इंटरनेटमानक Disclosure to Promote the Right To Information Whereas the Parliament of India has set out to provide a practical regime of right to information for citizens to secure access to information under the control of public authorities, in order to promote transparency and accountability in the working of every public authority, and whereas the attached publication of the Bureau of Indian Standards is of particular interest to the public, particularly disadvantaged communities and those engaged in the pursuit of education and knowledge, the attached public safety standard is made available to promote the timely dissemination of this information in an accurate manner to the public. “जान1 का अ+धकार, जी1 का अ+धकार” “प0रा1 को छोड न' 5 तरफ” “The Right to Information, The Right to Live” “Step Out From the Old to the New” Mazdoor Kisan Shakti Sangathan Jawaharlal Nehru IS 14458-2 (1997): Guidelines for retaining wall for hill area, Part 2: Design of retaining/breast walls [CED 56: Hill Area Development Engineering] “!ान $ एक न' भारत का +नम-ण” Satyanarayan Gangaram Pitroda “Invent a New India Using Knowledge” “!ान एक ऐसा खजाना > जो कभी च0राया नहB जा सकता ह” है” ह Bhartṛhari—Nītiśatakam “Knowledge is such a treasure which cannot be stolen” . . INDIAN STANDARDS 9 BAHADUR SHAH ZAFAR NEW DELHI 110002 October 1997 MARG Price Group 4 .( Reaffirmed 2002 ) Indian Standard RETAINING WALL FOR HILL AREA GUIDELINES PART 2 DESIGN OF RETAINING/BREAST Its WALLS 93.020 @ BIS 1997 BUREAU OF MANAK BHAVAN. Construction of banded dry stone walls. Construction of timber crib walls. This standard (Part 2) is. observed or calculated. CED 56 FOREWORD This Indian Standard was adopted by the Bureau of Indian Standards. therefore. Retaining wall is a structure used to retain backfill and maintain difference in the elevation of the two ground surfaces. Retaining wall may be effectively utilized to tackle the problem of landslide in hill area by stabilizing the fill slopes and cut slopes. In the formulation Handbook. after the draft finalized by theHi Area Development Engineering Sectional Committee had been approved by the Civil Engineering Division Council. Construction~of cement stone walls. one metre of extra width in filling. The composition Annex B. . Similarly the cost of a breast wall is several times more than a non-walled cut slope. However. Design of RCC cantilever wall/buttressed walls/L-type walls. being formulated to provide necessary guidance in design of retaining/breast walls for stability of hill slopes. requiring retaining walls. progressive slope instability and environmental degradation from unprotected heavy excavations. costs much more than constructing the same width by cutting inside the hill. and Design and construction of reinforced earth retaining walls. the use of retaining walls on hill roads and terraces becomesessential. expressing the result of a test or analysis shall be rounded off in accordance with IS 2 : 1960 ‘Rules for rounding off numerical values (revised)‘. The number of significant places retained in the rounded off value should be the same as that of the specified value in this standard. considering maintenance cost. the other parts of the code being as follows which are under preparation: Part Part Part Part Part Part Part Part Part 1 3 4 5 6 7 8 9 10 Selection of type of wall.Hill Area Development Engineering Sectional Committee. Construction of RCC crib walls. assistance has been derived from Mountain of technical committee responsible for the formulation Risk Engineering of this standard is given at For the purpose of deciding whether a particular requirement of this standard is complied with the final value. Construction of gabion walls. of this standard. Construction of dry stone walls. From the initial construction cost considerations. At the time of publication.1 TYPICALARRANGEMENTOFRETAININGWALLANDBREAST WALLINAROADCROSS-SECTION 1 IINS . 