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BIS 200 4

B U R E A U O F I N D I A N S T A N D A R D S

MANAKBHAVAN , 9 BAHADURSHAH ZAFARMARGN E WD ELH I 110002

IS : 4880 (P a r t I V) - 1971

( Re a f fi r m e d 2 00 0)

E d i t ion 1 .1

(1986-06)

P r i ce G r ou p 7

Indian S tandard

CODE OF P RACTICE FOR

DESIGN IN TUNNE LS CONVEYING WATER

P A R T I V S T R UC TU R AL D E SI G N O F C ON CR E T E

L INING IN ROCK

(Incorpora ting Amendm ent No. 1)

UDC 624.196 : 624.191.1

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B U R E A U O F I N D I A N S T A N D A R D S

MANAKBHAVAN , 9BAHADURSHAH ZAFARMARGN E WD ELH I 110002

Indian S tandard

CODE OF P RACTICE FORDESIGN OF TU NNE LS CONVEYING WATER

P A R T I V S T R UC T UR AL DE S I GN OF C O NC R E TEL INING IN ROCK

Water Condu ctor Syst ems Sectiona l Comm ittee, BDC 58

Chairman

SHR I P. M. MANERamalayam, Pedder Road, Bombay 26

M em bers Represen ting

SHRI N. M. CHAKRAVORTY Damodar Valley Corporation, Dhanbad

CHIEF CONSTRUCTION E NGINEERSUPERINTENDING E NGINEER(TECHNICAL/CIVIL) (Alternate )

Tamil Nadu Electricity Board, Madras

CHIEF ENGINEER (CIVIL)SUPERINTENDING E NGINEER

(CIVIL AND INVESTIGATIONCIRCLE) (Alternate )

Andhra P radesh St ate E lectricity Board, Hyderabad

CHIEF ENGINEER (CIVIL) Ker ala Sta te Electr icit y Boa rd, Tr ivan dr um

DEPUTY DIRECTOR (DAMS I ) C en t ra l Wa t er & P ower Com m is sion , N ew D elh i

DIRECTOR Irrigation & Power Research In stitute, Amritsar

DR GAJINDER SINGH (Alternate )

SHRI D. N. DUTTA Assam Sta te Electricity Board , Shillong

SHRI O. P. DUTTA Beas Pr oject, Nangal Township

SHR I J. S. S INGHOTA (Alternate )SHRI R. G. GANDHI The Hindust an Constru ction Co Ltd, Bombay

SHR I M. S. DEWAN (Alternate )

SHRI K. C. GHOSAL Alokudyog Cement Service, New Delhi

SHR I A. K. BISWAS (Alternate )

SHRI B. S. KAPRE Irrigation & Power Department, Government ofMaharashtra

SHR I R. S. KALE (Alternate )

SHRI V. S. KRISHNASWAMY Geological Survey of India, Calcutta

SHRI K. S. S. MURTHY Ministry of Irrigat ion & Power

SHRI Y. G. PATEL Patel Engineering Co Ltd, Bombay

SHR I C. K. CHOKSHI (Alternate )

SHRI P. B. P ATIL Gammon India P rivate Ltd, Bombay

SHRI A. R. RAICHUR R. J. Shah & Co Ltd, Bombay

SHRI G. S. SHIVANNA Public Works & Electricity Department, Governmentof Mysore

SHR I S. G. BALAKUNDRY (Alternate )

( Continu ed on page 2 )

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( Continued from page 1 )

Mem bers R epresen ting

SECRETARY Centr al Board of Irrigation & Power, New Delhi

SHR I J. E. VAZ Public Works Department, Government of TamilNadu

SHR I J . WALTER (Alternate )

SHR I D. AJITHA SIMHA, Director General, ISI (Ex-officio M ember )

Director (Civ En gg)

Secretary

SHRI BIMLESH KUMAR

Assista nt Director (Civ En gg), ISI

Pa nel for Design of Tunn els, BDC 58 : P1

Convener

SHR I C. K. CHOKSHI Patel Engineering Co Ltd, Bombay

Memb ers

DEPUTY DIRECTOR (DAMS I ) C en t ra l Wa t er & P owe r Com m is sion , N ew De lh i

SHR I O. P. GUPTA Irrigation depart ment, Government of Utta r Pr adesh

SHR I B. S. KAPRE Irrigation & Power Department, Government ofMaharashtra

SHR I R. S. KALE (Alternate )

SHR I V. S. KRISHNASWAMY Geological Sur vey of India, Ca lcut ta

SHR I A. R. RAICHUR R. J. Shah & Co Ltd, Bombay

SHR I J. S. SINGHOTA Beas Pr oject, Nangal TownshipSHR I O. R. MEHTA (Alternate )

SHR I J. E. VAZ Public Works Department, Government of TamilNadu

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Indian S tandard

CODE OF P RACTICE FOR

DESIGN IN TUNNE LS CONVEYING WATER

P A R T I V S T R UC TU R AL D E SI G N O F C ON CR E T EL INING IN ROCK

0. F O R E W O R D

0.1 This Indian Standard (Part IV) was adopted by the Indian

Standards Institution on 15 March 1971, after the draft finalized byth e Wat er Conductor System s Sectional Comm ittee ha d been approvedby the Civil Engineering Division Council.

0.2 Water conductor system occasionally takes the form of tunnelsthr ough high ground or mounta ins, in r ugged terr ain where t he cost ofsurface pipe line or canal is excessive and elsewhere as convenienceand economy dictates. This standard, which is being published inparts, is intended to help engineers in design of tunnels conveyingwat er. This par t lays down the criteria for str uctur al design of concret elining for tunnels in rock, covering recommended methods of design.However, in view of th e complex na tu re of th e subject, it is not possibleto cover each and every possible situat ion in the st anda rd a nd man ytimes a departure from the practices recommended in this standardmay be considered necessary to meet the requirements of a project or

site for which descretion of the d esigner would be r equired.0.3 This standard is one of a series of Indian Standards on tunnels.( see page 28 ).

0.4 Other part s of this sta ndar d ar e as follows:

0.5 This edition 1.1 incorpora tes Amendmen t No. 1 (Jun e 1986). Sidebar indicates m odificat ion of the t ext as th e resu lt of incorpora tion ofthe amendment.

0.6 For the purpose of deciding whether a particular requirement ofth is sta nda rd is complied with, th e fina l value, observed or calculat ed,expressing the result of a test or analysis, shall be rounded off inaccordan ce with IS : 2-1960*. The num ber of significan t placesretained in the rounded off value should be the same as that of thespecified value in th is stan dar d.

