Bull Eng Geol Env (2006) 65: 209–216 DOI 10.1007/s10064-005-0020-3 ORIGINAL PAPER Helmut Bock Common ground in engineering geology, soil mechanics and rock mechanics: past, present and future Received: 14 May 2005 Accepted: 1 October 2005 Published online: 16 February 2006 Ó Springer-Verlag 2006 Abstract Engineering geology, together with soil mechanics and rock mechanics, is commonly considered to be one of the three fundamental scientific disciplines in ground engineering. Historically, the interrelation between these three disciplines has never been free of ambiguity. This, for instance, is highlighted by the fact that both Karl von Terzaghi, the founder of soil mechanics, and Leopold Muller, the founder of rock ¨ mechanics, considered themselves foremost as engineering geologists without, however, succeeding in establishing engineering geology as a free-standing discipline with autonomous intellectual merits, methods and procedures. This situation has changed recently as evidenced in Knill’s fundamental publication (2002) on Core Values in Engineering Geology and by the fact that the relevant three International Societies are currently in the process of moving together towards a ‘‘Federation of Geo-Engineering Societies’’. Keywords Engineering geology Æ Soil mechanics Æ Rock mechanics ´ ´ ´ ´ Resume La geologie de l’ingenieur, ´ avec la mecanique des sols et la H. Bock Q+S Consult, International Consulting for Quality Control and Safety Management in Geotechnical Engineering, Stoltenkampstr. 1, 48455 Bad Bentheim, Germany E-mail:
[email protected] Tel.: +49-5922-2700 ´ mecanique des roches, est com´ ´ ´ munement consideree comme l’une des trois disciplines scientifiques fondamentales dans le domaine de la ´ ´ geo-ingenierie. Historiquement, les relations entre ces trois disciplines ´ ´ ´ ´ n’ont jamais ete denuees d’ambi´ guı¨ te. Ceci, par exemple, est mis en ` ` lumiere par le fait que a la fois Karl von Terzaghi, le fondateur de la ´ mecanique des sols, et Leopold ´ Muller, le fondateur de la mecanique ¨ ´ des roches, se consideraient eux´ memes avant tout comme des speˆ ´ ´ cialistes de geologie de l’ingenieur, ´ ` ´ sans cependant avoir reussi a etablir ´ ´ la geologie de l’ingenieur comme une ` ` discipline a part entiere avec des ´ valeurs, des approches et des methodes autonomes. Cette situation a ´ ´ ´ change recemment comme l’a de´ montre la publication fondamentale de J. Knill (2002) sur les valeurs ` ´ ´ premieres de la geologie de l’ingeni´ ´ eur et par le fait que les trois societes ´ internationales concernees sont ac´ tuellement engagees dans un processus de rassemblement vers une ´ ´ ´ ´ ´ « Federation des Societes de Geo´ ingenierie ». ´ ´ ´ Mots cles Geologie de l’ingenieur Æ ´ ´ Mecanique des sols Æ Mecanique des roches Introduction In his keynote address to the millenium conference GeoEng 2000 in Melbourne, the eminent Canadian engineer Morgenstern (2000) emphasised the need to make the general public much more aware, than is currently the case, of the pivotal role of ground engineering. In his contribution, Morgenstern (2000) He considered engineering geology as an absolutely essential component of ground engineering: ‘‘If you do not succeed in grasping the concepts of . unstable ground in abandoned mining areas. Currently. appropriately entitled ‘‘Common Ground’’. An alternative term to ‘‘ground engineering’’ is ‘‘geo-engineering’’ (JTF 2004). a soft rock which currently has the attention of the scientific community as well as the general public as a potential host rock for the safe embedment of radioactive waste. Historically. land remediation. the interrelationship between these three disciplines was never free of ambiguity and animosity. one of the most urgent ground engineering problems of our times. oil and gas from wells. Renewed co-operation between the three fundamental geotechnical disciplines offers considerable potential for further scientific progress in ground engineering. in the field of ground engineering. Morgenstern (2000) also emphasised the need for an integrated (or holistic) approach to solving ground engineering problems. have existed between the various ground engineering disciplines. He was involved in important projects as diverse as coal mines. In Bock Bluming and Konietzky (2005). were relevant to ground engineering. and – Sustainable development (conservation of the environment including geological habitats. energy and minerals (groundwater. It became increasingly difficult to stay in command of all relevant aspects of any broader subject area. earthquakes. The earliest years of engineering geology are often reflected in the person of William Smith. paved the way for a renewed sense of common purpose across the various disciplines involved in ground engineering. William Smith was thus able to cover all pertinent aspects which. historic monuments. Examples include (JEWG 2004): – Safety of residential and industrial structures (foundations of dwellings and industrial plants) – Cost effective design and construction of the engineering