3.IS 14458 (Part 2) : 1997 Indian Standard . The Indian Standards listed in Annex A contain provisions which through reference in this text.1.1. 1).1 The allowable bearing capacity shall be calculated in accordance with IS6403 on the basis of soil test data. A toe wall cannot be used to stabilize an unstable slope. The retaining walls are also used extensively to develop sites for building complexes. and parties to agreements based on this standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated in Annex A 4 BEARING CAPACITY 4. RETAINING WALL FOR HILL AREA GUIDELINES PART 2 DESIGN OF RETAINING/BREAST a) b) 1 SCOPE This standard (Part 2) deals with design of gravity type structures used to support earth or other materials behind them which would otherwise not stay in that position.1 Breast walls are normally stone masonry walls provided to protect the slopes of cutting in natural ground from the action of weather and cut slope failure but not from impact of snow avalanches. the editions indicated were valid. Other types of retaining structures are covered in Part 9 and Part 10 of this standard (underpreparation) 2 REFERENCES WALLS Breast wall. the bearing capacity shall not exceed one-half the unconfined compression strength of the rock if the joints are 3 GENERAL 3. constitute provision of this standard.1 Gravity type retaining structures in hills are generally of two types: HILL SLOPE ROAD SIDE DRAIN \PARAPET WALL SLOPE FIG.2 Retaining walls are built to resist the earth pressure of filling and the traffic loads of the road. In case of non-erodible rocks. These are commonly used in hill roads when the road goes in embankment or partly cutting and part!y filling (see Fig. All standards are subject to revision. and Retaining wall. 3. silty or blayey medium to fine sand SP. Fine sand.60 0 38 0. In the absence of soil test data.3) Group Symbol 4.87 - > 31 > 0.79 SP 0 0 0 37 0.15 33 0. Table 1 Safe Bearing Capacities for Different Typesof Soil (Clause 4.3 The value of cohesion ‘c’ and angle of internal friction ‘a vary for different backfill and foundation materials.1 32 0. of Spit) (t/m’) of Soil . the bearing capacity shall not exceed one-tenth the unconfined compression strength of the rock.1.2 When earthquake forces are included. SC Very compact Medium to compact Loose 30 20 15 Homogeneous sandy or silty clay CL. SP Very compact 80 Medium to compact Loose 60 40 Coarse to medium sand. if any. the evaluation of loads and pressures that may act on the structure and the design of the structure to withstand these loads and pressures.1 The design of a retaining structure shall consist of two principal parts.1 Following forces shall be accounted for in the design: a) Self weight of the retaining structure.15 28 0.60 ML 0. SC Very compact 100 Gravel. However for preliminary design~the values given in Table 2 may be used. the permissible increase in allowable bearing capacity shall be in accordance with 3. loose soil.5 0. GC.66 SC 0.IS 14458 (Part 2) : 1997 tight.54 MH 0. sandy or clayey silt.47 CH 1.3 of IS 1893. b) Live load and imposed loads.35 SW 5. etc) gabion walls shall be preferred as they can withstand high