P a rt I Gen er a l d esignPart I I Geometr ic des ignPart III Hydraulic designPar t V Stru ctur al design of concrete lining in soft stra ta a nd soilsPar t VI Tunnel supports

*Rules for r ounding off numer ical values ( revised ).

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1. SCOP E

1.1 This standard (Part IV) covers criteria for structural design ofplain and reinforced concrete lining for tunnels and circular shafts inrock mainly for river valley projects.

NOTE The pr ovisions m ay, neverth eless, be used for design of any other t ype oftunnel, like railway or roadway tunnel, provided that all the factors peculiar to suchprojects which ma y affect the design ar e tak en int o account .

1.2 This standard, however, does not cover the design of steel andprest ressed concrete linings, tun nels in swelling an d/or squ eezing type

of rocks, soils or clays an d cut a nd cover sections.2. TER MINOLOGY

2.0 For the purpose of this standard, the following definitions shallapply.

2 .1 M in i m u m E x c a v a t i o n L i n e ( A-L i n e ) A line within which nounexcavated ma terial of any kind and no support s other tha n perma -nent st ructur al steel supports sh all be permitted to remain ( see Fig. 1 ).

F IG . 1 TYPICAL SECTIONSOF CONCRETE LINED TUNNELSSHOWING A- AND B-L INES

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2 .2 P a y L i n e ( B -L i n e ) An a ssum ed line (beyond A-line) denotingmea n line to which paymen t of excavat ion a nd concrete lining is ma dewheth er th e actual excavat ion falls inside or out side it.

2 .3 C o ve r Cover on a tun nel in an y direction is the distan ce fromthe tunnel soffit to the rock surface in that direction. However, wherethe thickness of the overburden is sizable its equivalent weight mayalso be reckoned pr ovided that th e rock cover is more t ha n t hr ee timesthe diameter of the tun nel.

3. MATERIAL

3.1 Use of plain and reinforced concrete shall generally conform toIS : 456-1964*.

4. GENER AL

4.1 Str uctural design of tunn el lining requires a t horough st udy of thegeology of rock mass, the effective cover, results of in situ tests formodulus of elasticity, poissons rat io, stat e of stress an d other m echa nicalcharacteristics of the rock. It is preferable to make a critical study ofthese factors which may be done in pilot tunnels, test drifts, duringactua l excavations or by oth er explora tory techniques. The assessm entof rock load on the lining and portion of the internal pressure whichshould be assumed to be transmitted to the rock mass, will have to bedone by the designer on th e basis of th e resu lts of th ese investigat ions.

4.2 It is essential for the designer to have fairly accurate idea of theseepage, and the presence or absence of ground water under pressurelikely to be met with . Where hea vy seepage of wat er is an ticipat ed, thedesigner shall make provisions for grouting with cement and/orchemicals or extr a d ra inage h oles, and also consider th e feasibility ofproviding steel lining, if necessary. It is recommended that suchdesigns of alter na te u se of steel lining be made a long with th e design ofplain or r einforce lining so tha t a design is readily available should theconstruction personnel require it when they meet unanticipatedconditions.

4.3 The portions of a tunnel which should be reinforced and theamount of reinforcement required depends on the physical features ofthe tunnel, geological factors and internal water pressure. For afree-flow tunnel normally no reinforcement need be provided.

However, reinforcement shall be provided where required to resistexternal loads due to unstable ground or grout or water pressures.Pressure tunnels with high hydrostatic loads shall have liningreinforced sufficiently to withstand bursting where inadequate coveror unst able supporting r ock exists.

*Code of practice for plain and reinforced concrete ( second revision ).

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4.3.1 The provision of reinforcement in the tunnel lining complicatesthe construction sequence besides requiring a thicker lining. The useof reinforcement should, therefore, be restricted, as much as possibleconsistent with the safety of lining. For free flow tunnels it isrecommended that as far as possible, no reinforcement should beprovided to resist external loads. Such loads should be resisted andta ken car e of by steel supports a nd/or pr ecast concrete r ings.

4.3.2 A pressure tunnel should ordinarily be reinforced wherever thedepth of cover is less th an th e intern al pressu re hea d. The final choicewhether reinforcement should be provided or not would be guided by

th e geological set up a nd economics.

4.3.3 For design of junctions and transitions for tunnels detailedstructural analysis shall be made. Such transitions are difficult toconstruct in the restricted working space in tunnels, and the designershall keep in view this aspect and propose structures which are easyfor construction.

4.3.4 An adequate amount of both longitudinal and circumferentialreinforcement in addition to steel supports may be provided, ifrequired, near the portals of both pressure and free-flow tunnels toresist loads resu lting from loosened r ock h eadings or from sloughing ofthe portal cuts.

4.4 If the seepa ge of water th rough t he lining is likely to involve heavyloss of water an d th e stru ctur al stability of th e rock ma ss ar ound the

tu nn el is likely to be affected a dversely or m ight lead t o such situ at ionas to be damaging to the tunnel or adjoining structures, steel liningshall be provided. Where rock cover is less than that specified in 4.5and 4.5.1 or where t he cavitat ion of lining is expected du e to the h ighvelocity of water or erosion is expected the provision of a steel linersha ll be considered.

4.5 Where t he r ock is r elatively imper vious a nd th e dan ger of blow outexists, the vertical cover shall be greater than the internal pressurehead in the tunnel. In other cases the weight of the rock over thetun nel shall be great er than t he interna l pressure.

NOTE The convent ional practice is to provide a vertical cover equal to the int ern al

water pressure head ( H ). Recent tr end, however, is to provide lesser cover ( as lowas 0.5 H ) depending upon th e nat ure of the rock.

4.5.1 For tu nnels located n ear mountain slopes, the lateral cover rat herthan the vertical cover may be the governing criteria many times. Insuch cases the effective vertical cover equivalent to the actual lateralcover shall be found out, by drawing a profile of the ground surface(perpendicular to the cont our lines) an d fitting th e cur ve shown in Fig. 2in such a way tha t it touches th e ground surface. The vertical distance

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marked Cv sha ll be designa ted a s t he effective vertical cover a nd sha llbe great er tha n th e inter nal pressure head in the tunn el. This methodof estimating the effective cover shall not hold good where joints,str at ificat ion, faults, etc, in th e rock a re a dversely located t o invalidat eth e assum ption th at horizont al cover is half as effective as th e verticalcover on t he ba sis of which th e curve of Fig. 2 is dra wn. In such casesspecial an alysis shall be ma de for det erminin g th e sta bility of th e rockmass around the t unnel.

F IG . 2 ESTIMATION OF EFFECTIVE COVER

5. LOADING CONDITIONS

5 .1 G e n e r a l Design shall be based on t he most adverse

combination of probable load conditions, but shall include only thoseloads which ha ve reasona ble probability of simu ltan eous occur rence.

