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  1. 1. इंटरनेट मानक 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 12169 (1987): Criteria for design of small embankment dams [WRD 9: Dams and Spillways] “!ा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 है” ह ह” Bhartṛhari—Nītiśatakam “Knowledge is such a treasure which cannot be stolen”
  2. 2. IS : 121. ·1887 «R••ttlrmecl 1"7) Indian Standard CRITERIA FOR DESIGN OF SMALL EMBANKMENT DAMS ( FUll Reprint FEBRUARY 1999) UDC 627.81 : 624.136 : 624.31 C Copyright 1988 BUREAU OF INDIAN STANDARDS MANAK BRAVAN, 9 BAHADUR SHAH ZAFAR MARO NEW DBLHI 110002 Gr5 Feb",d'" 1988
  3. 3. IS • 12169 • 1'.7 Indian Standard CRITERIA FOR DESIGN OF SMALL EMBANKMENT DAMS Dams ( Overflow and Non-Overflow) Sectional Committee. BDC 53",.,. SOl V. B. R'lr'J,."ill, Irrigation Departmeal, GoverDment of Gujarat, PATBL M""6,,, R. BAL • • AMA.1t SaBI R.. K. BBA81. Kefale State Electricity Board, Trivandrum Dbakra Be.. Management Board, NaDlal Townlhip 8.81 SRRI SRBI KaURA• • ( ~l"'"," BSAT M. V. BRAR.. S8BI R. SlY AB• •ltAR ( SBRI B. K. CR ADSA Pao.. ) In perlOD.I capaeity (No. 599, 10th Cross,]a),,MI", B.,.,Glor, ) Tata ConiultiDI EDliaeen, BaDla10r. J. S. S.81 H. S. HARI KRISB.A ( Pao.. M. C. AI,,,,,.,.) Coalulting EDlineering Services ( India) Private Ltd, New Delhi AI'"IUII, ) CS.A.TURVEDJ CBIBI' EMOIN1i:BR (RANIIT SAGAR DAM) DIRBCTOR DAM ) ( (R.A.lfIIT Indian In,titute or TechnololY, New Delhi Irrilation Department. Government of Punjab, Chandi.erh SAGAB Alt6rnc', ) SBRI C. ETTY DAICoWlN In penonal capacity ( P. O. Mu".da, TriotJ"drUfll ) DJ.acToR Central Water It Power Research Station, PUDe SRal S. L. MOKA8HI (All""''') DJB.OTOR OP DB810.N8 Irri.atioD "Waterways Departmeae, Government of Welt BeDlal, Calcutta . DIB.CTOB ( Eat RDO-I ) CeDtral Water CommialioD, New Delhi D•• VTY DJBBOTOR ( E Ie RDD-I ) (Al",n,,',) DJBBOTOR, IN8'1·ITOTB ur HYDaAOLice & HYDROLOGY E.GI. M,,,,..,, ). . . Public Work. Department, GoverDment of Tamil Nadu, Madr.. SU. . .I.TDDIMG ( D.B.G•• ) ( So. M. V. S. IY••GAB HiDduitaD CoDitructloa Company Ltd, Bombay (C.,.,j"",d ." /HIg' 2 ) (f) or e.t1ri,,,, 1988 BUREAU INDIAN STANDARDS TIaII publlcatlaD II protected uacler tb. ,.... ~,' XIV or 1957 ) aDd nprocl~ ia wbol. 01' iD part by ua, me. . with written permiaioD of the publ'" ..... be d..... to be aD 01 copyrilbt uDder tbe said Act. e."n,,,, (
  4. 4. III 12169 • 1987 ( C.",in",d f,om /NI" I ) b/W6unlin, Irrigation Department, Government of ADdhr. Pradab, Hyderabad M,mHrs O .. FICBR-ON-S APERL D PEe I A L SUPBRIN'J'BltDJJUJ U T Y, EJfGI•••• ( D AK8 ) ( COO ) (AI,,,,,.,,) Sa.1 M. U. PUROBIT IrrigatioD Department, Government of Gujarat, Gandbinag.r Al'ma.', ) SRBI P. M. SOMI ( SUI R. AK IQBAL 8111GB SRal BISHAX LAL JATA• • ( RAilA RAO S•• I M. S. S••J M. S. RBDDY RlCpa8sBNTATIVII SECRETARY Irrigation Department, Government of Uuar Pradelh, Lucknow A.l'"",," ) Power Corporation Ltd, Bangalore K.rnataka Alt","", ) DIRJtc'roB ( CIVIL) ( S".JtRINTlIiNDJNO Elf Q I N B • B ( MD ), CDO SaBI K. N. VSNKATAB • • AN Central Water Commission, New Delhi 1••titutioD of Engineers ( India ), Calcutta CeDtral Board of Irrigation & Power, New Delhi Irrlladon Department, Government of Maharashtra, Bombay Major. Medium &t Minor Irrigation Department, GoYerDmeDt of Madhya Pradttsb, Bhopal O. N. T ••p.& (AI,,,,,.,, ) G. RAJI£N, Director General, SIS Director ( Civ Enll ) SSBJ SUBI (&-01"10 M'rtlbn ) SIn,'.", K. K. SHABKA JoiDt Director ( Ciy Enll ), BIS I SBBI Earth and Rockfill Dams Subcommittee, BDC 53 : 2 Co"",,,., M. U. PUROHIT Irri.atiOD DepartmeDt, GovernmeDt of Gujarat, OaDdhiaalar MIfIINr, SUP.RllfTDDI_O EJfQI~J aDO (AI.,,,.,. to Shri M. U. Purohit) .BBI N. K. A.o.... 8Bal K. K. S. BBAJlD....1 PROI' M. C. CHATUav.DI S••IIl. P. C80..... A.IIl. ( ~".,,..,,) S... K. N. T 8••1 It. R. DAT". ~ lallC.rOa ( It • D •• u~y Shallra Bea M......m••t Board, NaDiaI TowDihip (MImudI ) ladiaalnltitute of Techaol.,. Ne. Delbl Natio.a1 Project. CoaatructioD Corporatioa L'd, New Delbi RDD-I ) DI •• o~o. ~1InMI, ) B.,S••,,,".-, fa penoaal capacity ( .".. M"'II No.2, 14.S. C"'N, . ..",) CeDlral Water ColDmillloa, New D.lbi ( B a RDD-I ) ( ( c . . . - . , . " 20) 2