infrastructure (all types of transportation routes. The scientific disciplines which are fundamental in ground engineering are soil mechanics. ground engineering contributes to the well being and advancement of our society in many ways. sub-surface emplacement of chemical and radio-active waste in geological repositories). Engineering geology. This will be underlined in the following section by some observations on Karl von Terzaghi and Leopold Muller ¨ who are commonly recognised as the fathers of soil mechanics and rock mechanics respectively. metals and minerals from open-cast and underground mines) – Mitigation of geological hazards (geologically compatible urban and regional planning including flooding. Soil mechanics and Karl Terzaghi In line with the accelerated pace of industrialisation in the early twentieth century. Throughout his professional life Terzaghi considered himself not only as an engineer but equally as an engineering geologist. ISRM and IAEG are undertaking promising steps to overcome the reservations which. This dilemma was even experienced by Terzaghi (1883– 1963) (Fig.210 H. electricity and communication cables) – Supply of water. liquefying and/or collapsing ground) – Alleviation of human-induced hazards (ground pollution. around the turn of the eighteenth to nineteenth century). the international Learned Societies ISSMGE. the body of technological and scientific knowledge and methods increased immensely. this is demonstrated by means of a micro-mechanical model of the Opalinus Clay. pavements and tunnels. In creating solutions which are both environmentally and technically sustainable as well as cost-effective and safe. e. circumstances which fostered specialists rather than generalists. As this term is commonly associated with the application of soil mechanics to civil engineering problems. 1) who is universally recognised as the father of soil mechanics and admired as one the most outstanding engineers of the twentieth century. volcanic activities. rock mechanics and engineering geology. landslides. gas. It was also at the time of a new demand for civil engineering expertise on construction projects at the onset of industrialisation. hydro-power energy from reservoirs and underground caverns. Ground engineering is engineering with. His contribution. He is noted as ‘‘The Father of British Geology’’ (Legget 1962) as well as for his eminence as a civil engineer. and in the sense of Morgenstern (2000). water. So. on or within geological materials. landforms and artefacts in local. buried lines of power. Within his own expertise. land drainage and canal construction. soil mechanics and rock mechanics in the past The advent of engineering geology occurred at about the same time that modern geological concepts were being worked out (i. coal. urban and regional development). This and relevant perspectives into the future will be outlined in the final section of this contribution. sewerage. for decades. within this paper and in line with JEWG (2004) the wider term ‘‘ground engineering’’ is preferred. at that time. too. Bock employed the term ‘‘geotechnical engineering’’ to our lives. This confession is quite surprising as. and as is well known across the engineering community. Terzaghi was a master of geological site characterisation and the development of appropriate strategies as.. in geo-engineering practice. 1 Karl von Terzaghi as painted by Harold Reiterer mid-1930s (from Goodman 1999) engineering geology you . the First International Conference on Soil Mechanics at Harvard in 1936 and the formation of an international learned society now known as the ISSMGE. Terzaghi – in marked contrast to his pioneering work on soil mechanics – experienced major difficulties in coming to grips with the principles of engineering geology.. In many of his publications.’’ in 1925. Fig. Muller (1908 – 1988) ¨ (Fig.. that ‘‘. the Fig. Soil Mechanics and ¨ Rock mechanics and Leopold Muller Strangely enough. like Terzaghi. some 6 years before his death. With a certain degree of frustration. time for publishing generalities on this subject has already passed . it is even more dangerous than rock construction without rock mechanics’’ (Muller-Salzburg 1980. 2 Leopold Muller in 1970 (from Baudendistel 1989) ¨ .. slippery like a reptile’’ (1945). Terzaghi must have felt his own failure to unify the theoretical and applied aspects of engineering geology when stating in 1947. soil mechanics and rock mechanics 211 International Society for Geotechnical Engineering.Common ground in engineering geology. statements can be found like this: ‘‘Rock engineering remains a sheer nonsense without engineering geology. on the question of a co-operation between geologists and engineers. ¨ p 5–6). As is documented in Goodman’s (1999) thoroughly researched and brilliantly written monograph. he conceded that there was no further hope of finishing his own book on engineering geology ‘‘because this subject is. The landmarks in this development were the publication of his book on ‘‘Erdbaumechanik .. thought of himself foremost as a professional engineering geologist. he never identified himself with this work. Muller believed that all of ¨ his undertakings were in ‘‘the spirit’’ of his university teachers Josef Stini (the eminent Austrian engineering geologist who introduced statistical joint measurements into ground engineering) and Hans Cloos (the brilliant structural geologist who intuitively discovered the scale effects in geomechanical models). 