5 .2 L o a d C o n d i t i o n s The design loading applicable to tu nn ellinings s ha ll be class ified as Norm al an d Ext rem e design load ingcondit ions. Design sh all be ma de for Norm al loading condit ions an d

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sha ll be checked. for sa fety un der Ext rem e load ing cond itions( see Appendix A ). The design loading sha ll be as follows:

a)External Rock Load( see7.4.2 )

b) S elf Load of Linin g

c)Design E xternal W ater Pressure ( see7.4.3 ):

1) Normal design loading conditions The maximum loadingobtained from either maximum steady or steady statecondition with loading equal to normal maximum ground

water pressure and no internal pressure, or maximumdifference in levels between hydraulic gradient in the tunnel,under steady stat e or stat ic conditions a nd t he m aximum downsurge under normal tr ansient operat ion.

2) Extreme design load ing cond itions Loading equal to themaximum difference in levels between the hydraulic gradientin the t unn el under stat ic conditions an d the m aximum downsurge under extreme transient operations or the differencebetween th e hydrau lic gradient and the t unn el invert level incase of tun nel em pty condit ion.

d)Design In ternal Wa ter Pressure:

1) Normal design loading conditions Maximum static

conditions corresponding to maximum water level in the headpond, or loading equal to the difference in levels between themaximum upsur ge occurr ing under n orma l tran sient operationand th e tunn el invert .

2) Extreme design load ing cond itions Loading equal to thedifference between the highest level of hydraulic gradient inthe tu nnel under emer gency tra nsient operat ion a nd th e invertof th e tun nel.

e) Grout Pressures ( see7.4.4 )

f) Other Loads Pressure tra nsmitted from buildings andstr uctur es on extern al sur face lying with in th e area of subsidenceand non-permanent loads, such as weight of vehicles moving inth e tun nel or on th e surface above it, where a pplicable.

5.3 The loading conditions vary from construction stage to operationsta ge and from operat ion sta ge to ma inten an ce sta ge. The design shallbe checked for all probable combination of loading conditions likely tooccur dur ing all these sta ges.

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6. STRE SSES

6.1 For design of concrete lining, the thickness of concrete up to A-lineshall be considered. The stresses for concrete and reinforcement shallbe in accordance with IS : 456-1964* for design of lining for conditionof normal load.

6.1.1 For extreme conditions of loading, the stresses in accordancewith 6.1 sha ll be increased by percent.

7. DES IGN

7.1 The design of concrete lining for external loads may be done byconsidering it as an independent structural member ( see 7.4 ). Thedesign of concrete lining for internal water pressure may be done byconsiderin g th e lining as a par t of composite th ick cylinder consistin gof peripher al concrete a nd sur roundin g rock m ass subjected t o specificboun dar y condit ions ( see7.5 ).

NOTE To ensu re th e validity of th e assump tion tha t lining is a par t of compositethick cylinder in t he latter case adequate measures sha ll be taken, such as pressuregrouting of the rock ma ss surrounding th e tun nel.

7 .2 T h i c k n e s s o f Li n i n g The thickness of the lining shall bedesigned such that the stresses in it are within permissible limitswhen t he m ost a dverse load conditions occur . The minimu m t hicknessof the lining will, however, be governed by requirements of

construction. It is recommended that the minimum thickness ofunreinforced concrete lining be 15 cm for manual placement. Wheremechan ical placement is cont emplat ed the t hickness of the lining shallbe so designed th at th e slick line can be easily introduced on t he t op ofthe shut ter without being obstr ucted by steel supports. For a 15-mmslick line a clear space of 18 cm is recommended. For reinforcedconcrete lining, a minimum thickness of 30 cm is recommended, thereinforcement, however, being arranged in the crown to allow forproper placement of slick line.

7.2.1 However, for preliminary design of lining for tunnels inreasonably stable rock, a thickness of lining may be assumed to be6 cm per metre of finished diameter of tunn el.

NOTE Minimum t hickness of lining, as necessary from stru ctura l considerat ions,should be provided since thin linings are more flexible and shed off loads to the

abutments .

7.3 Where str uctura l steel supports are used, they shall be considered asreinforcement only if it is possible to make them effective asreinforcement by use of high t ensile bolts a t t he joints or by welding th e

*Code of practice for plain and reinforced concrete ( second revision ).

33 13---

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joints. A m inimum cover of 15 cm sh all be pr ovided over th e inner flan geof steel support s an d a minim um cover of 8 cm over th e reinforcementbars .

NOTE Welding of joints in soft str ata tu nn els may not be possible, and it m aybecome necessary to embed the steel supports partly or fully in primary concrete

immediat ely after erection. Welded joints should, th erefore, be avoided.

7 .4 D e s ig n f or E x t e r n a l L o a d s The lining may be considered asan independent str uctura l element assuming tha t it deflects under t heactive external loads and its deflection is restricted by the passiveresista nce developed in the su rr ounding rock ma ss. At a ny point on t heperifery of the lining th is may be st at ed by the following equat ion:

p = r+ e + w ywhere

7.4.1 The following loads and reactions are involved in the design of

lining :a) Rock load ( see7.4.2 ) ;

b) Exter na l pressur e of wat er, if an y ( see7.4.3 ) ;

c) Grout pr essur e, if an y ( see7.4.4 ) ;

d) Self weight of linin g;

e) Weight of water cont ained in th e tun nel;

f) Reaction du e to active vert ical load s ( see7.4.5 ); an d

g) Lateral passive pressure due to the deformation of lining( see 7.4.6 ).

NOTE As compared t o the other loads, the self weight an d th e weight of watercontained in the tunnel are small. These loads are not discussed in detail. However,the formulae for calculating bending moment, thrust, radial shear and horizontal

and vertical deflections caused by self load an d th e weight of water conta ined in t hecondu it ar e given in Appendix C.

7.4.2 Rock Load Rock load acting on th e tu nnel varies dependingupon th e type and mechan ical char acteristics of rock m ass pr e-existingstresses in the rock mass and the width of the excavation. The rockload is also affected by ground water conditions which may lubricatethe joints in rock an d cause greater load th an wh en the m ater ial is dry.

p = deflection du e to passive resistance;r = deflection du e to rock load;e = deflection due to self weight of lining and th e water

cont ained in it;

w = deflection due to the external water pressure, if any; andy = yield of surr ounding rock ma ss due to abutting of the

lining against it.

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The existing stresses and their distribution after tunnelling has agreat effect on the development of load on tunnel lining. Theredistribution may take considerable time to reach an equilibriumcondition. Wherever it is felt that rock loads are likely to developexcessively it is advisable to prevent the movement of rock byimmediately supporting it by shotcreting and/or steel supports andprimary lining. Where weak rocks are supported by steel rib supports,much of the rock load would be taken by the supports and the liningwould take the load developed after its placement. There may also beredistr ibution of str esses in support s due t o deform at ion of th e lining.

