLDWIDE Increased Output in Portugal The Neves Corvo Copper Mine in southern Portugal. Asia Minor. Rockbolting is the bottleneck in the production cycle. Swellex bolts have been used at the mine for many years. Two Atlas Copco Boltec rigs for mechanized rockbolting. Mining method: Longwall mining. ROCK & SOIL REINFORCEMENT Project: Underground coal mine. Mining method: Drift and fill with benching. two of which are Atlas Copco Simba units. Rock reinforcement required: Replace steel arches with bolts. and several bolting units have to be used because of the long distances between the different faces. 10% from mini-benching. Location: Çeltek.000 are installed annually. This follows a joint effort involving Atlas Copco Turkey and a team led by rock support expert Professor Erdal Ünal of the Middle East Technical University. and more than 60. Time spent on roof support in a cycle decreased from two hours to between 20 and 30 min/m of advance in the gate road. 67 .1 to 2. . Hinteregger. or possibly turn around. Rock: Mix of biotite gneiss and non-glaciated folded. Austria is building more dual carriageways. the risk of traffic nuisance is such that trucks are currently banned from its highways during the night hours. Rockbolts selected: Super Swellex and self drilling anchors. Around 1. on A2 Vienna-Klagenfurt highway.148 km-long tube was driven parallel to the existing Graebern tunnel in highly variable ground conditions. on the Vienna to Klagenfurt section of the important A2 motorway which connects Vienna with Carinthia and Italy. Austria presents the shortest route. a favourite skiing destination for the Viennese. The faces at either end were in different strata. For traffic between the Balkan States and the north.5 km of the tunnel was excavated to standard 70 sq m section. or diagonally across Europe from east to south. 400 m of which was in excavation class 7 and needed a reinforced shotcrete or concrete invert. such as the Atlas Copco Rocket Boomer drillrigs. Austria serves as a transportation hub for virtually any business needing to move goods across the continent. Contractor: Joint venture of Ostu Stettin. Rock reinforcement requirement: Spiling followed by immediate face support. a similar dualling project on the A9 motorway at Graz. Location: Graebern. requiring a flexible approach to excavation and support. Indeed. The contractors used some equipment. including the Rocket Boomer L2 C and self drilling anchors.TUNNELS IN AUSTRIA Removing Bottlenecks in Austria Crossroads of Europe With its position in the heart of Central Europe.9 km-long Plabutsch tunnel. requiring an enlarged section of 78 sq m. Project: Parallel tube for existing bi-directional road tunnel. where vehicles may park in an emergency. The area was intensively folded and faulted. the latest in Atlas Copco technology is being employed. faulted. In its efforts to upgrade to full European standards. so that the face could be mechanically excavated. located near Semmering. and tectonised strata. and driving parallel tunnels for a number of existing bi-directional tunnels across the country. which is big enough for trucks. that was released following the completion of the 9. Two such projects are the parallel tunnel recently completed at Graebern. and a twin tube tunnel project at Steinhaus. Second Tube for Graebern The new 2. ROCK & SOIL REINFORCEMENT An oversize safety section in the centre of the alignment provides a third lane over a distance of 48 m. where the rock was generally too soft for blasting. Atlas Copco Rocket Boomer L2 C at Graebern south face. an Atlas Copco two-boom Rocket Boomer L2 C drilled for spiling and bolting in the top heading. In the tunnels. Excavation method: Drill/blast and mechanical excavation. South Attack At the south end of the alignment. with a mixture of competent and 69 . They may also turn to enter a wide cross passage leading to the second tube. and Porr Tunnelbau. 4 mlong pipe spiles were set around the roof profile in 45 mm-diameter holes drilled by the Rocket Boomer L2 C. Super Swellex 4 m-long bolts were set in the roof at the face as immediate support. Blasting agents were dynamite and cartridged slurry. It has been constructed by Bilfinger Berger for the Austrian highways authority. with 19 intervals of electronic detonators with millisecond delays at 80 milliseconds per step.5 kmlong. Therefore. ROCK & SOIL REINFORCEMENT Steinhaus at Semmering The Steinhaus tunnel is on the B306 Vienna to Bruck road. The rock quality is variable. which were grouted in place. phyllite. calcite and quartzite. in addition to blasthole drilling. As there was no glacial cover during the past million years. Drilling of a full round of approximately 130 x 2 m-deep holes in the top heading took an hour. but periodically slipped back to 150 m behind the face.2 m centres. The top heading was followed by a 2. spiling with pipes was often an absolute necessity. in which the village of Steinhaus is located. There are three cross-passages. The tunnel is twin-tube and 1. generally soft and non-glaciated. Regular support comprised 15 cm of shotcrete with one layer of wire mesh and 4 m-long rockbolts. glacial erosion did not remove the highly tectonised and incompetent parts present at the southern portal. For systematic bolting. and so mostly decomposed and friable. Predominantly. and shotcreted in place. with a maximum cover of 60 m. and will form part of the new S6 highway. the rock mass was jointed and faulted. The drilling rounds were set up using an array of seven lasers to establish a perfect profile. A three-boom semiautomatic Rocket Boomer L3 C performed the support drilling duties at the north end. In addition. with the middle one having a large cross-section to facilitate the switching of trucks between tubes in emergency situations. which were excavated some 60-80 m back from the face. The centre section of the top heading was generally left in place as a safety pillar.7 m-high bench and invert. The tunnels accommodate a two-lane highway in each direction. 25 mm-diameter. Part of the excavated face was also temporarily secured by 12 m-long self drilling anchors. Any blastholes required were drilled using 45 mm Atlas Copco Secoroc bits. on a double curving alignment that takes it into the side of the valley 70 . This will connect with the San Miguel interchange on the section of the A9 Trans-European Highway between the main centres of Graz and Linz. together with rockbolts and shotcrete. When required. If spiling was required. North Face The north end of Graebern featured biotite gneiss.0-1.TUNNELS IN AUSTRIA Rock Support at Graebern Tunnel incompetent rock. which passes through Semmering. The B306 is being upgraded. lattice arches were erected. a more-competent metamorphic sedimentary rock with a high amount of quartz and feldspar. a favourite skiing resort for the Viennese. to support the tunnel face while sectional lattice arches were installed at 1. comprising chalk. in addition to a half-hour for charging and blasting. self drilling or cement grouted anchors with lengths of 4 m or 6 m were used. The faces. Usually. fortunately for the tunnellers. and two blast vibration monitoring stations were set up.5 m intervals in each face during a 24 h cycle of three shifts. 71 . a screw plate and a nut. within which the pillar between the two main tubes was cast using self-compacting concrete. three or four arches were set at 1. ROCK & SOIL REINFORCEMENT Once into more competent ground. Rockbolts selected: Self drilling Atlas Copco MAI rockbolts.5-1. the drillrigs were able to deliver 80-90 holes/round in the top headings. only 10-20 blast holes were required in the faces of the top headings. Some 30 cu m of 8 mm concrete was then pumped through the drillholes. Blasting was by millisecond and long delay non-electric detonators and encapsulated slurry main charge. In order to maintain reasonable underfoot conditions. They spent 80% of their time drilling for rock reinforcement because. and one newer Rocket Boomer L2 C. Advance over a 10 m stretch beneath the filled cavity was protected by arches of 20-30 spiles made of 51 mm x 8 m-long R32 pipe installed at 2 m increments. a single-usage drill bit. Project: Twin tube 1. from where a mixer truck transported it to the face jumbo. generally speaking. non-glaciated chalk. increasing progressively to 60 m at the halfway mark. The rockbolts are available in standard lengths. calcite and quartzite. The faces passed beneath some village houses with around 50 m cover. tightened by plates on both sides. proved to be dry. The rock pillar on the second 50 m of drive was anchored using pre-stressed bolts.5 km-long road tunnel. The bench followewd at between 90 m and 220 m behind the face. The drillrig fleet comprised three lateseries Atlas Copco Rocket Boomer 352S. drilled to depths of 1. Excavation method: Mechanical excavation with some drill/blast. Umbrella Working At the 90 m mark on the south drive. with special customer-designed lengths of up to 12 m. Roof and side support was achieved mainly with grouted rebars and self drilling rockbolts from Atlas Copco MAI. Drainage holes were drilled in the face whenever necessary. bench and invert excavations. A concrete pump was stationed at each bench as a convenient way of pumping shotcrete past the ramp position. Self drilling rockbolts have become very popular in recent years. a temporary shotcrete invert reinforced with steel mesh was laid in the top headings. phyllite. Location: Steinhaus on the B306 Vienna-Bruck road through Semmering. The drillrig was pulled back to drill over the face and into the cavity. using one of the shotcrete jumbos. a connection casing. were secured by up to nine 16 ft-long self drilling anchors with mortar injection.7 m. a 20 m-high Karst cavity was encountered. which. their primary use is for advance support of extremely friable rock. Rock reinforcement requirement: Forward support and immediate face support. for both surface and underground drilling. every 4 or 5 arches on advance. and five MAI M400 water mixing pumps were used for grouting. by the metre from 2-6 mlong. In tunnels. which were mechanically excavated. where the temporary invert was ripped out by an excavator with hydraulic hammer. Rock: Soft. The bolt is made up of five essential parts: a threaded bolt.TUNNELS IN AUSTRIA The full 80 sq m section of each main drive was achieved with top heading. Cautious Advance Work at Steinhaus commenced at the west portal with a 47 m-long central pilot tunnel. and are now used in a number of different applications. The separation over the first 50 m of alignment was 2 to 4 m. Contractor: Bilfinger Berger. or in formations where the drill hole will collapse before a normal rockbolt can be put in place. s Rocket Boomer 352S at Steinhaus portal. . 600 km south. and linked by an allweather road to ship-loading facilities at ROCK & SOIL REINFORCEMENT Location of Raglan Mine in Northern Quebec. where there are two mining methods in use: long-hole stoping and cut and fill. the main rock support consideration is the risk of falling blocks. Although large stopes are not typical at the mine. as well as significant recoverable cobalt and platinum-group metals. despite being more labour intensive. Deception Bay. the mine used mechanical bolts and rebar set in resin for rock support. With the ground permanently frozen to a depth of 425 m.5 million t. Previously. The normal maximum stope size is 30 m-wide and 105 m-long. and limiting the fetching and carrying to be done under extreme conditions. However. This is truly a market sector where Swellex is unbeatable! Project: Raglan Katinniq nickel mine. Mining methods: Longhole stoping. Not only has the bolt been found to perform to full capacity in all temperature conditions. It is a conventional shovel-and-truck open pit. grading 2. and the footwall dips at a 45° angle. This was labour intensive. Katinniq has 10-15 stopes in operation. the mechanical bolts required periodic re-tensioning to be effective. so ground stability is important. Rock reinforcement required: Long bolts not requiring resin. The nearest supply town is RouynNoranda. Location: Northern Quebec. significantly reducing the transportation costs to remote mines.000 t/month of ore produced. with only one or two being the more productive longhole stopes. but these may increase to 4 m-long or 5 m-long bolts when big blocks occur. Because of its light weight. making most of it unfavourable for development of longhole stopes. the ground is more stable because there is no water moving through fissures in the rock. Another bonus is that grout mixes and resin ampoules are not required.79% copper. a stope opened in 2003 measured 160 m-long x 63 m-wide. The mine is accessible by air. and the use of resin posed significant logistical and transportation problems. with an underground mine at Katinniq. Rockbolt selected: Swellex Mn24 and Connectable. but it has also found favour with the operators. with no ground stress problems. Rock: Blocky with permanently frozen fissures. with an ambient temperature underground of minus 15°C.4 m bolts for stability. Canada. where the mean annual temperature is minus 10°C. At any given time. The rest are cut-and-fill which. 73 . Performing in Permafrost The Raglan mine is located on the remote Ungava Peninsula of northern Quebec. The mine generally uses 2. without Swellex. cut and fill.CANADA & JAPAN Swellex in Extreme Temperatures Hot and Cold Mining Swellex rockbolts are used successfully in hot and cold extremes on both sides of the world. The orebody is wide. Katinniq has reserves of 19. about 100 km to the east. the operators are finding that Swellex does not overexhaust them under the rigorous conditions in which they work. account for over half of the 50. With joint spacing over 2 m. about 1.00055. Although the cold makes working conditions difficult. Operator: Falconbridge Nickel. rockbolting at Raglan could be a difficult and time-consuming procedure. with limited height and strike length. The host rock is extremely competent. and speed of installation.85% nickel and 0. and do not require grouting. In these difficult conditions. Raglan uses brine to expand the Swellex bolts in order to avoid freezing problems. The mine management insists that only Swellex can give superior safety in hot 74 rock such as this. Mining method: Sublevel stoping. which are well suited to the large diameter explosives now being used. which enables bolt after bolt to be expanded in just 22 seconds apiece. carries out sublevel stoping in the steeply inclined orebody. Rock: Volcanic host. or heavy tools and equipment. Since then. This is a very fast production rate. Due to the volcanic rock in the area. Japan. they have been using Swellex almost exclusively. and since neither cement grout nor resins can be easily handled in such high temperatures. and 2. Hokkaido. and rates the easy and trouble-free installation system as a big plus. Two-thirds of the bolts currently used in the mine are Swellex.6 m bolts used largely in wall rock. where drifts are 3 m-high and 4 m-wide.000 of the 1. Location: Hokkaido. in order to ensure consistent quality of rockbolting while maximizing productivity. keeping the work area clean. This has not resulted in detectable corrosion in the bolts.000 bolts/month of the 2 m-long Midi Swellex type. s Installing Swellex at Toyoha Mine.8 m Super Swellex bolts as needed. Japan. and a heatwave follows the opening of any new areas.5 m-long Swellex bolts in the normal pattern used at the Toyoha mine to stabilize a round is performed by a single miner in just 32 minutes. Drilling and installation of 1. Toyoha uses up to 2. The operators prefer Swellex bolts because they can be set in the hot conditions without using a work platform.000 of the 2. At Raglan. extreme conditions under which to install effective rock reinforcement! Toyoha. Raglan made the switch to Swellex bolts in 1999.CANADA & JAPAN Easy Installation After an extensive research and testing period. especially considering the high temperature and humidity. These are. The mine is budgeted to use: 6. quick and safe to work with. The key is in the Swellex system itself. Rockbolt selected: Standard and Midi Swellex. indeed. the mine uses Swellex rockbolts from Atlas Copco for rock reinforcement. all drifts are screened and all stopes are bolted. and it is not unusual to see jets of steam coming from newly drilled rockbolt holes. Humidity is extremely high. which is the world’s largest producer of the rare metal Indium from its lead and zinc operations. 50. easy.000 of the 3.500 of the 600 mm Swellex bolts for fastening screens in the 5 m-wide drifts. and recent pull tests confirm this.5 m bolts used for the back. the mine generates rock temperatures of 130°C. The number of holes required at the face has been reduced as a result. Swellex Mn24 has now replaced Super Swellex at the mine. Hot Work in Hokkaido Drillers at the Toyoha mine in Japan get more than a warm welcome when they arrive for work each day. Project: Toyoha lead/zinc mine. They are lightweight. ROCK & SOIL REINFORCEMENT . Rock reinforcement required: Easily installed non-grouted rockbolts. 62. It was found that several point anchor expander bolts installed in 1968 had rusted through 0. when Coated Swellex rockbolts became available. 2. with two Celtite cartridges. The following rock bolts and grouting agents were used during the production phase of the mine: cement grouted rebar. with two Celtite cartridges. Recently. The company contacted SvBeFo. The sandstone is porous. The Stockholm-based consulting company Sycon was contracted to carry out the investigation. During this development of rock support. which are often not more than 1 mm-thick. and in 1987 to Atlas Copco Swellex bolts. time-consuming. and is known to be corrosive. The rock is sedimentary. The groundwater is corrosive. construction and building. This has the advantage of providing more immediate support. The ground water in Kvarntorp seeps through the overlaying shales. ROCK & SOIL REINFORCEMENT Rock Reinforcement Support was exclusively by rockbolts. 1. to solicit their involvement. but relatively homogeneous. point anchor expander bolts proved entirely inadequate. and does not provide any support before the cement hardens. 2.2 m-long. resingrouted rebar. a disused underground sandstone mine that has been converted as an archive store. 75 . the mine switched to resin cartridges as the grout medium used to install rebar dowels. There was a considerable amount of water present in the rock during the excavation of the openings. which have relatively high sulphur content. In 1969. so. Expander type point anchor bolts were used initially. the Swedish scientific organization involved in studying the behaviour of rock in mining.8 m-long. the mine was quick to realize the advantages. 1. varying from white to light grey in colour. SWEDEN Coated Swellex Examined Unique Testing Opportunity Not far from Orebro in central Sweden lies Kvarntorp mine. owner Yxhult AB experienced a number of small falls of roof at Kvarntorp mine. and Coated Standard Swellex. tests were conducted on two of these bolts that had been installed nine years earlier. These were used from 1967 to 1969. and had fallen out. The Swedish industrial safety authority requested Yxhult AB to launch an investigation to determine the extent of the problem. with sandstone overlain by shale. and Atlas Copco agreed to take part in the project. Support Investigation A few years ago. then the mine switched to cement-grouted rebar.8 m inside the rock. occurring in horizontal layers. and began using them in 1987. Cross-section of bolt No 1 shows corrosion described as insignificant. It is lightly laminated with thin clay seams. and to recommend a rock support programme that would ensure the safety of people working underground. resin-grouted rebar. when they switched to resin-grouted rebar. The disadvantage of cement-grouted rebar is that it is messy.2 mlong. installed vertically as the drives and rooms were excavated. and were replaced by cement-grouted rebar. but this had disappeared over the years.8 m-long. making it difficult to establish the exact conditions to which the bolts have been exposed. and it was found that virtually no corrosion had taken place.KVARNTORP. Internal surface of bolt No 2 shows it is practically free from corrosion. installed 5 bolts/row. it is still arduous and. It was decided to perform pull tests on a number of bolts at Kvarntorp mine to test their integrity after having been in the rock for nine years. and the expanded bolt is pressed tightly against the rock. Contact Turgay Ozan turgay. there is no doubt that mines and tunnels with aggressive environments can benefit from the many advantages of Swellex rockbolts. All Swellex rock bolts are stamped with an alpha-numerical identification. “over-spin” or “underspin”. is pressed into the microstructure of the rock on the inside of the drillhole. The Swellex exceeded 76 Conclusion The conclusion was that. Coated Swellex Swellex rockbolts are manufactured from folded steel tubing that can be inserted in the drill hole manually or mechanically. with 2 m between each row. The full report from the Swedish Corrosion Institute is available from Atlas Copco in English upon request. They were not involved in any of the rock falls that had occurred. and from tunnel to tunnel. As the bolt is expanded. showing that this was a 1. 1993. s ROCK & SOIL REINFORCEMENT . which is semi-viscous. The result of this investigation establishes Coated Swellex rock bolts as long term support suitable for use in a variety of environments. However. This provides guaranteed full column support. the result is a guaranteed quality installation. The recovered bolts were marked 1. Situations differ from mine to mine. as the water pressure is applied equally throughout the [email protected] 930125 B STD Sweden. They were recovered in mid-May. One of the bolts had two small local corrosion penetrations that did not affect the breaking strength. and the bolt expands over its full length. there are high wastage factors. Coated Swellex bolts had not lost any of their strength or support capability. As the coating completely covers the outside of the bolt. However.8 m Coated Swellex bolts fitted with 150 mm x 150 mm bearing plates. SWEDEN their minimum specified breaking strength during these tests. deforming to the irregular sides of the drill hole. as in the case of resin. 2002. this coating. The coating provides a barrier between the rock and the bolt that prevents the ingress of corrosive water.com and ask for report number 80 103 (rev 1). so were in the rock for a little over 9 years. after which cross-sectional pieces were sawn out for more detailed inspection. as with cement. with a few small shallow patches. At the Corrosion Institute. These range from inadequate grout in the hole or. less than 0. The installation takes a few seconds. the rock cores were removed and the bolts visually inspected. and require careful study by qualified people. Both resin and cement grouting of rebar present the operator with a number of installation quality concerns.8 m-long bolt manufactured in Sweden on January 25. Internal corrosion was mostly non-existent. after more than nine years in the corrosive environment of Kvarntorp mine.1 mm-deep. Coated Swellex has a rubberized bitumen coating on the outside of the bolt. and expanded with high-pressure water.KVARNTORP. Sycon made the following recommendation: the area where the rock falls had occurred should be re-bolted using 1. Observations by the investigating engineer were that uniform corrosion on the outside of the bolts was very small. These were forwarded to the Swedish Corrosion Institute for further examination. Overcored Bolts It was then decided to over-core two Swellex bolts to establish their condition. both of which adversely affect the support capability of the installation. and Curved drive at Yucca Mountain ESF tunnel. resulted in rejection of most available ground support products. Super Swellex rockbolts were chosen. This has impact on ground support design. Contractor: Kiewit/Parsons Brinckerhoff. close to Las Vegas. A large percentage of the ESF tunnel design has been done according to a Nuclear Quality Assurance program (‘Q’-standard). located in the Nevada desert approximately 160 km from Las Vegas. Location: Yucca Mountain. USA Tunnelling with Nuclear Quality Assurance Stability for a Hundred Years The construction of the Exploratory Studies Facility (ESF) at Yucca Mountain has set new quality standards for tunnelling operations. The Exploratory Studies Facility (ESF). Tunnelling at Yucca Mountain will probably go on for many more years. together with welded mesh and a rolled steel channel. Rock: Volcanic tuff. The requirements on long-term stability for radiological safety of a future repository. The 7. type of ground support chosen. similar to that used for nuclear power plants. will be ROCK & SOIL REINFORCEMENT an underground laboratory for engineers and scientists to help determine the ability of natural and engineered barriers to safely store spent nuclear fuel and high-level radioactive waste in a geologic repository. Nevada. Rockbolt selected: Super Swellex. procurement of ground support products (including lifetime documentation and traceability of materials used in manufacturing). Project: Nuclear waste repository investigation. With nuclear waste accumulating in many other countries. Underground Laboratory Yucca Mountain. installation of ground support. is today the only site that the US Department of Energy (DoE) is studying for the nation’s first permanent high-level nuclear waste repository. while at the same time maintaining flexibility for scientific investigations and acceptable tunnelling productivity. Ground support is ‘Q’ classified.681 km-long East-West Cross Drift tunnel to investigate ground conditions over the proposed repository. part of the Yucca Mountain project.8 km-long ESF tunnel has been driven by TBM within the rock formation that is being evaluated to determine suitability for the final repository. and may become a part of the repository itself. in this case equal to 100 years. A similar system was used to support the more recent 2. adding invaluable practical experience to the world’s pool of knowledge of how to construct repositories for nuclear waste. 77 . Rock reinforcement required: Systematic roof support with 100 year stability. for permanent support in the ESF tunnel. Instead.NEVADA. this project is being watched very closely by a number of agencies around the world. Excavation method: TBM and roadheader. It has been proved possible to build a tunnel according to nuclear quality standards. the TBM entered softer material in which steering was difficult. Exploratory Studies Facility The 7. Minor faulting events had caused through-going joints. local economic and socio-economic impacts. 