2). for instance. In 1957. Terzaghi was talked into co-authoring a textbook on engineering geology (RedlichTerzaghi and Kampe 1929). is documented in Rogers (2004).. however.. An example is always more convincing than the expression of intention’’.. who is widely considered as the father of rock mechanics. better keep away from earthwork engineering’’ (1957). for the time being. Terzaghi was instrumental in the establishment of soil mechanics as a free-standing scientific discipline. In contrast to engineering geology. ‘‘this strangely elusive subject. too much in a state of flux and my time is running out’’. in 2002. faults. soil mechanics and rock mechanics of today and in the future General If. in 1966. in 1962 in Salzburg. A number of reasons which have contributed to such a change can be identified: – Decades after Terzaghi’s struggle to come to terms with the ‘‘strangely elusive subject’’. expressions of interest for a closer co-operation between the three international ground engineering societies ISSMGE. the First ISRM Congress in Lisbon. analysis and design (e. The JEWG . With the move towards unified standards and the establishment of a world-wide network of professional services. to a Joint Task Force (JTF). g. the publica¨ tion of Muller’s first book on rock mechanics in 1963 ¨ and. as a free-standing discipline with autonomous intellectual merits. to a certain degree. ISRM and IAEG were formulated by the respective Presidents of the societies and by the organisers of the Geo Eng 2000 Conference in Melbourne. also segregation. The formation of a new scientific discipline alongside soil mechanics. – There is an ongoing debate about the particular contribution and responsibilities of engineering geologists and geotechnical engineers in the solution of problems in ground engineering. then today. precluded the possibility of obtaining sufficient information for a reliable assessment of the mechanical behaviour of rock structures. It may be of some interest to briefly recall the coming of age of rock mechanics as a free-standing scientific discipline. Opponents argued that the principles of soil mechanics (in particular the interaction between solids and fluids) are equally applicable to rocks. An integrated approach of all ground engineering partners is therefore required. methods and procedures. his views on the state of engineering geology as an autonomous discipline were not generally shared by the ground engineering community as is evidenced in Knill (2002). Bock In 1976. in 2003. in the past. it would have been unlikely that the considerable progress in rock mechanics over the last 30 or so years would have been achievable without the formation of a new. combined with the great expense of available testing procedures. Portugal. This is emphasised by differing professional definitions and accreditation rules that exist for geologists and engineers within major industrialised countries. Muller was convinced that engineering ¨ geology had established itself ‘‘as an independent scientific discipline and [the] basis of all geotechnical practice’’. bedding and schistosity planes. for some 30 years had been an established discipline. tasked with working out proposals for a restructuring of the three international societies in the move to establish a ‘‘Federation of International Geo-Engineering Societies’’. Amongst the landmarks of this development were the formation of the International Society for Rock Mechanics. in contrast to soil. which. Rock mechanics proponents pointed to the importance of discontinuities which. identifiable interna- tional society with its own interests and the clear mandate of its members. Terzaghi himself (1963) was convinced that the high degree of variability of rock masses. As evidenced by Knill (2002) it has established itself.212 H. – In our media-dominated world there is a definite need to raise public awareness and the profile of the ground engineering profession with clients. With hindsight and developments since that time. particularly as this period was closely witnessed by Niek Rengers as a Ph-D student of Leopold Muller at the Institute of Soil Mechanics and Rock ¨ Mechanics of the Technical University in Karlsruhe. it is integration and co-operation. and hopefully into the future. Morgenstern (2000) acknowledged the specific and valuable contribution of rock mechanics in the wider field of ground engineering. engineering geology has finally found its own identity. However. to the formation of a Joint European Working Group (JEWG) for the definition of a common scientific and professional platform for the three ground engineering disciplines (Bock et al. Subsequent meetings of the presidents led. occurred not without dispute. are prevalent in rock in the form of joints. Particularly noticeable were the development of powerful numerical models of jointed and discrete media and the fostering of links between geotechnical. He concluded that. the dominant feature of the three scientific ground engineering disciplines was differentiation and. Against this background and instigated by Morgenstern (2000). next to soil mechanics and rock mechanics. Austria with Leopold Muller being Inaugural President. 