  5. 5. AMENDMENT NO.1 OCTOBER 2008 TO IS 12169 : 1987 CRITERIA FOR DESIGN OF SMALL EMBANKMENT DAMS (Page 9, clause 4.1.4) - Substitute 'IS 4999 : 1991·' for 'IS 4999 : 1968*' . (Page 9, footnote marked *) footnote: Substitute the following for the existing 'Recommendations for IfOUpina of plWioussoill (ftr. IWUIon). ' (Page 11, clause 4.8) - Substitute 'IS SOSO : 1992§' for 'IS S050 : 1968§'. (Page II, footnote marked §) footnote: Substitute the following for the existing 'Code of practicefor dOli..., construction IIld maintcnlDCC ofreliefwells (fvs' ,"18;011). t (Page 12, cltnl.fe S.I.1) - Substitute 'IS 10635 : 1993·' for 'IS 10635 : 1983*'. (Page 12, footnote ",arud *) - Substitute the following for the existing footnote: 'Freeboard laIuircments in emblDkment cIamI- Guidelines (fir" MluloII). • (Page 18, clause 7.2.1) - Insertthe following sentence at the ead: &After assessment of geo-technical panmeters of flyash and based on technoeconomic considerations, tlyash conforming to IS 3812 : 1981 may be used in therandom zones ondownstream of inclined filter in a zoned dam.' (WRD9) Ropropaphy Unit,DIS,New Delhi. India
  6. 6. III 1218 • 1987 Indian Standard CRITERIA FOR DESIGN OF SMALL EMBANKMENT DAMS o. FOREWORD 0.1 This Indian Standard was adopted by the Bureau of Indian Standards on 24 August 1987. after the draft finalized by the Dams ( Overflow and Non-overflow) Sectional Committee had been approved by the Civil Engineering Division Council. 0.2 A fairly large number of small embankment dalM are being built all over the country. These are generally designed locally and central design facilities are not made use of. In designing, a small embankment dam many of the provisions specified in IS: 8826-1978· are required to be modified or relaxed. It was, therefore, felt that a separate standard should be prepared for guiding the design of small embankment dams. 0.3 For the purpose of deciding whether a particular requirement of this standard is comr1ied with, the final value, observed or calculated. expressing the result 0 a test or analysis, shall be rounded off in accordance with IS : 2·1960·. The number of significant places retained in the rounded off value should be the same as that of the specified value in this standard. 1. SCOPB 1.1 This atandard la)'l down guidelinel for design of 'small embankment dams. 2. TERMINOLOGY 2.0 For the p ~ of this ..taDcIard. the (ollowing definitions in addition to those given in IS : 8826-1978* ahall apply. 2.1 Bm-·.....t Dam - A dam composed of any type of IOU including rock. 2.2 B.......... BlDh. . . .t Dam - AD embankment dam compoled or linBle type of material. . lor dee•• 01 I tllu•• for rOUDdiDI • DU MIt""" rock.1I clam.. aI,•• ( ,,.,. ). 3
  7. 7. 2.3 Lar•• Dam - A dam exceeding 15 m in height above deepest river bed level and a dam between 10 and 15 m height provided volume of earthwork exceeds 0·75 million ml and storage exceeds 1 million rnl or the maximum flood discharge exceedI 2 000 cumecs. 2.'.1 Modifi'd HomDII",DfU E",6""lcm,,,' Dam - An embankment dam in which Imall quantities of pervious material. selected to control the action of seepage, are carefully placed in an otherwise homogeneous dam ($I, Fig. 1 ). 2.4 RockfUI Da. - An embankment consisting of various sizes of rock t? provide Itability and an impervious core of membrane to provide watertightness. 2.5 Sman D.... - A dam not satisfying the criteria of a large dam ( sI,2.3 ). 2.6 Zea'" Bmb• • Dam - An embankment dam composed of of difF~rent types of soil ( '" Fig. 2A and 2B ). zon~. S. COMPONENTS OP EM8AKMBNT DAM 3.1 An embankment dam generally consists of the following components ( Fig.2A and 2B ). a) b) c) d) e) r) Cut-offj Core; Caling; Internal drainage .yltem and foundations; Slope protection; and Surface drainage. 3.2 The following componenta are provided in lpecial cues: a) ImpervioUi blanket; and b) R.elief well. ~. lVNarJON8 AND DBIION RBQ,UIRBMBNTI The (unctions and deaigD requirement. of the components are dambed in f.1 to fA. f.' 4.1 Cae..• •• 1.1 The cut-off is required for the following Coaction.: a) To reduce lou of stored water through foundationl and abutmentaj and b) To prevent subsurface erOlion by piping. 4
  8. 8. "'" Fla. 1 s: ~l_ Imperirous Sub·Stratum DAY SaDd Filter 6. Rock Toe 7. R.ubble PitchiDg 8. Tee Drain 5. CROSS-SECTION OF MODlnED HOMOGBNBOUS EARTH 4. 1. Selected Earth Fill 2. Impervious Fill 3. FoundatioD H N ....,. . • C • ... = ... ...