78 . 3. ease and cost of constructing and operating the site. Most of the excavation will be in the uppermost and middle Topopah Spring formations. The first 200 m of tunnelling were difficult.NEVADA. groundwater.700 m of tunnelling from the entrance at the North Portal. The ESF has been geologically mapped along its total length. encountered approximately 200 m into the mountain. public safety and concerns.8 km-long. two testing alcoves were excavated to gain access to the fault deep inside Yucca Mountain. necessitating backfilling and grouting of the void created. with a total thickness of at least 1. which is a part of the ESF. verification of the function of the products used. the scientists will be able to thoroughly investigate rock strength and movement.8 km.4 MPa. Yucca Mountain consists of layers of volcanic tuff. The Bow Ridge Fault. having an unconfined compressive strength as low as 1. environmental concern. USA The data gathered. oriented in the same direction. Even though the fault had slipped approximately 100 m. the North Ramp. has been completed. By examining the surface and the underground space that will be accessed via the ESF. Other factors that will be considered in the site characterization include: geologic history.22 m centres. After approximately 2. geologic information. For about 1.000 m of the ESF main tunnel was ROCK & SOIL REINFORCEMENT Part of the ESF main tunnel with typical ground support installed. led to block fallouts. and steel sets were installed on 1. Close to the Ghost Dance Fault. in combination with low stressed rock. will assist in the final decision on whether Yucca Mountain is suitable for a nuclear waste repository. ESF Tunnelling Progress The TBM was launched from a 60 m-long drill/blast starter tunnel. using a 55 m-long gantry built into the TBM trailing gear. and earthquake and volcanic activity. After crossing the fault. 7. Investigations to determine the suitability of Yucca Mountain as a potential repository are well underway.000 m. and the effect of high temperatures on the strata. A 7. was driven at a 2% downgrade against rock beds dipping 2° to 15° to the east. and steel sets combined with steel lagging had to be used extensively. This. closely spaced and nearly parallel. together with results and conclusions from the investigations. tunnelling was through the Imbricate Fault Zone. weak tuffaceous material. the TBM reached the Topopah Spring potential repository host rock at approximately 300 m depth. located approximately 300 m below the surface. Ground was lost above the TBM. following which a repository licence application will be submitted to the Nuclear Regulatory Commission. The first part of the ESF tunnel. In this formation. it was only a few metres wide.8 km-long tunnel. which proved very difficult. This is the potential subsurface repository horizon. was filled with a soil-like.6 m-diameter ESF tunnel was excavated by Kiewit/PB using a CTS TBM to a design by TRW Environmental Safety Systems Inc. and is more than 100 m above the groundwater table. Cement grouted rebar bolts cannot be used in areas where scientific investigations will take place. About 70% of the tunnel has been supported by Super Swellex rockbolts. Also. were used. since it can interfere with geological mapping and geochemical tests. Ground Support System As main support. Hence. since the amount of organic material in the tunnel has to be minimized in order not to pose any threat to nuclear waste packages. providing the surface and track to support the TBM trailing gear. and internal and external audits are carried out to certify that everything is done according to specifications and procedures. The steel channel and WWF prevent rocks falling from the roof of the tunnel. NQA System Applied to Ground Support Since the ESF is an underground laboratory. manufactured by Atlas Copco. were approved for permanent rock reinforcement in the ESF tunnel. For many such reasons. Bushings are then pressed onto the collapsed steel tube. In addiROCK & SOIL REINFORCEMENT 79 . and high advance rates were achieved. The Super Swellex rockbolt is a friction bolt manufactured by Atlas Copco. tion to this. for the installation report. More than 20. The bolt is made from a welded circular steel tube. USA constructed using Swellex bolts.000 Super Swellex bolts have been installed in the ESF tunnel. where rock characteristics are studied. The tunnel must be reinforced in such a way that stored nuclear waste could be retrieved 100 years after it is put in place. depending on ground conditions. this type of bolt cannot be tested immediately after installation. The use of shotcrete is limited. 3 m-long Super Swellex bolts complete with the domed Super Swellex face plate on a 1. the ground support must ensure long-term stability and maintainability.5 to 1 m pattern. There is also a ban on the use of epoxy resin based rockbolting systems. to fully inspected installations. from materials used in the manufacturing. Swellex rockbolts. and the ends sealed by welding.NEVADA. Installing Atlas Copco Super Swellex from the TBM bolting station in competent ground. the DoE stresses that ground support must not interfere with the geotechnical and geological testing. Also. together with a 250 mm rolled steel channel and welded wire fabric (WWF). due to the curing time of the grout. steel reinforced concrete inverts were installed as the TBM advanced. with steel sets used for the remaining 30%. to create a Each steel set and position for the Super Swellex bolts has a number. then folded on itself into a ‘W’-shape to decrease the diameter. Procurement of ground support materials requires lifetime documentation and traceability. Records are kept in a thorough and precise way. the final ground support system must be installed as the tunnel progresses. because the grout may penetrate rock fractures and contaminate test results. wire mesh and rolled steel channels for support. and best week of 266. five out of every 100 rockbolts installed were tested to check if the proof load was reached. with allowable maximum of 1. When the bolt has been positioned in the borehole. Super Swellex 1.8 m-long rockbolts were used for ground support on a 1. with a pressure between 290 and 310 bar. Once again.NEVADA. s ROCK & SOIL REINFORCEMENT Using the drill feed to press the screen against the rock while installing a Swellex rockbolt.2 m-long steel channels. the Nuclear Regulatory Commission is considering licensing the repository. which started at an intersection with the North Ramp of the ESF and. The resulting frictional and mechanical interlocking reinforces and increases the stability of the rock surrounding the drilled hole.6 m. to terminate in the Topopah Springs geological formation. Not a single bolt failed in the pull-out tests.681 km-long exploratory East-West Cross Drift Tunnel across the potential repository.2 m grid over the full crown. five destructive pull-tests were carried out to verify that the Swellex bolts met the minimum anchoring requirement. and the pump automatically stops.7 m. best day of 73. the steel tubing adapts to the shape of the borehole. followed a tangential alignment. 2002. When each batch of bolts arrived at site. A hole is then drilled in the lower bushing. and the remaining three bolts installed. with a best shift of 34. The design of the repository is not yet finalized. This employed a 5 m-diameter Robbins hardrock TBM. The TBM was mining for only 25% of the time. If the TBM entered a new geological formation. As the pressure inside the bolt reaches 30 Mpa. causing the tube to unfold. Rockbolt drilling and installation was carried out at two stations on the TBM. and crossed over the proposed repository block west of the main loop of the ESF tunnel. During tunnelling. water is injected through the hole drilled in the bushing. Future Tunnelling Further tunnelling since completion of the ESF tunnel has included the 2. The Swellex pump unit was checked with a calibrated gauge at least once a day by the Shift Engineer to ensure that the pump was giving the correct pressure.2 m. The TBM average advance was 25 m/day over 106 mining days. and may consolidate the surrounding material while it expands to fit the irregularities of the hole. and that the dimensions were according to the specifications. Spacing and pressurization of the bolts was monitored to verify that they were properly installed. where the Super Swellex bolts could not provide long-term support. a system of tunnels totalling more than 200 km is being discussed in which more than 1 million bolts will be installed over a period of 20 years. confined space inside the bolt. The nominal 80 . due to the concurrent scientific and environmental experiments being carried out. Following the signing of the Yucca Mountain Resolution on 23rd July.500 mm. At the second station three holes were drilled.687 mm. USA spacing was 1. At the first station. with welded wire mesh and 1. together with the screen and the channel. A total of 20 steel sets was required in only one area of the tunnel. 20 non-destructive pull-test were made. including the bolt located at the highest point in the tunnel. Complementary to this. the Kiewit/PB Quality Control group carried out thorough tests and inspections to verify that they had not been contaminated or damaged.2 m x 1. However. after an initial curve. At 30 Mpa the bolt is full expanded in the hole. four Swellex bolts were installed. fast-advancing railway tunnels in China and Switzerland. while conditions are made safe.85 km-long alignment from Gorbitz to Sudvorstadt.1 km and 2. In this environment. as the most cost-effective solution. and Boodex close to the portals. and give immediate support. fractured and weathered in places. drilling preset hole patterns with contour and profile control. Contractor: Walter Bau. focus has been brought to bear on the rock reinforcement systems in use. a hard rock with around 10% quartz content. Fast drilling and slow rockbolting rarely make economic sense. Driving from Dresden to Prague The new 200 km-long A17 autobahn under construction from Prague in the Czech Republic to Dresden in eastern Germany will provide the Czech capital with rapid access to northern Europe and the North Sea ports. and will also form a vital section of the Trans-European road network. Location: Motorway between Germany and Czech Republic. Rock reinforcement requirement: Immediate support. Both tunnel alignments are predominantly in syenite. making the face available for further operations in the shortest possible time. drilling is no longer necessarily the bottleneck in tunnelling operations. Inevitably. top heading and benching. 81 . Mounted on sophisticated rigs. Rock: Syenite. these machines have encouraged their owners to reappraise every aspect of the face operation.1 km-long Doelzschen and the 2.3 kmlong Coschutz tunnels using sequential excavation techniques. They were each ROCK & SOIL REINFORCEMENT Atlas Copco Rocket Boomer 352 umbrella drilling at Dresden. The following case studies trace this theme. three-lane 1. Project: 1. three-lane road tunnels. Rockbolt selected: Super Swellex.3 km twin tube.TUNNELS WORLDWIDE Swellex Versatility in Tunnelling Fast Installation and Immediate Support Since the introduction of the Atlas Copco COP series of high-performance rock drills. 150 sq m section. Excavation method: Drill/blast. where contractor Walter Bau undertook the twin-tube. not least because expensive equipment may be underutilized. through difficult motorway tunnels in Germany and Spain. They are fast to install. The most difficult part of this section is the 8. and in the new road system on the volcanic Atlantic island of Madeira. Swellex bolts come into their own. and their impact on overall productivity. due to large span. each around 60 sq m section. Atlas Copco Swellex rockbolts are also a favourite reinforcement method in the typical strata of volcanic basalt and tuff. a self-governing region of Portugal. with a further six to be constructed. Contractors: Zagope. Inland routes are slow and winding. This facilitated up to four rounds in each 24 h period. Rock: Volcanic formations with lava streams. advancing mainly in soft. an autonomous Portuguese region with its own government. using Odex eccentric bits and extension drillrods. through which cement grout was pumped to form a protective umbrella. comprised five tunnels up to 1. A total of eight Atlas Copco Boomer 352 drillrigs were used for face drilling. Tamega. When the ground got too soft for conventional excavation. Fast Bolt for Madeira The chain of mountain peaks that forms the Madeira Islands. Tamega. Funchal. and 5% of these were randomly tested at 10 t pulling pressure. Where immediate support is required. sides and floor. leaving 14 h available for support work and rock reinforcement. of whom 120. The full. as a routine stipulated in the contract. two Atlas Copco Boomer 352 machines equipped with drillrod cassettes were available. The Porto Moniz project. a 12 m advance could safely be made. and Avelino Farinha & Agrela. and a 37 sq m invert. These drilled 15 m-long holes around the periphery of the crown. to the extent that the entire excavation cycle could be completed in 2. Location: Madeira Island. Project: A dozen km-long road tunnels. Beneath this umbrella.000 live in the capital. near São Vicente. The resulting mountains are steep. and Avelino Farinha & Agrela. Rock reinforcement requirement: Versatile system to cope with extremely irregular geology. Swellex rockbolts can be in place and providing full support up to seven hours earlier than conventional cement grouted bolts. Heavy-gauge steel arches were set in the top headings. Roads are tortuous and often dangerous.800 m into deep valleys. in better rock conditions. Rocket Boomer 104 and 135 drillrigs were used.300 m from the bed of the Atlantic Ocean. The added flexibility of the two-rig system speeded up the drilling and charging process. having been formed by volcanic eruption. The holes were then lined with perforated steel tubes.TUNNELS WORLDWIDE driven by drill/blast in a single direction from twin portals. flattened ovoid section of 150 sq m was achieved with a 41 sq m following bench. and the coastal roads are fringed by high cliffs. mixed ground requiring a lot of support. ashes and tuff.000. Elsewhere. Epos. The islands are located 545 km from the coast of north Africa. and umbrella drilling. two of a total of eleven Rocket Boomer rigs that are employed on tunnelling projects in Madeira. Madeira is the largest island of the archipelago. with two layers of Q378 steel mesh and two applications of shotcrete to roof. The consistent use of top specification rockbolts was reckoned to improve the overall quality and integrity of the tunnel. Excavation method: Drill/blast.5 h. rises some 5. and is 57 kmlong and 22 km-wide. It has a population of around 260. Top headings of 72 sq m section preceded the benches. The new Via Rapida tunnels were built by three contractors: Zagope. Tunnels have been employed to carry the roads beneath the mountains and under the cliffs. Face drilling in the top headings was undertaken by two Atlas Copco 352 Boomers. mostly at full section.269 m-long. levelling the routes and making them safer. running over bridges and through 22 tunnels. and travelling is fraught with problems. the contractor favoured the system because Swellex bolts are fast to install and offer guaranteed support. and plunge from elevations of 82 1. A row of 4 m-long Swellex rockbolts was set in a 22 m-long radial arch at the face to give early support. much of which was scheduled for the night shift. Rockbolt selected: Standard Swellex. rockbolting. where pattern rockbolting was used. and are prone to rock falls caused by winter floods from the mountains. It was designed to divert ROCK & SOIL REINFORCEMENT . fractured basalt. This was invaluable in the softer ground towards the ends of the tunnels. standing side by side. The picturesque Via Rapida road from the airport to the capital Funchal is a typical example. Rockbolt selected: Standard Swellex. 110 sq m Tai Lam tunnel on the West Rail development was a Nishimatsu-Dragages joint venture. Location: Hong Kong. Rock reinforcement requirement: High productivity systems to speed up excavation. Hong Kong Cannot Wait Major new tunnelling operations in Hong Kong have used Atlas Copco drilling and bolting equipment fitted with the very latest computerized capabilities. Ponta do Sol was a project comprising three road tunnels. The Ecumeada Tunnel. Madeira. resulting in an average advance of 7 m/24 h.TUNNELS WORLDWIDE heavy traffic from the scenic coastal road that runs under the cliffs by the ocean. and utilize their equipment more efficiently. Standard Swellex rockbolts. 5. Contractors: Nishimatsu-Dragages joint venture. making the journey much safer. built through the Serra de Agua mountain in the centre of the island. Porto Moniz. Rock: Mainly hard rock. where Avelino Farinha & Agrela used an Atlas Copco Boomer 352 for drilling the blast holes and bolt holes. with a total length of 1. wire mesh and shotcrete. and advance varied between 3. using Standard Swellex rockbolts. together with mesh and shotcrete. Contractor EPOS excavated the tunnel by drill and blast. together with wire mesh and shotcrete.2 m-deep. The 5. not least because of rock falls and floods. cast-in-place concrete lining. 20. Black Hill and Pak Shing Kok tunnels.5 m and 4 m/blast. with the two contractors driving the single ROCK & SOIL REINFORCEMENT Projects: Tai Lam tunnel–West Rail. and provided good reinforcement in the constantly changing rock conditions. 83 .5 km. Dumez. together with steel fibre reinforced shotcrete when the rock was good enough.900 m. The volcanic rock formations are prone to change very quickly. Excavation method: Drill/blast.1 km. is the longest single tunnel at 3. Very large water inflows were experienced. 80 sq m. full section. 110 sq m.5 km. and steel arches. The heads of all bolts were cut away to provide an even surface for the membrane. The geotechnical engineer reported that the Swellex bolts proved very quick and easy to install. where topography favours tunnels as a means of shortening distances. The speed of installation enabled Tecnorocha to finish the project sooner. and up to 30 bolts/h using a hydraulic pump. Portuguese contractor Tecnorocha used three of their fleet of nine Atlas Copco Boomer drill rigs equipped with COP 1238 rock drills to develop the tunnels. A Boomer 352 installed 15 bolts/h with a pneumatic Swellex pump. and heavy water inflows were often experienced. provided the permanent support. and a waterproof plastic membrane was installed prior to the final 25 cm-thick. together with Swellex rockbolts and full service back-up agreements. because they proved to be the most cost-effective solution. when it was not. and has cut driving time from the north to the south coast by 20 minutes. Rock reinforcement comprised Swellex rockbolts. This is a dangerous route. China. Blastholes were 4. such as granite.5 km on the MTRC (metro). five-station extension which will serve a population of 340. The project and works promoter is the Ministry of Public Works. Biscay. Rock: Weak strata of slates and fractured limestone. with two blasts/day. Contractor: Joint venture Dragados and FCC.5 km- long. ROCK & SOIL REINFORCEMENT 84 .6 m rounds. Parts of the eastern section are already open to traffic. Atlas Copco agreed a drillmetre contract linked to spare parts and rock drilling tools supply. Location: Northern Spain Excavation method: Drill/blast. Oviedo. The Black Hill tunnels total 8 km. top heading and bench. the contractor was able to maintain an average progress of 550 m/month. linking the cities of Bilbao. are under construction. Although the tunnels are amongst the most complicated on the MTR. Here. The Black Hill and Pak Shing Kok tunnel projects on the MTRC Tseung Kwan O Extension are part of a 12. Holding Fast on Slipping Ground In Spain. The Pak Shing Kok tunnels project was also a complex job. The 1. in predominantly fractured limestone with slate and quartzite.TUNNELS WORLDWIDE Rocket Boomers WL3 C drilling rockbolt holes at Tai Lam in Hong Kong.3 km-long El Fabar twin tubes. tunnel from opposite ends. from San Sebastian in the east to La Coruña in the west. like the 65 km-long stretch from Ribadesella to Gijón. completing the job in less than a year. were driven by a jv of FCC and Dragados using Atlas Copco Rocket Boomer L2 C drillrigs on each face. A major factor in the progress of both projects was the performance of six Atlas Copco L2 C Rocket Boomer rigs. compared to the forecast of 18 months. with a best daily advance for a single face of more than 12 m.3 km El Fabar. and some 5.000. and a centre siding.000 Atlas Copco Swellex rockbolts. and they achieved an average advance of 200 m/month with Rocket Boomer WL3 C rigs. were excavated by joint venture contractors Dumez of France and Chun Wo of Hong Kong.4 km built by a jv of Hyundai and Kier International. even in clay-bearing formations. Nishimatsu’s stretch was 2. compared to the 10-15 minutes for conventional bolts. Swellex was chosen primarily for its fast installation time of around one minute. and two crossovers with 80 sq m cross sections. and two second-hand Boomer 281 units for rockbolting. Three Atlas Copco Wagner ST 8A Scooptrams were employed shifting the muck. Gijón and La Coruña. six junction chambers.2 m. Tunnelling was carried out in a mixture of volcanic tuff and granite. the Autovia del Cantabríco motorway will eventually run some 500 km along the coast of the Bay of Project: 1. The contractor used three new Rocket Boomer L2 C rigs for face drilling. using the fully-automated ABC mode for 80% of the time. using three Rocket Boomer L2 C drillrigs with two booms. Santander. drilling to a depth of 4. Poor rock areas required around 60. as well as an around-theclock service arrangement. Their best monthly performance was 230 m. with four tunnels designed to serve the up and down trains of two MTR lines. Rockbolt selected: Standard Swellex. and some 30 m/day were achieved for all four tunnels. The rigs drilled 4.000 cu m of fibre-reinforced shotcrete. Rock reinforcement requirement: Anchorage capacity.6 km-long. with nine tunnels totalling 6. twin tube road tunnel. Other sections. Both of these were gripper TBMs. versatility to cope with geology and load requirements. In rockburst. then the whole operation moved to the west portals. Contractors: Satco jv (Mitholz). The TBMs advanced an average of around 90 m/week. 6 day/week schedule was operated at the site. Yielding Super Swellex. Rockbolts selected: Standard Swellex. with the fractured rock limiting depth to 1.43 m diameter. A 24 h/day.5 m-high face was drilled to 4. Lotschberg base tunnel. amphibolite. Experience gained at Raron has been used to develop the new Swellex Manganese Line. ten 3. Rockbolting and meshing was undertaken 4. Operations in the north were concentrated at the lateral adit at Mitholz. from where two faces were driven south. then the bursting effect can be mitigated without compromising on support. schist. granodiorite. some rock bolts have to withstand rock bursts.TUNNELS WORLDWIDE The 54 sq m top headings were driven some 700 m from the east end. These are each followed by a suspended trailing backup carrying transformers.5 m. using Atlas Copco Rocket Boomer XL3 C three-boom rigs. Super Swellex. caused by the increased overburden in competent gneiss. The Scooptrams were fully effective at this range and section. enabling the normal number of load/haul operators to be halved. gneiss. 34 km. the pressure builds up in the rock around the tunnel perimeter. 