2911 1 4+CONCRETE+PILES+Bored+Precast+Concrete+Piles

7/30/2019 2911 1 4+CONCRETE+PILES+Bored+Precast+Concrete+Piles

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BIS 2003

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 BAHADUR SHAH ZAFAR MARGN E WDELHI 110002

I S : 2911 (P a r t 1/S ec 4) - 1984

(Re a ffi r m e d 2 00 2)

Ed i t ion 1 .1

(1987-10)

P r i ce Gr o u p 7

Indian S tandardCODE OF P RACTICE FOR DESIGN

AND CONSTRUCTION OF PILE F OUNDATION

P AR T 1 CONCR E TE P I LE S

Se ct ion 4 Bor e d P r e c a st Con c r e t e P i le s

(Incorp ora tin g Amen dm ent No. 1)

UDC 624.154.34 [ 691.327 ] : 006.76


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BIS 2003

BURE AU OF INDIAN STANDARDS

This publication is protected under the Ind ia n Cop yr igh t Act (XIV of 1957) andrepr oduction in whole or in pa rt by any mea ns except with written permission of th e

publisher sh all be deemed to be an infringement of copyright u nder th e said Act.

Ind ian S tandard

CODE OF PRACTICE FOR DESIGN


P AR T 1 CONCR ETE P I LE S


Foundation Engineering Sectional Committee, BDC 43

Chairm an R epresenting

BRI G OMBIR SINGH En gineer-in-Chiefs Br an ch, Army H eadqua rt ers

Mem bers

COL K. P. ANAND (Alt ern ate toBrig Ombir Singh )

SH RI B. ANJIAH Andhra Pradesh Engineering Research Labora-tories, Government of Andhra Pradesh,Hyderabad

DR R. K. BHANDARI Central Building Research Institute (CSIR),Roorkee

SHRI CHANDRA P RAKASH (Alt ern ate )

SH RI A. K. CHATTERJEE Gammon India Ltd, BombaySHRI A. C. ROY (Alt ern ate )

CHIEF ENGINEER

SHRI S. G UHA (Alt ern ate )Calcutt a P ort Tru st, Calcut ta

SH RI M. G. DANDAVATESHRI N. C. DUGGAL (Alt ern ate )

The Concret e Associat ion of In dia, Bombay

SH RI R. K. DAS GUPTA

SHRI H. G UHA BISWAS (Alt ern ate )Simplex Concrete Piles (I) Pvt Ltd, Calcutta

SH RI A. G. DASTIDAR In personal capacity ( 5, Hungerford Court, 121Hungerford S treet, Calcu tta )

SH RI V. C. DESHPANDE The P ressu re P illing Co (I) Pvt Ltd, Bombay

DIRECTOR (CSMRS) Centra l Soil & Mater ia l Research Sta t ion,New Delhi

DEPUTY DIRECTOR (CSMRS) (Alt ern ate )

SH RI A. H. DIVANJI Asia Foundation and Construction Pvt Ltd,Bombay

SHRI A. N. J ANGLE (Alt ern ate )SH RI A. G HOSHAL Stup Consulta nts Ltd, Bombay

( Continu ed on page 2 )


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( Contin ued from page 1 )

Mem ber s R epresen tin g

DR J AGDISH NARAIN Indian Geotechnical Society, New Delhi

PROF SWAMI SARAN (Alt ern ate )

SHRI ASHOK KUMAR J AIN G. S. J ain & Associat es, Roork eeSHRI VIJAY KUMAR J AIN (Alt ernate )

SHRI N. J AGANNATH Steel Authority of India, New Delhi

SHRI A. K. MITRA (Alt ern ate )

J OINT DIRECTOR (DESIGNS) Nat ional Buildings Organisa t ion, New Delh i

SHRI SUNIL BERY (Alt ern ate )

J OINT DIRECTOR RESEARCH(GE)-I, RDSO

Minist ry of Railwa ys

J OINT DIRECTOR RESEARCH (B & S),(RDSO) (Alt ern ate )

DR R. K. KATTI Indian Inst itut e of Techn ology, Bombay

SHRI S. R. KULKARNISHRI S. ROY (Alt ern ate )

M. N. Dast ur & Co Pvt Ltd , Calcut ta

SHRI A. P. MATHUR Centr al Wareh ousing Corporat ion, New Delhi

SHRI V. B. MATHUR McKenzies Limited, Bombay

SHRI S. MUKHERJEE In personal Capacity (E104A , S im la House,N epean S ea R oad, Bom ba y )