  9. 9. 0 IMPERVIOUS STRATUM I { .. TOP WIDTH RANDOM FILL RELATIVELY IMPERVIOUS PERVIOUS COVER 2A Embankment Dam with Central Core and Positive Cut-Off 6. lDcliDed aDd Horizontal Pilter I. Positi.-e Cut-oft" 7. Rock Toe aod Toe Dram 2. Grout CurtaiD 8. R.ipnp with Filter 3. CeDtral Impervioul Core 9. Catch Water Drain 4. Upstream Cui.. 5. DOWDItream Cuing NQIftI- HorizoDtal filter at intermediate levels are sometimes placed in the upltream cuiag zone wbere casiDI material is of Impervious Dature. fAl .. • .N • i I;
  10. 10. ..., 1. Impervious Blanket 2. Rock Toe aud Toe Dram 3. RelierWell f. TurfiDI 5. Berm 28 Embankment Dam with Inclined Core and Partial Cut-Off Flo. 2 COMPONENTS OP EIIBANEIfBNT DAM PERVIOUS FOUNDATION INCLINED IMPERVIOUS CORE DOWNSTREAM CASING ! • • .... N • ... ...
  11. 11. II t 1218 • 1117 I f.~.2 The type of cut-off should be decided on the basis of detailed geological investigation. It is desirable to provide a positive cut-off. Where this is not possible, partial cut-off with or without upstream impervious blanket may be provided. In any case, adequate drainage arrangements may be provided on the downstream which may, inter-alia, include relief well. Cut-off may be in the form of trench, sheet piling, cement bound curation, diaphragm of bentonite, concrete or other impervious materials, f.l.3 Recommendations for location and size of cut-off are given in to A drainage cut-off is the most common form of cut-off. f.I.S.l The alignment of the cut-off should be fixed in such a way that itl central line should be within the base of the impervious core. In case of positive' cut-off, it should be keyed at least to a depth of 0-4 m into continuous impervious sub-stratum or inerodible rock formation. The partial cut-off is specially suited for horizontaUy stratified foundations with relatively more pervious layer near top. The depth of the partial cut-off in deep pervious alluvium jlJ be governed by: a) Permeability of substrata; and b) Relative economics of depth of excavation governed usually by cost of dewatering versus length of upstream impervious blanket. 4.1.3." The bottom width of the cut-off trench may be fixed taking following factors into consideration: a) Provide sufficient working space for compaction equipments; b) Provide sufficient working space to carry-out curtain grouting; and c) Provide safety against piping. A minimum width of 4·0 m is recommended. A bottom width or 10 to 30 percent of hydraulic head may be provided to satisfy requirement of piping. This may be suitably increased to satisfy other requirements of mechanical equi pments and curtain grouting. The side slopes depend upon sub-strata. Side slopes of at least 1:1 or flatter may be provided in case of overburden, while i: 1 and i: I may be provided in soft rock and hard rock respectively. The back fill material for cut-off trench shall have same properties as those specified for impervious core in 4.2.1. The cut-off in the flanks on either side should normally extend up to the top of impervious core. 8
  12. 12. IS I 1218' • 1117 At the abutment contacts of the cut-off trench, care should be taken to avoid seepage by outflanking. 4.1.4 Necessity of grouting below the bed of cut-off trench will arise if the cut-off trench is terminated in rock formation and the rock is weathered or having cracks, joints and crevices. Necessity of grouting may be decided based on percolation tests. Rock having a lugeon value of more than 10 should be grouted so as to bring post-grouting lugeon value of about 5. The depth of grouting does not normally exceed half the head of water at the level from which grouting is done. The necessity of grouting below the bed in case of partial cut-off trench will be governed by the cost and effectiveness of the grout curtain vis-a-vis the value of water loss through seepage below and beyond the partial cut-off trench If grouting is done, provisions of IS : 4999-1968* may be followed. Alluvial strata having permeability in excess of 10-1 emls shall be treated thoroughly by grouping with a suitable material. Strata of permeability between 10'" emls and 10-8 emls may be treated to reduce the permeability to the extent possible. The grouping or strata having permeability less than 10-1 emil will be difficult, expensive and time consuming. 