A reasonable approach is to determine the diametral changes in thesupported section with respect to time before concreting to estimatethe extent of deformation that has already taken place. Thisinvestigation may be conveniently done in an experimental section ofthe tu nnel or pilot tu nnel with pr oper instru menta tion.

In m ajor tun nels, it is recomm ended th at as excavat ion pr oceeds loadcell measur ements an d diametra l chan ge measurements a re carried outto estimat e the r ock loads. In rocks where t he loads a nd deform at ions donot att ain stable values, it is recommended th at pr essure measurem entsshould be made u sing flat jack or pressu re cells.

7.4.2.1 In the absence of any data and investigations, rock loads maybe assumed to be acting uniformly over the tunnel crown as shown inFig. 3 in accordance with Appendix B. However, Appendix B may betak en as an aid to judgement by the designer.

F IG . 3 EXTERNAL LOADSON LINING

7.4.3 External Water Pressure Lining shall be designed for extern alwater pressure, if any. However, in areas where drainage holes areprovided, lining shall not be designed for external water pressure

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( see 8.1 ). For conditions of loading for external water pressurereference may be made to 5.2 . For design of lining for exter na l waterpressure where effective pressure grouting has been done, the waterpressure may be assumed to act on the whole grouted cylinder whichmay be taken as a stru ctur al element for comput ing the stresses anddeformation of lining.

7.4.4 Grout Pressures The lining shall be checked for str essesdeveloped in it at the pressure on which grouting is done and it shallbe ensured that the stresses are within the limits depending on thestrength att ained by concrete by th en ( see9.1 and 9.2 ).

7.4.5 Vertical Reactions Reactions due to the vertical loads may beassumed, reasonably, to be vertical and uniformly distributed on theinvert of the lining as sh own in F ig. 3.

NOTE In fact, th ese reactions, may, however, not be un iform depending upon th efoundation conditions. Nevertheless, with the uncertainties involved in the design of

tunnels, the assumption may not give far out results. Moreover, normally, uniformreactions would give m ore critical condition.

7.4.6 Lateral Passive Pressure The lateral passive pressure may beestimated either by considering the lining as a ring restr ained by elasticmedium with a suitable modulus of deformation or by restricting themaximum deflection of the lining at the horizontal diameter to anassu med value (depending upon th e yield of the sur round ing rock ma ss)by th e lat eral passive pressur e. The latt er met hod is discussed in detailin 7.4.6.1 for d esign of circular linin gs. For design of non-circular liningsth e former m eth od sha ll only be used.

7.4.6.1 For analyzing a circular lining, the designer will have toassume the maximum deflection to be permitted along the horizontalcentral axis of the tunnel. This value of horizontal deflection willconsist of the yield of the rock mass surrounding the tunnel( see Note 2 ). It may be assumed th at a ny furt her deflection of thelining is restricted to this value by the lat era l passive resistan ce of thesur round ing rock ma ss in a pa tt ern given in Fig. 3. The design sha ll besuch that the maximum value of the passive resistance is within themaximum permissible values.

NOTE 1 For a circular lining the deflection is outward in a zone extending

appr oximat ely from 45 above the horizont al diameter to the invert a s the invert m oveup. The m aximum value is n ear horizontal diameter. On the a bove consideration andneglecting th e effect of vertical tran slation of th e lining, the lat eral rock restr aint maybe assumed t o have approximat ely a straingular distribution as shown in F ig. 3. Thevertical translation of the lining would cause a shifting of the point of maximum

intens ity slightly below the horizonta l diameter an d restr iction of th e upper limit to anangle slightly less than 45, but t he effect of vertical tra nslat ion would be sma ll and canbe neglected. The pa ssive pressur es would, in fact, be also radial to the su rface but inview of the fact th at the deflections would be mostly in h orizonta l direction a nd ver tical

deflections would be sma ll, it m ay be assu med t o act in horizontal dir ection.

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NOTE 2 The rock mass surr ounding the tunn el yields due to the bearing pressure of

lining against it. This yield may be due t o closing up of joints a nd fra ctures in the rockmass and also due to its elastic or plastic deformation. The value of yield taken fordesign should be based on th e experiments carr ied out in t he test sections ( see4.1 ).

At Bhakra Dam, rock deflection tests indicated yield of either face in poorshat tered r ock as 1.25 mm u nder a stress of 54 kg/cm2. However, a t otal deflection of3.8 mm was a ssumed in t he design of lining though a ctual bearing pressure on th e

rock was anticipated to be much less. Experiments on Garrison Dam tunnels, in clayshale of int ern al diamet er 8.8 m an d lining th ickness of 0.9 m indicated deflection ofeither face of lining at horizontal diameter to range between 3 to 4 mm. In design ofRamganga Dam tunnels, outer deflection of either face of lining at horizontal

diameter was assum ed to be 3.8 mm.

7.4.6.2 Formulae for determining the values of horizontal deflection,vertical deflection, bending moments, normal thrust, radial shear forthe various circumferential points on a circular lining are given inAppendix C considering the invert as the reference point for variousloads excepting th e intern al pressu re. In derivat ion of th ese values th epatt ern of vertical reaction a nd pa ssive pressure ha s been assum ed inaccordance with 7.4.5 and 7.4.6 as sh own in F ig. 3.

7.4.7 For non-circular lining model tests are recommended todetermine the stress distributions. However, the design may be doneassuming uniformly distributed loads as in the case of circulartunnels, and using the same distribution for passive pressures. Thedesign of such indeterminate sections may be done by standard

methods and is not covered by th is stan dard.7 .5 D e si gn F o r I n t e r n a l Wa t e r P r e s s u r e Lining shall be conside-red a s a par t of composite th ick cylinder consistin g of peripher al concretean d sur roundin g rock m ass su bjected to specified boun dar y conditions.

NOTE This method suffers from un certaint ies of external loads, mat erial

properties an d indetermina te t ectonic forces. In t his meth od the rock su rroundingthe tu nnels is assumed to have reasonably uniform characteristics and strength andthat effective pressure grouting has been done to validate the assumption that

concrete lining a nd su rr ounding r ock beha ve as a composite cylinder . The grout fillsthe cracks in the rock and thus reduces its ability to deform inelastically andincreases the modulus of deformation. If the grout pressures are high enough tocause sufficient prestress in the lining the effect of temperature and drying

shrinkage and inelastic deformation might be completely counteracted.