57 km. Largest European Tunnelling Project Lotschberg was being driven from the south by a 9. The top headings were holed through in the middle of the tunnel before bench excavation started. The Boomer L2 C units drilled 40-50 blastholes per round. ROCK & SOIL REINFORCEMENT Projects: Gotthard base tunnel.38 m-diameter TBM from the Raron portal and a similar machine from the Steg lateral adit.6 m Swellex rockbolts were installed for instant support. high productivity with drill/blast and TBM. MaTrans jv (Raron). COP 1432 rock drills speeded up the drilling. and the roof and sides were shotcreted. TBM 9. each equipped with work platforms with anchor drills immediately behind the face. Designers: Consortium of best Swiss engineering and consulting companies. which offers more loading capacity and enhanced elongation. which sprayed a concrete lining over the crown. Yielding Swellex was installed to counter expected problems of rockburst. Rocket Boomer L2 C in top heading at El Fabar. the blasted area was mechanically scaled. and this is followed by independently operated shotcrete robots.2 m behind the cutterhead. causing dangerous spalling. Some 20-30 Swellex 3 m or 4 m rockbolts were then installed into holes 85 . with the average daily advance 4 m on each face. and one north. and the easy and fast installation of the Swellex bolts provided immediate support behind the TBM. in holes drilled by the Boomer rigs. Rock: Mainly hard rock such as granite. limestone. During and after mucking out. If the rockbolt is designed to take up some of this swelling pressure. AlpTransit. AstHolzmann (Amsteg). For every metre of advance. Location: Switzerland Excavation method: Drill/blast. A full 8 m-wide x 8. ventilation fans and ancillary equipment. and can yield explosively.5 m depth for each blast. Rock reinforcement requirement: Safety. and steel arch support with mesh and reinforced concrete was required. cable reels. full section and top heading. The face took around 1 h 50 min to drill out. one of three delivered to Mitholz. with average overbreak of 18-22 cm measured by the Bever profiler on the drillrig. a 90 m-long x 13 m-wide x 12. In the opposite direction.58 m TBMs started on the 11. The profile of the running tunnels was near perfect. in the extreme south of the drive. At the base of the adit. and. reducing to 108 sq m at the back. Swellex rockbolts of lengths 3 m or 4 m were installed into holes drilled by the Boomer 353E. contractor Ast Holzmann completed the 1.4 km drives towards Sedrun in mid2003.7 m-diameter hardrock TBM.5 m-high top heading and 4 m bench to create a 125 sq m cross-section. A further 5 cm of fibrereinforced shotcrete was then applied to the walls. Swellex has a prominent role in AlpTransit. or four rounds. a 5 cm layer of shotcrete was applied to the roof.88 km-long cable tunnel between the transformer room and the existing Amsteg power station using a Robbins 3. Murer and Strabag have driven a 1. Average daily advance was 10 m. improving productivity and helping to keep costs under control. drilled by the Boomer XL3 C. with 40 m-long crosspassages at 320 m intervals. Following each second round of advance. In squeezing ground. Two 9. wire mesh and fibre reinforced shotcrete were used.TUNNELS WORLDWIDE Mountain of Swellex at Mitholz on AlpTransit Lotschberg. excavation towards the portals has not yet started. particularly in view of the 1. Meantime. An Atlas Copco Rocket Boomer 353E drillrig was used on the adit to drill a full face of 105-110 holes to an average 3. again using the Rocket Boomer. since Swiss designers can rely on the safety and controllability of its installation. Most of the support was by 3 m and 4 m-long Swellex set in 38 mm holes. where four faces were established. The junction with the running tunnels is hugely impressive. where crystalline rock may produce rockbursts.5 m-high transformer room was excavated. and the holes were charged with aluminized slurry with non-electric detonation. which is particularly important in long and deep tunnels. as well as its versatility.5 m depth. using the rig basket for access.000 m of overburden at this point. This was advanced as an 8.78 km Amsteg access adit on a 1% downgrade through the Aar Massiv and Erstfeld gneiss to the main tunnel horizon. Swellex Manganese and MAI SDA were used. At Alptransit Gotthard. Atlas Copco Rocket Boomer XL3 C. and another 2 cm to the roof. Contractors are happy that Swellex is a good investment. s ROCK & SOIL REINFORCEMENT 86 . installing support close to the face results in downtime. of which more than 50 km are in Italy. it was kept to a minimum. a division of Austrian contractor Strabag. Rock: Soft. Alassio Motorway Link Road Ilbau. However. In highly fractured rock. Excavation method: Open face TBM. such stoppages are a major concern for both the contractor and the client. but volcanic and seismic activity over the millennia has rendered it highly fractured and disturbed. Rock reinforcement required: Fast. or more. Ground support by rock classification behind a TBM. for most types of TBM. the client specified Swellex and supplied a stock of bolts to the contractor. With a stroke of 1. TBM utilization in Italy can be as low as 30% to 50%. reinforcement. dependable roof support with five-year life. should be installed as quickly. some clay and blocky rocks. the Jarva TBM allowed installation of immediate support within 3 m of the face. and how quickly it can be installed.ITALIAN TBM APPLICATIONS Rapid Support Behind the TBM Improving Utilization For TBM tunnelling. Location: Alassio. This also allowed installation of truly radial rockbolts in the crown.6 m-diameter Jarva Mk12 TBM to excavate the pilot for the 2. such was the interest in improving TBM utilization. Contractor: Ilbau srl. The company employed its veteran 3. The main challenge is to limit machine downtime and increase productivity while at all times respecting safety requirements. since this involved TBM downtime. of the total production time. the aim at Alassio was to install adequate support with minimum impact on TBM productivity. When rock support is required in conjunction with a TBM operation. the Alpine and Appenninic geology of Italy is both good and bad. At Alassio. has excavated a total of over 100 km of TBM tunnels. non-abrasive calacareous marls. with rock support and reinforcement accounting for 50%.4 km-long two-lane road tunnel on a new link road between Alassio and the nearby Genoa-Firenze motorway. consideration must be given to the type of support required. The four-lane highway was built in the 1960s. requiring a relatively high degree of support. principally rockbolts. dry. as possible. Given the relatively high cost/m of TBM tunnelling. Italy. and passes through many tunnels and over many bridges on its route parallel with the Italian coast.2 m and a cutterhead body of about 2 m. The relatively hard rock suits TBM tunnelling. However. ROCK & SOIL REINFORCEMENT 87 . with most support work carried out concurrent with TBM advance from the platform on the trailing backup some 16 m back. Project: Pilot tunnel for motorway link road. Rockbolt selected: Swellex. As with all TBM projects. and as close to the face. Developments in the speed and ease with which support can be applied to improve TBM utilization are of interest to all parties involved in TBM tunnelling in disturbed rock. Although sometimes perceived as more expensive than alternative rock support and reinforcement systems. and often from stroke to stroke of the TBM. F5 and F6.9 m dia. ground consolidation techniques.0 12. and easier communication with its client.5 8. clients and contractors. Support installed was about 10% more than originally estimated. This was close to the optimum 60 m/day achievable in a short tunnel operating a single track muck hauling system. dry. These created no serious safety hazards. Adapted from established Austrian practice. and three stations containing three groups of 1. because of the potential impact on TBM utilization. thin layers of shotcrete spalled off. the payment schedule for rockbolting and other support requirements varied according to where it was installed. may be required. the consultant monitored geotechnical instrumentation installed by Ilbau. but also specifies where. Swellex is applicable in all classes requiring rock bolts. In the first 1. mesh and shotcrete could be installed from the working platform without interrupting TBM progress. and its geomechanical properties and speed of installation are attractive to consulting engineers. with 15% in type F5. Along the tunnel there were 15 convergence measuring stations. The easy handling of Swellex is welcomed by tunnelling crews. Class F7 constitutes rock with no selfsupporting capacity. and zones of fractured and blocky rock. with a corresponding 10% reduction in productivity. The client specified the use of Swellex for rock reinforcement at Alassio. there is no need to keep a stock of any other type of bolt on site. and broke through on schedule. and supplied the requisite bolts to Ilbau for installation. involving TBM downtime. For more reliable estimating.09 F1-F2 F3 F4 F5 F6 I II III IV V As part of its contract. In Ilbau’s table of rock support for instance. In better rock conditions (Classes F1. working 127 h/week on a 2 x 11 h shift/day. the unit price of Swellex becomes substantially less significant when compared with the costs saved in labour and TBM downtime. In addition. Swellex reinforcement over the same length averaged about four bolts/linear metre. Average advance was about 15 m/day. installing 110 bolts. neither too much. nor too little. Ilbau was responsible for the design of the pilot tunnel support. Data gathered greatly assisted the main tunnel final support and lining designs. wire mesh and shotcrete were used in fault zones where roof falls had occurred. ROCK & SOIL REINFORCEMENT . Rock support accounted for approximately 50% of TBM downtime on the Alassio pilot tunnel. Comparison of rock classifications methods. some clay content. the table not only considers the most appropriate rock support for given rock conditions. and how quickly. TBM) 33. and 15% in type F5.ITALIAN TBM APPLICATIONS Table 1. F2 and F3) bolts. the support should be installed. The TBM completed the 2. To monitor the quantity and quality of support installed. with small falls of rock away from bedding planes. and 4.5 1. Swellex is effective over a particularly wide range of rock and soil types. and requires a halt in TBM advance.5 m long extensometers in the crown and into each wall.918 m of the Alassio pilot tunnel. the client’s consultant geologist visited the site about twice a week.5 m-long. or full lining support with ribs and timber lagging or bolted liner plates. Class Bieniawski 1973 RMR 83 67 52 29 15 Deere 1969 RQD 90 75-90 50-90 25-50 less than 25 Barton 1974 O-Norm Q Class (3.5 m. Together with its ease of application and immediate support potential. from class F1 to F6. required support was mostly that of types F2 to F4. Alassio geology comprises mainly soft. Swellex has the all-round advantage. 3 m.472 m-long pilot tunnel in eight months. consolidation and support measures ahead of the TBM should be considered. Ilbau developed a rock class and support measurement system specifically for TBM tunnelling (Table 1).1 m. In such conditions. In other areas. as well as five tangential and five radial pressure cells. with a best advance of 53 m/day in class 2 rock. 60% of which were 1. In Classes F4. Rock quality tends to change very rapidly.5 0. At Alassio. As a rock reinforcing tool. non-abrasive calcareous marls with 88 defined bedding. with most falling into support types F2 to F4. with higher unit prices for support installed close to the face. 5. mainly from the backup platform. Swellex. and confirmed that Ilbau was installing adequate support for a pilot tunnel. and the remainder 2.5 days/week. support must be installed as close to the face as possible. In zones of extremely difficult ground. By specifying Swellex. and improve ventilation systems. Luckily nobody was injured. Italy. The penetration rate was between 5. Excavation method: Robbins 4. The area is highly seismic. 89 . interspersed with mudstone. Best performance was 54 m/day in Class Fl. where heavy rock reinforcement was required. but tunnelling stopped for three weeks to upgrade gas detection. which accumulated close to the machine and caused an explosion. overthrusts. Average advance rate was 20. and weathered rock close to the surface or affected by underground water.6%. and only 2 m to 4 m/day would be expected. TBM utilization varied from a maximum of 45% in Class Fl to a minimum of 8.4 m/day in Class F6. averaging 25. unstable ground (Class F4 to F6). 11 hours/shift.5% in Class F6. and the tunnel crosses the main fault zone. and highest advance rate was 90 m/day and 808 m/month. Rock class distribution at Alassio. It is interesting to note that the good overall performance was achieved in spite of two poor months of around 50 m/month.ITALIAN TBM APPLICATIONS Val d’Arzino Water Diversion The Val d’Arzino is north of Venice. mudstone and claystone. but which would still be able to overcome difficulties in weak and unstable rock. with faults. ROCK & SOIL REINFORCEMENT Project: Water diversion tunnel.5 m diameter. A large section of the tunnel (63%) was driven through good.5 m TBM at Val d’Arzino. but the remainder was through difficult. A scheme to divert water from Arzino River to the city of Pordenone included a tunnel.5 m-diameter TBM. Rock reinforcement took 44. Effect of rock conditions on the 4. in 1976. The contractor worked 2 shifts/day. The rock encountered along the tunnel alignment demonstrated a large variation in stability. The weak formations include rocks such as marl. The older formations overthrust the younger strata. but a significant achievement was 7. The contractor. Pordenone. near the border with Slovenia and Austria.4% of the total time. 4. Contractor: Ilbau. The challenge was to select a machine with high productivity in good rock. used a brand new Robbins TBM. claystone and weathered formations. 5. A delay was caused by an unexpected methane gas inflow emanating from a black marl formation. and. Austria. mostly through stable limestone and marl strata.9 m/day and 453 m/month. Rock: Limestone and marl. Rock reinforcement required: Rapid support behind TBM in variable strata. a major earthquake with epicentre near the Val d’Arzino was apparently linked to the faults crossed by the tunnel. with a slope inclination of 1. fair or fairly unstable rock (Class Fl to F3). with Swellex rockbolts as support. install safety devices.5% to 2%.5 m/h in Class Fl and 3. Ilbau.5 in Class F5. Location: Arzino River. Rockbolt selected: Swellex.7 km long. 27 5. The headrace tunnel and 326 m-long pilot tunnel for the central cavern were driven by an Atlas Copco Jarva Mk12 TBM.6 25.70 5.4 99.5 m bolts for pilot tunnel and cavern support. preliminary sedimentation. was carried out with an Atlas Copco rig equipped with a BUT 35 boom and automatic rod adding system.88 3.1 46.9 m-diameter headrace tunnel. for drillrigs. and will serve 95. Bolting. using both Super Swellex and cable bolts.7 56. In the drilling and bolting operations.0 47. which conveys the sewage into large caverns where screening. Alto Adige.2 14.4 76.000 drillmetres.28 35.9 125 138 137 133 144 114 130 128 J1 to LT are volcanic rocks-pyroclastites.96 4. Some of the resulting sludge is processed for agricultural applications.ITALIAN TBM APPLICATIONS Project: Underground sewage treatment plant and tunnels.3 43. drill/blast. Atlas Copco Secoroc rock tools were used throughout. This was uppermost in the minds of planners when a sewage treatment plant became an urgent necessity in the Media Pusteria valley.1 62. Rock: Alpine schist. TBM usage statistics for different rock types. Relation between Classification. achieving a 50% saving in energy costs. A service contract provided for regular maintenance of the COP rockdrills.4 38. ROP and TBM Utilization Rock ROP (m/h) Utilization % Daily average (m/day) 35. Rockbolts selected: Standard Swellex. near the Austrian border.7 49.4 12.61 5.5 10. Excavation methods: 3.1 86. s ROCK & SOIL REINFORCEMENT 90 . and more than 4.5 82.000 sq m plant underground.71 7. 3.9 73. This plant is the first of its kind in central Europe. they opted to place the 25.9 13. Contractor: Ilbau srl.5 44. eliminating odour and noise. Standard Swellex bolts were used for reinforcement in the pilot tunnel. nitrogen and other oxygen-depleting pollution out of the waste water. Location: Media Pusteria valley. In addition. The design and size are in accordance with the latest European regulations.2 38. where protection of the environment is of paramount importance. with a view to building other facilities such as reservoirs.6 19.000 people. Rock reinforcement required: 3 m and 4. cleaning 95% of phosphorus.5 m lengths were used for reinforcement of the central and side caverns. valleys and rivers. drilling 51 mm and 64 mm holes. which were dispatched to the Atlas Copco workshop in Milan after every 5. where drilling long holes for bolting in a narrow space is normally difficult.000 Super Swellex in 3 m and 4. Italy.2 41. Alto Adige was a pilot project for Italy as a whole.3 23. They were fast to install and gave immediate rock support. biological and chemical treatment. especially as the local economy relies heavily on tourism.1 9. The site manager found it a great benefit to have a single supplier covering the job. the rod adding system on the BUT 35 boom made it easy.6 8. and will achieve strict purification limits. and rock reinforcement.1 24. and some is converted into biological gas to feed a built-in heating plant. Super Swellex. an Atlas Copco ROC 612HC with folding boom was used for benching on the construction site where the administration and service buildings were erected.3 11.6 Thrust (bar) Cutter load (t/cutter) Torque (amps) J1 J2 J3 T1 R LT F CF 4. are carried out. F and CF are Brixen quartz-phyllites. Above ground. The plant consists of a 950 m-long.9 21. Blasthole drilling was carried out by an Atlas Copco Boomer H 188 two-boom rig. storage depots.9 m-diameter TBM. The plant will occupy the smallest possible surface area at the bottom of the valley.22 5.0 48. The geologist found that the Swellex bolts fulfilled their safety function excellently in the schist rock. degreasing. car parks and sport and recreational facilities underground.7 93. desanding. equipped with service platform. and will also be safer in the event of earthquakes. rock drilling tools. Rather than upset the environmentalists.0 10. Alto Adige Treatment Plant The Alto Adige area of the Italian Alps is a paradise of mountains. These were supported by a further ten of the smaller Wagner ST-2D units for use in the dam’s grout gallery tunnels. capacity to work in soft and weak rock.WORLDWIDE HYDRO Swellex in Large Hydroelectric Projects Construction Reliability International consultants are increasingly specifying Swellex in their designs for hydro projects. Rockbolt selected: Super Swellex. because of the need for absolute controllability of installation.5Z loaders worked on the main tunnels. and supply power to the national grid from the dam’s integral 345MW hydroelectric power station. It will normally have a flow of about 120 cu m/sec. Contractor: Raytheon Ebasco Overseas Limited. 6 m x 6 m.5 units. about 250 km north of Manila. and is the twelfth largest in the world. It will create a vast 14 sq km reservoir for recreation. Excavation method: Drill/blast. which is part of the company’s on-site full service package. Removing the Bottleneck at San Roque US contractor Raytheon Ebasco Overseas Ltd. Designer: Golder Associates. the Philippines capital. 188 m-high dam embankment is believed to be the biggest in Asia. Unlike railway and highway tunnels. flexibility and reliability factors are fully covered. 345 MW. Using Swellex as the specified support system reassures both parties that the quality. six of the Wagner ST-2D loaders were replaced with the larger Wagner ST-3. matched by the same number of MT-436B mine trucks. can be a cause of great concern to both the hydro tunnel designer and his client. When the size of the tunnels was increased.5 m-high. which is 817 m-long. combined with operative training. provide downstream irrigation to 87 sq km of farmland. hydro tunnels are not easy to inspect. The underground fleet at San Roque comprised 22 Atlas Copco Wagner Scooptram loaders and Mine Trucks.100 cu m/sec. Atlas Copco Wagner’s comprehensive preventative maintenance programme. Location: Philippines. Three diversion tunnels were designed to accommodate a flood flow of 4.100 m-long. They will each cater to flows up to 2. (REOL) was responsible for the San Roque dam project on the River Agno in the Cordillera Mountains of Pangasinan province. Project: San Roque on Agno River. Exceptional availability of between 92% and 96% was achieved. The 1. The fact that projects can be designed in one country for construction in another. 11 m-wide and horseshoeshaped. Six ST-7.600 cu m/sec. The remaining 400 cu m/sec of flood water will go through the smallest low-level tunnel. so there has to be a greater emphasis on reliability of construction methods and materials. Three diversion tunnel portals at San Roque. Rock: Mainly volcanic tuff. The two largest high-level tunnels are 16. the ROCK & SOIL REINFORCEMENT first such equipment to be used in the Philippines. was the key to the equipment’s success. using materials from a variety of sources. and also horseshoe-shaped. exceeding the 85% guaranteed by Atlas Copco. Rock reinforcement requirement: Quality control. 91 . because they are quicker to install. installing 700 x 3 m-long bolts/week. The new hydropower plant will harness the flow of the Jhelum river. a 7 m-diameter irrigation tunnel and a 9 mdiameter tunnel to the main powerhouse. and has an excellent quality control procedure during its installation. Urico contractors. Super Swellex was specified by the designer. Economical Support Solution at Uri Atlas Copco Boomer H178 face drilling at Uri hydro scheme. and its 480 MW turbines will supply much-needed electricity to the region. with its three booms. Average progress in the tunnels was 250 m/week. This hydraulically-expanded bolt gives immediate rock support and full column bond. a design/construct joint venture led by Skanska and NCC.500 m-long tunnels at the site. generally from two 4 m rounds. The 11 m-wide. in such rock conditions. Moreover. was selected as the most flexible machine available to excavate faces of cross-sections between 25 and 100 sq m. before transferring ownership to the Philippines National Power Corporation. the exposed rock was sprayed with 50-75 mm of fibre-reinforced shotcrete before installation of the 4 m-long Super Swellex bolts. in the Kashmir Valley of northern India. so the contractor was pleased with the opportunity to use a fast and trouble-free bolt like Swellex to speed up production. Immediate rock support was especially important when facing the soft and unstable rock at San Roque. Swellex was chosen wherever possible. employed six Atlas Copco Boomer H178 drillrigs on the development of 22 km of tunnels at Uri. Atlas Copco assisted the contractors with an extensive training programme to teach the local employees how to operate the rigs. An average advance of 7 m/day was achieved on each face. San Roque Power Corporation will sell and supply electricity to the national grid from 2002 for 25 years. The Uri project is located in the foothills of the Himalayas. Rock reinforcement at Uri consisted of shotcreting and bolting. The Boomer H178. 8 m-high benches remaining in the two large tunnels were duly excavated on schedule before the start of the typhoon season. with a best week of 278 m. A second application of shotcrete was then applied to produce a smooth 350 mm-thick tunnel lining. The Atlas Copco Wagner fleet then moved on to muck out two 1. with Swellex comprising 75% of the bolts used. together with the 22 m-wide machine hall cavern.WORLDWIDE HYDRO Installing Super Swellex at San Roque. US. reinforcement is a bottleneck in the excavation cycle. Golder Associates of Georgia. blasting and mucking out. and more economical overall. than grouted ROCK & SOIL REINFORCEMENT 92 . After drilling. as the regular pattern bolt. The drillrigs were used for all rockbolting work. Right Combination at Alto Lindoso Atlas Copco was the main supplier to Italian contractor Torno for the Alto Lindoso 600 MW underground hydroelectric plant located in northern Portugal. The combination of Torno skills with Atlas Copco service succeeded in completion of what had previously been a very troublesome project. Project: Uri hydroelectric power station. View of dam site at Alto Lindoso.5 m/round. schists. Jammu and Kashmir. Rock: Hard granite. and Alto Lindoso is now contributing power to the Portuguese national grid. Contractor: Torno Construction. tunnel and chambers. Contractor: Joint venture Skanska and NCC. close to Spanish border. and provided a manned workshop container for hydraulic service operations at site. wire mesh and steel arches.WORLDWIDE HYDRO rebar bolts. Rockbolt selected: Standard Swellex. ROCK & SOIL REINFORCEMENT 93 . and the placement of 375.800 and 2. Designer: Skanska/NCC. top heading and bench. weathered granite. Rock reinforcement requirement: To cut bottleneck in production cycle. Rock: Variable. Swellex was the only realistic option. from weak to hard rock. The rock encountered varied from quartz schist to shale.2 million cu m of rock underground. Indeed. Location: Northern Portugal. Around the tailrace tunnel exits. in places where water was flowing. The five Boomer rigs employed drilled mainly in hard granite with a compressive strength of between 1. with some of more recent volcanic origin. Torno operated a two-shift system of 12 h/shift. Construction at Uri involved the excavation of 1. tailrace and access tunnels. The company provided all of the drilling equipment needed for 12 km of headrace. drillers faced weathered granite. Rock reinforcement requirement: To provide temporary support for access ramps.000 bar. Excavation method: Drill/blast. complemented where necessary by shotcreting. which provides a maximum head of 338 m. close to the border with Spain. Rockbolt selected: Standard Swellex. gaining advances of 3. Atlas Copco helped train the drillrig operators and maintenance personnel. and shales. as well as some schists and shales.000 cu m of concrete lining along the 15 km of water tunnels. the Project: Alto Lindoso hydropower. Client: EDP – Portugal National Power Board. Swellex rockbolts were used exclusively for rock reinforcement. Excavation method: Drill/blast. The power generating plant was installed in a chamber 70 m south of a 110 m-high arched dam with a span of 296 m near the confluence of the Castro Laboreiro and Lima rivers. Location: Northern India. and 12 m were guided into the 48 mm-diameter drillholes by hand. Strabag. Accordingly. even in the long lengths required in this unusual installation. and then pushed home by one of the two Atlas Copco drillrigs employed at site. including the time spent drilling. Stuag. and it was decided to install an additional 48 MW turbine. The project involved the excavation of a 180 m-long x 40 m-deep x 20 m-wide open pit alongside the existing station. Universale. combined with faulting in the bedrock in the vicinity of the station.000 Super Swellex bolts were used. at Ybbs-Persenbeug. By the early 1990s. more capacity was required. Austria. The chief engineer of the joint venture constructing the power station observed that it would have been impossible to stick to the construction schedule without the rapid and secure installation offered by the Swellex bolting system. 10 m. 900 of which were 12 m-long. Super Bolts on the Danube The River Danube drives turbines in no less than nine power stations as it wends its way through Austria. Trials with drill/blast indicated an unacceptable high level of vibration which. was built in 1959 with General view of open pit at YbbsPersenbeug power station. take only 15-20 minutes to install. 94 ROCK & SOIL REINFORCEMENT . which take up to a week to set. Hofmann Maculan. Excavation method: Hydraulic breakers and excavators. Contractor: JV of Mayreder-Kraus. Porr. Ilbau. Rock: Faulted bedrock. The oldest. Inserting 12 m-long Swellex rockbolt to support the cut beside the Danube. The bolts gave instant support to the walls of the pit. It was decided to use hydraulic breakers and excavators. six turbines installed. without interrupting its operation. helping keep the project on time and within budget. Rockbolt selected: Super Swellex up to 12 m-long. Bolts of lengths 8 m.WORLDWIDE HYDRO Project: 40 m-deep open pit at Ybbs-Persenbeug power station. Some 2. together with additional rock reinforcement of the vertical walls of the pit. it was decided to use Atlas Copco Super Swellex bolts which. Location: River Danube. threatened the existing turbine installations. Rock reinforcement required: To secure vertical faces of open pit. would cause excessive delays to the project. The design consultants advised the client that cement-grouted rockbolts. In the tunnels. some 3km downstream of the existing Chukha tailrace outfall. strutted. Atlas Copco Boomer 352s were used in rock classes 1. on the Wangchu river. The wall of the chamber was anchored to the deeper competent rock using one row of 114 MAI SDA with 20 m length and 38 mm-diameter at 3 m centres.9 m x 18. and as primary support during excavation of the Head Race Tunnel (HRT). Project manager. which has been excavated at 7. achieved up to 30% longer life than expected. These passed. Excavation method: Drill/blast. and another row of 36 MAI SDA with 24 m length and 51 mm-diameter at 3 m centres. utilized five construction adits. Here. and an underground powerhouse 206 m-long by 19 m-wide and 45. they were grouted. Client: Tala Hydro Power Authority (THPA). well within specification. Excavation. If no water seepage resulted. with displacements of 16 mm and 22. a 22. 