differential settlements.1) Type of Bearing Material consistency Symbol of Place Recommended Value of Safe Bearing Capacity (t/m2) (1) (2) Well graded mixture of fine and coarse-grained soil. These values shall be determined by experiment. GC 2 - @’ (Effective Stress Envelope) (degrees) tan@’ (3) 0 (4) > 38 (5) > 0. GP SW. SM.79 0 > 37 > 0.65 0. c) Earth pressure acting on the wall.9 0. SM. silty or clayey medium to coarse sand SW. Inorganic silt. varied silt-clay-fine sand SC 4.74 - > 34 > 0. Bearing capacity of rocks may be determined in accordance with IS 12070.7 0.75 0. sand with little gravel SW.2 32 0.5 0.1 31 0. SP Very compact Medium to compact Loose 40 30 30 Very compact Medium to compact Loose 30 25 15 (3) (4) Fine to medium sand. CH Very stiff to hard Medium to stiff Soft 40 20 5 ML.67 CL 0.75 0. hard pan. MH Very stiff to hard Medium to stiff soft 30 15 5 inorganic clay.2 34 0. boulder clay GW-GC. glacial till. for preliminary design.21 25 0. c (Cohesion (1) (2) GW 0 0 GP 5 DESIGN CRITERIA GM 5.74 SM 0.1 19 0. Bearing capacity for weak and closely jointed rock shall be assessed after visual inspections supplemented as necessary by field or laboratory tests to determine their strength and compressibility. In case of erodible and weak foundations (clay. the values given in Table 1 may be adopted.62 ML-CL 0. boulder-gravel mixtures GW.67 SM-SC 0. gravel-sand mixtures. Where the joints are open.0 0. Table 2 Typical Strength Characteristics (Clcluse 4. 2(b) and thereby resist sliding it may be necessary to increase the base area or to add 3 6. For low volume roads. 5. 6. 6. f) Seismic forces.0 (with earthquake forces) NOTE .4 It is generally not possible to design each and every wall along the entire length of a road.0 (static loads) > 1. Adequate arrangement for release of this water pressure shall be made. Atleast 30 percent water pressure shall always be considered even in case of provision of good efficient pressure release system. 2. the factors of safety for slip surface below foundation shall be greater than 1. 3). and live and imposed loads shall be estimated in accordance with IS 875 (Parts 1 to 5). to achieve the minimum factor of safety given in 5. retaining walls with front face nearly vertical and back-face inclined shall be used as it will reduce the height of wall considerably.5 (with (see also earthquake IS 1904) forces) b) Factor of safety > 1. The consideration of full water pressure behind the wall may lead to quite heavy section.5 (static loads) against sliding > 1. if any. provided breast wall is founded on rock or firm natural ground.33 qa (during earth-quake) FIG.~ STEPPINGOFFOUNDATIONOFWALLON ROCKSLOPE Minimum base > 0 (zero) [see also pressure IS 4247 (Part 3)] Factor of safety > 1. foundation slab or to 5. All multiple breast walls shall be taken to the firm rock surface. concrete keys monolithicwith provide piles.5 and 1.3 Dip of the Base of Wall Towards Hillside A dip of the base of wall towards hillside to the extent of 3 : 1 (horizontal : vertical) proves very economical in seismic conditions (see Fig. using following criteria: a) Factor of safety against overturning > 2.2(a) and 5. Standard designs as given in Table 3 may be adopted for walls less than 8 m in height and 120 m2 area in a low hazard zone provided the allowable bearing capacity is more than the maximum pressure indicated in the table. In the usual cases live load may be taken between 250 kg/m2 to 500 kg/m2 on the top width of the wall. In case of steep slopes (>35“). Negative batter of