7.5.1 For analysing a circular lining the method given in Appendix Dmay be adopted. The design sh all be such t hat at no point in t he liningan d the su rr oun ding rock th e stresses exceed the perm issible limits.

If the rock is very good, and cracking of lining is not otherwiseharmful, cracking of the lining may be permitted to some extent. Inthat case, tangential stress in concrete lining will be absent andcorr espondingly, tan gential st ress in rock will increase.

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If the rock is not good, tensile stress in concrete may exceed theallowable limit and in such a case, reinforcement may be provided.Reinforcement however, is not capa ble of reducing the t ensile str essesto a considerable extent. By suitable arrangement, it will help todistr ibute th e cra cks on t he whole peripher y in the form of ha ir crackswhich are not harmful because they may get closed in course of time,or at least th ey will not resu lt in serious leakages.

7.5.2 For analyzing non-circular linings, the stress pattern may bedeterm ined by photo-elastic studies.

8. GROUND WATER DRAINAGE H OLES

8.1 Drainage holes may be provided in other than water conveyingtu nn els to relieve extern al pr essur e, if any, cau sed by seepage along theoutside of the tu nn el lining. In free flow tu nn els draina ge holes may beprovided in th e crown above th e full supply level. In case of pressuretun nels, if the external water pr essure is substan tially more than theinternal water pressure, drainage holes may be provided in the crown.However, when the mountain material is likely to be washed into thetu nn el th rough such dra inage holes they shall not be provided.

8.1.1 The arrangement of drainage holes depends upon the site condi-tions and shall be decided by the designer. A recommendedar ra ngement is described below:

At successive sections; one vert ical hole drilled in t he crown alt er-nating with two drilled horizontal holes one in each side wall

extending t o a depth of at least 15 cm beyond t he ba ck of the lining.8.1.2 If the flow thr ough the t un nel is conveyed in a sepa ra te pipe, thehorizont al holes shall be drilled near t he invert.

9. GROUTING

9 .1 B a c k f il l G r o u t i n g Backfill grouting sha ll be done at apressure not exceeding 5 kg/cm 2 and shall be considered as a part ofconcreting. It shall be done throughout the length of the concretelining not earlier than 21 days after placement after the concrete inthe lining has cooled off. However, stresses developed in concrete atthe specified grout pressure may be calculated and seen whether theyare within permissible limits depending on the strength attained byconcrete by then. The grout pressure mentioned above is the pressureas measur ed at th e grout h ole.

NOTE Backfill grouting serves t o fill all voids an d cavities between concrete liningand rock.

9 .2 P r e s su r e G r o u t i n g Pr essure grouting shall be done at amaximum practicable pressure consistent with t he str ength of liningan d safety against uplift of overbur den. The depth of grout h oles shallbe at least equal to the diameter of the tu nnel.

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NOTE 1 Pressure grouting consolidates the surr ounding rock and fills any gaps

caused by sh rinka ges of concrete. This gr outing is n ormally specified wher e lining isreinforced, to improve the rock quality and, therefore, to increase the resistance ofrock to carry internal water pressure. As a rule of thumb a grout pressure of 1.5times the water pressure in the tunnel may be used subject to the conditions that

safety against uplift of the overburden is ensured. Grout pressures of up to 5 to 10times the water pressure in t he tu nnel have been used in Italy.

NOTE 2 It is advanta geous to provide a grout curtain by means of extensive deepgrouting at t he reser voir end of the tun nel to reduce loss of water due to seepage.

9 .3 P a t t e r n o f H o le s fo r G r o u t i n g For small tunn els, rings ofgrout holes, may be spaced at about 3 m centres, depending upon the

nature of the rock. Each ring may consist of four grout holesdistributed at about 90 around the periphery, with alternate ringsplaced vert ical a nd 45 axes.

A P P E N D I X A

( Clause 5 .2 )

BASIC CONDIT IONS FOR INCL UDING T HE E FF E CT OFWATER HAMMER I N THE DE SIGN

A-1 . The basic conditions for including effect of wat er h am mer in th edesign of tunnels or turbine penstock installations are divided intonormal and emergency conditions with suitable factors of safetyassigned t o each type of opera tion.

A-2. NORMAL CONDITIONS OF OP ER ATIONS

A-2.1 The ba sic conditions t o be consid ered a re a s follows:a) Turbine penstock installation m ay be operated at any head

between th e maximum and the m inimum values of forebay watersur face elevation.

b) Tur bine gates ma y be moved at an y rat e of speed by action of th egovernor head up t o a predetermined rat e, or a t a slower rat e bymanual control through the auxiliary relay valve.

c) The tur bine may be operating at any gate position an d berequired to add or dr op any or all of its load.

d) If the tu rbine penstock insta llation is equipped with any of thefollowing pressure control devices it will be assumed that thesedevices are properly adjusted and function in all manner forwhich the equipmen t is designed.1) Surge tan ks,

2) Relief valves,3) Governor cont rol appar at us,4) Cushioning str oke device, an d5) Any other pressure control device.

e) Unless the actual t urbine chara cteristics ar e known, the effectivearea t hrough the tur bine gates during the maximum ra te of gatemovement will be ta ken a s a linear r elation with r eference to time.

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f) If a surge tan k is present in th e penstock system, the upsur ge inth e tan k will be computed for t he ma ximum r eservoir hea d condi-tion for the rejections of full gate turbine flow at the maximumrate for which the governor is designed. The downsurge in thesurge tank will be computed for the minimum reservoir headcondition for full gate opening from the speed-no-load position atthe maximum rate for which the governor is designed. Indetermining the top and bottom elevations of the surge tanknothing will be added to the upsurge and down surge for thisemergency condition of operation.

A-4 . E ME RGE NCY CONDIT IONS NOT T O BE CONSIDE RE D

AS A BASIS FOR DESIGN

A-4.1 The other possible emergency conditions of operation are thoseduring which certain pieces of control are assumed to malfunction inthe m ost u nfavour able mann er. The most severe emergency head risein a turbine penstock installation occurs from either of the twofollowing conditions of oper at ion:

a) Rapid closure of tu rbine gates in less th an s, when th e flow ofwater in t he penstock is maximum.

b) Rhyth mic opening and closing of th e tur bine gates when a

comp lete cycle of gat e opera tion is per form ed in s.

Since these conditions of operation require a completemalfunctioning, of the governor control apparatus at the mostunfavourable moment, the probability of obtaining this type ofoperation is exceedingly remote. Hence, the conditions shall not beused as a basis for design. However, after the design has beenestablished from other considerations it is desirable that the stressesin t he t ur bine scroll case pen stock a nd pressur e cont rol devices be notin excess of the ultimate bursting strength or twisting strength ofstr uctur es for th ese emergency conditions of opera tion.