32 t pull out tests conducted on the 38 mm-diameter and 20 m-long MAI SDA resulted in displacements of 11 mm and 17 mm respectively. For anchoring steel arches. in combination with Odex Piperoofs. where the average advance was 120 m/month. Rock reinforcement requirement: Roof support. using more than 40 items of capital equipment supplied by Atlas Copco. Location: Wangka.5 m-diameter with rock cover of 60 m to 1 km. Hindustan Construction Company. 2 and 3.8 m finished diameter. and is located near the village of Wangkha. The dam site is about 85 km by road from the border with India.WORLDWIDE HYDRO Rock Mass Stabilization at Tala Hydro Tala Hydro scheme has been constructed in the remote Himalayan kingdom of Bhutan. in combination with MAI SDAs. The HRT.5 mhigh. to make tunnelling possible through soil. 50 sq m modified horseshoeshaped.s Atlas Copco Boltec 435H at work in Tala headrace tunnel. with transformer cavern 191 m-long by 16 m-wide and 27 mhigh.5 m. Hindustan Construction found MAI anchors were crucial for stabilization of the walls of the desilting chambers at Tala. Support Solution (DRESS) in the 330mlong section of HRT affected by adverse geology in Package C4.020 MW. Rockbolt selected: MAI SDA. 8 m-long MAI anchors to check the efficacy of grouted anchors in the poor strata in the HRT. Rock: Gneiss with quartzite bands and biotite schists. Hindustan Construction. which had to be fully ribbed at 60-75 cm intervals. meshed and shotcreted. C4 Package used Atlas Copco Odex for piperoofing. concrete-lined headrace tunnel (HRT). Hindustan Construction used MAI self drilling anchors (SDA) for stabilizing the reinforced concrete wall of desilting Chamber No 3. Major features of Tala are: three desilting chambers sized at 250 m x 13. Hindustan Construction used the Drainage. Two 38 t pull out tests were conducted on 38 mm-diameter. 1. Contractors: Jaiprakash.8 mm. and in class 4 rock up to 70 m/month. Project: Tala Hydro on Wangchu river. bolted. Reinforcement. ROCK & SOIL REINFORCEMENT 95 . MAI SDAs were used both as radial bolts and as drainage elements. slowed advances to 30 m/month. Larsen & Toubro. The Atlas Copco Secoroc button bits were reported by the contractors to have S.97 km-long. Jeur. 6. SDA of 8-12 m lengths were installed in a systematic pattern. Class 5 rock.D. Kingdom of Bhutan. The same anchors have also been found to be very useful in reducing pore water pressure behind the support system. . Experience obtained on the more difficult projects has led to Swellex being specified as a pattern bolt in current projects. In Japan.394 m-long tunnel. Swellex has been used to replace steel arches on a number of projects. Bullet Train Secured on Kyushu Daini Shibisan is a twin-track railway tunnel. who had to overcome major problems with the amount of groundwater present in the sandstone. Rockbolts selected: Super Swellex. Swellex bolts are known to perform much better than conventional bolts. Rock: Weak formation of shale. The site manager described the Swellex contribution to the operation as highly valuable. The 3. Their introduction into Daini Shibisan tunnel ended the expensive ROCK & SOIL REINFORCEMENT business of having to re-excavate rock when it had been deformed by lesseffective reinforcement methods. Southern Japan. and have the advantage of providing immediate reinforcement to the surrounding rock. Project Owner: JR – Japan Railways. and an extremely efficient and reliable method of dealing with the porous and highly-fractured rock formation. Wherever there is rapid deformation of the strata. mainly where grouted rebars are considered too slow to install and take load. Midi Swellex. to good effect. Atlas Copco Boomer drifting rigs installed the bolts. 97 . controllability and reliability. non sensitive to water inflow. In this type of environment. Contractor: Kajima-Zenitaka-Shita joint venture.MAINLAND JAPAN Top Combinations in Japan Speed with Safety Tunnelling operations in Japan are to the highest standards of quality and safety. sandstone and clay strata. Installing Swellex rockbolts at the Daini Shibisan face. Swellex is the bolt of first choice because of its fast installation and immediate load bearing characteristics. need no cement. The solution was Atlas Copco Swellex rockbolts. Portal at the Daini Shibisan high speed railway tunnel. making it virtually impossible to inject the cement required to grout rockbolts. Since then. Project: High Speed Railway. which expand to fill the hole. south of the Japanese mainland. Rock reinforcement requirement: Versatility to cope with geology. shale and clay strata. it is a popular combination of speed with safety. Drilling and reinforcement was complicated. Excavation method: Drill/blast. and are also more cost-effective. Location: Kyushu Island. one of thirteen in the section. immediate rock support. which were expanded using an ESPA51 electric Swellex pump. with some holes collapsing as soon as they were drilled. was excavated by the Kajima-Zenitaka-Shita joint venture. part of the high-speed railway system under construction between Kagoshima and Kumamoto on the large island of Kyushu. Daini Shibishan. and Swellex was originally introduced as a problem solver in specific rock conditions such as high water inflow and squeezing ground. Designers: JH. with penetration rates of 2. s Rocket Boomer H 195 micro-benching at Sobu road tunnel. Rockbolt selected: Super Swellex. in Japan. Rocket Boomer 352-2B rockbolting at Shin-Iwatono highway tunnel. Japan Highways. where grouted rebars are considered too slow to take load. Rock: Variable volcanic formation including andesite. even in soft layers. Excavation method: Roadheader.692 m-long Sobu tunnel located in mountainous terrain on the road between Kyoto and Yonago Tottori prefecture. such as squeezing ground and high water inflow. the first in Japan. Location: Honshu Island. Initially. with a penetration rate of 3 m/min. Rock reinforcement requirement: Safety. top performance was achieved by COP 1838 rock drills fitted to a Rocket Boomer H 195. tuff and porphyrite. large quantities of Swellex bolts have been employed in pattern bolting on a number of projects in heavy and fast deforming ground. The rock is sandstone. Rock: Mixture of sedimentary and volcanic rock formations. with COP 1838 rock drills mounted on BMH 6812 feeds. They have also been used in difficult situations to replace steel arches. Lately. 98 ROCK & SOIL REINFORCEMENT . Midi Swellex. Rock reinforcement requirement: Safety. Drilland-blast operations then commenced in andesite lava using an Atlas Copco Rocket Boomer 352-2B. Shin-Iwatono is one of the tunnels excavated along the alignment. and is located 100 km north west of the capital. Rockbolt selected: Super Swellex. are paramount. a common method in Japan. Rock at the site is andesite lava and tuffbreccia. Swellex rockbolts were selected because of their versatility and effectiveness in the varying ground conditions. There is also increasing acceptance of Atlas Copco MAI SDA self drilling rockbolts. The first 126 m of tunnel excavation was by roadheader in soft tuff-breccia. Advance per round was 1. was carried out by the Tobishima/Aisawa joint venture for Japan’s Public Highway Corporation. Work on the 1. microbenching. tuff and breccias. and leased by local distributor Drill Machine. The Rocket Boomer 352-2B is equipped with two BUT 35 booms. Swellex bolts were employed as a problem solver for specific rock conditions. and work is under way to widen the road from two to three lanes. Solving a Geological Puzzle with Swellex At the 3. The cross-section at Sobu is between 90 and 100 sq m. and the speed with which they could be installed. and their standard of installation. Midi Swellex. and excavation was by micro-benching.0 m/min in the harder andesite. drill/blast. Shin-Iwatono tunnel. Easily Through Difficulties on Honshu The Chuo Highway connects Tokyo and Nagoya in central Japan.2 m. Contractor: Tobishima/Aisawa joint venture. shale. versatility to cope with geology. with its cross-section of 130 sq m. and total advance was 6 m/day. even in soft layers. These properties were particularly important in the softer strata mined by the roadheader. Location: Honshu Island. Project: Sobu road tunnel. Central Japan. and the quality of rockbolts. with a compressive strength of 400-500 bar. Central Japan. Site management reported low consumption of shank adapters and other accessories.MAINLAND JAPAN Project: Chou Highway.5 m/min in the tuff-brecchia. versatility to cope with geology. The drillrig achieved 100 holes in 40-50 minutes. Japanese tunnels require the highest standards in safety and support. and 3.591 m-long tunnel. Excavation method: Drill/blast. This method presupports the planned roof area with steel rods. A conveyor belt for the movement of mineral to the Calusco d’Adda cement plant is installed in the tunnel. Rockbolt selected: Atlas Copco MAI Self Drilling Anchors. Large holes are drilled in the future roof perimeter.5 m-diameter. in which a high-strength reinforcement bar is grouted. as a supplier. Location: Pontida Valley. the rock mass is never without support. Fourth. Umbrella System at Montegiglio Montegiglio tunnel. rather than passive when installed later. been involved in a number of such projects. Excavation method: Open gripper TBM. The TBM was Umbrella of 24 MAI SDA type R51L at Montegiglio. even at the split second following blasting of the round.36 kmlong. Although highly effective for shallow tunnels driven in very adverse ground conditions.SDA WORLDWIDE Front Stabilization Using MAI Anchors Improving Rock Quality Drilling ahead of the tunnel face and installing bolts or grout is a common way of improving rock quality before actual excavation takes place. the support can be more active when installed early. it is easy to see that such a work-intensive operation would be deemed neither practical nor economic for mining applications. Pre-reinforcement is a different way of approaching ground control. Rock reinforcement required: Umbrella of 24 x 9 m-long bolts.4%. a pre-reinforced rock mass will be less damaged by blasting. prereinforcement increases rock strength prior to excavation. Rock: Flysch and micaceous sandstones with silts and clay layers. although the underlying concept could definitely be useful. First. a smaller hole is then drilled. Atlas Copco has. the umbrella grouting method of pre-reinforcement is frequently used. fine grained cement grout. both in mining and construction.36 km-long with 4. Instead of relying on supporting the ground following excavation. Italy. 4. pre-reinforced ground will not deteriorate or collapse as rapidly as a totally unsupported excavation. The tunnel was driven by TBM on a different alignment. From the south entrance of Montegiglio quarry. For the first 800 m. and less disturbed by elastic and non-elastic stress redistribution around the excavation. is a 9. In tunnelling. and grouted at high pressure with high strength. Through each cemented hole.5 m-diameter connection intended to support the mineral extraction activity of Colle Pedrino and Montegiglio quarries. ROCK & SOIL REINFORCEMENT 99 . There are several benefits to this. Second. allowing a safe working period for installation of regular support. westward and more northerly. Project: Mineral conveyor tunnel 9. the tunnel proceeded straight on a SW-NE heading beneath Carvico village at a downward slope of 11. a cableway to Pontida valley links the two quarries. in Italy. Third. Contractor: Strabag Del Favero. which may be subdivided into two main geological groups. NATM is being used. as part of the HanbauTsaotwen Expressway. excavation became difficult. The matrix is frequently slightly weathered. roof support. Rock: Gravel with mudstone and clay alternations. ranging from non-systematic intervention.SDA WORLDWIDE BSH 110-SDA for handling MAI anchor. with a length of 12 m and 3 m overlap. Rockbolt selected: Atlas Copco cement grouted SDA. The conveyor belt storage was located in the area in front of the south entrance. The 65 sq m top headings are maintained 60-70 m ahead of the benches. ribs and reinforced shotcrete. with maintenance carried out during the morning shift. with silts and clay layers with the consistency of damp sand. or no cohesion at all. to bolts with increasing thickness of shotcrete. one of 12 planned east-west connections. up to bolts with net. This allowed the contractor to excavate a total of 6 m. and performed a horizontal investigation along the axis of the tunnel. it was found that the umbrella could be installed within a period of 15 h. 20 m-long x 4 in-diameter drainage holes ROCK & SOIL REINFORCEMENT . with a length of 9 m and a overlap of 3 m. the TBM had to be stopped for a shift to extend the conveyor belt. with some collapse of material from the crown. appearing as loose to medium dense sand. to enable Strabag Del Favero to install radial anchors. Rock reinforcement required: Presupport around arch and sidewalls. despite the poor geological conditions. before placing the next umbrella. operated 5 days/week in three 8 h shifts/day. and cementation generally poor. The feed length was adapted to 4. Taiwan. 1 m-thick alternations of mudstone or clay of hard to very hard consistency and low degree of cementation. More importantly. Twin tubes with 120 sq m section are being excavated from all four portals. Secondly. silty-sandy gravel with cobbles and occasional boulders of maximum diameter 50 cm. Presupport at Pakuashan The 5 km-long Pakuashan tunnel is being constructed over a seven-year period in Central Taiwan. The results showed that further advance with the TBM would achieve only limited results. Due to the small tunnel diameter of 4. contractor Strabag Del Favero suspected weak ground conditions ahead. Excavation method: NATM with top heading.5 m. After some initial mechanical adjustments on the Boomer. which do not fit any of the commonly used rock classifications. Consultant: China Engineering Consultants Inc. During the initial excavation in the Flysch di Bergamo geology. and invert closure follows 6-10 m behind each bench. Location: Hanbau-Tsaotwen Expressway. only limited space was available for positioning and working the drilling equipment. Groundwater is a key factor governing rock mass behaviour. an umbrella could be installed consisting of 24 Atlas Copco MAI SDA of type R51L. The support design for this particular type of section specified an umbrella of steel pipes with diameter 104 mm. In fact. the excavation met micaceous sandstones. bench and invert. Every 200 m of advance. facilitating faster excavation of the tunnel. in steps of 1 m. and sandstone. so an alternative solution was needed. In these conditions. at that point. 100 The Pakuashan ridge is an anticlinal structure of rocks. Atlas Copco proposed the use of a Boomer H145 equipped with two booms and COP 1440 rock drills. due to the weak grain bond. in loose to heavily compacted gravels. These exhibited very low cohesion. Six types were defined. The stabilization and support interventions for the Montegiglio tunnel depended upon the observed geological and geotechnical conditions of the rock.4 m to suit the tunnel diameter. Firstly. Project: Twin-tube 5 km-long highway tunnel. and facilitating dewatering. slowing advance rates considerably. Effectiveness of the support regime is measured using arrays of convergence bolts installed at 20 m intervals. Maximum shotcrete stresses of 150-200 kg/sq cm have been measured. Excavation is by backhoe. Contractor: Bilfinger Berger and Max Bögl joint venture. three vehicle cross passages. the faces moved from compacted gravel into sand with very little cohesion. In addition to the main tunnels. using casing. in the centre of the alignment using NATM techniques. The Göggelsbuch tunnel. and 9 m into the profile rock.SDA WORLDWIDE are drilled ahead of the face. within the design shotcrete strength of 210 kg/sq cm. Results from all three sets of stations are analyzed and compared to theoretical behaviour. the Göggelsbuch is unique. with a ripper for profiling. Munich and Nuremberg. There is also a cross section of extensometers at 200 m intervals which measure at depths of 3 m.5 m spacing. radial pressure cells and strain gauges are installed in the shotcrete. A 400 mm-thick cast concrete lining with waterproofing membrane and drainage system will be installed as final support. Although smaller than the two 7 kmlong tunnelling projects in the middle ROCK & SOIL REINFORCEMENT Project: Nuremberg-Ingolstadt high speed railway. 6 m. This is the first use of SDA in Taiwan. Rockbolts selected: Atlas Copco MAI SDA.3 m/day of 24 h.6 t pullout test. Excavation method: Mechanical excavator. 50 mm is typical. section of the railway. Rock reinforcement requirement: Forward face support. A layer of wire mesh and 200 mm of shotcrete are laid on the floor of the top heading as temporary support. allowing four more faces to be opened.287 m and an excavated cross-section of 150 sq m. solid Feuerletten clay. is the only natural tunnel in the north section of this alignment. solid clay which is subject to shrinkage cracking when dry. It is equipped with an emergency shaft that is connected to the surface by two 150 m-long galleries. along with two layers of wire mesh and 300 mm of shotcrete. as its alignment runs through a layer of Feuerletten. The mechanical behaviour and engineering characteristics of the gravel formation are related to the degree of cementation of the matrix and the percentage gravel content. Around 800 m from the portals. Once in contact with water. One in 50 of the installed bolts is subjected to a 17. Based on the monitoring data. systematic roof support. together with measuring anchors to record stress and strain in the ground. Reinforcing Feuerletten Clay In Autumn 1998. which has a total length of 2. maximum crown settlements of about 400 mm have been observed in areas of fine sediments with ground water. 101 . Rock: Hard. Location: Ingolstadt. work started on a new high speed railway line between the cities of Nuremberg and Ingolstadt. while in sections with dense gravel. Germany. and 4 m and 6 m SDA cement grouted rockbolts installed. and ten emergency parking bays. there are nine pedestrian cross passages. Lattice arches are then set at 1 m centres. Maximum advance on a top heading has been 3. SN anchors. Presupport consists of 3 m-long forepoling using SDA around the arch and sidewalls at 0. and the site works 7 days/week. Every 500 m. A 240 m-deep x 10 m-diameter ventilation shaft has been constructed Installing 6 m-long SDA at Pakuashan. a hard. Feuerletten softens and becomes impermeable due to a swelling of its clay minerals. forming the northern part of the proposed high speed connection between the two major Bavarian cities. All the tests demonstrated that the pressure due to swelling. Swelling Clay The Göggelsbuch tunnel runs exclusively in the Feuerletten layer. Dywidag Systems International (DSI) supplied both systems. A single 3 mm layer of polyethylene membrane helps to seal the tunnel lining against a water head of 30 m. and the pressure exerted. and the quick and economical installation method. The 35 km-long northern section of the railway line. The top heading forming the crown was holed through before the bench and invert were started. from south to north.SDA WORLDWIDE Aerial view of Göggelsbuch tunnel. and by up to 10 m-thick sequences with alternating sandstone and clay stone. which is locally interrupted by up to 5 m-thick sequences of pure sandstone. The DSI hollow bolt anchor type MAI is optimally used wherever geological conditions would normally require cased drilling to place anchoring or nailing elements. took some five months from December. which took another 4-5 months. have been examined and analyzed precisely. Its advantage lies in the simplicity of the system. After the whole tunnel had been excavated. with a hydraulic breaker in sections with thick layers of sandstone. length achieved by coupling sections together. and the roof above the crown had to be 102 ROCK & SOIL REINFORCEMENT . Supporting the face at Göggelsbuch. Groundwater-filled layers of sandstone. The clay comprises a clay stone with fine to medium sand. were present during the complete advance works. 2000. The advance per section was limited to 1. and impermeable layers of clay with groundwater flowing on them. The layers of Feuerletten are usually orientated horizontally. The swelling of the clay. an underground water flow of 5 l/s was measured. The tunnel was secured with a 20-35 cm-thick layer of site-mixed shotcrete. Trials without the temporary support showed unpredictable results. 2000 with one wagon for the invert formwork. carrying two forms.3 m. The anchorage systems used in the construction of the tunnel comprised 4 m-long SN anchors and Hollow Bolt Type MAI anchors with varying lengths. and which is a constant 35 cmthick in the arch. 1999 until September. including the Göggelsbuch tunnel. advancing simultaneously from both north and south portals. Two separately running forms were used for the crown lining. the flexibility in its Supporting Production The rock was excavated using a tunnel excavator along its entire length. with between 4 and 20 m of Feuerletten overhead. Concrete lining. Construction was from May. is under construction by a joint venture of Bilfinger Berger and Max Bögl. was not decisive in calculating the internal lining. and 4 m-long x 25 mm-diameter SN anchors were installed for systematic rockbolting. in connection with the hydrostatic load. It has a reinforced concrete lining varying between 75 and 125 cm in thickness at the invert. The crown invert was supported with a temporary shotcrete layer to minimize movement. The second phase will comprise four separate contracts and utilize a total of eight TBMs. England.5 m lengths of attached casing.2 kmlong North Downs tunnel along with three other major civil engineering contracts. geotechnical engineering calculations show that there are increased ROCK & SOIL REINFORCEMENT Project: High speed railway tunnel. A false portal was built at the entrance. and 6 m-long MAI R32 rods. where the weaker rock has been exposed to weathering. system anchorage with 4 mlong SN anchors.5 m centres around the crown of the tunnel. and Dumez/GTM. Despite continuously increasing the density of support. due to excessive movement. Phase Two started in 2001. Kent. Excavating the bench at Göggelsbuch. the north drive suffered poor face stability. at 7 units/m. at 9 units per section. 20 cm of shotcrete on the arch invert. Rock: Chalk with possible flint bands. While advance from the south progressed with hardly any problems. Acknowledgements Thanks are due to Thomas Müller of Bilfinger Berger. Miller. The contract to construct the North Downs tunnel was awarded to Eurolink. a joint venture between Beton und Monierbau of Austria. The tunnel was constructed through chalk strata common to the region. Location: North Downs. Contractor: Eurolink jv of Beton & Monierbau. The excavation of the bench and the invert of the tunnel were subsequently completed in about the half the scheduled time. It was decided to keep the same types of support. and Frank Schmidt of DSI. Miller of the UK and Dumez/GTM of France. The likelihood of poor ground conditions is increased at the tunnel portal. The first comprises the 3. 1999. These were installed 15 m deep at 115 mm diameter. It was decided to drill a total of 24 holes at 0. for describing the construction process. Also. which was completed without further delay. s 103 . using the Atlas Copco Boodex system.SDA WORLDWIDE strengthened over a length of 50 m. Rock reinforcement required: Secure portal area for NATM advance. Rockbolt selected: Atlas Copco MAI SDA. Excavation method: NATM. at 35 units/m. The holes were lined with easy-to-handle 1. The supports that were installed at that time were: 30 cm of shotcrete in the arch. but those guaranteeing the stability of the working face were intensified. The length of the MAI face anchors was increased to 12 m. 10 cm of reinforced shotcrete on the working face. once the collapsed face had been cleared. a face collapse occurred in July. Self Drilling Anchors at North Downs The Channel Tunnel Rail Link (CTRL) is the link between King’s Cross Station in North London and the tunnel terminal on the coast. using NATM techniques.5 m as the tunnel advanced under the crown umbrella. No further collapses occurred on the remaining crown drive. The length of the MAI R32 steel rods was also increased from 6 m to a maximum 8 m. This link is being built in two phases. stresses where the tunnel barrel is discontinued at the portal. This intensified system of face support was installed over a length of 500 m. some form of additional ground support was required to allow NATM tunnelling to progress. At the London portal. catching up on the contract. and the spacing of the steel arches was continued at 1. 8 m-long MAI R32 face anchors. and the number doubled to 18 per round. and was begun in 1998/99. These are hugely significant proportions of a market that has risen by an average of 5. Mainstay of the Outokumpu strategy is its highly cost-efficient fully integrated mine-to-mill production chain in the KemiTornio area of northern Finland. and a similar share of cold rolled production. 