2004) and. Engineering geology. ISRM. the general public and with decision makers and politicians. The latter view was reinforced by the formation of the International Association for Engineering Geology (IAEG) and the successful staging of the First IAEG Congress in 1970 in Paris. John 1962). This can only be achieved through an integrated effort. mining and petroleum engineers. whilst there was much overlap in both technical content and audience within the soil and rock mechanics communities. any deficiencies in this regard will be counterproductive to the ground engineering profession at large. It was argued that the mechanical behaviour of such discontinuous materials is distinctively different from that of soil and requires special methods in testing. In the process of specifying a common platform. This model requires the specification of two general features. The arrows of Fig. soil mechanics and rock mechanics 213 delivered its Final Report to the three presidents in June 2004 (JEWG 2004). Soil mechanics and rock mechanics. whilst the JTF submitted an Interim Report in July 2004 (JTF 2004) with the intention to release its final report in February 2005. e. namely. as the umbrella term for both soil mechanics and rock mechanics – Engineering geology and – Design and implementation of ground engineering structures (ground engineering in its narrow sense) Each of the three areas was associated with three key aspects that. structures and processes. These three mechanical disciplines define the ‘‘Triangle of Geomechanics’’ (Fig. The triangle of geomechanics: soil mechanics and rock mechanics Ground engineering is based on a sound understanding of the mechanical behaviour of geological materials. which can pose a hazard to ground engineered structures. The triangle of ground engineering (in its narrow sense) The ‘‘Triangle of Ground Engineering’’ (Fig. are branches of material science. material science in general and soil and rock mechanics in particular. 3 The triangle of geomechanics discontinua. i. Within the triangle. Due to their major field of application. The specification and acceptance of such a platform is one of the keys in the intended formal co-operation of the international geo-engineering societies. 3). The objective is the setting up of a comprehensive geological model. Current geological conditions and landscapes are the result of past and ongoing geological processes. the relative positions of soil mechanics and rock mechanics can be located as shown in Fig. whilst rock mechanics has a strong adherence towards the mechanics of discontinua with major influences from solid and fluid mechanics. the JEWG identified the following three areas as fundamental to ground engineering: – Geomechanics. are grouped in subject specific interaction triangles as delineated in the following three subsections. like solid mechanics.Common ground in engineering geology. 3. coupled (often numerical) models play an outstanding role in both soil mechanics and rock mechanics. the JWEG Report was endorsed by the IAEG Council as a ‘‘Reference Document’’ of the IAEG. This places engineering geology firmly within geological science. Soil mechanics is the discipline that is characterised by the mechanical interaction between solids and fluids. the analysis and design of ground engineering structures and the super- . The common platform as formulated by the JEWG The following is a brief account of the common scientific and professional platform developed by the JEWG. The design and construction of sustainable structures requires understanding and accommodation of these processes. are commonly considered to be engineering disciplines. 4). In August 2004. Due to the assemblage of solids and fluids and their intrinsic nature within a fractured system. Accordingly. fluid mechanics and the mechanics of Solid Mechanics Soil Mechanics Geomechanics Fluid Mechanics Rock Mechanics Mechanics of Discontinua Fig. fluid mechanics and the mechanics of discontinua is intrinsic to geomechanics. The triangle is centred around the main engineering geological activities of site characterisation and synthesis based on the genetic understanding of geological materials. 