upto 1 : 3 (horizontal : vertical) is recommended. In case of retaining walls for roads earth pressure due to surcharge shall be in accordance with IRC Codes.2 Stepping of Base of Wall on Rock Slope If the retaining wall is made on rock slope. if any.0 in static and seismic conditions respectively.4 Negative Batter of Backside of Breast Wall Breast wall with negative batter (see Fig. 5. .25 against floatation I In case of steep hills.2 Retaining walls and breast walls shall be designed as rigid walls. The self weight of the structure. the foundation shall be stepped as shown in Fig. The design of wall foundations shall meet the requirements of IS 1080 and IS 1904. So even nominal section of breast wall stabilizes cut slopes in soil.1 Depth of Walls The earth pressures and other seismic forces on the retaining structure shall be estimated in accordance with IS 1893. 3) on cut-slope side reduces earth pressure significantly.IS 14458(Part 2) : 1997 d) Water pressure due to water table/subsurface seepage. e) Water pressure due to water table on toe side. Maximum base 5 qa (allowable bearing pressure capacity) 5 1.3 Sometimes. The depth of retaining wall and breast wall below ground level or terrace level shall be at least 500 mm below side drain within soil or highly jointed rock and foundation shall be on natural firm ground. It increases factor of safety against sliding significantly. the walls may not be designed for earthquake forces.The live loads and imposed loads adding to stability of the structure shall not be considered in working out the factors of safety given in 5. 6 OTHER DETAILS 6.2(b). and g) Special loads. SP pressure Fair Top width Back-till in m hater Low pore pressure in m GM.___ I.94 9.81 2.33 6.0 20.11 - - 4.00 2.49 7.00 1.00 1.65 8. SC Foundation ML pressbre in t/m* 25.57 - 2. base inclined with hill.00 5.47 4.90 HI hhl Ht 3M Ht XM Ht IOh1 1.90 IS.00 25.00 39.00 20.00 1. SC presS”re in t/m* Poor Top width Back-fill in m / 0.00 32.26 20.59 8 I4 6.70 - - 0.80 1.89 I i.32 8.00 in t/m’ 0.89 8.00 I .58 - 17.00 100 _ _ __ _ _ -- I.00 18.81 6. bearing capacity is greater than the foundation pressure.00 25.00 19.00 I 00 I.8. I .50 10.00 - 2.79 - - - - - - - 22.00 1.00 I.1 I II.00 20.90 I.00 ~__.00 36.00 16.5.92 4.00 - -- - -- - - - - - - - - 6.11 - 4.00 0.65 0.00 21.00 20.01 - - 3.00 17.64 14.10 10.00 0.00 I.75 1.96 14.42 - 5.64 13.54 8.00 29.5 1.00 ‘+ :J friction of back fill in the case of dry stone masonry z 3 .00 25.00 075 ~ ~~ 0.00 13. SM Foundation SM.84 23.70 - %~~-~v~-~ 0.00 1.00 13.00 - 14.88 6.00 1.00 20.E Table 3 Standard Design of Cement Masonry and Dry Stone Masonry Retaihing Walls (Clause 5.00 22.78 841 523 8.50 7.00 28.5.00 1.00 1.70 7.00 20.00 NOTES 1 Wall Geometry : Front face vertical back.00 - 0.S t/m*. is slightly less for cement masonry wall because wall friction angle is likely to be equal to angle of internal 22. Ht 6M Ht 3M P Good Top width Back-fill in m FUll Base width Drainage in m GW.7s 0.95 1.00 - ll.00 1.12 4.94 I I 00 - - 22.00 0.00 1.4) Back Fill Cement Particulars c E Dry Stone Masonry Masonry 3 Type & / \ A f \ 5 ?? .12 4.75 - 0.03 II.00 22.63 649 6 94 6.00 IO.SO 5.00 34.85 1.00 20.00 2o.00 I 00 I I 01 ~- - - - - - 6.00 - 6.wo 0.00 1.00 - - 22. 