SHRI T. K. D. MUNSI En gineers India Limited, New Delhi

SHRI M. IYENGAR (Alt ern ate )

SHRI B. K. P ANTHAKYSHRI V. M. MADGE (Alt ern ate )

The Hindu sta n Cons tru ction Co Ltd, Bomba y

SHRI M. R. P UNJASENIOR ENGINEER (Altern ate )

Cemindia Co Ltd, Bomba y

SHRI N. E . V. RAGHVAN The Braithwaite Burn & Jessop Construction CoLtd, Calcutta

DR V. V. S. RAO Nagadi Consulta nts Pvt Ltd, New Delhi

P ROF GOPAL RANJAN Un iversity of Roorkee, Roork ee

SHRI ARJUN RIJHSINGHANISHRI O. P. SRIVASTAVA (Alt ern ate )

Cement Corporat ion of India, New Delhi

DR A. SARGUNAN College of Engineering, Guindy, Madras

SHRI S. BOMMINATHAN (Alt ernate )

SHRI N. S IVAGURUSHRI K. B. SARKAR (Alt ern ate )

Ministry of Shipping and Tran sport

SUPERINTENDING E NGIN E E R

(DESIGNS

)EXECUTIVE E NGINEER (DESIGNS) V(Altern ate )

Centr al Pu blic Works Depar tm ent , New Delhi

DR A. VARADARAJ AN Indian Inst itut e of Techn ology, New Delhi

DR R. KANIRAJ (Alt ern ate )

SHRI G. RAMAN, Director General, ISI (Ex-off icio M em ber )

Director (Civ En gg)

S ecretary

K. M. MATHURSen ior Depu ty Director (Civ Engg)

( Contin ued on page 29 )


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Indian S tandard

CODE OF P RACTICE FOR DESIGN


P AR T 1 CONCR E TE P I LE S


0. F O R E W O R D

0.1 This Indian Standard (Part 1/Set 4) was adopted by the IndianSta nda rds Inst itut ion on 27 F ebrua ry 1984, after t he dr aft finalized bythe Foundation Engineering Sectional Committee had been approvedby the Civil Engin eer ing Division Coun cil.

0.2 Piles find application in foundation to transfer loads from astructure to competent subsurface strata having adequateload-bearing capacity. The load transfer mechanism from a pile to thesurrounding ground is complicated and could not yet be fullydetermined, although application of piled foundations is in practiceover many decades. Broadly, piles transfer axial loads eithersubsta nt ially by friction along its sh aft a nd/or substa nt ially by the endbearing. Piles are used where either of the above load transfer

mechanism is possible, depending upon the subsoil stratification at aparticular site. Construction of pile foundations requires a carefulchoice of piling syst em , depending upon the su bsoil conditions, th e loadcharacteristics of a structure and the limitations of total settlement,differen tial sett lemen t an d a ny other special requiremen t of a pr oject.The installation of piles demands careful control on position,alignmen t a nd dept h a nd involve specialized skill a nd experience.

0.3 This stan dar d (Pa rt 1) was origina lly published in 1964 an d includedprovisions regarding driven cast in-situ piles, precast concrete piles,

bored ( cast in-situ ) and under-reamed piles, including load testing.Subsequently portions pertaining to under-reamed pile foundationswere deleted and which are now covered in IS : 2911 (Part 3). At thattime it was decided that the provisions regarding other types of pilesshould also be published separ at ely for t he ea se of reference an d to takeinto account the recent developments in this field. ConsequentlyIS : 2911 (Pa rt 1)-1964* ha s been r evised in various sections. So fa r t hefollowing sections have been formulated.

*Code of practice for design and construction of pile foundation: Part 1 Load bearing

concret e piles.


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Section 1 Driven cast in-situ concret e piles

Section 2 Bored cast in-situ piles

Section 3 Dr iven precast concrete piles

Section 4 Bored precast concret e piles

0.3.1 This section covers the bored precast concrete piles which havenow come in to use in r ecent tim es.

0.4 Bored precast concrete pile is a pile constructed in a casting yardand subsequently lowered into pre-bored holes and the space grouted.These piles find wide applications where safety against chemicalaggressive subsoil and the ground water condition is needed. Suchprotection is possible with bored precast concret e piles, because t hese

are made using vibrated dense, matured concrete, with low watercement ra tio an d a re n ot su bjected t o driving str esses. These a re a lsouseful where artesian conditions exist or where local obstructions areencoun ter ed a bove th e foun ding level or su bsoil wat er flow exists. Theyalso offer facility for applying protective coating on the pile surfaces.The provision in respect of segmental piles with properly designed

joint s a re under considera t ion of t he Commit tee and it s provision s willbe covered a t a la ter sta ge.