5) encompasses the main activities which are intrinsic to engineering in a narrow sense. composition and geological boundary conditions. The composition of the ground and the geological processes prevailing at the site are most clearly identified and specified if they are considered within a genetic context. in line with Knill (2002). The triangle of engineering geology Ground engineering requires the project specific delineation of the sub-surface ground conditions. the mechanical behaviour of geological materials must incorporate principles of solid mechanics. 3 indicate that interaction between the three principal mechanical disciplines of solid mechanics. fluid mechanics and the mechanics of discontinua. The principal aspects involved constitute the ‘‘Triangle of Engineering Geology’’ (Fig. Degree of co-operation between engineering geologists and geotechnical engineers The requirement for formal linkages and feedback between the various professional practitioners within the field of ground engineering is project specific. 3. static and dynamic forces. physical and/or numerical). shown in Figs. 4. petroleum). often critical to the quality of the overall result. 6 which is characterised by the links between all three interaction triangles considered (Figs. ground water Boundary conditions: Geological processes Ground engineering in its broad sense Ground engineering in its broad sense is understood to comprise all of the aspects shown in Figs. 4 The triangle of engineering geology vision and monitoring of their construction. the ground model is subjected to a series of modelling investigations (conceptual. In the analysis and design. encompassing the most demanding Site characterisation Synthesis (based on genetic understanding) Geological hazards Geological Model of the site Fig. supervision. 5). 4. possible scale effects. The transfer from derived (EN 1997-2) to characteristic and design values (EN 1997-1) is based on the evaluation of sampling and testing procedures. 3. 5. natural and man-induced. adjustments may be implemented.214 H. ‘‘Geology’’ and ‘‘Engineering’’. 5 The triangle of ground engineering (narrow sense) . It is obvious that this central catalogue of tasks is best discharged in co-operation between engineering geologists and geotechnical engineers. in the end. 5 and described in the previous sections: ‘‘Geomechanics (Soil Mechanics and Rock Mechanics)’’. Ground engineering is based on a ground model that incorporates the geological model and the relevant engineering parameters and material properties. 5. The focus is to predict the ground behaviour that is the key to cost effective and safe structures. in particular. 4. Ground Model Modelling: conceptual. structural. applies to the ‘‘central oval’’ of Fig. civil. It is highest in projects of the geotechnical category 3 defined in Eurocode 7. regional context and experience with the materials. physical. Amongst others. g. usually in line with scenarios considered as part of an observational design procedure. The process is characterised by an integration of all relevant aspects. 3. ‘‘Engineering Geology’’ and ‘‘Ground Engineering’’ (in its narrow sense). and depending on the type of structure. state conditions. The ground is analysed under the influence of external and internal. The latter three terms constitute the fundamental elements of Ground Engineering. During the construction the ground performance is monitored and the actual behaviour compared with the predictions. contracting and construction. it includes an actualisation of the geological model. numerical Analysis and Design Construction: Specification. Bock Composition: material. mining. 6. monitoring Ground behaviour: predicted / actual Geotechnical uncertainty Fig. 3. An optimal configuration of the design parameters is established and provided in project drawings and specifications for tendering. The task which is required in this phase is considerable and. Effective ground engineering requires feedback between the various disciplines and interaction across the numerous aspects involved (interaction arrows throughout Figs. The analysis includes the safety of the ground against various types of failure and the deformational behaviour that might impair the performance of the structure. This. structure. For analysis and design. 6). When auxiliary terms are eliminated. 4. the derivation of their mechanical properties in laboratory and/or field testing and interpretation in terms of characteristic and design values. The development of the ground model is central to this process and includes the embedment of engineering parameters and material properties into the model. The integrated approach to solving ground engineering problems Ground engineering is essentially a serial process directed towards the ground engineering structure. the terms reduce to ‘‘Mechanics’’. into a comprehensive scheme as depicted in Fig. In the case of major discrepancies. it is commonly necessary to cooperate with engineers who specialise in other fields of engineering (e. the specification of constitutive laws appropriate for the soils and rocks in the model. Civil. soil mechanics and rock mechanics 215 Solid Mechanics Fluid Mechanics ISSMGE Soil Mechanics Geomechanics ISRM Rock Mechanics Idealisation of geomaterial behaviour Mechanics of Discontinua Modelling: conceptual. 