4.2 Core . f.2.1 The core provides impermeable barrier within the body of the dam. Impervious soils are generally suitable for the core. IS: 1498-1970t may be referred to for suitability of soils for the core. Appendix A Rives recommendations based on IS : 1498· 1970t. However, soils having high compressibility and liquid limit and having organic content may be avoided, if possible, as they are prone to swelling and formation of cracks. f.2.2 The core may be located either centrally or inclined upstream. The locations will depend mainly on the availability of materials, topography of site, foundation conditions, diversion considerations, etc. The main advantage of a central core is that it provides higher pressure at the contact between the core and the foundation reducing the possibility or leakage and piping. On the other hand, inclined core reduces the pore pressure in the downstream part of the dam and thereby increases its safety. It also permits the construction or downstream casing ahead of the core. The section with an inclined core allows the use of relatively large volume of random material on the downstream side. 4.2.3 The following practical considerations govern the thickness of the core: a) Availability of suitable impervious material; b) Resistance to piping; • Recommend.tioDI (or lroutlul or previous loill. tClu.iftcatioD and identificatioD of soil. Cor general engineering purposes (first "';S;otI ). 9
  13. 13. II • 12181 • 1117 c) Permiilible seepqe through dam; d) Availability of other materials for casing, filter, etc; and e) Minimum width that will permit proper construction. The minimum top width of the core should be 3 m, Its thickness at any sectlen Ihall not be lesser than gO percent (preferably Dot lesser than 50 percent ) of maximum head of water acting at that section. 4.2.t The top level of the core should be fixed at 0-5 m above MWL. 4.3 f.3.1 Tbe function of caling is to impart stability and protect the core. The relatively pervioul materials, which are not subject to cracking on direct exposure to the atmosphere, are suitable for casing. IS : 1498-19iO· may be referred to for auitability of loils for casing. Appendix A gives recommendationa baaed on IS : 1498·1970*. f." late..... DnIa.,. By.te_ 4.4.1 Internal drainage sy.tem comprises an inclined or vertical filter, a horizontal filter, a rock toe, a toe drain, etc. For the design of the components of the internal drainage system IS: 9429-1980t may be referred to. AI far as possible locally available sands, gravels, etc, should be used. 4.4.2 The design of filter consisb of applying the conventional filter criteria which take into account only the grain size distribution and the shape of the grainse However, in addition to the grain size, the stability of the base soil adjacent to a given filter depends on its resistance to drag forces. In view of this, when the soil containing 20 percent or more clay ia used .s a base soil and hal Don-dispersive properties, the filter criteria may not be enforced Itrictly and the clean land available locally may be used irrelpective of the gradation. This relaxation should be applied to dam. up to 10 m height only. For dams of height more than 10 m, the criteria for filtea protecting cohesive soil may be relaxed by the designer depending upon his judgement and experience, ".".3 Inclined or vertical filter together with the base filter. if required, il desirable to be provided especially to protect silty core material. However, the inclined or vertical filter may be deleted in zoned sections having perviOUI downltream abell and clayey cores but a transition filter between the core and the downltream shell would be necessary in case of dams where rockfill is used .. Ihell material. In case of dam reaches, where the bead of water il 3 m or JCII, it may not be necessary to provide blanket or chimney filte,.. Adequate toe protection shall, however, be provided. ·C1UlificatloD aDd identification of 1011. for general ~nllneeriDI purpOiN (fir,' ,lr/isiDII ). +c'.ode or practice lor draiDa.e IYlt8m Cor earth and rockSl1 dam•• 10
  14. 14. 4.4.~ Wherever there is silty material to be filled in the cut-off and the downstream face of the cut-off is sufficiently open to receive soil particles migrating under high seepage Rradienu, it is adviaable to provide a protectivc filter layer along the downstream face of the cut-oft' trench also. 4.5 Slope ProteetloD 4.5.1 Upstr'flm Slop, - The upstream slope protection is ensured by providing riprap. For design of the riprap, IS : 8237-1985* may be referred. A minimum of 300 mm thick riprap over 150 mm thick filter layer may be provided. 4.5.2 Dowllsl""", Slop, - The downstream slope protection is ensured by providing riprap or turfing. It is usual practice to protect the downstream slope from raincuta by providing suitable turfing on the entire slope. For details of downstrcam slope protection, IS : 8237·1985* may be referred. 