A P P E N D I X B

( Clause 7.4.2.1 )

ROCK LOADS ON TUNNEL LI NING

B-1. SCOP E

B-1.1 This appendix contains recommendations for evaluating rockloads on tu nn el lining.

2La

-------

4La

-------

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B-2. LOAD DISTR IBUT ION

B-2.1 Rock load may be assumed as an equivalent uniformlydistributed load over the tunnel soffit over a span equal to the tunnelwidth or diameter a s the case may be.

B-3. LOAD

B-3.1 Rock loads may be estimated by any of the methods givenin B-3.1.1 to B-3.1.3.

B-3.1.1 Rock load a t dept hs less th an or equa l to 1.5 (B +Ht ) may betaken as equal to depth of actual rock cover where B is the width a nd

Ht is the h eight of th e tun nel opening. In case of circular t un nelsB andHt both will be equal to the diam eter of tu nn el D.

Rock load (Hp ) on the roof of support in tunnel with width B andheight Ht at depth of more than 1.5 (B +Ht ) may be assumed to beaccord ing to Table 1.

B-3.1.2 Rock load ma y also be work ed out u sing F enn ers ellipse ( seeFig. 4 on P 21 ) by th e following equat ion:

where

The weight of rock in th e shaded port ion m ay be tak en as r ock load andma y be considered a s uniform ly distr ibuted on th e diameter of tunn el.

NOTE The above treat ment assumes th e rock to be homogeneous an d to behavewithin elast ic ra nge. It ha s also limited ap plication as it does not give any rock loadsfor value of poissons ratio equal to 0.25 and above. It does not also take intoconsideration the strength and characteristics of rock.

B-3.1.3 The rock load accordin g to the Russian pra ctice depends upon th edegree of rock firmn ess. The rock load ma y be taken as t ha t for r ock areaenclosed by a para bola sta rt ing from int ersection points of th e rup tu replanes with h orizont al length dr awn t o th e crown of th e tun nel section.The dimen sions of the pa ra bola a re given below ( see Fig. 5 on P 21 ):

B = b + 2 m ta n (45 /2)where

= th e an gle of repose of the soil,f = the st rength factor after Pr otodyakonov ( see Table 2 ).

In t he case of circular tu nn els,B = D [ 1 + 2 t an (45 /2) ]

where

D = diameter of the tunn el.

a = ma in axis of ellipse of rock load,b = tunnel diameter (excavated), andm = inverse of poissons ratio for rock (which usually varies

from 2 t o7).

ab

2--- m 2( )=

hB

2f-----=

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6.

T AB LE 1 R O CK LO AD

( Clause B-3.1.1 )

ROCK CONDITION ROCK LOAD HPm

REMARKS

1. Har d and in tact Zero Light lining required on ly if spalling or popping occurs

2. Hard s t rat i fied or schis-

tose

0 to 0.50 B Ligh t suppor t

3. M a s s i v e, m oder at ely

jointed

0 to 0.25 B Loa d may ch ange er ra t ically

from point to point4. Moderately blocky and

seamy

0.25 B to 0.35 (B + Ht ) N o s id e p r es su r e

5. Ver y block y a nd sea m y (0.35 t o 1.10) (B + Ht ) L it t le or no s ide pres sure

6. Completely crushed butchemically int act

1.10 (B + Ht ) Considerable side pressure.Softening effect of seepage

towards bottom of tunnel.Requires either continuoussupport for lower ends ofribs or circular ribs.

7. Squeezing rock, mode-rate depth

(1.10 to 2.10) (B + Ht )Heavy side pressure. Invert

struts required. Circular

ribs are recommended.8. Squeezing rock, greatdepth

(2.10 to 4.50) (B + Ht )

9. Swelling rock Up to 80 m ir respect ive

of value of (B + Ht )

Circular ribs required. In

extreme cases use yieldingsupport

NOTE 1 The above Table has been arrived on the basis of observation an d

behaviour of supports in Alpine tunnels where the load was derived mainly onloosen ing t ype of rock.

NOTE 2 The roof of the t unn el is assumed to be located below the water table. If itis located perm an ently above the water table, th e values given for types 4 to 6 may beredu ced by fifty per cent.

NOTE 3 Some of th e most common rock forma tions contain la yers of shale. In anunweather ed state, real sha les are no worse than other stra tified rocks. However, theterm shale is often applied to firmly compacted clay sediments which have not yetacquired the properties of rock. Such so called shales may behave in the tunnel like

squeezing or even swelling r ock.

NOTE 4 If rock formation consists of sequence of horizont al layers of san d stone or

lime stone and of immature shale, the excavation of the tunnel is commonlyassociated with a gradual compression of the rock on the both sides of the tunnel,involving a downward movement of the roof. Furthermore, the relatively low resis-tance against slippage at the boundaries between the so called shale and rock islikely to reduce very considerably the capacity of rock located above the roof to

bridge. Hence, in such rock formations, the roof pressure may be as heavy as in avery blocky and sea my rock.

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T AB LE 2 S TR E N GT H F AC TO R S

( Clause B-3.1.3 )

CATE -GORY

STRENGTH GRADE

DENOTATIONOF ROCK

(SOI L)UNI T

WEIGHTCRUSHINGSTRENGTH

STRENGTH FACTOR

( kg/m3 ) (kg/cm2) f

I H igh est Solid, da nse qu ar tizit e, ba sa ltand other solid rocks ofexceptionally high strength.

2 800-3 000 2 000 20

I I Ve ry h igh S olid , gr a nit e, qu a rt zp or ph yr ,silica shale. Highly resistivesandstones an d limestones.

2 600-2 700 1 500 15

III High Granit e and a like, ver y

r e s i s t i v e s a n d a n dlimestones. Quartz. Solidconglomerates.

2 500-2 600 1 000 15

IIIa High Limestones, wea th ered

granite. Solid sandstone,marble.

2 500 800 8

IV Moder atelystrong

Normal sandstone. 2 400 600 6

IVa Mod er at elystrong

San dstone sha les. 2 300 500 5

V Mediu m Cla y-sha les. Sa nd and Lime-stones of smaller resistance.

Loose conglomerates.

2 400-2 600 400 4

Va Medium Va riou s sh ales an d sla tes.Dense marl. 2 400-2 800 300 3

VI Moder atelyloose

Loose shale and very looselimestone, gypsum, frozenground, common marl.Blocky sandstone, cementedgravel and boulders, stoney

ground.

2 200-2 600 200-150 2

VIa Mod er at elyloose

Gravelly ground. Blocky andfizzured shale, compressedboulders and gravel, hard

clay.

2 200-2 400 1.5

VII Loose Den se clay, Coh esive ba llast .Clayey ground.