104 140 m3/s Backfilling station 190 m3/s 70 m3/s EAR4 115 Repair shop FAR2 EAR3 Final pit bottom Trial Stoping area 275 Backfill raise 277 Backfill raise 300 350 Repair shop 350 Pump station 450 Expl. An ongoing investment programme of EUR1. Reserves The Kemi deposit is hosted by a 2. so chromite and ferrochrome production technology has had to be continuously upgraded to remain competitive. storage 450 475 500 550 600 580 Pump station 500 Pump station and Repair shop Crusher ROCK & SOIL REINFORCEMENT . accurate coring with Craelius rigs. Aerial view of Kemi mine.9 million t.4 billion year old mafic-ultramafic layered intrusion extending for some 15 km north-east of the Kemi underground mine simplified long section. reliable rock reinforcement with Cabletec and Boltec rigs with Swellex bolts and pumps. and is currently enjoying 7% growth. located close to Finland’s border with Sweden. mine-wide information system that can help optimize financial results for the whole operation.2 million t to 1. Underground mining started in 2003 at 150. where intensive use is being made of information technology to optimize the overall mining and processing operation. and the efficiency of the Tornio smelter is enhanced by its proximity to both the mine and harbour facilities. The result is cost-efficient. Finland has a lower than average Cr2O3 content of about 26%. FINLAND Rock Reinforcement at Kemi Chrome Mine Intelligent Mining The large chromite deposit being mined by Outokumpu at Kemi. and production will increase to the planned level of 1. and coil rolling capacity from 1. accounting for about 8% of global stainless slab output. The system utilizes a fast. Mining production has been progressively switched from surface to underground.75 million t to 2. and the dependability and longevity of Secoroc drilling consumables support this unique mine strategy.75 million t.000 t/y.KEMI.5% per annum over the last 20 years. on a model which may form the basis of the next generation of mining techniques.2 million t/y by 2007. integrated production. Computerized drilling with Atlas Copco Rocket Boomers and Simbas. The Intelligent Mine Implementation Technology Programme of 14 projects achieved real time control of mine production in precise coordination with the needs of the mineral processing plant and the ferrochrome smelter. Introduction Outokumpu is one of the world’s largest stainless steel producers. Ore reserves at Kemi chrome mine are abundant. Open pit mining will cease in 2006.1 billion will expand total slab capacity from 1. Over the years. there is strong granite some 80 m below the footwall. The yield is 220. A two shift/day. Manual input can be used.2 mm grain size. Concentrator operation is optimized by accurate calibration of the feed slurry analyzers. At the footwall. Technical innovations for ore characterization and quantification include OMS-logg down hole logging. Basic production data about mineralogical and process histories are logged for each ore stope on a daily basis. with 750 m having been reached by the deepest exploratory hole. both by compensating for changes in feed type. and has an average dip of 70 degrees northwest. depending on the proportion of lumpy ore. FINLAND town itself. The former is pelletized at Tornio. and automated image analysis for establishing grain size distribution. as well as on-line information. Atlas Copco Rocket Boomer L2 C is used for sublevel development. The Kemi chrome deposit comprises 11 mineralisations within a 4.5 km-long zone varying from 5-105 m in width.5 km-long x 500 m-wide main pit has a final planned depth of 220 m. Ore Grade Control Ore grade control in both the open pit and the underground mine involves intensive wire line diamond core drilling. and must be mined selectively. the chromite and host rock are inter-layered. The ore body continues at depth. and control of product quality from each unit process. The 1. 105 . resulting in 130 million t in waste heaps. using a Maxibore system.6% Cr2O3. in which the hanging wall contact is clearly defined. probably to 1. However. some 30 million t of ore have been produced from open pits. Atlas Copco Simba M6 C at work in the sublevels at Kemi mine. Based on the drill hole data.2 million t/y of ore grading 24-26% Cr2O3 is processed continuously by the concentrator. a mineral resource of 150 million t of 28. a 3D model of the orebody is created and used as a basis for production planning. The chromite-rich horizon appears 50-200 m above the bottom of the intrusion. and measuring product quality on-line. with average thickness of 40 m. Metallurgical grade ROCK & SOIL REINFORCEMENT concentrate contains about 45% Cr2O3 of 0. In addition. from which about 1. in order to minimize feed variation and maximize process stability.000 t/y metallurgical grade concentrate at 45% Cr2O3. Drill sections are established every 10 m and downhole survey is standard procedure. and 420. The main immediate host rock is weak talc-carbonate. all blast holes in the open pit are sampled. five day/week pattern is worked in the mine. to determine boundaries and qualities of specific ore types. Each ore blast is treated selectively at the concentrator.000 m. In the concentrator.KEMI. and then mixed with upgraded lumpy ore before smelting to produce ferrochrome.000 t/y of 12-100 mm lumpy concentrate with 35% Cr2O3. A Craelius Diamec 264 APC drill rig carries out 10 km of coring each year. and this is merged and compared with daily and blast-specific production histories from the database. while upgraded lumpy ore is about 35% Cr2O3 with 12-100 mm size. total chromite recovery is around 80%. Of this there are 50 million t proven reserves underground between the 500-m level and the bottom of the open pit. FINLAND Atlas Copco Craelius Diamec 264 APC at work underground. A 40 t travelling gantry crane services the entire crusher house. The final 23. The washing bay is equipped with two Wallman hydraulically controlled washing cages. interfacing with a single master database. is placed in the primary stopes. Tying all these streams of collected data and planning outputs together requires an extremely fast communications network. 106 . Underground Production Trial stopes in three areas accessed from the 275 m and 300 m levels were mined to determine the parameters of the bench cutand-fill technique to be used.5 m high. with cable bolt and mesh support to minimize dilution.000 cu m repair shop for open pit equipment at the 115 m level. with 25.000 cu m main workshop is under construction at the 500-m level. There is also a 5. while the secondary stopes will be backfilled with mine waste rock. and connects with several intermediate sublevels. The slurry-type pumps. Mining sublevels with 5 m x 5 m cross sections are being established at 25 m vertical intervals. The decline is asphalted throughout most of its length. which keep in the heat so that an ambient 18 degrees C can be maintained. Rounds of 60-80 holes take about 2 hours to drill. using cement. and secondary stopes 20 m wide. The decline is mostly 8 m wide x 5. Crushed ore gravitates onto a conveyor in a tunnel below the crusher for transport to the shaft loading pockets 500 m away. Two other dewatering pumping stations are located at the 500 m and 580 m levels. to accommodate passing vehicles. An emulsion charging truck with elevating platform and Atlas Copco ROCK & SOIL REINFORCEMENT Atlas Copco Boltec LC installing Swellex Mn12 rockbolts. pump the unsettled mine water to the surface with a total head of 360 m.000 t of ore apiece. This is fed from two sides by vibrating feeders from separate 8 m-diameter main ore passes from the 500 m level. 25 m-high transverse stopes are laid out. The service bay is equipped with a 10 t travelling gantry and 16 m-long inspection pit. Underground Infrastructure The main decline starts at a portal in the footwall side of the pit. Cemented fill. and from one side by a plate feeder. using one Atlas Copco Rocket Boomer L2 C drillrig equipped with 1838 ME rock drills and 5 m-long Secoroc steel and bits. The main pumping station is located at the 350 m level. Primary stopes are 15 m wide. For production purposes. at about 100 m below the rim. to which the ore can be dumped from the 550 m level. and were 30-40 m-long. These had a width of 15 m. The 350-m level workshops are enclosed by megadoors. The crusher station at the 560 m level is equipped with a 1.000 t/h Metso gyratory crusher. charge and prime. The primary stopes are being extracted one or two levels above the secondary stopes. furnace slag from an iron ore smelter and fly ash from local power stations.000-30.000 cu m workshop at the 350 m level for the underground mobile equipment fleet. so there is no need for operatives to climb onto the mobile equipment. It descends at 1:7 to a depth of 600 m at the base of the hoisting shaft. and has pumping capacity of 2 x 250 cu m/h. Both uphole and downhole drilling methods were tested.KEMI. and a larger 14. with mechanical seals. and 51 mm-diameter downholes selected as being the safest. KEMI, FINLAND GA15 compressor provides fast and efficient explosives delivery. The footwall granite is very competent, but lots of rock reinforcement is required in the weaker host rock, where all drives are systematically rock bolted and secured with steel fibre reinforced shotcrete. The planned nominal capacity is 2.7 million t/y of ore, which allows for increased ferro-chrome production at Tornio when Outokumpu decides to expand the smelting operation. The total cost for mine development is EUR70 million. Rock Reinforcement Swellex Mn12 2.4 m-long bolts are used for support in ore contact formations. These are being installed at a rate of 80-120 bolts/shift using an Atlas Copco Boltec LC rig, which is returning drilling penetration rates of 3.2 to 4 m/min. The CAN-bus controlled LC rig mounts the latest Swellex HC1 pump, for bolt inflation at 300 bar pressure, and reports progress on the operator’s screen. The HC1 hydraulic pump is robust, simple, and with low maintenance cost. Coupled to an intelligent system, it reaches the 300 bar pressure level quickly, and maintains it for the minimum time for perfect installation. Combined with the rig’s CAN-bus system, the pump can confirm the number of bolts successfully installed and warn of any problems with inflation. Over 50,000 bolts have been installed to date without problems. A series of slip-pull tests carried out throughout the mine proved the strong anchorage capacity of Swellex Mn12, both in the orebody and for the softer talccarbonate and mylonite zone. Cable Bolting Kemi installs some 80 km of cable bolt each year using its Atlas Copco Cabletec L unit, which is based on the longhole production drilling rig Simba M7, with an added second boom for grouting and cable insertion. The Rig Control System (RCS), enables the operator to pay full attention to grouting and cable insertion, while drilling of the next hole after collaring is performed automatically, including pulling the rods out of the hole. The main benefit of the two-boom concept is to drastically reduce the entire drilling and bolting cycle time. Also, separating the drilling and bolting functions prevents the ROCK & SOIL REINFORCEMENT risk of cement entering the rock drill, thereby reducing service and maintenance costs. Kemi tested the prototype Cabletec L and eventually purchased the unit after minor modification proposals. During the testing period, where most holes were in the 6 to 11 m range, the rig grouted and installed cables at rates of more than 40 m/hour. The capacity of the unit, which is governed by the rate of drilling, provided around 50 per cent extra productivity compared with alternative support methods. The Cabletec L is equipped with a COP 1838 ME hydraulic rock drill using reduced impact pressure with the R32 drill string system for 51 mm hole diameter. The machine’s cable cassette has a capacity of 1,700 kg and is easy to refill, thanks to the fold-out cassette arm. It features automatic cement mixing and a silo with a capacity of 1,200 kg of dry cement, which is mixed according to a pre-programmed formula, resulting in unique quality assurance for the grouting process. Atlas Copco Cabletec L installing cable bolts at Kemi. Bench Cut and Fill The current mining method is bench cut and fill, a type of sub-level stoping with downhole production drilling, in which primary stopes are 25 m high, 15 m wide and between 30 and 40 m long. Using a Rocket Boomer L2 C rig, the drifts for the primary stopes are developed laterally from the footwall through the ore zone. Then a Simba M6 C production rig drills down 51 mm diameter blastholes in fans 2 m apart. Each stope yields between 25,000 and 35,000 t of ore. 107 KEMI, FINLAND Inside the 350 m level workshop at Kemi. Tests showed that drilling upwards would be about 30 per cent more efficient, but because of safety issues related to the poor rock conditions, it was decided to start with downhole drilling while getting experience with the rock and the mining method. Meantime, Kemi has ordered a Simba L7 C rig with a long boom to be delivered in August, 2005. With the M6 C and L7 C, operators will be able to cover all kinds of drilling patterns. Mining of the 20 m wide secondary stopes will start in 2005, while sub-level caving with uphole drilling will be tested at one end of the main pit in 2006. Secoroc rock drilling tools are used for production drilling. The previous 64 mm holes over-fragmented the ore, but a switch to 51 mm resulted in lower specific charges and better fragmentation, while retaining the same number of holes. When developing the secondary stopes, the mine may well go back to 64 mm drilling if there are problems keeping the holes open due to the stresses and rock movements. Kemi is carrying out slot hole drilling with a Simba M4 C rig mounted on a Scania truck. The front part of the rig has been redesigned to accommodate the Secoroc COP 84L low volume DTH slothammer, which is used to drill the 305 mm-diameter opening hole for the longhole raises. The blasting holes are drilled off using a COP 54 with 165 mm bit with the same tubes. The 20-m raises are blasted in two 10-m lifts. work that eventually will cover the whole mine. Currently, this 1 GB network, which is based on commercially available equipment, covers the declines, the workshops and parts of the production area. This network infrastructure not only allows effective underground communication but also means that all the Atlas Copco drill rigs equipped with the Rig Remote Access (RRA) option are logically integrated into the information systems in Outokumpu’s administrative organization. The RRA is installed on the Rocket Boomer and Simba rigs. The RRA, which consists of a communication server on-board the rig and a network adapter, integrates with the mine’s network to allow data transfer and remote monitoring and troubleshooting. It works as a two-way communication system, since data can be sent and received in real-time between Atlas Copco and the mine. For instance, should one of the drillrigs encounter a problem, the warning seen by the operator will also be shown in the mine office, which can then contact Atlas Copco immediately, enabling them to enter the rig’s electronic system and diagnose the fault. The RRA’s main benefits are: the administrative system can be updated automatically with the latest information with no manual handling; the rig operator always has access to the latest production planning; no need to write work reports after each shift, since all log files are automatically saved to the planning department; instead of forcing work orders to be written before each shift, they can be issued during the shift and directed onto the specific drillrig; and fault diagnostics can be conducted remotely, which allows the service technician to diagnose the problem and choose the correct spare parts before travelling to the drillrig.s Acknowledgements Atlas Copco is grateful to Juha Riikonen, manager of the underground mine for his assistance in arranging the site visit and reading draft. Contributions by Esa Lindeman, open pit manager, Heikki Pekkarinen, concentrator manager, and Jukka Pitkajarvi, chief geologist (all [email protected]). ROCK & SOIL REINFORCEMENT Rig Remote Access The drill rigs at Kemi are integrated into the Ethernet WLAN communications net108 LOTSCHBERG, SWITZERLAND Repairing Squeezing Ground at Mitholz Flexibility of Purpose The Satco joint venture, under technical sponsorship of Strabag, installed a complete purpose-designed excavation system at their Mitholz contract on the Lotschberg base tunnel in Switzerland. Speed and efficiency were the key elements of a successful project, for which Satco chose Atlas Copco Rocket Boomer XL3 C drillrigs with ABC Regular semi-automatic boom control for production drilling, and Rocket Boomer L2 C twin-boom machines for the smaller-section work. The rigs were equipped with Secoroc rock drilling tools, and Swellex rockbolts were used for immediate support. This combination of job-matched Atlas Copco equipment, together with first-class on-site maintenance support, helped Satco to get six months ahead of contract schedule over a period of three years. However, close to the boundary of the contracted distance south, the faces unexpectedly hit soft carboniferous banded deposits, some 1,400 m beneath the Lotschen summit. Huge ground pressure was transmitted to the tunnel lining, causing compression and distortion of the steel arches. Satco used its Rocket Boomer XL3 Cs to install 16 m-long MAI SDA self drilling anchors to stabilize the strata for replacement of the steel arches, overcoming a difficult support problem. Lotschberg Alignment The 34.6 km-long Lotschberg base tunnel, which has been developed from a number of access points, is in an advanced stage of construction, and will be ready for use in 2007. From the base of the 1.5 km-long, 67 sq m Mitholz access adit, located about 8 km from the north portal site at Frutigen, three ROCK & SOIL REINFORCEMENT main running tunnels are contracted to Satco, a joint venture led by Strabag with Vinci, Skanska, Rothpletz & Lienhard, and Walo Bertschinger. The east and west tubes have been driven by drill/blast some 8.7 km southwards, to meet faces coming north from Ferden. At the same time, the east tube has been advanced some 7.5 km northwards to break out at the Frutigen portal. The west tube from Frutigen portal has also been driven 800 m to junction with the east tube. The nominal cross-section of excavation of the main running tunnel faces is approximately 65 sq m, depending upon the required support, with a maximum of 280 sq m at junction caverns. These have been advanced using sophisticated three-boom and basket Atlas Copco Rocket Boomer XL3 C drillrigs equipped with ABC Regular semi-automatic boom control with two control systems, operated by two drillers working from separate panels. Drillplan data is transferred from the planning office to the machines on PC cards. The big Rocket Boomer XL3 Cs were backed up by a pair of twin-boom Atlas Copco L2 C drillrigs, which handled work Satco reached Frutigen portal 8 months ahead of schedule. Wolfgang Lehner, project manager for Satco at Mitholz. 109 LOTSCHBERG, SWITZERLAND This arrangement afforded maximum manoeuvring room for the large numbers of mobile equipment in operation. When in good rock, each full, 8 m-wide x 8.5 m-high arched face was drilled out by a Rocket Boomer XL3 C to 4.5 m depth using Secoroc model–37 48 mm, 9-button ballistic bits with R35 thread. Between 105 and 120 holes were normally required, together with two 102 mm breaker holes in the centre. Average drilling rate was 3 m/min, and face and rockbolt drilling took around 3 hours in normal ground. The rock generally comprised good, hard limestone, which could be screened and crushed for aggregate. Total volume of excavated rock was around 1.8 million cu m, of which some 700,000 cu m is being reused. Excavation and Mucking All blasting at Mitholz utilized site sensitized emulsion (SSE) explosives supplied by Dyno Nobel Sweden. The profile holes were charged at 50% density to control overbreak, and the blasted faces were safened using an excavator-mounted rock scaler. Overexcavation of 45 cm width on horseshoe section and 60 cm width on circular section was required to accommodate squeezing under normal circumstances. An LHD equipped with 5.4 cu m side-tipping bucket carried the spoil back to a 1,000 t/h mobile crusher located some 50-100 m behind each face. From here, the crushed rock was delivered by a 330 m overlap stage conveyor to a 300 t/h trunk conveying system, and thence to a handling plant close to the adit bottom where the rock was further crushed to –200 mm, with oversize scalped by a grizzly. Vertical pocket elevators carried the spoil 20 m up to the adit conveyor loading points, from where two 400 t/h tubed belt systems took it to the surface for transport to the nominated stockpiles. The south section is serviced by two 2,700 kW air conditioning units which are cooled by 150 lit/sec of recycled groundwater, and fresh air is supplied by a pair of 2.4 m ventilation ducts. The air is contained by automatic roller shutter doors, and driven around the faces by auxiliary fans. The Frutigen TBM tunnel is the main fresh air intake and, by the time that the air reaches the south faces, most of it has travelled more than 15 km. All told, there are ROCK & SOIL REINFORCEMENT Atlas Copco Boomer XL3 C drilling MAI SDA to repair squeezing at Mitholz. such as bolting, cross passage development, and extraneous excavation. Standard Swellex rockbolts, in 3 m and 4 m lengths, were installed as immediate support, normally at 1.5 m spacing in the roof and shoulders of each drive. All of the ancillary face equipment such as transformers, ventilation extensions, and cable reels were carried on backup platforms suspended on rails slung from the roof. Torqueing up a 16 m-long grouted MAI SDA. 110 with a maximum pressure of 54 bar. In squeezing ground. This was accompanied by water over a 400 m length. The main tunnels are being finished to a standard 62 sq m cross-section.000 m to a maximum of 2.5 mlong Swellex were necessary for each metre of advance. squeezing caused deformation over a 100 m-long section close to the face of each drive. using a Rocket Boomer XL3 C to drill the 38 mm holes. causing a pause in advance while the situation was assessed. especially where crystalline rock was encountered. with the crown of the tunnel positioned 7. with four crews of 9 or 10 men rotating on each face. This unprecedented density of support sometimes reached 350 m of rockbolting for each metre advance. Rockbursting was a hazard at the far south end of the alignment.5 km before the south faces reached the boundary of the Satco contract. and seven 4. they introduced R32 MAI SDA in 8 m and 12 m lengths at a density of ten per metre of advance to replace the grouted rebar. This indicated that the MAI SDA under installation alongside replacement steel arch. and a grouting regime established. before entering an unexpected 600 m-long carboniferous section. in which thin seams of anthracite appeared in the shale. Hydraulic testing and ground probing radar were also used. For the circular ROCK & SOIL REINFORCEMENT profile. By the end of June.2 m above the top of the rail track.000 m beneath the Mitholz peaks. then limestone. some 1. in a mix of 8 m and 12 m lengths. 2004 the ground conditions had deteriorated to the extent that fifteen 8 m-long R32 MAI SDA. and average water inflows up to nearly 100 lit/sec were experienced. A complex probe drilling system using 250-300 m-long cored holes was employed to investigate conditions ahead of the face. 111 . wire mesh and steel fibre reinforced shotcrete were used. and it was decided to upgrade from R32 to R38 MAI SDA. Rock cover varies from 1. Each face was secured using 12-15 off 4 m-long fibreglass bolts. with a maximum achieved of 343 m/month. a section of softer rock was encountered. following which the faces progressed through first granite. Shotcreting a repaired section in the south drives. Carboniferous Encounter In April. sandstone and shale. Permanent lining comprises 250 mmthick cast in-situ concrete formed over a drainage membrane. SWITZERLAND in excess of 120 km of pipelines installed underground for various purposes. The site worked a 7 day/3 shift operation. eight 12 m-long MAI SDA. Tunnelling progress was well ahead of schedule when the south faces reached the predicted water-bearing karstic limestone. 2004. the drillrigs having advanced 250-300 m/month on each face. They had been setting six 6 m-long grouted rebars and four or five 4 m-long Swellex bolts for each metre of advance using the arched profile. and a 470 m-long cored exploratory hole drilled to probe the ground ahead. At this point. Support and Lining The roof and sides of each excavated round were shotcreted and 20-30 Swellex rockbolts installed. Satco modified the excavated section from arched profile to circular profile. Nevertheless. Stronger rock reinforcement was required.LOTSCHBERG. GERMAN 2500 2000 1500 1000 500 0 Section of Lotschberg tunnel from Frutigen to Raron. All cross passage excavation between the east tube and the TBM tunnel is now complete. Tunnelling at the north face was completed in May 2003. 