4.6 Sarface Oral_aBe - For surface drainage of the downstream alopc of the dam, reference may be made to IS : 8237-1985*. 4.7 Impervlo•• Blaaket . 4.7.1 The horizontal upstream impervious blanket is provided to increase the path of seepage when full cut-off is not practicable on pervious foundations. The impervious blanket may be provided either with or without partial cut-off. Impervious blanket shall be connected to core of the dam as shown in Fig. 2B. f.7.2 The material used for impervious blanket should have far less permeability than the foundation soil. To avoid formation of cracks, the material should not be highly plastic. Reference may be made to IS : 1498-1970t for suitability of soils for blanket. Appendix A lives recommendations based on IS : 1498.197Of. A 300 mm thick layer of random material over the blanket is recommended to prevent cracking due to exposure to atmosphere. 4.7.3 The impervious blanket may be designed in accordance with IS : 8414·1977~. As a general guideline, impervious blanket with a minimum thickness of 1·0 m and a minimum length of 5 timcs the maximum water bead measured from upstream toe of the core may be provided. f.8 ReHel WeD. - If relief wells are provided, they should meet the requirements of IS : 5050-1968§. I ·Cocle or practice for protection of .lope Cor relervolr embaDkmlDti (fi'" "WI;'" ). tcl...iftcatioD aDd identificatioD of .oill Cor leDera. eDliDeerlDI purpose (fi',' ,.si.II i, de.ilD or uDder-.eepage control meaaure for eartb.rockfill dam•• ICode of practice Cor de.iID, cOD.truction and maiDtelWlce orrelW weill. ~GuideliDei Cor 11
  15. 15. II. i2169 .1981 S. BASIC DESIGN REQ,UIREMENTS 5.1 The basic requirements for design of embankment dam are to ensure: a) safety against overtopping, b) stability, and c) safety against internal erosion. 5.1.1 Ovnto/J/Jing - Sufficient spillway capacity should be provided to prevent overtopping of embankment during and after construction. The freeboard should be suffici~nt to prevent overtopping by waves and should take into account the settlement of the embankment and foundation. Free board for wave run up on slope shall be provided in accordance with the provisions contained in IS = 10635-1983*. 5.1.2 Stability Analysis The slopes of the embankment shall be stable under all loading conditions. They should also be flat enough so as not to impose excessive stresses on foundation. For small dams stability analysis may not be necessary provided a good foundation is available and the designer with his experience can decide adequate side slopes. However, where weak foundation conditions viz. fissured clay, expensive soils, shales, over consolidated highly plastic clays, soft clays dispersive soils, etc, are met within the substratum in the dam-seat, extensive investigations of the foundation soil and borrow area soil are required to be carried out and the design of the embankment dam carried out in accordance with IS : 7894-1975t The design of small embankment dam sections may be divided into the following three categories based upon the height of the embankment in its deepest portion. a) Embankments where the height is below and up to 5 m; b) Embankments where the height is more titan 5·0 m and up to 10 m; and c) Embankments where the height is above 10 m and up to 15 m, For small dams under category Cal and (b) above the stability analysis may not be necessary. General guidelines of the sections and the recommended slopes are given in Table I for guidance of the designer. The average properties considered for different soils are given in Table 2. However, the designer with his experience and judgement may decide the ·GuideIiDe. for Cree board requirement. ID embankment dams. tCode of practice for stability of .arth dam•• 12
  16. 16. .1.1218.1.7 adequate side slopes where special technical or economic considerations may have to be taken into account. Stability analysis may be carried out in accordance with IS : i894·1975· based upon the detailed foundation and borrow area investigation and laboratory testing if the soil strata below the dam seat consist of weak foundation as given in 5.1.2 2 and/or the height of embankment is more than 10 m. 6. SPECIAL DESIGN REQ,UIREMENTS 6.0 In addition to basic design requirements given in 5, the following special design requirements, should also be satisfied for embankment dams. 6.1 Coatrol of CracklDI - Cracking of impervious zone results in the failure of an embankment dam by erosion, piping, breaching, etc. Due consideration to cracking phenomenon shall, therefore, be Riven in the design of embankment dam. For classification of cracks and their importance, &.1.1 to 6.1.3 of IS : 8826-1978t may be referred. 