2 000-2 200 1.0

VIIa Loose Loose loam, loess, gravel. 1 800-2 000 0.8

VIII Soils Soil wit h veget at ion peat , soft

loam, wet sand.

1 600-1 800 0.6

IX Gr anula r

soils

Sand, fine gravel, upfill. 1 400-1 600 0.5

X Plast icsoils

Silty ground, modified loosesand other soils in liquidcondition.

0.3

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The load ma y be ta ken as u niform ly distribut ed over the diam eter ofthe tun nel.

NOTE The above is applicable when the distance between th e vertex of the pr essurepar abola from th e bottom of the weak layer or from the groun d sur face is not less th anh . However, where this condition is not fulfilled the total value of rock load may be

assumed.

A P P E N D I X C

(Note Under Clause 7.4.1 a nd Clause 7.4.6.2 )

FORMUL AE FOR VAL UE S OF BE NDING MOME NT S,NORMAL THR UST, RADIAL SH EAR, HORIZONTAL AND

VE RT ICAL DE F L E CT ION

C-1 . The values of bending moment, normal th rust , radial shear andhorizontal and vertical deflection for the loading pattern shown inFig. 3 are given in Tables 3 to 7.

C-2 . For pu rpose of this appen dix, th e following notat ions sh all apply:

F IG . 4 FENNERS E LLIPSE F IG . 5 ASSUMED ROCK LOADON A CIRCULAR CAVITY

E= Youngs modulus of th e lining mater ial,I= moment of inert ia of th e section,K= intensity of latera l triangular load at horizonta l diameter,P = total rock load on mean diameter,r= internal radius of tunnel,

R = mean r adius of tun nel lining,t= thickness of lining,

W= unit weight of water,We = un it weight of concrete, and

= angle that t he section mak es with the vertical diameter a t th ecentre measur ed from invert.

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C-3. For th e pu rpose of th is app endix, the following sign convent ionssha ll apply:

a) Positive moment indicates tension on inside face and compr essionon outside face;

b) Positive thr ust means compression on the section;

c) Positive shear mean s th at considering left half of the ring th esum of all the forces on left of the section acts outwards whenviewed from inside;

d) Positive horizont al deflection mea ns out war d deflection withreference to centre of conduit; and

e) Positive vert ical deflection mea ns downwa rd deflection.

T AB L E 3 VAL U E S OF B E N D I NG M OM E NT S

( Clause C-1 )

UNIFORM VERTICALLOAD

CONDUITWEIGHT

CONTAINEDWATER

LATERALPRESSURE

0 + 0.125 0 PR + 0.440 6 Wc tR2 + 0.220 3 Wr2R 0.143 4 KR 2

Zero 0.033 4 Wc tR2 0.016 7 W r2R 0.008 4 KR 2

0.125 0 PR 0.392 7 Wc tR2 0.196 3 W r2R + 0.165 3 KR 2

Zero + 0.033 4 Wc tR2 + 0.016 7 W r2R 0.018 7 KR 2

+ 0.125 0 PR + 0.344 8 Wc tR2 + 0.172 4 W r2R 0.129 5 KR 2

T AB L E 4 VAL U E S OF N O R MAL T H R US T

( Clause C-1 )

UNIFORM VERTICALLOAD

CONDUITWEIGHT

CONTAINEDWATER

LATERALPRESSURE

0 Zero + 0.166 7 Wc tR 1.416 6 Wr2 + 0.475 4 KR

+ 0.250 0 P + 1.133 2 Wc tR 0.786 9 Wr2 + 0.305 8 KR

+ 0.500 0 P 1.570 8 Wc tR 0.214 6 W r2 Zero

+ 0.250 0 P + 0.437 6 Wc tR 0.427 7 W r2 + 0.267 4 KR

Zero 0.166 7 Wc tR 0.583 4 W r2 0.378 2 KR

4---

2---

34------

4

---

2---

34------

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T AB L E 5 VAL U E S OF R A D IAL S H E AR

( Clause C-1 )

UNIFORM VERTICAL

LOADCONDUIT

WEIGHTCONTAINED

WATERLATERAL

PRESSURE

0 Zero Zero Zero Zero

0 2 50 0 P 0.897 6 Wc tR 0.448 8 Wr2 + 0.305 8 KR

Zero + 0.166 7 Wc tR + 0.083 3 W r2 0.024 6 KR

+ 0.250 0 P + 0.673 2 Wc tR + 0.336 6 W r2 0.267 4 KR

Zero Zero Zero Zero

T ABL E 6 V AL U E S O F H O RI ZO N T AL DE F L E CT I O N

( Clause C-1 )

UNIFORM VERTICALLOAD

CONDUITWEIGHT

CONTAINEDWATER

LATERALPRESSURE

0 Zer o Zero Zero Zero

+ 0 01 4 7 3 + 0.050 40 + 0.025 20 0.017 50

+ 0.041 67 + 0.130 90 + 0.065 45 0.050 55

+ 0.014 73 + 0.042 16 + 0.021 08 0.016 24

Zer o Zero Zero Zero

T ABL E 7 V AL U E S O F VE RT I CAL DE F L E CT I O N

( Clause C-1 )

UNIFORM VERTICAL

LOADCONDUIT

WEIGHTCONTAINED

WATERLATERAL

PRESSURE

0 Zer o Zero Zero Zero

+ 0.026 94 + 0.092 79 + 0.046 40 0.031 76

+ 0.041 67 + 0.139 17 + 0.069 58 0.049 95

+ 0.056 40 + 0.185 35 + 0.092 68 0.068 10

+ 0.083 33 + 0.261 80 + 0.130 90 0.097 39

4---

2---

34------

4--- P R 3

E I------------

Wct R4

E I------------------ W r

2R 3

E I-------------------

K R 4

E I------------

2--- P R

3

E I------------ Wct R

4

E I------------------

W r2R 3

E I------------------- K R

4

E I------------

34------ P R3

E I------------ Wct R

4

E I------------------ W r2R 3

E I------------------- K R 4

E I------------

4--- P R

3

E I------------ Wct R

4

E I------------------ W r

2R 3

E I-------------------

K R 4

E I------------

2--- P R

3

E I

------------ Wct R4

E I

------------------W r2R 3

E I------------------- K R 4

E I------------

34------ P R

3

E I------------ Wct R

4

E I------------------

W r2R 3

E I------------------- K R

4

E I------------

P R3

E I------------ Wct R

4

E I------------------

W r2R 3

E I------------------- K R 4

E I------------

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A P P E N D I X D

( Clause 7.5.1 )

BASIC E QUATIONS FOR ANALYSIS OF TUNNEL LININGCONSIDER ING IT AND THE S URROUN DING ROCK AS A

COMPOSIT E CYL INDE R

D-1. SCOP E

D-1.1 This appendix contains basic equations for calculating radial

and tangential stresses in concrete lining and the surrounding rockma ss considering both as par ts of a composite cylinder.