16 off 16 m-long grouted R38 MAI SDA were installed radially in 4 m-long coupled lengths in 76 mm holes. and were soon into good rock. in particular. Concrete lining is proceeding apace in the south drives. The main concrete lining operation went well in the north drive. following which there would be a transition to comparatively good sandstone. both to stabilize the strata around the tunnel and to pin the arches in place. where pair of 12. tunnelling operations resumed. ST. ELSIGHOR ADELRAIN SE-GRAT carboniferous section would run out after another 50 m in the west face and 10 m in the east face. The unexpected area of soft sedimentary rock is delineated by red dotted lines. to Wolfgang Lehner of Strabag.l. installing Mithollz lateral adit EGGESCHWAND Ferden lateral adit LÖTSCHBERG 2500 2000 1500 1000 500 0 112 ROCK & SOIL REINFORCEMENT . Steg lateral adit LÖTSCHENTAL South Raron portal m. Acknowledgements Atlas Copco is indebted to Satco and Alptransit Lotschberg for permission to publish this article and. Once the relining was completed. for his assistance with interviews and site visit. project manager at Mitholz. probeholes were maintained 40 m ahead of the face. These were grouted in place at 2040 bar pressure. Buckled arch with emergency retaining bolts. For each arch.s Tungsten carbide bit used along with EYY type with MAI SDA at Mitholz.s. SWITZERLAND circular steel compression arches at 1 m intervals.s.LOTSCHBERG. Detection of methane would trigger a warning system on the drillrigs. It was decided to reline the deformed tunnel in sections 50 m-long. as a result of which Satco was awarded a further contract to excavate some 800 m of the west tube from the Frutigen portal.l.5 m formworks returned 25 m/day of completed lining. North Frutigen portal m. North Completion In the north. some 8 months ahead of programme. and the monitoring system on the suspended backup would switch off HT electrics if a dangerous concentration were encountered. Satco is carrying on beyond the original contract southern boundary for more than an extra 1 linear km of drive awarded as a bonus for early completion. drilled in the crown by one of the Rocket Boomer XL3 Cs equipped with a RAS rod adding system. Using these machines. Rock Reinforcement The mine installs up to 20. where the requirement is for 18 rounds/week ROCK & SOIL REINFORCEMENT Vital Combination The Rig Control System (RCS) features an interactive operator control panel with 113 . Zinkgruvan Mining produces zinc and lead concentrates for shipment to smelters in northern Europe. The ramp will be driven from the current 980 m to the 1. The mine has an option to purchase a second twin-boom Rocket Boomer. The Boltec LC is a fully mechanized rockbolting rig with computer-based control system for high productivity and precision.100 m level. Lower Development In order to mine below the 800 m level. and. The machine produces some 50. which includes four Simba production drillrigs. A Simba M4 C longhole drilling rig is used on production. since the continuous manual handling of resin cartridges has been eliminated. drilling up to 40 mlong x 76 mm or 89 mm-diameter blastholes.000 resin anchored rockbolts each year. which applies constant pressure to keep it stable at the hole during the entire installation process. the mine now uses paste fill.100 m under present plans.000 drillmetres/year. this time an M2 C. Key to Zinkgruvan production efforts is equipment supplied by Atlas Copco. The mine has been continuously in production since 1857. while an older Simba 1357 drills a similar number of metres in the 51-64 mm range. on a 2 x 7 h shift basis. Production is obtained from open stopes where. Atlas Copco Rocket Boomer L2 C developing the sublevels. which is the mining version of their existing L2 C. following difficulties with seepage from hydraulic fill when rock quality diminished. together with 185.ZINKGRUVAN. having upgraded its production process. three Rocket Boomers and two Boltec rigs. A Simba M7 C is being delivered for cable bolt drilling. they ordered two units. The Zinkgruvan models feature a new type of magazine holding 80 resin cartridges. It is equipped with a stinger. Rather than deepen the main hoisting shaft. sufficient for installation of 16 rockbolts before refill. is a part of Lundin Mining Corporation. The operator can select the number of resin cartridges to be shot into the hole. After prolonged testing of the latest Atlas Copco Boltec LC. for which the rig air capacity is excellent. Sweden’s third largest mining company. the mine uses three Kiruna Electric trucks for ore and waste haulage to the main crusher. An Atlas Copco Rocket Boomer L2 C is used on ramp and sublevel development. found that bolting became the new bottleneck.000 t of waste from development. and will bottom out at 1.000 t/year. SWEDEN Mechanized Bolting at Zinkgruvan Partners in Production Zinkgruvan Mining AB. The drilling consumables are supplied by Atlas Copco Secoroc under contract. together with maintenance and consumable supply contracts. The mine is so impressed with the stability of the Simba M4 C rotation unit that it has had an old Simba 1354 rebuilt to incorporate the same unit. the working environment for the bolting operatives has improved immeasurably. the main ramp access was developed below the 800 m level. and ore output now stands at about 835. and a distributed Profitable Collaboration The Rig Control System (RCS). The BUT 35HBE heavy-duty bolting boom is perfect for direct. Automatic functions in the drilling process. as well as improved regulation of the rock drill.ZINKGRUVAN. full-colour display of the computer-based drilling system. plus indexer for grouting. which can be adapted to certain drill steel/rock combinations. provide high performance and outstanding drill steel economy. particularly in the field testing of the new generation rigs. all of Zinkgruvan Mining. so the mine benefits from the common concept. The COP 1532 rock drill is the shortest in its class. such as auto-collaring and anti-jamming protection. at the top end. and a robust drill steel support. Atlas Copco Boltec LC installing rockbolts in a development drive. Data transfer is by PC-card. 114 ROCK & SOIL REINFORCEMENT . Atlas Copco has total responsibility for all service and maintenance operations on its equipment at Zinkgruvan. and has three service engineers stationed permanently at site. There is integrated diagnostic and fault location. is now also installed on Simba and Boltec rigs. The editor also gratefully acknowledges the inputs of Jonas Sodergren. From the mine point of view. Large capacity working lights. The MBU bolting unit on the Boltec LC features a single feed system. giving them a head start on the savings to be achieved. SWEDEN hydraulic system with fewer and shorter hoses for increased availability. Grinding Secoroc bits on a Grind Matic BQ2 machine. and a joystickoperated spotlight. It is equipped with a low-mounted magazine for 10 bolts. overseen by a Secoroc specialist. Early exposure to the capabilities of these machines has allowed them to adapt their mining and rockbolting methods to the new technology. designed for maximum flexibility during drilling and bolting. The company is also under contract for the supply. maintenance and grinding of Secoroc rock drilling tools. which also allows service engineers to store optimal drill settings. s Acknowledgements This article is based on a paper written by Gunnar Nystrom. fast and accurate positioning between holes. It has separately variable frequency and impact power. ensure that the operator has outstanding visibility from his working position. with modern hydraulic reflex dampening for high-speed drilling and excellent drill steel economy. Hans Sjoberg and Conny Ohman. originally developed for Boomer rigs. they believe they have profited by their collaboration with Atlas Copco. utilizing a cradle indexer at the rear end. The overall design has been rethought. and. The Zekidagi fault dips at almost 90 degrees. accommodating three lanes per tube. Austria. a threelayer lining. 1999. and the practical solutions involve the extensive use of Atlas Copco MAI Self Drilling Anchors (SDA) as primary support. with an excavation area ranging between 190 sq m and 260 sq m. and represents the most challenging section of the motorway construction. When the Duzce earthquake occurred in 1999. The Bolu tunnel is a twin-tube motorway tunnel of about 3 km length. is approximately 6 to 8 km-long. The original static design was by Geoconsult GmbH of Saltzburg. Atlas Copco Boomer drilling over the face for forepoling. Seismic principles have been applied to this project. directional effects. soil amplifications and distance from the seismic source. involved preliminary excavation and backfill of bench pilot tunnels. a stretch of about 350 m of tunnel collapsed behind the eastern faces. linking the western Asarsuyu valley to the eastern Elmalik village. problems were encountered with clays. and the tunnel is now again under construction. and. on the Ankara side. History The Bolu Mountain Crossing is midway between Ankara and Istanbul. and a panel of experts was set up to study the results. and major ROCK & SOIL REINFORCEMENT damage was done to the lining and invert of both tunnels. Excavation of the tunnel started in 1993. Active Faults Two active faults were recognized along the tunnel alignment: the Zekidagi and Bakacak faults (Barka-W Lettis & Associates).BOLU. This caused the collapse of a section of mined tunnel. which had been excavated with preliminary primary support of soil nails and shotcrete. Consultants Lombardi SA were brought in to analyze the seismic loads induced by the earthquake. and possibly intersects with the tunnel alignment at nearly right angles. almost immediately. around chainage 62+430 in the left tube and Plan of Astaldi section of the IstanbulAnkara highway. These analyses examined the depth. The design criteria have defined the fault crossing strategy. which originated at the North Anatolian Fault. Along this 20 kmlong stretch. four important viaducts and a long tunnel are under construction. and two at the portals. and a deep monolithic invert. The original design featured five support classes in the tunnel. 115 . for the worst rock condition. TURKEY Seismic Tunnelling at Bolu Overcoming Natural Disaster The attempt in the mid-nineties at tunnelling through the Bakacak Fault near the Turkish town of Bolu was aborted following the massive earthquake in November. which is crucial to completion of the Gumusova-Gerede section of the important North Anatolian Motorway linking Ankara and Istanbul. leaving independent sections across the fault. and for the excavation geometry that had already been defined. two strategies are feasible to mitigate the seismic risk induced to tunnels by ruptures of active faults across the alignment. reduces the width of the lining segments. In a fault rupture. A double lining is installed. almost one year after the Duzce event. 116 ROCK & SOIL REINFORCEMENT . and will be most effective when a fault rupture is concentrated within a few metres. the tunnel is driven through the fault with an enlarged cross section. Articulated design was selected as the most appropriate for the large cross section of the Bolu tunnel. commonly used for metro projects. This clay fault exhibits low potential for right lateral strike-slip displacements. Design Philosophy When the Bakacak fault was recognized as active.150. TURKEY Two likely traces of the Bakacak fault. Crossing Active Faults Basically. such as width of the cross section. on the other hand.BOLU. and element kinematics. and rupture displacements of up to 50 cm can be expected in an earthquake of magnitude 6. containing any damage in a few elements. composed of several segments ranging from 3 to 5 km-long.25.5. and the shape and type of the cross section adopted was already defined. and articulated design. over a distance of about 100 m. although high deformations were recorded. and filled by a porous material. This manner of protection. the movement is concentrated at the joints linking the segments. expected movement of the fault. which dips at 40 degrees. without uncontrolled propagation. This is precisely the zone where excavation was proceeding at the time of the earthquake.25 in an earthquake of magnitude 6 to 6. were identified crossing the Bolu Tunnel between chainage 62+800 and 62+900 at the left tube. It has a potential for small future displacement in the range of 0. the clearance profile is guaranteed by the gap between the outer and inner linings. These are commonly referred to as over-excavation. over a length of 25 m to 30 m. In the first case. The bench pilot tunnels of the original excavation had already been backfilled. is limited by the width of the cross section that must be excavated. The articulated design strategy. The Bakacak Fault has been identified as a secondary fault in the step-over region between the two major North Anatolian Fault (NAF) branches in the Bolu region. 52+350 in the right tube. compressibility of the surrounding soil. This section of tunnel was lined according to the original design. and no particular problems were experienced crossing the fault. Shotcrete operations underway in the top heading. It is some 10-45 km-long. and for a distance beside the fault. The maximum length of any single element depends on several factors. and 52+730 to 52+800 at the right tube. such as foam concrete. Standard cross-section of Bolu tunnel showing massive support.25 to 6. the restoration of the original tunnel was almost complete. If there is a fault rupture. and the gap will be covered by a steel plate. three levels of linings are installed: a shotcrete lining. is that a rupture will be uniformly distributed across the fault boundaries. resulting in an element length of about 5 m. or applying an equivalent double mesh layer. each segment will be free to move independently.BOLU. whose extremities are displaced by the lateral offset of the fault. The 50 cm-wide joint is filled by two layers of concrete blocks. The assumption made. according to external loads. for the purposes of ventilation and fire resistance. Up to rupture of the joints. an intermediary lining of poured concrete. at the crown. the tunnel will act longitudinally as an embedded beam. with a 10 cm low density PS layer in between. These measures were installed within the fault. The waterproofing membrane bridges the seismic joint gap between intermediary and final lining.4 m-thick fibre reinforced shotcrete beam is applied to bridge the gap. and compared to the estimated rotation for the load conditions. 117 . The joint opening in the final lining has been enlarged to 70 cm. with soil modelled as springs acting in compression. The reinforcement bars have been placed only in the inner (final) lining and at invert. different support measures have been adopted. The joints. At the crown. the length of the segments was reduced to 4. the most important is an 80 cm-thick concrete 40 N/sq mm prefabricated concrete slab intermediate lining to be installed between the primary lining and the inner lining. This facilitated retention of the original modular reinforcement cage. To provide ring closure of the joint at the invert. The backfilled bench pilot tunnels were heavily reinforced to provide sufficient abutment to the crown loads during the excavation. The allowable rotation has been estimated. the tunnel will be sheared and bent by the soil as an embedded beam. and also by introducing a light dosage of steel fibres in the concrete mix. the regular 40 cm-thick shotcrete preliminary lining has been assessed as sufficient. Following a fault rupture. with a 50 cm joint gap at invert. so the cutting of Installing prefabricated concrete slab intermediate lining. but opposing a sufficiently low shear resistance in the event of fault rupture. Of these. TURKEY The segments geometry was defined by considering a ratio between length and width of the tunnel segment equal to one third.2 m spacing. In general. A waterproofing membrane is installed below the concrete block slabs and the invert. This was achieved by introducing stirrups at shear. Therefore the shear strain in the fault soil can be reasonably assumed as the ratio between expected offset and width of the fault at tunnel level. at 4. and a reinforced final lining. a 0. and to bridge the static soil pressure to the surrounding elements. and up to a distance of 30-40 m from the fault borders. with horizontal displacement. These beams cannot be interrupted while excavating.4 m. The primary aim of the reinforcement design is to provide a high ductility to the lining. while the shotcrete and intermediate linings have been fibre-reinforced. For practical reasons. have been detailed to prevent soil squeezing between the segments. Reinforcement and Joints Across the fault zone. Once the joint’s shear resistance is attained. The maximum acceptable shear resistance of the joint has been defined on an equivalent elastic model. justified by the geologists. and the shear stiffness of the joints is designed so as to reach the shear failure of the joint before lateral overload of the element cross section. or bending failure at extremities. ROCK & SOIL REINFORCEMENT keeping the spacing below 30 cm. This geometry kept the load on the single crown segment below an acceptable threshold value. A displacement is gradually applied to the extremities. the joint in the section can only be executed once the invert is in place. The bench is then advanced 2. faulted amphibolite rock. 12 m-long anchors. It is being driven from newly established faces within the abandoned tunnel on the Istanbul side. TURKEY General view of the Bolu tunnel face with invert pouring underway. then loaded into road tipper trucks. A purpose-built. 2005. The final lining operation is kept within 75-85 m of the face. 118 ROCK & SOIL REINFORCEMENT .BOLU. s Acknowledgements Atlas Copco is grateful to the management of the Bolu project for permission to visit the site. This is followed by a mass concrete in-situ lining. Then 20 off. and the legs of the steel arches are installed. The invert concreting is maintained within 25 m of the face. and to Olivio Angelini.5 m-long self propelled formworks. The first tube breakthrough is scheduled for August.2 m at each side. Gaetano Germani and Aziz Õzdemir of Astaldi for their help and assistance in preparation of this article. and G Germani (Astaldi). very-heavy lattice girders are placed as temporary support.4 m allow the invert to be excavated 5 m-deep over the full width of the heading. A 150 m-long cut-and-cover section was completed at the Ankara portals before excavation work could commence from this end.1 m intervals. Where the rock is particularly poor. Two incremental advances of 4. The roof and sides are given a 40 cm-thick application of steel fibre reinforced shotcrete. and these are cut away as soon as sufficient permanent support is in place. Where necessary. backed by a 350 t cement storage silo. The total excavated area of the tunnel is 160-200 sq m. with vehicle cross passages at 500 m intervals. a 60 cm-thick concrete slab intermediate lining is installed. each comprising 3 x 4 m lengths of Atlas Copco MAI SDA. under which three pieces of the Heavy steel reinforcement of the 5 m-deep concrete invert. which diverts around the collapsed section. The finished twin-tube tunnel will accommodate three lanes of traffic in each direction. using 150 sq m x 13. are drilled in and grouted using an Atlas Copco Boomer drillrig. self-propelled stage conveyor is used to transfer the concrete from the fleet of 8 cu m mixer trucks. together with bolts and shotcrete. is broken up by a Krupp hydraulic hammer mounted on a Cat 235 excavator. and the annulus backfilled with concrete. and this is filled with mass concrete with two prefabricated steel reinforcement cages. Reference is made to Design and Construction of Large Tunnel Through Active Faults: a Recent Application by M Russo and W Amberg (Lombardi Engineering). to ensure permanent support as early as possible. 5-piece steel arches are set at 1. The 7 m-high top heading is opened using 30 x 6 m-long forepoles over the crown. Concrete is supplied from two plants on site with 80 cu m/h output capacity. Excavation and Support The Bolu tunnel has been advanced on a new alignment. and a 50 cm-thick steel bar reinforced shotcrete temporary invert is installed. with the second following before the end of the year. The weathered. with up to 140 m cover. a Latvian specialist contractor. However. Their installation is being carried out by the marine construction division of BMGS. 7 days/week whenever the dock was free. which is around a metre seawards from the previous position. the Barge-mounted drillrig installing 48 m-long MAI SDA anchors at Riga docks. using the same principles as for the first stage. in which MAI SDA and grout pumps are the key elements. and these were installed in a horizontal line above the high water mark at 3 m intervals.5-2. Atlas Copco MAI anchors are being used as both temporary and permanent support for the sheet piling operation.BALTIC STATES. a plate and nut were screwed onto the protruding end of each anchor. during which retarders were used to keep the cement workable. The annulus between the two walls is being concreted. Each anchor was pull tested at 90 t. Sheet piling operations then took place during the winter 2004/2005. This is being accomplished with minimum intrusion using micropiling techniques. Then 47 m-long. Riga Coal Dock Riga coal dock handles a million t/y of coal from the Kuzbas region of Russia. Latvia and Tartu. subsidence is now the main enemy in Riga. for which the harbour has to be deepened. This allowed dredging of the dock from its previous depth of 10 m to 13. where the race is on to underpin the buildings most affected. In this case. Some 120 anchors were required for the first stage. The diversity of these jobs highlights the flexibility of MAI SDA as an essential construction tool. 130 mm-diameter holes were drilled 40 degrees below horizontal through the surface sand to penetrate the sandstone bedrock below.5 m. deeper wall is being installed. The barge had to be towed out of the way every time a coal ship tied up. where the sheet piling of the dock wall is being secured using long grouted SDA while the harbour is deepened. At each anchor position. 119 . The first stage involved anchoring the upper section of the existing steel sheet piles by drilling from a purpose-built barge floating in the dock. Continuous grout injection was carried out at 40-60 bar pressure in the 4 h-long drilling operation. and stressed up to 60 t. some dating from the Middle Ages. Estonia. a 150 mmdiameter cored hole was drilled 1. and is looking to expand its business by using larger ships. Each drillstring comprised a cross bit with 16 x 3 m-long threaded MAI T76 bars and 15 couplings. The second stage of anchoring is being undertaken in 2005.0 m into the dock wall to penetrate the ROCK & SOIL REINFORCEMENT concrete cladding and the steel sheet pile. following which a new. A week later. Similar techniques are also being used to great effect in Riga coal docks. It was necessary to anchor the existing dock walls to solid ground prior to the dredging operation. an operation which carried on 24 h/day. NORTHERN EUROPE Stabilizing Foundations in Baltic Cities Ancient and Modern The Baltic States of Northern Europe have done well to preserve most of their historic buildings. along the line of the new dock wall. This will result in 240 permanent 47 m-long ground anchors at 1. The micropiles are formed by the introduction of grout during the drilling operation. is built upon riverine deposits of the Daugava flood plain. 3 m . and the grout pump can be remotely ROCK & SOIL REINFORCEMENT 120 . with a lookout angle of 15 degrees or less. The sinking has not been uniform. For six hundred years. The micropiles are generally drilled tight to the building and as vertical as possible. The oxidation has promoted rot. Then. The anchors have been designed for a 40-year life expectancy. Since then.5 m to MAI 400 grout pump at work in Riga basement. and the dock will be deepened from 13. and differential subsidence along the facades. Drillbit ø 130 mm Schematic of drillrig mounted on floating platform to drill downward into the harbour wall. of the base of the structure. a hydro dam was built across the Daugava River some 20 km upstream of Riga. The Old City of Riga. When installed in a watersaturated environment. streets are narrow. in the 1960s. the water table has fluctuated. and allowing oxidation. while the grout itself stabilizes the hole during the drilling process. to produce crosspiles to support the base of the building. and the affected buildings have started to sink. much of which was constructed in the Middle Ages. because access is usually difficult.5 m intervals along the dock wall. This is accomplished by drilling and high pressure grouting through. spaced at 3 m apart. A small crawler rig is generally used. NORTHERN EUROPE 15 m. strengthening the dock walls prior to deepening the harbour. and a situation in which MAI anchors and grout pumps prove their value.BALTIC STATES. wooden piles will last indefinitely because oxidation is inhibited. The grout pressure is designed to create piles of the required diameter. and to ensure that the penetration is sufficient to produce a good pile without wastage. revealing the tops of the wooden piles. Dredging work can then be carried out without fear of the dock wall moving. resulting in tilting accompanied by severe structural cracking. sheet piles and into the bedrock.long Sheet pile Coupling T76 Concrete Soil Pre drilled at ø 150 mm FLOATING PLATFORM Grouting The 47 metre-long Atlas Copco MAI Self-Drilling Anchors are drilled through concrete. seeking to create a higher friction in the existing foundations of the building. Inlet grouting Micropiling For Support Cutter Adapter H55-MAI T76 Anchored rod T76. the water table in Riga Old City was stable. Addition of accelerators or retarders allows the installer to vary the set of the grout according to the specific ground conditions. The theory behind micropiling for support is very simple. or in the vicinity. new row of anchors will be drilled between the earlier anchors on the same line. and working places restricted. using wooden piles as foundations. Halting subsidence of old buildings is not easy. This is the precise scenario for which micropiles were developed. and low intrusion method of underpinning buildings. Saving Riga Installing MAI SDA using a handheld pneumatic jackhammer. micropiling offers a dependable. MAI fully-threaded pipe can be cut into any suitable length. a leading Baltic micropiling contractor. without influencing its function. Grout is mixed in an MAI M400 pump on which the pressure and quantity can be varied to suit the job. has underpinned a number of ancient buildings and office blocks in Riga Old City. MAI Self Drilling Anchors The MAI SDA self drilling anchor. possibly conveniently close to the cement storage.BALTIC STATES. FORE installed 200 micropiles to 8-9 m using MAI R38. The self drilling aspects of the MAI SDA system allow drilling in unconsolidated or non-cohesive soil which would otherwise require casing. The left-handed standard rope thread accepts standard drill tooling. and can be supplied in a variety of diameters and threads. To support the new Hotel Man-Tess. and the hollow rod permits simultaneous drilling and grouting through an adapter. if the designer has done his job correctly. The machine’s galvanized frame and stainless steel charging hopper guarantee corrosion protection and withstand the toughest treatment. the pipe. is ideally suited to the requirements of micropiling. and the pump itself is easy to dismantle for cleaning and maintenance. although designed primarily to operate in tension. Overall. For drilling purposes. using couplings for extension. Once a hole has reached the required depth. This allows the system to be installed in even the tightest situations. fast. The pullout force for a micropile is less than its load bearing capacity. and the drilling techniques used penetrate both wood and masonry without problems. Generally. situated. FORE. and the right diameter of anchor and drillbit are used. low-technology. The 200 year-old adjacent building was supported by 114 mm steel Atlas Copco ROC 712HC used by FORE to install MAI SDA. couplings and ROCK & SOIL REINFORCEMENT 121 . reinforcing the finished pile. speeding up pile installation. the grouting effectiveness can be gauged visually by the appearance of grout at the collar of the hole. NORTHERN EUROPE disposable bit are simply left in the hole. so a hydraulic testing jack can be used to check that any pile has achieved its design capacity. FORE is installing MAI R38 8 m-depth grouted anchors to provide stable foundations for new high-voltage electricity pylons crossing Riga docklands. Work was undertaken from both the street and basement of the building to produce crosspile support. Located on the same street as Pikadilija Café. In Valnu Street. These were then secured using 15 m-long MAI anchors drilled at 7 degrees from horizontal. situated close to Parliament House. A 14th Century grain warehouse in Aldaru Iela was underpinned by FORE in 2002 using MAI R38 SDA to produce crosspiles. and the micropiles are designed to take the whole weight of the building at around 20-25 t/unit. was refurbished. FORE installed 350 micropiles in the basement of the existing block. close to the Opera House. NORTHERN EUROPE L above: Ancient warehouse in Old Riga was saved by underpinning. and needed stabilization before refurbishment. The subsidence was arrested. and installed using Atlas Copco MAI SDA self drilling anchors. and filled with concrete. and designed to pass through the mud layer and penetrate 1 m into the sand layer beneath. At Pikadilija Café on Valnu Iela. MAI R38 SDA grouted by an MAI M400 grout pump produced high friction piles. In a totally different application. the six-storey structure has been subsiding into the very soft deltaic riverine deposit. and the building. The piles are 15 m deep and 15 degrees from vertical. each providing 30 t of anchoring force. The ground is non-supporting.BALTIC STATES. R above: Subsidence was arrested on the six-storey Pikadilja Cafe. Preserving Tartu Tartu City Hall has been successfully underpinned using micropiling techniques developed by local contractor Mikrovai. pipes installed to 8 m depth at half-metre spacing using an Atlas Copco 712HC drillrig. which is being converted to offices and flats. the Terranova building has been underpinned by FORE using 350 micropiles formed from MAI R38 self drilling anchors to 9 m depth grouted using an MAI M400 grout pump at 25 bar pressure. ROCK & SOIL REINFORCEMENT 122 . managing director of Geomek. if access is not a problem. and this takes a certain time according to the ground characteristics of each job. Because the more traditional wire rope anchors require a casing system of drilling. A rule of thumb when installing 15 m-long anchors is 15-25 holes/day/rig. with 76 mm EX bits. chief of BMGS geotechnical department in Riga. an old student dormitory block is being refurbished as a science department for the University. and uses MAI SDA T76 hollow threaded bar for longer micropiles up to 18 m.1 km of MAI SDA. The City Hall was underpinned in 10 weeks using a crew of 8 men. the anchors. this building would probably have been knocked down rather than refurbished. and poor choice can adversely affect the cost equation.100 m of R32 and R38 MAI SDA hollow threaded bar with 76 mm bits. the R32 micropiles were credited with 15 t bearing weight. Some 514 holes were drilled and grouted at 20 bar pressure. Thanks also to Nils Hellgren. spaced horizontally at 4 m intervals along the upper wall section. 