6.1.1 ~1'(Jsu"'fo, Control '!f Cratki", - Following measure! are recommended for control of cracking: a) Use of plastic clay core and rolling the core material at slightly more than optimum moisture content, In case orl~ss plastic clay, 2 to 5 percent bentonite of 200 to 300 liquid lirnit may be mixe d to increase the plasticity. b) Use of wider core to reduce the possibility of transverse or horizontal cracks extending through it. c) Careful selection of fill materials to reduce the differential movement. To restrict the rockfill in lightly loaded outer casings and to use well graded materials in the inner casings on either side of the core. d) Wide transition zones of properly graded filters of adequate width for handling drainagr. if cracks develop. e) Special treatment. such al preloading, presaturation. removal of weak material, etc, to the foundation and abutment. if warranted. f) Delaying placement of core material in the crack region till mOlt of the settlement takes place. R) Arching the dam horizontally between Iteep abutments. h) Flattening the downstream slopes to increase slope stability in the event of saturation from crack leakage. j) Cutting back the steep abutment slopes. -Code of practice for I'ability analysis of earth dams. tGuidelincl £01' deailD of larle eanb aDd rocldill dams. 13
  17. 17. III 1218 • 1917 6.2 ltablU*7 at J_.ctl... - Junctions of embankment dam with foundation abutments, masonry structures, like overflow and non-overflow dams and outlets need special attention with reference to one or all of the following criteria: a) Good bond between embankment dam and foundation; b) Adequate creep length at the contact plane; c) Protection of embankment dam slope against scouring action; and d) Easy movement of traffic. 6.2.1 JII1I,';01l wi'h Fo"ndtlli01l - Embankment dam may be founded on soil overburden or rock. For foundation on soils or non-rocky strata, vege- / tation like bushes, grass roots, trees, etc, should be completely removed.' After removal of these materials, the foundation surface should be moistened to the required extent and adequately rolled before placing embankment material. For rocky foundation, the surface should be cleaned of aH loose fragments including semi-detached and overhanging surface blocks of rocks. Proper bond should be established between the embankment and the rock surface prepared. 8.2.2 ]"",tio", wil" AlJutmlnlJ - The rocky abutments should be suitably shaped and preapred in order to get good contact between the impervious core of the embankment and the rock over-hangs, if any, should be removed. Vertical surfaces should be excavated to form slopes, not steeper than 0·25 H to 1 V. A wider impervious zone and thicker transitions should be provided, at the abutment contacts to increase the length of path of seepage and to protect against erosioD. The bond between rocky or non-rocky abutment should be estabU.hed al in 6.2.1. In additioD, sufficient creep length should ~ provided between impervious aection of the dam and the abutment, 10 al to provide safety ag&lDlt ~ping. The creep length mould be not leal than 4 times the hydraulic bead. . N'''-DWi/ID. 1.2.3 .1.,"'",11 wit" Da", - Junction of Don-overftow masonry concrete dam with embankment dam is provided by a better not .teeper than 0-5 H to 1 V to the end race the non-overS ow block cominl in contact with the imperviOUI core. A wider impervioUi zone and thicker transitioDi shall be provided at the abutment CODtaetl to increue the lenBth 01 path of leepale and to protect alainlt eroaiOD. Sometimes thae contact layen are mixed with 2 to 5 perceDt bentonite with liquid Umit of 200 to 300 to callie expansion and hence to have joiDta. Sometimes the junction of earth dam with Don-ovdflow dam ia provided with earth retaining wall. perpendicular or akew at. the jUDctioa DOD-ovcr8ow clam or or 14