D-2. NOTATIONS

D-2.1 For t his appen dix the following notat ions sh all apply:

D-3. BASIC EQ UATIONS

D -3 .1 P l a i n C e m e n t C o n c r e t e L i n i n g C o n s id e r i n g t h a t i t i s n o t

C r a c k e d

a)Basic Equations :

r

= B ( m + 1 ) ( m 1 )

t = B ( m + 1 ) + ( m 1 )

U= Bx + C/x

P =internal hydrostatic pressure (negative compression);

t1, t2, t3 = ta ngent ial str ess in rock, concret e and st eel respectively;r1, r2, r3 = ra dial str ess in rock, concret e and steel respectively;

E,E2,E3 =modulus of elasticity of rock, concrete and steelrespectively;

m 1, m 2 = poissons nu mber of rock and concrete r espectively;

U1, U2, U3 =radial deformation in rock, concrete and steelrespectively;

x =r adius of element;

B & C, etc= integration consta nts;

A s= ar eas of reinforcement per u nit length of tu nn el;

a =int ernal ra dius of the tunn el; and

b = extern al ra dius of th e lining up to A-line.

m E

m 2 1-----------------

C

x2-----

m E

m 2 1-----------------

C

x2-----

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b)Limit Conditions and Constants :

D -3 .2 P l a i n C e m e n t C o n c r e t e L i n i n g C o n s i d e r i n g t h a t i t i sC r a c k e d

a)Basic Equa tions for Rock:

r1 = B1 ( m 1 + 1 ) ( m 1 1 )

t1 = B 1 ( m 1 + 1 ) ( m 1 1 )

b) For Concrete:

r2 =

t2 = 0 (since concrete does not ta ke an y tan gential stress)c)Limit Conditions:

d) Constan ts are calculated a :B1 = 0

( r2 )x = a = pD -3 .3 P l a i n C e m e n t C o n c r e t e L in i n g C o n s i d e r i n g t h a t i t i sC r a c k e d a n d S u r r o u n d i n g R o ck a ls o is C r a c k e d f or a D i st a n c eE q u a l t o R a d i u s B e yo n d w h i c h R o c k i s M a s si v e a n d U n c r a c k e d

a) For Concrete:

r2 =

t2 = 0b) For Cracked Rock:

r1 =

t1 = 0NOTE Symbol r1 and t1 refer to cracked zone of rock.

1) When x = r 1 = 02) When x = b, r 1 = r23) When x = b, r 2 = p4) When x = b, U1 = U2

1) When x = r 1 = 02) When x = b, r 1 = r23) When x = a , r 2 = p

m 1 E1

m 12

1

------------------- C1

x2

-------

m 1 E1

m 12 1

------------------- C1

x2-------

a . r2 )( x a=x

--------------------------------------

C1a .b .p m 1 1+( )

m 1E1-----------------------------------------=

a . r2 )( x a=x

-----------------------------------

a . r2 )( x a=x

-----------------------------------

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D -3 .5 R e i n fo r c e d C e m e n t C o n c r e t e L i n i n g C o n s i d e r i n g t h a t i t

i s Cr a c k e d a n d t h a t B e ca u s e o f R a d ia l C r a c k s i t C a n n o t T a k e

T a n g e n t i a l T e n s il e S t r e s s

Basic Equations

F o r r o c k

t1 =

r1 = t1U1 =

F o r c o n c r e t e

t1 =

U2 = .log b/a

F o r S t e el

t3 =

r3 = ( aB 2 + C2/a )

U3 =

C o n s t a n t s

(r2)x = a =

r3 = (r2)x = a +p

E1m 1C1

m 1 1+ )( 2x2---------------------------------

C1x-------

a r2 )(x a=

x---------------------------------

a r2 )( x a=E2

--------------------------------

a .r3A s--------------

E3A s

a2--------------

a2r3E3A s---------------

pam 1E1E2

am 1E1E2 m 1+ E1E3A s b /a )( m 1 1+ )( +log E2E3A s------------------------------------------------------------------------------------------------------------------------------------------------

C1 a b m 1 1+( ) s r2 )( x a=m 1E1

----------------------------------------------------------------=

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B u r e a u o f In d i a n S t a n d a r d s

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of implementing the standard, of necessary details, such as symbols and sizes, type or grade

designations. Enquiries relating to copyright be addressed to the Director (Publications), BIS.

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Amendments a re issued to standards as t he need arises on the basis of comments. Stan dards are also

reviewed periodically; a stan dard along with am endment s is reaffirmed when such review indicates

that no changes are needed; if the review indicates that changes are needed, it is taken up for

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This Indian Stan dard ha s been developed by Techn ical Committee : BDC 58

A m e ndm e n t s I s s ue d S i nc e Pub l i c a t i on

Am e n d No. Da t e of Is su e

Amd. No. 1 J une 1986

B U RE AU O F I ND IAN S TAN DAR D S

Headquarters :

Manak Bhavan, 9 Baha dur Sh ah Zafar Marg, New Delhi 110002.

Telephones: 323 01 31, 323 33 75, 323 94 02

Telegrams:Mana ksanstha

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Regiona l Offices: Telephone

C en t r a l : M ana k B hava n, 9 Ba ha dur Sha h Za fa r M ar g

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323 76 17

323 38 41

Eastern : 1/14 C. I. T. Scheme VII M, V. I . P. Road, Kankurgachi

KOLKATA 700054

337 84 99, 337 85 61

3 37 8 6 2 6, 3 37 9 1 2 0

Northern : SCO 335-336, Sector 34-A, CH ANDIGARH 160022 60 38 43

60 20 25

South ern : C. I. T. Campu s, IV Cross Roa d, CHE NNAI 600113 235 0 2 1 6, 235 04 42

2 35 1 5 1 9, 2 35 2 3 1 5

Western : Manakalaya, E9 MIDC, Marol, Andheri (East)

MUMBAI 400093

8 32 9 2 9 5, 8 32 7 8 5 8

8 32 7 8 9 1, 8 32 7 8 9 2

Branches : AHMEDABAD. BANGALORE. BHOPAL. BHUB ANESH WAR. COIMBATORE.

FARIDABAD. GHAZIABAD. GUWAHATI. HYDERABAD. JAIPU R. KANPUR. LUC KNOW.

NAGPUR. NALAGARH. PATNA. PUN E. RAJKOT. THIRU VANANTH APURAM.

VISHAKHAPATNAM