0.5 The Sectional Committee responsible for the preparation of

standard, while formulating this standard, gave due consideration toth e available experience in th is coun tr y in pile cons tr uction a nd a lso th elimita tions regar ding the availability of piling plan t an d equipment .

0.5.1 The information furnished by the various construction agenciesand specialist firms doing piling work in this country and technicaldiscussions thereon considerably assisted the committee inform ula t ion of th is code.

0.6 This edition 1.1 incorporates Amendment No. 1 (October 1987).Side bar indicates modification of the text as the result ofincorporat ion of the a men dmen t.

0.7 For the purpose of deciding whether a particular requirement ofth is sta nd ar d is comp lied with , t he fina l valu e, observed or calcula ted,expressing th e res ult of a tes t, sh a ll be roun ded off in a ccorda nce withIS : 2-1960*. The nu mber of significan t places ret ain ed in t he r oun dedoff value should be the same as that of the specified value in thisstandard.

*Rules for round ing off nu mer ical valu es ( revised).


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1 . SCOP E

1.1 This standard (Part 1/Sec 4) covers the design and construction ofload bear ing bored pr ecast concret e pile which t ra nsm it th e load of th e

stru ctur e to the str at a where resista nce is adequate.NOTE This standa rd is based on a ssumpt ion t ha t str ength of grout fill up in thespace shall be at least equivalent to that of surrounding soil and the skin frictiondeveloped on th e pile shall be determ ined by probative test.

2 . TER MINOLOGY

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

2 .1 Al lo wa b le Lo ad The load wh ich ma y be applied to a pile aftertaking into account its ultimate load capacity, pile spacing, overallbearing capacity of the ground below the pile, the allowablesett lement , negat ive skin friction a nd t he loading condit ions in cludingreversa l of loads, et c.

2.2 B a t t e r P i le (R a k e r P i l e ) The pile which is insta lled at anan gle to th e vertica l.

2.3 B e a r i n g P i le A pile form ed in t he groun d for tr an smitt ing theload of a structure to the soil by the resistance developed at its tipand/or along its surface. It may be formed either vertically or at an

inclina tion (Bat ter Pile) an d m ay be required to ta ke u plift.If th e pile support t he load prima rily by resista nce developed a t th e

pile point or base it is r eferr ed t o as End Bear ing P ile, if pr ima rily byfriction a long its su rface then as Friction P ile.

2.4 B or e d P r e c a s t P ile A pile cons tr ucted in rein forced concret e ina cast ing yar d a nd subsequent ly lowered into prebored h oles a nd spacegrouted.

2 .5 Cu t -o ff Level - It is th e level wher e t he inst alled pile is cut-off tosupport th e pile caps or beam s or a ny oth er st ru ctu ra l components a t

th at level.

2.6 F a c t or o f S a fe t y The r at io of th e ultima te load capa city of apile, to th e sa fe load of a pile.

2.7 S a fe L oa d The load derived by ap plying a factor of sa fety on t heultima te load ca pacity of th e pile or a s determ ined in th e loa d test .

2.8 U lt i m a t e L oa d C a p a c it y The ma ximu m load wh ich a pile orpile sh a ft can car ry before fa ilur e of groun d (when th e soil fa ils by shea ras evidence from t he load sett lemen t cur ves) or failur e of pile mat eria ls.