  18. 18. 18 1121" • 1181 TAiLlI GBNIIAL GUmlLINII rOIPIIAND11NT IICTlONI (ClaI' 5,1.2,3 ) SL No. DIIOllftIOI i) Type of lectiOO ii) SI." HOlloteneoul lectioa/Modi&ed ZoDed IICtioD/Modified helBO.'. homopoeoul HetioD OIOUilectioa/Homopleoul IICtioD ,._ _-.A--._ _ ,.... U,,,,.. a) Cot.drained loil (OW. p.SW, SP) (H) (V) c) FiDe ~rained 1011 (eL. L, CI, MI) d) FiD, pined lOiI (CH,MH) ~ #, ~ DelIS". Not Iuitable b) CoIne IralDed lOiI (GC. GM, SC, 8M) iii) IllIG.! AloVi 5m'ID V'TO 10 m WIIGI! U.TO 5m H_,IODe a) Top width UIs"· D."". Hllos! AJmlO mAID U.fO 151l ZODed section/Modified homOle· oeoulllCtioa/HoDaOIeDeoUi lIetlOl ,.-_...A._____....... D,w""',.,,. U,st,.. Not luitable for core Suitable for cum, Iooe Not luitlble (H) (V) (H) (V) 2: I 2: 1 2: I (H) (V) (H) (V) (H) (V) 2: I 2'5: I 2'251 : I (H) (V) (H) (V) (H) (V) (H) (V) 2: I 2: I 3'75: 1 Section to be decided baaed UpoD the 'tibilitllaDlly. iaaccordlice with S: 7894-1975 (H) (V) 2: I 2'5: I 2: 1 (H) (V) do do b) Top level May be provided Nuaary 3m 0'5 mabove MWL Not required Sm 0'5 Dl above MWL Necessary iv) Rock toe beilbt Not leeeuary up to 3m, Above Smheiahl, I Dl htl or rock toe .IYbe provid Neceury Ht 5. where Hiltbe heilht H/S. where H it tbe beilht or emblDkmeD' v) Bera Notoec_ry Notnle." The berm may be provided u per del:. Tbe miJaimum berm width II b.3m, The berm may be provided alto on tb, _Iream lIope ror (acilities duriq maiDt..... is
  19. 19. 18 , 12169 • 1981 TAILE 2 A VlRAGI PROPERTIES 'OR DmERENT TYpg or lOlLS (Cilu5.1,2.3) SL ENGINEBRING No. CLUtl'101'1'1010' SOIL (,,, IS:1498-1970-) i) GO ii) OM iii) iv) so SM v) ML vi) CL CH vii) viii) MH or ,-----------_..Jt.-___.. ____ SOIL AV.BAGI PROPl.TIII MDD k./ma > 1840 > 1830 1830 ± 16 1840 ± 16 1650 :I: 16 I 730 ± 16 1510 ± 32 1310:i: 64 OMC perceDt < 15 <15 15 ±04 IS:!: Off Coh,.iDD t _ _ _. . , TID~ k"m' NA NA 500±500 1100 Z 600 19 ±0'1 900 ±NA 17 ± 0'03 1200 ± 200 25:1: )'2 I !OO ±600 36 ±3'2 2000 :: 900 >0'60 >0'67 O'58:!: 0'07 0'6 ±0'07 0'62 ±0'04 0'54 :t: 0'04 0'35 ±0'09 0'.7 :l: 0'05 'Claujfication ud ideDti6catioD or loil. for ,eneral eD,meeriDl purpolea (firs' ,,,"ill ). 16 t" SOIL Co'I'AftI '01 RICO.IIIDID SLOP. - - . A . -__- - " " MDD OMC CobIll. kl/ml percelt kl/m' TID' I800 IS I 100 0'60 1650 19 900 0'55 1300 35 1sao 0'35
  20. 20. with the overftow dam. Such retaining walls shorten the length of nonoverflow dam (transition length) but they themselves add to the cost. The alignment or the dam and the junction may sometimes have to be modified to suit smooth transition of road on top of dam from non-overflow section to embankment dam section. 6.2.t Ju"ctio" with Outl,tr - Proper bond should be provided between the earthwork and the outlet walls. Staunching rings should be provided along the outlet conduits in the impervious zone, at intervals, so as to increase the path of percolation along the contact. Backfilling of the trench for the outlet conduit should be done with concrete up to the top of rock surface and the portion of the trench above the rock level should be refilled with impervious material compacted with moisture contact about 2 percent more than optimum. The shape of conduit ceming in contact with earthwork shall be given a aide better of 0·25 H to 1 V to provide a better contact with the earthwork. Sharp corners at the top should be avoided. Special care should be taken to ensure tigbt contacts between the trench fact and the backfill. 7. SELECTION OF DAM SECTION or 7.1 No single type core-section of embankment dam is suited for aU lite conditions. The adoption of the particular type of embankment section depends upon the following factors: a) Availability of the suitable local material in sufficint quantity within reasonable range; b) Foundation conditions and cut-oft' requirements; c) Types of construction plant, earth moving, compaction and other equipment; d) DivenioD consideratioDi and construction Ichedulei e) Climatic conditions in relation to placement, moisture content control, lublequent moisture content change, etc; and r) Safety with respect to ltability and seepage. 7.0'-- - 7.2 If only one type of lUitabJe material is readily available nearby, a homOleneoua section iI genenlJy preferred. If the material available 11 impervious or aemi-perviouI, a amall quantity pervioua material II required u cuiDB Cor proteclioD asUDII cr.cki~l. On the other hand, if it it perviou.. a thin imperviOUI memberane iI required 10 .. to or form. wat~r barrier. 17