2 Back Fill Top : Horizontal with surcharge 3 Select wall dimensions such that allowable 4 The base width for dry stone masonry wall - face inclined.97 16.90 1. GP Foundation SW.92 4.53 20.00 I.01 - 3.00 20.00 - Base width High pore Base width Water in m pressure Ht IOM Ht 8M GC.00 I 00 0.00 40.00 13.60 0.00 1.OO- 13.00 8.oo I 00 1.00 29.00 - 1.oo I 00 20.00 33.91 2.00 2..95 I. 5.5 m centre-to-centre in neither direction. If necessary. A catch water drain shall be provided at the toe of the breast wall to collect water from weep holes and surface runoff of the slope. .5. This may lead to toe erosion of soft rocks (shale/sand rock/conglomerate. Stones of 150 mm size may be laid on slope for a distance of 1 m below the toe of retaining walls. 6.5 Drainage Plan 6. the back-fill shall be of selfdraining material (coarse sand.5 Catch water drains shall be avoided near the top of the breast walls as they allow seepage of water in unmaintained conditiions into the cut slope and destabilize it.IS 14458(Part 2) : 1997 300mm LAYER OF SILTY SOIL WITH BOULDER TO PREVENT INGRESS OF RAIN WATER BREAST WALL RETAINING SLOPE 1 IN5 ATCH DRAIN LSLOPE 1 IN 5 FIG.3 Impervious silty soil layer or back-till of about 300 mm thickness shall be provided on the top to prevent seepage o( rain water in the back-fill or into the foundation of buildings on terraces (see Fig.2 Weep holes shall be provided in cement stone masonry walls at spacing of about 1. etc) at the foundation. So dry stone pitching may be done as shown in Fig. gravel and boulder).~ TERRACEDEVELOPMENTFORBUILDINGCOMPLEXESWITH RETAININGWALLANDBREASTWALL 6.5.51 Inverted filter shall be provided behind retaining walls to drain off ground water table or rainwater seepage. 6. 6. catch water drains may be provided far away from breast walls for above reasons. free of fines. 3. 6. 3). Grass turfing shall be laid on the ground slope to prevent erosion. However. 6.6 Erosion Control of Toe of Retaining Walls The rain water flows at a high speed from high retaining walls (~3 m).5. The size of weep holes shall be 100 mm to 150 mm PVC (flexible) pipes and shall be embedded at 10” down from the horizontal towards valley side to effectively drain the water from ground.4 Natural gullies shall be diverted away from the building site so that flow of rain water does not cause erosion of breast walls on topmost terrace. 1986 * (Part 2) : 1987 Imposed loads (second revision) (Part 3) : 1987 Wind loads (second revision) (Part 4) : 1987 Snow loads (second revision) (Part 5) : 1987 Special loads and load combinations (second revision) 1080 : 1986 Code of practice for design and construction of shallow foundations on SOih (other than raft. (Part 1) : 1987 Dead loads .IS 14458 (Part 2) : 1997 ANNEX A (Clause 2) LIST OF REFERRED INDIAN STANDARDS IS No. Title Code of practice for design loads (other than earthquake) for buildings and structures: .Unit weights of building material and stored materials (second revision) 875 IS No. ring and shell) (second revision) Title Criteria for earthquake design of structures revision) resistant (fourth Code of practice for design and construction of foundations in soils: General requirements (third revision) Code of practice for structural 4247 (Part 3) : 1978 design of surface hydel power stations: Part 3 Substructure Cfirst revision) 6403 : 1981 Code of practice for determination of bearing capacity of shallow foundations (first revision) 12070 : 1987 Code of practice for design and construction of shallow foundation on rock . 