6 The position of soil mechanics. 6 and as elaborated upon throughout the JEWG Report. cost effective and safe engineering solution. Engineering geologists and geotechnical engineers are unified in their overall objective to create a geologically and technically sustainable. Insurers Engineers (e. Funders. engineering geology is positioned at the same hierarchical level as soil mechanics and rock mechanics. Table 1 Level of co-operation between engineering geologists and geotechnical engineers Geotechnical categoryEurocode 7 1 2 3 Co-operation Optional Desirable Essential ´ ´ Resume of the position of engineering geology within ground engineering To our knowledge. state conditions ground water Geological Model Ground behaviour: predicted / actual Geotechnical uncertainty IAEG Engineering Geology Boundary conditions: Geological processes Geological hazards Project Partners General Public. structure. unanimously with the soil and rock mechanics engineers. Clearly. physical. Structural. the degree of explicit co-operation between engineering geologists and geotechnical engineers can be linked to the geotechnical categories as specified in Table 1. this is an achievement in its own right... Mining. numerical Constitutive laws Laboratory and field testing Material properties Derived.Common ground in engineering geology. Although based on a non-engineering scientific field. g. rock mechanics and engineering geology and the associated international societies within ground engineering (modified after JEWG 2004) geotechnical projects.. interacting with them in many aspects. Such dominance gradually decreases with the geotechnical categories 2 and 1. Planners.. it is for the first time ever that. engineering geology is seen as one of the scientific disciplines intrinsic to ground engineering in its broad sense. Accordingly. on an international level. characteristic and design values Ground Model Ground Engineering Structure Ground Engineering Cost effective and safe Geologically and technically sustainable Composition: material. the position of engineering geology in ground engineering has been defined within an official document. is essentially that of a service agent’’ to engineers . There is no room for some of the more traditional views that ‘‘engineering geology’s role . Clients.. As shown in Fig. Petroleum) Fig. In: Proceedings of Symposium of AEG. Felsmechanik. Int Conf Geotech Geol Eng. Quart J Eng Geol 30:293– 424 Goodman RE (1999) Karl Terzaghi. Bull Eng Geol Env (in press) DOI 10. In: Proceedings Amercian Society Civil Engineering 88:SM 8:1–30 JTF (2004) Federation of international geoengineering societies. Konietzky H (2005) ¨ Study of the micro-mechanical behaviour of the Opalinus Clay – an example of co-operation across the ground engineering disciplines. Rock Mech Suppl 10:1–8 Redlich K. Deuticke. Durban pp 1–45 Legget RF (1962) Geology and Engineering. Site characterization Terzaghi Kv (1925) Erdbaumechanik auf bodenphysikalischer Grundlage. p 340 JEWG (2004) Professional tasks. In: Report of the Athens Meeting. Reston. Reik G (eds) Geologie. Bull IAEG 9:75– 78 Muller-Salzburg L (1980) Aktuelle Fragen ¨ auf dem Grenzgebiet zwischen Ingenieurgeologie und Felsmechanik. ASCE Press. within the broader ground engineering context. p. Proceedings of American Social Civil Engineering 89:SM 1:295–300 . Lecture Notes in Earth Science Berlin (Springer). prediction and performance. McGraw-Hill. Geotechnical design—EN 1997-1. the engineer as artist.007/s10064-0050019-9 Eurocode 7. Clearly. vol 3. Blumling P. vol 1. New York. ¨ Stuttgart. Wien. June 2004 Knill J Sir (2002) Core values: the first Hans Cloos Lecture. References Baudendistel M (1989) Dem Lehrmeister Professor Leopold Muller-Salzburg. Wien. EN 19972. Enke. In: Report of the joint European working group of the IAEG. ISRM and ISSMGE John KW (1962) An approach to rock mechanics. In: Proceeding of 9th IAEG Congress. Reflections on the occasion of the 25th anniversary of the death of Hans Cloos. ISRM and IAEG for the definition of professional tasks. Felsbau. 104:1–8 Bock H. Part 2: Ground investigation and testing Fookes PG (1997) Geology for engineers: the geological model. special publication 19. p 708 Rogers JD (2004) Lessons on site characterization gleaned from geoforensic studies. responsibilities and cooperation in ground engineering. Kampe R (1929) Ingenieurgeologie. Bock (Fookes 1997). Melbourne 1:1–30 Muller L (1963) Der Felsbau. Part 1: General rules.216 H. 15).) pp 43–46 Bock H et al (2004) The joint European working group of the ISSMGE. p 399 Terzaghi Kv (1963) Discussion on John KW. An approach to rock mechanics. Terzaghi Kv. In: ¨ Egger P. pp 884 Morgenstern NR (2000) Common ground. pp 624 Muller-Salzburg L (1976) Geology and ¨ engineering geology. ‘‘all aspects must be kept in balance and no pertinent aspect should be omitted’’ (Knill 2002. Fecker E. Springer. ClausthalZellerfeld (Trans Tech Publ. responsibilities and co-operation in ground engineering.