  21. 21. IS I 12169 • 1981 7.2.1 A zoned dam ii, however, preferred where different types oflOila are available from borrow area. I t also facilitates the we of compulsory excavation from foundation, approach channel, tail channel, etc. The zoned embankment dam is generally composed of an impervious core bounded by transitions and/or outer casing of pervious material. In zoned embankment dam, the weaker materials are oflen utilized most econmically in the form of random zones. Maximum utilization of the material available from compulsory excavation should be aimed at. Random zonea are generally provided below minimum draw down level on upstream side and on downstream of inclined filter. When upstream casing zone is of relatively impervious mate I ial J horizontal filters at suitable intervals, say 5 to 6 m, may be provided to limit the drawdown pore pressures for dams of height more than 10 m, ( &, Note below Fig. 2A). 7.2.2 The zoning of embankment dam as planned in the design may have to be altered or modified during execution stage in view of the lollowing: a) The materials estimated are not available according to requirement; b) Different types of material encountered whicb could not be ascertained during investigations; c) Construction difficulties; d) Construction schedule; and e) New foundation features. 7.3 Top Wiclt. --.,. The width of the dam at the crest should be fixed according to the working space required at the top. No dam should have crest width of leal than 4·5 m,
  22. 22. III 12169 • 1117 APPENDIX A ( Claus" 4.2.1, 4.3.1 and 4.7.2 ) SUITABILITY OF SOIL FOR CONSTRUCTION OP DAMS R,I.,irJ' Su;lflbility HomtJlnuoul Dylc" ~o",d Dam l",JImIitnu Impervious Core Pervious Casing SW,GW Very 8uitable GO GC Suitable OLtOI OL,OI Fairly suitable SP,8M GM,GO SM, SC, OR OR Poor Net suitable Bl""k" r-------v-------~ OM GO CL,OI SP, GP OR, 8M SO, GO ML,MI,MH OL, 01, OR Pt. NOTB - R.Cer to IS : 1498-1970 ·CI...ifie.doD and leDeral eDliDeeriDI purpOlea (firs' r.isi.,. ) •• '9 id~Dtific.tion of lOll. for
  23. 23. 18 I 12169 • 1987 ( CIIfIIirIuHft.", Pa,' 2 ) M""IJ", DIBIlCTOB (DAII) ( It .& )I J I T SAOAR DAM) 8a81 Y. B. MATHUR (All"..,,) DB M. C. GOBL SBBI V. K. JAI. SR.I Bllt8AM BALDBV RAJ ( SRaI D. G. KADEAD. SHaI T. K. NATABAJAJf R.",."", Irri,adon Department, Governmeat Chandilarh or PUDjab. Water R.esource. Development and Traininl Centre. Univenity of Roorkee, Roorkee Irrigation Department. Government of Uttar Prade.h, Lucknow All"."" ) Jaiprakaah Aaociated Private Ltd, New Delhi CeDtral Road Research IDlthule (CSIR), New Delhi ()I'I'IOn-oJ(-S • • o I A L D U Tor, IrritratioD Department, Governm~Dt ADdbr. Pradesh, Hyderabad APERL or SUJ-.BnrrzlfDI_O bGIOBB ( DAMS) ( CDO ) (AII'rI."" SRBI BaIlENDBA KOMAR SHARMA SOI'DI.TDDJll1G ENOIN. . . . DAM COJl8TBUCTIO. Zo•• SUPRBINTENDJNG E 11 0 III • • B (EA.TH DAM), CDO ) National Hydro-Electric Power CorporatioD Ltd. New Delhi IrrilatioD Departmeat, GovernmeDt of Bibar, Pataa Irril_doD Department, GoVel1lmflDt or Mahan.btra, Bombay EX.OUTIVB ENOIJ'• •S ( EARTH D AX ) J CDO ( ~l'""," ) 20
  24. 24. ... BUREAU OF INDIAN STANDARDS "".....,.: MM. BhaV." 9 e.hadur ShM zalar Marg. NEW DELHI 110002 Telephones: 323 0131, 323 3375, 323 8402 F8x : 91 11 3234082, 91 11 3239380, 91 11 3239382 T.-grams : Manakl8nstha (Common to all Offices) c..fnII~: Plot No. 2018, Site 11, 8ahIbabad Industrial Area. SAHIBABAD 201010 R..,...,Ome.: ceratr.. : Manak Bhavan, 9 Bahadur Shah lafar Marg, NEW DELHI 110002 -Eutern : 1/14 CIT Scheme VII M, V.I.P. Road, Manlktola. CALCUTTA7000s. Northern: 335-336, Sector 34-A, CHANDIGARH 180022 Southern : C.I.T. campus, IV Cross Road, CHENNAI 800113 TII8phone 8-77 00 32 323 78 17 3378882 seo 803843 236 23 1& tW.3tern : Manakalaya, E9 Behind Marol T_hone Exchange, Anetter; (Ealt), 132 82 86 MUMBAI 400093 BlWIICh Ome.: 'Pushpak', Nurmohamed Shaikh M_g, Khanpw, AHMEDABAD 380001 *Peenya Industrial Atea, 1st Stage, BengaIore- TUmkur Road, 550 13 48 839 49 &6 BANGALORE 560058 Gangotrl Complex, 5th Floor, Bh8dbhada Road, T. 1: Nagar, BHOPAL .e2OO3 Plot No. 62-63, Unit VI, Ganga Nagar, BHUBANESHWAR 751001 Kalaikathlr Bullclnga, 870 Avlna.hl Road, COIMBATORE 841037 554021 40 38 27 21 01 .1 Plot No.•3, Sector 18 A. Mathur. Road, FARIDABAD 121001 8-28 88 01 Savltrt Complex, 118 0.1: Road, GHAZIABAD 201001 8-71 19 98 54 11 37 R. G. Road, 5" By-I."., GUWAHATI 781003 5-8-58C, L. N. Gupta Marg, Nampally Station Road, HYDERABAD 500001 5316 W.d No. 29, 20 10 83 E-52, Chitaranjan Marg, C-Scheme, JAIPUR 302001 372925 117/.18 B, Sarvodaya Nag8f, KANPUR 208005 Shawan, 2nd Floor, BehInd LMla Cinema, N8VaI Kiahor. Road, 231923 seth 21 88 78 LUCKNOW 228001 Patllputra Indultr181 e..., PATNA 800013 T. C. No. 14/1421, Un'v• •1ly P. O. Palayam, THIRUVANANTHAPURAM II5OS4 NIT Bulking, second Floor, Gokulpat Mnet. NAGPUR 440010 Institution of Er9n'" ( Incla ) Bulking, 1312 Shlvejl NagIr, PUNE 411005 ·S• • 0ftIce I. at 5 Chowrtt9'M ApprC*h, ~ O. Prlncep Str..t, CALCUTTA 700072 tBaIM ome. 18 at Novelty Chamber', G,ent Road, MUMBAJ «XJ007 Offtce II at 'F' Block, Unity Bulking, tWMhIrMr. Sq.,., BANBALORE 680002 *a.. 282305 e 21 17 62 61 71 123135 ~ 1081 aoe II 28 222 tl71