1893 : 1984 1904. New Delhi Uttar Pradesh Irrigation Design Organization. Jorhat Ministry of Railways.K.KALITA SHRIB. Madras Central Public-Works Department.KAUL SHRIKIREETKUMAR PROFA. New Delhi Forest Survey of India.K. Dehra Dun Regional Research Laboratory. Dehra Dun National Buildings Construction Corporation.GUPTA SHRIJ. New Delhi National Institute of Hydrology. CI~AKRABORTY SHRIR.UPADHYAY (Alternate) SHRIPAWANKUMARGUPTA FIELDCOORDINATOR(Altemare) SHRIT.JAIN (Alternate) SHRIBHOOPS~NGH SHRIR. Assam Public Works Department.K.C. New Delhi Indian Meteorological Department.K.BORTHAKUR (Alternate) SHRIS.DuBEY DRD.I (NZ)(AZtemafe) Indian Institute of Remote Sensing. Roorkee Members SHRISHEIKHNAZIRAHMED Public Works Department. Roorkee Ministry of Surface Transport. New Delhi IIT.JAGANNATHARAO SHR~D. New Delhi Central Water Commission. New Delhi Sikkim Hill Area Development Board.IRC(Alternate) DIRECTOR.GOPALAKRISHNAN(Alternate) SU~GSURVEYOROF Woags(NZ) SURVEYOROFWORKS.MA~TRA PROFARVINDKRISHAN(Aliemate) DRG. Army Headquarters. Jammu & Kashmir PROFAK.GOPALAKRISHNA(Alfemare) SHRIG. CED 56 Representing University of Roorkee.S.PATHAK (AZtemate) DRU.SAINI DRBHAWANISINGH DRP. New Delhi Central Mining Research Institute.L. Mussorie Building Materials and Technology Promotion Council. Dhanbad University of Roorkee.P. Gangtok Central Road Research Institute. S.B. Pant Institute of Himalayan Environment and Development.SINHA SHRID.HARBOL. School of Planning and Architecture.A SHRIP.PRADHAN SHRIP.SRINIVASULU SHRIN.P. New Delhi Indian Roads Congress. New Delhi Almora Central Building Research Institute.TOL~A(Alfemale) DR K.DASGUFTA(Altemnte) SHRIMATIM. New Delhi Directorate General Border Roads (D&S). Calcutta Engineer-in-Chief’s Branch.PARTHASARATHY SHRIN.BHAGA~‘(Alternate) SHRIP.K. Simla Structural Engineering Research Centre.S. HCD (N&W) DIREC~OR(SARDARSAROVAR)(@~~~~~) DRR.KLJMAR(Alfemare) CHIEFENGINEER(DAMDESIGN) SUNG ENGINEER(TEHRIDAM DEXGN CIRCLE)(Alfemnre) CHIEFENGINEER(ROADS) SUPIDGENGINEER(RoADS)(AZ~~~U~~) DEPLJTYDIRECTORGENERAL (D&S DT& DGBR) DEPUTYSECRETARY (T).BALI (Alremate) SHRID.D.SENGUPTA (Alternate) SH~UM.B.SINGH(Alternate) SHRILAKHBIRSINGHSONKHLA DRP.C. Roorkee North-Eastern Regional Institute of Water and Land Management. New Delhi G.K. Roorkee Department of Science and Technology.IS 14458 (Part 2) : 1997 ANNEX B (Foreword) COMMITTEE COMPOSITION Hill Area Development Chairman DRGOPALRANJAN Engineering Sectional Committee. New Delhi (Continued onpage 8) . S.LAKHERA (Alternate) CHAIRMAN-CUM-MANAGINGDIRECTOR SHRIB.S.C. RAo SHRIP.SINGH DRSUDHIRKUMAR (Alternate) PROF C.C.MEHROTRA SHRIN.N.M.SAH SHRIJ.C. Roorkee Geological Survey of India. New Delhi Society for Integrated Development of Himalayas.NARUW SHRIS. New Delhi U. BIS (. BIS SHRISANJAYPANT Deputy Director (Civ Engg). Lucknow Central Soil and Material Research Station.VIRDHI SHRIVINODKUMAR. Director (Civ Engg) Housing and Urban Development Corporation (HUDCO).5x-opficio Member) Member Secretaries SHRIT. New Delhi Wadia Institute of Himalayan Geology.C. BIS 8 . Hill Area Development Board.nWARl SHRIK. NARAYM’AN Joint Director (Civ Engg).IS 14458(Part 2) : 1997 (Continuedfiom page 7) Representing Members SHlUV.K BASBBAR(Alternate) DRN.P.SURESH SHRID. B. Dehra Dun Director General.S. VENKATACHALAM SHRIS.SINGH(Alternate) SHRlS.P. Marol. This Indian Standard has been developed from Dot: No. IV Cross Road. 9 Bahadur Shah Zafar Marg NEW DELHI 110002 Eastern 337 84 99. PUNE. BHOPAL. JAIPUR. Maniktola CALCUTTA 700054 Northern : SC0 335336. CHD 56 (5546). BHUBANESHWAR. Sector 34-A CHANDIGARH Southern : C. if the review indicates that changes are needed. Rintcdat Simco Printing Press.832 78 92 E9 MIDC. Scheme VII M. GHAZIABAD. of necessary details. C!lENNAI Western : Manakalaya. Branches : AHMADABAD. 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