123 . MAI produces a full range of disposable bits in diameters for every condition. s Imposing City Hall at Tartu was underpinned in 10 weeks using 3. Dainis Musins. Mikrovai underpinned the basement foundations by installing 230 off 6 m-long R32 micropiles using MAI SDA. NORTHERN EUROPE Mikrovai commonly installs 10-12 mlong piles using a 210 mm conical bit and square section pipe. they find that the drilling operation must not be carried out too quickly. they take longer to install and are more expensive for this type of job. representative agent for MAI products in the Baltic States. Also. can penetrate 4 m into the sandstone. Mikrovai has found that the drillbit is critical to a good job. and the R38 with 30 t. The R32 anchors have been tested at 20 t and the R38 at 40 t. with bit diameter up to 130 mm. for which temporary works include a steel sheet piled retaining wall to the high side of the sloping site. a large shopping mall is being constructed by the local Skanska company. and Urjo Eskel of Mikrovai for their help and assistance in the formulation of this article. Generally. The MAI hollow threaded bar has been used in 4 m lengths. By drilling at 10 degrees below horizontal. managing director of FORE. and a too-large diameter may cause the hole to collapse. Acknowledgements Atlas Copco is grateful to Valery Zagulin. 16-18 m-long R38 MAI SDA to anchor the wall to the sandstone substrata. Once the permanent retaining wall is built. At the crossroads in Tartu city centre. Here Mikrovai has installed 42 off. A too-small diameter drillbit will result in a smaller grout column than required. Also in Tartu.BALTIC STATES. the temporary wall will become redundant and the anchors will be cut ROCK & SOIL REINFORCEMENT and the sheet piles withdrawn for reuse. These were drilled at 15 degrees from vertical both inside and outside the building. The subsidence at the City Hall has been successfully arrested. and minor refurbishment works are now being undertaken with confidence. using a total of 3. 14-18 m-long R32 MAI SDA and 20 off. If micropiling were not available as a proven foundation underpinning technique. because the grout column has to form properly. or in other aggressive ground conditions. lightly loaded. ROCK & SOIL REINFORCEMENT . if developed by conventional means. sloping site comprising a relatively soft clay mix which. so here the MAI SDAs were inserted directly into a level surface which would eventually be 124 covered up to form the gardens of some of the new properties. At the lower end of the site local conditions over a short length did not permit the creation of an embankment. the site has been terraced with embankments supporting the service roads at the end of the gardens of adjacent new properties. UNITED KINGDOM MAI SDAs Increase Land Use for English Housing Support for New Housing In the UK soil nailing represents the vast majority of the market for selfdrilling anchors and housing development forms a large part of market growth. Kent to stabilize chalk and clay Daventry Development The main development contractor at Daventry is a joint venture of Thomas Vale Construction (Site Manager Dave Casey) and Westpoint Construction. At the Admirals Way housing development in the English Midlands town of Daventry. has been supplying geotechnical specialist contractor Keller Ground Engineering with hollow-bar MAI anchors for clay sub-soil stabilization. Exceptions are coastal areas where the effect of saline water is significant.DAVENTRY. Keller also recently carried out similar work at Snodland. Atlas Copco’s UK MAI distributor. A substantial development cost saving will result. In the background soil nailing is progressing on the section already marked out. tasked with building 26 houses. Installing soil nails in one of the development service road embankments. Most UK inland soil nailing applications are classified by geotechnical engineers as low-risk. The soil nails are installed by drilling into these embankments at 15-20 degrees. five pairs of flats and two bungalows on the site. Setting out the embankments in the central part of the housing development. As facilitated by the MAI Anchor soil nailing method. Dywidag Systems International. passive installations with a design life of 60 or 120 years. The housing development is on a wedgeshaped. would probably necessitate the excavation and construction of expensive deep foundations for the houses and service roads. This is achieved by using coupling sleeves to connect the standard lengths of threaded bar. permitting the rig to be driven along the row of soil-nails to be installed. sand. rotary drilling rigs to install the SDAs. generally with the boom Reinforcement is complete with a layer of geomat secured by SDA nuts and plates holding fine wire mesh. they are suitable for a wide range of ground materials including soft clay (as at Daventry).1 mm has an ultimate strength in this size of bar of 280 kN and yield strength 230 kN. Building from foundations commences with the completed embankment reinforcement in the background. measuring 32 mm diameter over the threads or effectively 29. and weathered and fractured rock.DAVENTRY. UNITED KINGDOM MAI SDAs The self-drilling anchors used by Keller at Daventry were of the R32N hollow ropethreaded bar design with 100 mm-diameter. rubble. views the installation of some of the last soil nails to be installed in the lower part of the site. John MacGregor Jr. inclined 15-20 deg and at right angles to the tracks. the consulting engineer’s ground reinforcement pattern called for soil-nail lengths of 5-13m depending on their position on the site. ROCK & SOIL REINFORCEMENT 125 . retroflush sacrificial drill bits suitable for clay. Depending on the type of bit used. The drill bit and rotation speed are chosen to ensure that the borehole is cut rather than Keller Ground Engineering’s Site Agent. open-face. inconsistent fill. hydraulic. The bar. MAI SDAs can be installed in unstable ground without the need for temporary hole casing by simultaneous drilling and grouting. boulders. gravel. The left-hand thread allows connection to standard drill tooling. A surveyor first lays out each portion of the site to be reinforced using red-painted markers to indicate the planned entry point for each soil nail according to the design of the consulting geotechnical engineer.. Installation At Daventry. Keller used two of their own crawlertrack. In all 750-760 soil nails are being installed at Admirals Way. A temporary bearing platform is installed since the test load would otherwise be pulling against a soft (clay) face.DAVENTRY.) through a special injection adaptor and thence through the hollow bar of the SDA. This allowed free access for a bulldozer to shape the bottom of the slope. The test establishes the true capacity of the soil nail bond in the stable zone rather than including the effect of the wedge zone. The facing components are held in place by the galvanized plates and threaded nuts of the SDAs. The completed slope stabilization showing the heads of the soil nails and the geogrid later displacing the soil through percussive action or a high feed pressure.1-4. Keller’s John MacGregor reported that. geosynthetic material incorporating a layer of lighter wire mesh. three or four metres long. represents an important application for embankment soil nailing to make the best use of landscaping. takes only about four minutes to insert using rotary percussive drill action and a 3-man crew. another to act as ‘spotter’ and to insert the MAI SDAs and extensions as drilling progresses. the geotechnical design called for ten ‘test’ soil nails across the site to which tension was applied once the grout had cured.s 126 ROCK & SOIL REINFORCEMENT . Keller employed a drill boom and feed mounted on the long backhoe boom of a hydraulic excavator to install five rows of soil nails in chalk and clay from the top of the embankment. Simultaneous with drilling a cementitious grout is pumped at 2.in. used 473 R32N MAI SDAs to create an embankment between the building area and a lake in an old chalk pit. sheets of welded heavy wire mesh are attached to the protruding SDAs. Once the soil-nails are inserted correctly into the ground. south-east England. After installing the soil nails the head plates and nuts were used to retain a geogrid layer of mesh and geosynthetic material to allow restoration with topsoil. Prestige Housing Keller Ground Engineering carried out work on another housing development in 2004. prior to excavating the low part of the slope.1 bar (30-60 lbf/sq. There is a drill-rig operator. non-woven. Dywidag’s own Stressing and Testing Services Department carried out all the testing work. followed by a layer of geomat. Keller Ground Engineering. and a grout mixer and pump operator. UNITED KINGDOM Installing the top row of soil nails at Woodlands Farm. on the Admirals Way site. albeit overlain with geogrid etc. The Woodlands Farm luxury housing development at Snodland in Kent. The soil nails were 10 or 12 metres total length. working for Berkeley Homes. This ensures better permeation of the grout and thus a better bond. Snodland. Each rod section of the soil nail. The use of large. This all acts mainly as erosion control of the stabilized surface. 100-mm bits enables a sufficiently large grout column to be created to meet the specification. but also aids the stability of the whole installation. designed a steep wall in a cutting. in conjunction with Atlas Copco Construction & Mining (UK). Midland Expressway (M6). ROCK & SOIL REINFORCEMENT 127 . the Birmingham Northern Relief Road. The fully galvanized. Alfred McAlpine. was the stabilization of a failing embankment on the Crewe-Salop Independent Line in the centre of the Midlands town of Crewe in October 2004. MAI SDAs varied in total length from 7 to 12m with couplers. Dywidag-Systems International. since many are over a century old. One recent rail project involving MAI SDAs. Some of the most prestigious recent transport construction and renovation projects in the UK have benefited from the use of the MAI SRN hollow-bar anchor system (Self-Drilling Anchors . Stabilizing Freight Route Britain’s transport infrastructure also includes many kilometres of rail routes. Using the alternative of soil nailing only limited access from the top of the embankment was required.SDAs). but this may have required lengthy closures of a busy rail route. the structures of which often require attention. whether for stabilization of cuttings walls or embankments. has been leading the way in slope stabilization using MAI self-drilling anchors. now known as the M6 Toll. Since this cutting construction was made in February 2003. the M6 Toll now forms a valuable and busy alternative to the previous congested routes of the old M6 and A5 linking the south-west Midlands of England to the North West. saving project expenditure. The engineer working for the Client. On behalf of the main contractor consortium CAMBBA (made up of Carillion. by-passing the Birmingham/Black Country conurbation. a deeper structure requiring more site investigation. a specialist sub-contractor installed 1000 soil nails using MAI SDAs in a grid pattern across the face of the cutting wall. First Toll Motorway One of the leading projects is the UK’s first toll motorway. chiefly for soil nailing. and some other environmental disturbance such as from noise. Network Rail (North West) and its Engineer considered the more conventional solution of sheet-piling the lower part of the embankment. Cutting during construction of the M6 Birmingham Northern Relief Road showing the (right) wall stabilized by MAI SDA soil nails compared with (left) a more conventional low-angle cutting slope requiring more surface area and volume of excavation. Balfour Beatty and Amec).UNITED KINGDOM Soil Nailing Infrastructure along England’s Routes A Major Force in Transport Slope Stabilization The UK distributor for MAI International. The use of slope stabilization with soil nails allowed the ‘footprint’ of the cutting to be reduced (see picture). The ground drilled is sandy clay with occasional boulders. R32N hollow-bar. protecting some existing trees. 678 in all. hence reducing the necessary land ‘take’ from the neighbouring landowner. necessitating the use of sacrificial drop-centre button bits with tungsten carbide peripheral blades to form a clean hole. The method. The slip had been caused by the presence of a perched water table. Using a series of one-way gates. Badger Bother The restored embankment on the London-Brighton line at Earlswood showing the soil-nailed gabions just below the rail level TSV Line near Henley-in-Arden had been suffering gradual subsidence due to both the type of fill material used and the activities of badgers burrowing in the embankments. Only the top-bar (down to the coupler) needed to be galvanized against atmospheric corrosion in order to preserve the structural integrity for the design life of the installation. and rail speed restrictions could be lifted. requiring a total of 1500 soil nails formed by R32N MAI hollow bar. Gabions are cuboid steel-wire-mesh baskets filled with rocks to form. The contractors used MAI SDAs to fix the gabions in position to form a platform under the track.UNITED KINGDOM On the Crewe embankment slope installing soil nails with excavatormounted drills. This enabled the soil nails to be installed in the embankment in an ‘underarm’ action. behind the slip plane. required major stabilization work for the Southern Zone of Network Rail. including simultaneous drilling and grouting. Also in the Midlands. Other Midlands rail projects have been carried out in Railtrack’s (now Network Rail) Midland Zone. with 100 soil nails in each. The head plates of the SDAs also serve to hold a layer of geosynthetic material in place to deter surface erosion. The effects of this on the track necessitated the imposition of a 20-mile/h (32-km/h) speed restriction on train movements. and employed R32N MAI hollow-bar of 16-m length. a self-draining wall. on the main London-to-Brighton railway line. using R32S galvanized MAI SDA hollow bar. Note protruding heads of installed SDAs The soil-nail reinforcement was designed in accordance with the new European soilnailing Standard EN 14490. The solution involved drainage of the perched water table and the installation of three rows. Following successful trials a specialist contractor installed the SDAs in both embankments. with neighbouring units. and also inserted the series of soil nails in the underlying embankment. the slope surface was reprofiled. Two embankments on the Nailed Gabions In March 2003 the Earlswood Embankment. Trial soil nails were first tested by Dywidag’s Stressing and Testing Department to establish the bond stress of the nail within the stable zone of the slope. The Client’s engineers chose a solution combining a layer of gabions immediately under the track with embankment slope soil nailing. leaving the rail lines below to be operated as normal and without disturbance to neighbouring structures. whilst also reducing overall installation time. enabled the reinforcement to be installed in the unconsolidated sand and gravel without resort to hole casing. Two drill booms were used. Following completion of the soil-nail grid. s ROCK & SOIL REINFORCEMENT 128 . mounted on hydraulic excavators with long-reach (22m) ‘sticks’. the badger population was ‘rehoused’ nearby before other rectification work began. The drilling equipment included a shank integrated into the injection adaptor enabling simultaneous drilling and grouting. there was a major slip in the Beehive Embankment on the West Coast Main Line in Leicestershire that needed to be rectified in February 2004. The embankment works were extensive. ITALY Portal Stabilization Using Swellex Olympic Deadline Improvements are being made to the state road EN23 near the town of Porte. particularly at the portals. Based on its proven quality and consistent performance. Turin in Italy ahead of the 2006 Winter Olympic Games. is using drill/blast techniques in the rock sections of the alignment. and Craviale with length of 991 m.PORTE-TURIN. in rock comprising gneiss-greenstone and gneiss mica-schist belonging to the metamorphic substratum of the Cristallino Massif of the Dora Maira. Atlas Copco Swellex Mn 16 was selected as the rockbolt for use in stabilizing the rock around the portal. Reinforcement of the slope by the eastern portal of the La Turina tunnel with 4 m-long Swellex Mn 16 rockbolts. a consortium known as Agency of XX Winter Olympic Games of Turin 2006. so rock reinforcement is critical to the success of the project. bi-directional natural tunnels are being built. Tunnel alignment is in gneissgreenstone. mica-schist and glaciallake loose ground. Mixed Ground The project designer for the underground work is Geodata SpA of Turin. and to reinforce the rock walls above the eastern portals of the tunnels. Swellex rockbolts were used both underground for primary support. Rock reinforcement is required to improve the quality of the rock. in the upper Chisone Valley of the Piedmont Region. The project is designed to relieve traffic congestion in the town centre. two single-tube. Italy. La Turina with a length of 601 m. for which Swellex Mn 16 rockbolts in lengths of 4 m and 6 m have been used for supporting the portal area. Project Description The project for the diversion of the Colle del Sestriere state road N23 is taking place near the town of Porte. whereas the Craviale tunnel was driven entirely ROCK & SOIL REINFORCEMENT 129 . for the client. Baldassini and Tognozzi SpA Costruzioni Generali of Firenze. approximately 40 km from Turin. The contractor. La Turina tunnel is being driven partly in rock and partly in softer ground. Slope Stabilization The geo-structural survey carried out on the slopes housing the portals showed that the Reinforcement of the slope at the eastern entrance of the Craviale tunnel using 6 m-long Swellex Mn16 rockbolts. In addition to embankments and dry bridges along the river Chisone. and a hydraulic hammer in the loose ground. . SMR classification. and resulting force applied a 120-150 kN/sq m.. being the rockbolts with the specified features. Delhi. ITALY Swellex rockbolts stocked by the eastern entrance of the Craviale tunnel. and around 200 bolts of lengths 4 m and 6 m were installed to support the eastern portal of Turina tunnel.s References: Palmstron. no blocks have moved and the entrances have been stabilized and safely supported. 130 ROCK & SOIL REINFORCEMENT . A. Int. To support the walls around the portals. M. Germany. 7th Congr. 1982. 1991. bolt strength 120-150kN. 4th Cong. They required immediate support using rockbolts and mesh with shotcrete to avoid the potential slide generated by a combined influence of the joints and inclination of the slope. Atlas Copco Swellex Mn16/Mn24 were installed. distance between bolts 1-3 m. and assessed as class IIISMR-Slope Mass Rating. Since the sides were reinforced in this fashion. These slopes. Assn Engng Geol. Some 450 bolts of 6 m length were used to stabilize the slope at the eastern entrance of the Craviale tunnel. Aachen. analyzed using the empirical approach of Romana (1991). On rock mech SRM. The formula of Palmstrom (1982) was used to calculate the required number of bolts based on the number of joints (Jv) per cubic metre of rock. rock was very altered and fractured. The volumetric joint count – a useful and simple measure of the degree of rock jointing. Proc. were classified as partially stable.. Proc.PORTE-TURIN. The bolt requirements indicated by this method were: length 3-6 m. Romana. In classes 4 and 5 an invert arch is added. Bratislava Contractor Banske Stavby is tunnelling under low overburden in heavy. and is carried out using drill/blast. NATM techniques are used.4 km-long twin-tube Sitina tunnel in Bratislava. Slovakia and the 380 m-long Valik tunnel at Plzen in the Czech Republic. Atlas Copco Rocket Boomer L2 C face drilling at Sitina south. The natural tunnel is being driven at an excavated section of 7998 sq m in crystalline rock comprising biotite and double-mica granodiorites with sporadic granites. In classes 1-3. These are difficult tunnels.SLOVAKIA AND CZECH REPUBLIC Driving From Budapest to Nürnberg Saving the Best Until Last Completion of missing links in the European Motorway system is rapidly producing fast connections between the most unlikely places. and excavation is by mechanical means.189 m of natural tunnel in between. with five basic rock classes. with systems of 1 mm-3 cm cracks and breaks which Grouting rockbolts from the basket of the Rocket Boomer 352. often with veins or pegmatites up to 1. Mucking out is by wheel loader into 25 t dumpers. each requiring 251 m of cut and cover at each end and 1. 131 . The client for the construction is Slovenska sprava ciest. The crystalline rock at Sitina is intensively tectonically disrupted. Symmetrix. Swellex. Often. a combination of drill/blast and mechanical excavation is employed. Key elements of the D2/D5 (E65/E50) motorway from Hungary to Germany are the 1. Boodex and MAI SDA are all employed to keep these jobs moving in the right direction. and the designer is Dopravoprojekt a. Sitina. Sitina tunnel comprises east and west tubes. broken granitoid rock using two Atlas Copco Rocket Boomers equipped with Secoroc T32 Speedrods and 45 – 51 mm bits. Both are using advanced rock reinforcement techniques to drive through incompetent rock with low overburden. Bratislava. together with Atlas Copco drillrigs and Secoroc drillsteel and bits. which is perhaps why they have been left until nearly last to be completed.5 m-thick.s. the excavation is divided into a top heading and ROCK & SOIL REINFORCEMENT bench. Injection grouting is carried out using an MAI m400NT grout pump. There is a serious blasting vibration restriction. using one of the Rocket Boomer drillrigs. 