2.9 Wo r k i n g Lo a d The load a ssigned to a pile accordin g to design.


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3. NE CE SSARY INF OR MATION

3.1 For t he sa tisfactory design an d const ru ct ion of bored pr eca st piles,the following information is necessary:

a) Site investigat ion dat a as laid down in IS : 1892-1979*, and oth errelevan t Codes. Sections of tr ial borin g, su pplemen ted, wher everappr opriat e, by penetra tion test s, should incorporat e da ta /infor-ma tion su fficient ly below t he an ticipa ted level of t he pile t ip; th eboring below the pile tip should generally be not less than 10 mun less bed rock or firm str a ta ha s been encoun ter ed earlier. Thenature of the soil both around and beneath the proposed pileshould be indicat ed on th e basis of appropriat e test s of strength ,comp ressibility, etc. Groun d-water levels and condit ions (such asa rt esian cond itions ) sh ould be indicat ed. Results of chem ical t est s

to ascertain the sulphate and chloride content and/or any otherdeleterious chemical content of soil and/or ground water shouldbe indicated, particularly in areas where large piling work isenvisaged or wh ere su ch inform at ion is not gener a lly available.

b) In cas e of bridge foun da tions, da ta on high flood level, ma ximumscouring depth, normal water level during working season, etc,should be provided. In the case of marine construction, high andlow tide level, flow of water and other necessary information, aslisted in IS : 4651 (Par t 1)-1974 sh ou ld be provided.

c) In case rock is en coun tered, adequa te description of rock t o conveyits physical conditions as well as its strength characteristicssh ould be indica ted.

d) Genera l pla n a nd cross section of th e str uctur e showing type ofstructural frame, including basement, if any, in relation to thepr oposed pile-cap top t r avels should be provided.

e) The genera l layout of th e stru ctu re sh owing estima ted loads,vert ical a nd horizont al, momen ts an d t orque at th e t op of pile caps,but excluding the mass of the piles and caps should be provided.The top levels of finish ed pile ca ps sh a ll be clear ly indicat ed.

f) All tra nsient loads due to seismic and wind conditions an d loa ddue to under wa ter should be indicat ed separa tely.

g) Sufficient inform at ion of str uctur es existing near by and th eexperience of piles in the area close to the proposed site andboring report thereof for assessing the founding level of pilesshould be provided.

*Code of pra ctice for s ubsu rface invest igations for foun dat ions (fi rst rev is ion ).Code of pra ctice for plan ning an d design of port s an d ha rbours: Par t 1 Site investi-

gation (first revis ion ).


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4 . EQUIP MENT AND ACCE SSOR IES

4.1 The equipment and accessories will depend on the type of boredprecast piles chosen in a job and would be selected giving due

consideration to the subsoil strata, ground-water conditions, type andfounding material and the required penetration therein whereverapplicable.

4.2 Among the commonly used plants, tools and accessories, thereexist a large variety; suitability of which depends on the subsoilconditions, ma nn er of opera t ion, et c.

Boring operations are generally done by any appropriate methodwith or without temporary casing. Boring may be carried out usingmu d st abilisation if required.

4.3 H a n d l in g E q u i p m e n t fo r L ow e r in g Ha ndling equipment

such a s cra ne, derricks, movable gant ry, ma y be used for h an dling an dlowering of the precast piles in the bore. The choice of equipment willdepend upon length, ma ss, an d oth er pra ctical requiremen ts.

4.4 G r o u t in g P la n t The m ixing of th e grout can be car ried out inany suitable high speed collidal mixer. For grouting a suitable groutpump with st irring/agita ting arr an gement ma y be used.

5 . DESIGN CONSIDE RATION

5.1 G e n e r a l Pile foun da tions sh all be designed in such a way th atthe load from the structure it supports, can be transmitted to the soil

with out cau sing any soil failure a nd without cau sing such set tlementdifferential or total under permanent transient loading as may resultin str uctur al da ma ge and/or functiona l distr ess. The pile sha ft sh ouldhave adequate structural capacity to withstand all loads (vertical,axial or otherwise) and moments which are to be transmitted to thesubsoil and shall be designed according to IS : 456-1978*. The shaft ofbored p recast piles m ay be of circular or octa gona l sha pe, an d may beof solid section or with a central hollow core. The limiting size of thepile will depend m ainly on a vaila ble ha ndling equipment a nd t he m assof th e pile sha ft t o be ha ndled.

5.2 Ad j a c e n t S t r u c t u r e s

5.2.1 When working near existing structures care shall be taken toavoid any damage to such structures. In the case of bored pile careshall be taken to avoid effect due to loss of ground; when boring iscar ried out using mu d, the st a bility of th e bore pa rt icular ly adjacent t oloaded foun da tions sh a ll be examin ed.

5.2.2 In case of deep excavations adjacent to piles, proper shoring orother suitable ar ra ngement sha ll be done to gua rd a gainst the lat eralmovement of soil st ra tu m or r eleasing th e confinin g soil st ress.