12 m-long pipes. lattice girders.SLOVAKIA AND CZECH REPUBLIC radially. The ground conditions may demand anything from 80 x 1. the Symmetrix system uses a rotating casing with rock cutting crown behind the pilot bit. and parameters are modified to counter undesirable effects. due to the proximity of the Slovak Academic Institute with its sensitive technical laboratory equipment. to which legs are bolted as the bench advances. the grouted columns formed complete umbrellas beneath which it was possible to excavate in 0. The bench is advanced to produce a full excavated section of 105 sq m. were drilled in with a pilot bit and disposable crown. The primary lining uses wet shotcrete with a non-alkaline accelerator. North portals of Sitina with east false tunnel nearing completion. The main faces are advanced as top headings. With 25-33 pipes in each top heading. Lately. Locally. Whereas Boodex employs a pilot bit with a following reamer. leaving a 5. These discontinuities result in rock splitting to produce large blocks which can fall from the roof and sides of the excavation. which enlarges the hole to allow the casing to be pushed in. 25 mm-diameter rebar rods is used in the worst ground conditions. and eight arches set and shotcreted.7 sq m top heading is micropiled through lattice girders to prevent falling ground. comprising 4 x 3 m lengths of perforated Boodex. and faster than Boodex where rock conditions have been particularly poor. mesh and 4-6 m-long grouted rebar rockbolts. each comprising 15–20 boreholes. Hence Symmetrix provides immediate support for the hole. blocky mylonite. with benches trailing at 50-120 m behind.5 m-deep blastholes using plastic explosives with millisecond delay detonation in the harder sections. beneath each umbrella. Initially. making it better in very poor ground conditions.8 m increments. to excavator-mounted hydraulic hammer or scaling bucket in the softer sections.4 m overlap beneath which the next umbrella could be safely drilled. In the areas of the main tunnels where the five crosspassages are being excavated ROCK & SOIL REINFORCEMENT 132 . locked tectonically into the granitodiorites. coarse blocks of schist-biotite paragneiss of several tens of metres in thickness occur. Symmetrix system umbrella drilling at Sitina portal. can be up to several metres wide. The 51. Forepoling with up to 40 x 4 m-long. and filled with clay material or breccia or mylonite. due to the shallow overburden and soft. Symmetrix has proved cheaper. Usually eight increments were advanced. more reliable. and some 20 Symmetrix 12 mlong umbrellas have been installed. Therefore continuous monitoring is necessary. The lattice girders comprise three pieces in the top heading. These were grouted for 10 minutes at 20 bar pressure to produce a concrete column around each pipe. and shotcreted prior to installation of 4 m-long grouted rebar bolts Symmetrix Complements Boodex Umbrella drilling has been needed throughout the alignment to date. Both Symmetrix and Odex can be used with all standard casings. one of two at site. and the rig to be used. but can also be used with top hammers such as the COP 1838 for small diameter holes for applications such as umbrella drilling where the lower torque requirement can be crucial. an excavator with scaling bucket or hydraulic hammer was used instead of the drillrig. It was driven as a 4 m-high top heading and 2 m bench. Valik tunnel west end showing south. Overall length of the tunnel is 380 m. a little slower. Main contractor Metrostav also has one Atlas Copco Rocket Boomer 352 at Valik. PVC and fibreglass casings. requiring buttress to be excavated and replaced in entirety Symmetrix or Odex? Both Symmetrix and Odex can be used for drilling holes up to 273 mm diameter. especially in urban areas. and may deviate if hard boulders are encountered.2 m. The central pilot tunnel. For shallow holes in soft ground. the presence of rock and boulders. A similar depth of concrete has also been laid at the ends of each of the tubes. where they are tending to replace pile driving and pipe jacking in ground containing boulders. the invert is concreted to a depth of 1. and for 10 m on either side. There is also a 900 m-long surface cutting at the east end to connect with the advancing motorway. comprising 330 m of natural tunnel. Atlas Copco Rocket Boomer L2 C starting south tube at Valik tunnel. depending upon the specific ground conditions.5 m.8 m. Odex is cheaper to use.SLOVAKIA AND CZECH REPUBLIC between the tubes. pilot and north tube excavations. and also with HPDE. The twin tubes have to be extremely close together. using an Atlas Copco Rocket Boomer L2 C. In very soft ground. Plzen Valik tunnel is situated about 30 km from the German border on the Czech Republic section of the Prague-Nürnberg motorway. ROCK & SOIL REINFORCEMENT 133 . when the choice of bit will depend upon the specific ground conditions. was excavated from the west end within a 4. Symmetrix is generally used with DTH hammers. 1.5-month timespan. with 20 m of cut-and-cover at the west end and 30 m of cut-and-cover at the east end. However. Excavation was in increments of 0. Drilled casings are becoming increasingly popular in underground construction. and is sometimes called upon to drill down to 100 m. and 1. will require more torque. and lattice girders were set at similar intervals. within which the reinforced concrete buttress for the main tunnel was constructed. with reinforced concrete before the main tunnel drives could commence. In these conditions. The natural tunnel is complicated by shallow cover and a very narrow corridor of surface rights beneath which it has to be excavated. together with four GIA DC16 service platforms based on Atlas Copco carriers. Valik. Symmetrix is often the only method that can penetrate successfully. a skilled driller will overcome these conditions.0 m. A beam support was also necessary immediately above the east portals. The remaining elements of the pilot tunnel lining are being removed on advance. The revealed ends of the rebars were hooked. 2006.000 of the 3 m version. together with 6 m-long face anchors. and then the remaining bench can be removed to construct a curved invert. Concrete Buttress The construction of the concrete support buttress between the two tubes of the main tunnel required foundation works through four separate soft ground sections.3 m to 0. manager at Valik tunnel.5 m. The final lining of the tunnel will comprise reinforced concrete of varying thickness from 0. to promote transfer of the ground pressure away from the main tunnel lining. who drilled 123 mm vertical Section of Valik tunnel showing concrete buttress between main tubes. MAI self drilling anchors SDA R 25 150kN in 3 m and 4 m lengths. Likewise. along with some 2. Some 3.SLOVAKIA AND CZECH REPUBLIC holes in the floor of the pilot tunnel. with shotcrete being applied systematically to roof and sidewalls. with shorter 3 m versions being used in the stronger rock sections. Main Tunnels Main tunnel excavations are being undertaken sequentially using NATM techniques. up to 27 SDA are being installed into each fan or profile. Depending on the geology. with a 1 m distance between fans. 6 mdeep micropiles were installed in rows of four and three at 1 m spacing. 134 ROCK & SOIL REINFORCEMENT . Immediate support was provided by 4 m-long Atlas Copco Swellex Mn12 rockbolts. Anton Sumerak jr and Anton Petko for permission to extract from their paper Technological Procedure of Construction for the Sitina Tunnel.000 of the longer units were installed. Acknowledgements Atlas Copco is grateful to Banske Stavby engineers Vladimir Kotrik. secured by 17 x 20 m-long grouted cable anchors. During the process. and installed two heavy rebars into each hole before pouring concrete to complete the piles in-situ. To improve the footing in these areas. the area above the concrete buttress is being grouted for consolidation. and to Metrostav engineer Miloslav Zelenka. an 18 m-deep pipe umbrella was installed. comprising a total of 90 linear metres. This work was undertaken by a specialist subcontractor. This involves top heading and bench excavation of the outside shoulders of each tube using lattice girders. This is followed by two-phase excavation of the upper sections of each tube to form the main tunnel roofs. The north tube is being developed in advance of the south tube. for his assistance at site.s Buttress formworks inside Valik pilot tunnel. Sitina tunnel is on schedule to open for traffic in August. Up to 25 Swellex bolts were installed for each metre of advance. In order to establish the east portals. and shotcrete. the crown of the pilot drive was reinforced by installation of 4 x 6 mlong grouted rebars per metre of advance to key into the buttress reinforcement. and to the face when necessary. in order to provide a secure connection for the main buttress concrete reinforcement. Ramp entrance to Oslo Subway tunnel development. The Unigrout EH 400-100-90 WBC described in this report proved to be the right machine for the job in every respect. Stop pressure 40-50 bar and be standing for 5 min. while in Norway leakage/min/drill hole is more popular. which called for an intense grouting operation. W:C ratio starts at 1.6/0. It comprises several new subprojects. Leakage<100 l/min drillhole. and leakage per drill hole must not exceed 10 lit/min. The total inflow of water in the tunnel was measured at 14. There is a difference between leakage per/min/100 m tunnel and leakage/min/ drill hole. The grouting stop pressure is set at 35-45 bar. In Scandinavian tunneling. the groundwater level could be maintained at the same level as before tunnel construction commenced.24 km-long tunnel.7 Leakage figures <1500 lit/min/drillhole gives a W:C ratio = 0. the leakage/min/100 m of tunnel the most important. with payment according to work and material quantities.8 Leakage figures < 1000 lit/min/drillhole gives a W:C ratio = 0. quantities of cement.OSLO. The main components were: drilled metres for investigation. numbers of packers. Contractor Veidekke chose the latest grouting technology from Atlas Copco Craelius to handle this challenge. bottom of the hole has to be 5-6 m outside the tunnel contour. leakage figures are most important and are used to guide the grouting operation.5 ROCK & SOIL REINFORCEMENT 135 .9 l/min/100 m.0 Leakage figures < 500 lit/min/drillhole gives a W:C ratio = 0. Leakage must be measured and recorded. and distance between two covers is set at 10 m. The systematic grouting procedure as laid out in the contract included following: 31 holes of 18 m-long. The alignment of the 1. The specification was set at 7 lit/min/100 m. NORWAY Systematic Grouting at Oslo Subway Half Century Progress The T-Baneringen project is the biggest enlargement of the Oslo Subway since the system got underway in the 1960s. with the grouting undertaken and with some infiltration. grouting and check holes. of which the first to be undertaken is the section from Ullevål Stadium to Storo. or two blasting rounds. Grouting Contract The contract differentiated between systematic and sporadic grouting. passes through a very difficult zone between sections 700 and 750. Pore pressure measurements showed that. In Sweden. where absolute control over the efficiency of the grouting operation was key to its success. and the working hours for the grouting operation. with a cross-sectional area of 65 sq m. pumping and placing of the grout. An operative works from the elevating basket. The left side of the grouting container features a wall divided into two flaps. Every step is recorded simultaneously on the Logac and the WBP. The grouting operator has full control of all the equipment and recorders within an arms reach. On the top of the Grout control station. On the silo section there is also a foldable walkway for the operator. NORWAY Grouting Quantities section 700-750 Drill metres: Micro cement: Grout Aid: Standard cement: Grouting time: Total cost: Grouting cost/m: for the 50 metre 9. The corresponding figures for the cement consumption were 425.255 kg 88. and the larger of the two also has an agitator level monitor. and the larger one for installation and removal of equipment. silo there are also a safety grill and a protecting lid. On the forward end there are protected connectors for the hoses. one for entry when the unit is not operating and there is no hydraulic power.609 kg 81. The electrical cable reel is located alongside the larger silo. Craelius Unigrout EH-400 The Unigrout EH 400-100 -90 WBC used in Oslo features two silos at the back of the unit. while the supervisor controls the results at the face.000 Atlas Copco Craelius Unigrout EH400100-90 WBC.000 kg big sacks.000-70. which sends a signal to the operator when the cement level is low. the small silo for bagged cement and the large silo for 1. He has three different operation modes to choose from: grout for the ROCK & SOIL REINFORCEMENT 136 .5 million NOK125. or. as in this case.860 kg compared with 50.234 kg 925 h NOK6. delivered by separate cement silo trucks.000 kg for the standard systematic method. placing the packers and grout lines in the grout holes in the order specified. Both onboard silos are equipped with vibrators. The lower part acts as a walkway during the grouting operation.081 m 426. Working platform at the front of the Unigrout truck.OSLO. The grouting operator carefully follows the different steps in the production. and the upper part acts as a protecting roof for the operator. both of which are operated hydraulically. On the right side of the container there are two doors. The grouting operation in this difficult section 700-750 was accomplished in 21 rounds compared with the 4-5 rounds required for the rest of the tunnel. OSLO, NORWAY standard grouting operation; GIN for performing grouting according to the GIN (Grouting Intensity Number) method; and Lugeon for water pressure tests. A roof over the control position protects him from dripping water and falling rock particles. The safety rack is folded in when the two flaps are unfolded, and the lights in the container roof reflect against the walls to provide good visibility for the grouters. Consultants set the GIN values based on the rock parameters for the maximum pressure, maximum volume/m/drillhole, and the allowed GIN max curve. They report that logging of the grouting operations and feedback from the LOGAC programs is a tremendous improvement. The quantities of cement per time unit for every Typical Logac screen dump. order receipts and mixing times are controlled by the formula system. The mixer is suspended on three strain gauge load cells. The Pumpac hydraulic control block has levers and knobs for the high pressure and low pressure valves and knobs for the flow setting valves. Beside the hydraulic Logac displays information about worksite and hole data. Worksite: 10 digits available Section: 10 digits available Hole No: 2 digits available Hole length: 3 digits + one dot(comma) digit Stage number: 3 digits available Recipe No: 2 digits available Injection round no: 1 digit File Name: A specific number for each and every hole Controlling overall grouting operation. single hole and for every water cement ratio are recorded, together with the start and stop times of grouting. The pressure history for every drillhole is also available. Cemix with two admixture tanks. Weight Batching The electronic weight batching processor Dosac SV 6804 is a compact modularbuilt, micro-controlled unit specifically designed for use on systems utilizing strain gauge load cells. It automatically weighs water, cement 1 and cement 2 on scale 1, and admixture 1 on scale 2 and admixture 1 on scale 3. All weighing can be done simultaneously. All instructions for weighing, emptying, ROCK & SOIL REINFORCEMENT Pumpac hydraulic control. control blocks are the hydraulic oil manometers. The Cemix 403 HWB mixer container is supported by three load cells which send the weight information to the WBP, which also controls the two admixture tanks 137 OSLO, NORWAY Refilling cement silos. hanging on load cells and the water inlet valve. Admixture Control The different types of admixture are supplied from 1,000 lit-capacity containers standing beside the Unigrout. Two pumps send the admixture up to two separate specially-designed distribution containers suspended on load cells for very accurate measurements. The load cells are monitored by the Dosac processor. A High Pressure Cleaning hose reel is placed next to the cement inlet for easy accessibility. Cement input is through a separate moisture-proof, dust-proof connection offering protection from splashed water. A special 300 lit-capacity water tank and booster pump are used for improving on the water filling speed. A good grout must be mixed according to specification and standard of cement, admixtures and other additives. There is a considerable difference in mixing Ordinary Portland Cement and microcement, and the admixtures also alter the quality of the grout considerably. can be different in each of the three agitators. At the Oslo Subway job, Veidekke chose to have two Cemags of different sizes in order to be better prepared for different qualities of grout. Both Cemags are supported by load cells, with weighing controlled by the operator from his panel Three Pumpac with 110 mm grout cylinders and standard ball valves are installed in the container, with room for a fourth pump above the third pump. Pumpac No 2 is installed above Pumpac No 1. All three installed pumps are easily accessible for service, and each can be supplied with a manifold with several grout lines if required. A drip pan under No 2 Pumpac collects any spillage. The grouting container is driven by two Power Unit Grouting PUG 45s with 45 kW electrical motors positioned to the front outside the container, in order to minimize any noise and disturbance. The compressor which operates the air regulated valves and cylinders is located between the two PUG 45s. The hydraulic pumps are lowered into the hydraulic oil in the tank beneath the electric motors.s For more info see the Atlas Copco Craelius Selection Guide on the Atlas Copco homepage. Twin Pumpac 110 B units. PUG 45 power unit grouting. Agitation and Delivery The three-way distribution valve is hydraulically operated from the operator’s panel, and the ready mixed grout can be directed to either of the two separate Cemags or to dump. Grout quality 138 ROCK & SOIL REINFORCEMENT ROCKBOLT SPECIFICATIONS ROCK & SOIL REINFORCEMENT 139 ROCKBOLT SPECIFICATIONS 140 ROCK & SOIL REINFORCEMENT ROCKBOLT SPECIFICATIONS ROCK & SOIL REINFORCEMENT 141 ROCKBOLT SPECIFICATIONS 142 ROCK & SOIL REINFORCEMENT . ROCKBOLT SPECIFICATIONS ROCK & SOIL REINFORCEMENT 143 . ROCKBOLT SPECIFICATIONS 144 ROCK & SOIL REINFORCEMENT . ROCKBOLT SPECIFICATIONS ROCK & SOIL REINFORCEMENT 145 . ROCKBOLT SPECIFICATIONS 146 ROCK & SOIL REINFORCEMENT . ROCKBOLT SPECIFICATIONS ROCK & SOIL REINFORCEMENT 147 . ROCKBOLT SPECIFICATIONS 148 ROCK & SOIL REINFORCEMENT . ROCKBOLT SPECIFICATIONS ROCK & SOIL REINFORCEMENT 149 . ROCKBOLT SPECIFICATIONS 150 ROCK & SOIL REINFORCEMENT . ROCKBOLT SPECIFICATIONS ROCK & SOIL REINFORCEMENT 151 . ANCHOR BOLT SPECIFICATIONS 152 ROCK & SOIL REINFORCEMENT . ANCHOR BOLT SPECIFICATIONS ROCK & SOIL REINFORCEMENT 153 . ANCHOR BOLT SPECIFICATIONS 154 ROCK & SOIL REINFORCEMENT . ANCHOR BOLT SPECIFICATIONS ROCK & SOIL REINFORCEMENT 155 . ANCHOR BOLT SPECIFICATIONS 156 ROCK & SOIL REINFORCEMENT . ANCHOR BOLT SPECIFICATIONS ROCK & SOIL REINFORCEMENT 157 . ANCHOR BOLT SPECIFICATIONS 158 ROCK & SOIL REINFORCEMENT . ANCHOR BOLT SPECIFICATIONS ROCK & SOIL REINFORCEMENT 159 . ANCHOR BOLT SPECIFICATIONS 160 ROCK & SOIL REINFORCEMENT . ANCHOR BOLT SPECIFICATIONS ROCK & SOIL REINFORCEMENT 161 . ANCHOR BOLT SPECIFICATIONS 162 ROCK & SOIL REINFORCEMENT . ANCHOR BOLT SPECIFICATIONS ROCK & SOIL REINFORCEMENT 163 . max. 20 kN 4400 lbf Tramming Tramming speed. Feed Feed length. 11700/13000 kg 25700/29300 lb Width 2370 mm 7'10" Length 10710 mm 35'2" Height 3100 mm 10'2" Visit www.1 Folding boom Fuel tank Capacity 280 l 73 US gal.1 km/h 2.COP 1840 Impact power.total 7140 mm 24' Travel length 4240 mm 15' Feed extension 1400 mm 4'3" Feed force.com for more information 164 ROCK & SOIL REINFORCEMENT . 8.max.max.T45 64-102 mm 13 /8"-4" T51 89-115 mm 31/2"-41/2" Hole depth 28 m approx. 18 kW 24.0 mph Tractive force 110 kN 2500 lbf Hill climbing ability 20 ° (30 ° with winch) Track oscillation ± 12 º Ground clearance 455 mm 171/2" Transport dimensions ROC D5/D7 Total weight.surfacedrilling.92' Recommended hole range for ROC D7 T38. 10.T38.DRILLRIG SPECIFICATION Main specifications Recommended hole range for ROC D5 R32.5 bar 152 psi FAD 105/127 l/s 215/270 cfm Engine ROC D5/D7 Caterpillar Diesel CAT 3126B Rating at 2200 rpm 131/149 kW 176/203 HP Boom -0.max.5 bar 125 psi FAD 85 l/s 180 cfm or Working pressure. 3.T45 35-89 mm 13 /8"-31/2" Hole depth 28 m approx.max.max. 12 kW 16 HP COP 1838 LE Impact power.approx.max. 16 kW 22 HP Hydraulic rock drill ROC D7 COP 1838ME/HE.5 HP Compressor Atlas Copco C 106 screw compressor Working pressure.92' T51 21 m 69' Hydraulic rock drills ROC D5 COP 1238ME Impact power. 1 km/h Traction force.DRILLRIG SPECIFICATION Main specifications Recommended hole range for ROC D5 R32.T38.COP 1840 Impact power.max.5 bar FAD at 10.92' 13 /8"-4" 31/2"-41/2" 92' 69' 16 HP 22 HP 24.cab version Fuel tank Capacity 280 l Feed Feed length. 20 kN Tramming Tramming speed.approx.max 110 kN Hill climbing ability (30 º with winch) Track oscillation ± 12 º Ground clearance 455 mm Transport dimensions Total weight.com for more information ROCK & SOIL REINFORCEMENT 165 . 10.5 HP 152 psi 215 cfm 156 HP/203 HP 73 US gal. 16 kW Hydraulic rock drill ROC D7 COP 1838ME/HE. 12500-13600 kg Width 2370 mm Length 10710 mm Height 13100 mm 13 /8"-31/2" approx. 28 m Recommended hole range for ROC D7 T38.total 7140 mm Travel length 4240 mm Feed extension 1400 mm Feed force.surfacedrilling.max.max.5 bar 105 l/s Engine ROC D5/D7 Caterpillar Diesel CAT 3126B Rating at 2200 rpm 131 kW/149 kW Boom -11 Folding boom.0 mph 25000 lbf 20 º 171/2" 27500-30000 lb 7'10" 35'2" 10'2" Visit www.T45 35-89 mm Hole depth.max.max. 18 kW Compressor Atlas Copco C 106 screw compressor Working pressure. 3. 24' 15' 4'3" 4400 lbf 2.T45 64-102 mm T51 89-115 mm Hole depth 28 m approx. T51 21 m Hydraulic rock drills ROC D5 COP 1238ME Impact power. 12 kW COP 1838 LE Impact power.max. BOLTING RIG SPECIFICATION Main specifications Boltec 235H-DCS Rock drill Bolting unit Boom Drilling system Bolting system Carrier Length.bom Width with bolt rack Height Turning radius Weight 1 x COP 1532/1132 1 x MBU 1 x BUT 35HB DCS 12-55 DCS DC 15C 6192 mm 2205 mm 2300 mm 5800/3000 mm 16600 kg 166 ROCK & SOIL REINFORCEMENT .excl. tramming Width Height.carrier roof min/max Turning radius Weight 1 x COP 1028 MBU 16SL 1 x BUT 32SL EDS 10000 mm 2480 mm 1300 mm 1300/1700 mm 6180/3550 mm 12800 kg ROCK & SOIL REINFORCEMENT 167 .BOLTING RIG SPECIFICATION Main specifications Boltec SL Rock drill Bolting unit Boom Drilling system Length. excl .tramming Width.standard Turning radius Weight 1 x COP 1532/1132 1 x MBU 1 x BUT 35HB RCS RCS L-series 13156 mm 2210 mm 3010 mm 6500/3600 mm 21600 kg 168 ROCK & SOIL REINFORCEMENT .bolt rack Height.BOLTING RIG SPECIFICATION Main specifications Boltec MC Rock drill Bolting unit Boom Drilling system Bolting system Carrier Length. standard Turning radius Weight 1 x COP 1532/1132 1 x MBU 1 x BUT 35HBE RCS RCS L-series 14096 mm 2510 mm 3100 mm 7650/4450 mm 26000 kg ROCK & SOIL REINFORCEMENT 169 .tramming Width.excl bolt rack Height.BOLTING RIG SPECIFICATION Main specifications Boltec LC Rock drill Bolting unit Boom Drilling system Bolting system Carrier Length. tramming Width.BOLTING RIG SPECIFICATION Main specifications Cabletec LC Rock drill Boom Feed Drill steel support Rod handling Control system 1 x COP 1838/1638 1 x BUT 35BB 1 x BMH 210-series BSH 55 RHS 17D RCS -Drilling RCS -Cable installation RCS -Cement handling L-series 14042 mm 2710 mm 3100 mm 7500/4550 mm 28000 kg Carrier Length.standard Turning radius Weight 170 ROCK & SOIL REINFORCEMENT .excl bolt rack Height. SCALING RIG SPECIFICATION Main specifications Scaletec LC Hammer Boom Control system Carrier Length.standard Turning radius Weight 1 x SB 300 Scaler 1 x BUT SC RCS M-series 13828 mm 2196 mm 3010 mm 6500/4000 mm 21000 kg ROCK & SOIL REINFORCEMENT 171 .tramming Width Height. DRILL RIG SPECIFICATIONS 172 ROCK & SOIL REINFORCEMENT . DRILL RIG SPECIFICATIONS ROCK & SOIL REINFORCEMENT 173 . HYDRAULIC DRILL SUPPORT BSH 110-SDA Kit Basic kit includes control panel.mounting kit and bushing halves. Bushing halves For Anchor rod R25 3128 2021 23 For Anchor rod R32 3128 2021 22 For Anchor rod R38 3128 2021 21 For Anchor rod R51 3128 2021 20 COP Conversion kit For COP 1238 3128 3124 80 For COP 1838 3128 3124 79 For COP 1440 3115 3129 90 174 ROCK & SOIL REINFORCEMENT . ROCKDRILL SPECIFICATIONS ROCK & SOIL REINFORCEMENT 175 . ROCKDRILL SPECIFICATIONS 176 ROCK & SOIL REINFORCEMENT . ROCKDRILL SPECIFICATIONS ROCK & SOIL REINFORCEMENT 177 . HYDRAULIC FEEDS 178 ROCK & SOIL REINFORCEMENT . HYDRAULIC FEEDS ROCK & SOIL REINFORCEMENT 179 . OVERBURDEN DRILLING 180 ROCK & SOIL REINFORCEMENT . OVERBURDEN DRILLING ROCK & SOIL REINFORCEMENT 181 . OVERBURDEN DRILLING 182 ROCK & SOIL REINFORCEMENT . OVERBURDEN DRILLING ROCK & SOIL REINFORCEMENT 183 . OVERBURDEN DRILLING 184 ROCK & SOIL REINFORCEMENT . OVERBURDEN DRILLING ROCK & SOIL REINFORCEMENT 185 . OVERBURDEN DRILLING 186 ROCK & SOIL REINFORCEMENT . and to depths beyond 100 metres.OVERBURDEN DRILLING Symmetrix Overburden Casing System The patented Symmetrix system can drill straight holes at any angle. ROCK & SOIL REINFORCEMENT 187 . including horizontal. power unit Length Width Height (transport) (operation) Line voltage Installed power Total weight 2 x CEMAG 203HWB 4 x CEMAG 402H 4 x PUMPAC 110B Basic 3 x PUG 45 12 m 2.9 m 4.8 m 3.GROUTING Main specifications UNIGROUT EH400-100-135WB Agitator Agitator Grout pump Hydr.7 m 690 V 150 kW 23 870 kg 188 ROCK & SOIL REINFORCEMENT . ROCKDRILL SPECIFICATIONS ROCK & SOIL REINFORCEMENT 189 . DRILLING EQUIPMENT 190 ROCK & SOIL REINFORCEMENT . DRILLING EQUIPMENT ROCK & SOIL REINFORCEMENT 191 . DRILLING EQUIPMENT 192 ROCK & SOIL REINFORCEMENT . DRILLING EQUIPMENT ROCK & SOIL REINFORCEMENT 193 . com/photo ROCK & SOIL REINFORCEMENT .atlascopco.raiseboring.com www.com 194 Link and Product pages: www.atlascopco.copdrill.com Atlas Copco Photo Archive: www.atlascopco.swellex.atlascopco.com/rde www.surfacedrilling.DRILLING EQUIPMENT Internet Guide Atlas Copco divisions: www.boomer-rig.com www.com/secoroc www.com/craelius www.com www.com www.atlascopco.atlascopcowagner.com/cmtportal www. DRILLING EQUIPMENT ROCK & SOIL REINFORCEMENT 195 . min-con.com 196 ROCK & SOIL REINFORCEMENT .DRILLING EQUIPMENT Keep up to date with the world of mechanized rock excavation – Visit Mining & Construction on-line at www. DRILLING EQUIPMENT Drill bit designs SECOROC Grind Matic: How to spend less on Secoroc products ROCK & SOIL REINFORCEMENT 197 . miningandconstruction.com 198 ROCK & SOIL REINFORCEMENT .DRILLING EQUIPMENT For a free subscription to Mining & Construction magazine visit www. ROCK & SOIL REINFORCEMENT 199 .DRILLING EQUIPMENT cont. DRILLING EQUIPMENT 200 ROCK & SOIL REINFORCEMENT . DRILLING EQUIPMENT . com 202 ROCK & SOIL REINFORCEMENT . To order.miningandconstruction.DRILLING EQUIPMENT All current Atlas Copco Reference Booklets are available on CD-ROM. visit www. DRILLING EQUIPMENT This issue of Rock and Soil Reinforcement is also available on CD-ROM. To order a personal copy visit www.rock reinforcement.com ROCK & SOIL REINFORCEMENT 203 . TAPERED EQUIPMENT 204 ROCK & SOIL REINFORCEMENT . TAPERED EQUIPMENT ROCK & SOIL REINFORCEMENT 205 . Button bit 156 exciting pages all about Surface Drilling Get your own copy at www.com 206 ROCK & SOIL REINFORCEMENT .TAPERED EQUIPMENT cont.min-con. TAPERED EQUIPMENT ROCK & SOIL REINFORCEMENT 207 . com 208 ROCK & SOIL REINFORCEMENT .min-con.TAPERED EQUIPMENT 152 exciting pages all about Face Drilling – Get your own copy at www. com and select “Country”. Or give us a call. Find out more at www. 9851 6283 01b The face of innovation . We’d be happy to listen to your requirements. Each and every product has been designed to help maximize your tunnel advance and minimize costs per drilled metre – and always with the highest level of safety in mind. Swellex rockbolts. and MAI self-drilling anchors.atlascopco. www. and even happier to meet them. we have the resources to be truly local. including fully-mechanized Boltec rock bolting rigs.com Printed matter no. Atlas Copco MAI Phone: +43 4245 65 16 60 Fax: +43 4245 65 16 68 00 Because we’re a global organization.Supporting your business wherever you are Atlas Copco supplies the widest range of advance cost-efficient rock reinforcement solutions for mining and tunnelling.atlascopco.