*Code of practice for plain an d r einforced concret e ( th ird revision ).


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5.3 S o il R e s is t a n c e The bear ing ca pacity of a pile is dependent on t heproperties of the soil in which it is embedded. Axial load from a pile isnorma lly tra nsm itted to th e soil th rough sk in friction a long th e sha ft a ndend bear ing at its tip. A horizont a l load on a vertical pile is t ra nsm itted

to th e subsoil prima rily by horizont al su bgra de rea ction genera ted in th eupper pa rt of th e sha ft . A single pile is n orm ally designed t o ca rr y loa dalong its axis. Transver se load bear ing cap acity of a single pile dependson the soil reaction developed and the structural capacity of the shaftun der bending. In case th e horizont a l loads a re of higher ma gnitude, itis essent ial to investigat e th e phen omenon u sing principles of horizont alsubsoil reaction ad optin g appr opr iat e values for h orizont al m odulu s ofth e soil. Alter na tively piles ma y be insta lled in ra ke.

5.3.1 The ultimate load capacity of a pile may be estimated using asuitable static formula. However, it should preferably be determinedby an initial load test [ see IS : 2911 (Pa rt 4)-1984]*. The crosssectional area for the purpose of the calculation shall be the concretesection excluding the grout where chemical aggression is likely toinhibit set tin g of cemen t.

The s ett lemen t of pile obta ined a t s a fe load /work ing load from loadtest resu lts on a single pile sha ll not be direct ly used in forecast ing th esett lemen t of str uctur e [ see IS : 8009 (Pa rt 2)-1980 ].

The average settlement may be assessed. It would be more appro-priat e to assess t he a vera ge sett lemen t on th e basis of subsoil dat a a nd

loading details of the structure as a whole using the principles of soilmechanics.

5.3.1.1 S tatic form ula By using stat ic form ula, the estima ted valueof ultimate load capacity of a typical pile is obtained, the accuracybeing dependent on the reliability of the formula and the reliability ofth e ava ilable soil pr oper ties for va rious str a ta . The soil pr opert ies to beadopted in such formula may be assigned from the results oflabora tory test s an d field test s like sta nda rd penet ra tion t ests ( see IS :2131-1981 ). Results of cone p enet ra t ion t est s m ay a lso be ut ilizedwhere n ecessar y corr elat ion with soil result s dat a h as been est ablished

[ see IS : 4968 (Pa rt 1)-1976 ], IS : 4968 (P art 2)-1976, IS : 4968(Pa rt 3)-1976. Two separa t e sta t ic form ula comm only ap plicable forcohesive an d cohesion less soil respect ively ar e indicat ed in Appen dix A

*Code of practice for design and construction pile foundations: Part 4 Load test onpiles (first revis ion ).

Code of practice for calculation of settlement of foundations: Part 2 Deepfoun dat ions subjected to symm etrical sta tic vertical loading.

Method for st an dar d penet ra tion t est for soils (first rev is ion ).Method for subs ur face soun ding for s oils:

Pa rt I Dyna mic meth od using 50 mm cone without bent onite slur ry (first rev ision ).

Pa rt II Dynam ic meth od using cone an d bentonite slur ry (fi rs t revis ion ).Par t III Sta tic cone penetra tion t est (fi rs t rev is ion ).


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to serve only as a guide. Other alternative formula may also beapplicable, depending on the subsoil characteristics and method ofinst a llat ion of piles.

5.4 N e ga t i v e Sk i n F r i c t io n o r D r a g d o w n F o r c e When a soilstra tu m t hr ough which a pile sha ft h as penetra ted into an underlyingha rd st ra tu m, compr esses as a result of either it being un consolidatedor it being un der a newly placed fill or as a resu lt of rem oulding of thepile, a dr agdown force is gener a ted a long th e pile sha ft u p to a point indepth where t he su rr oun ding soil does not m ove downwar d r ela tive toth e pile sha ft.

NOTE Est imat ion of th is dragdown force is still un der resea rch stu dies andconsiderations, although a few empirical approaches are in use for the same. Theconcept is constantly under revision and, therefore, no definite proposal is embodied

in this standard.5.5 S t r u c t u r a l C a p a c it y The piles shall have necessary structura lstr ength to tra nsm it th e loads imposed on it, ultima tely to th e soil.

5.5.1 Axial Capacity Where a pile is wholely embedded in t he soil( ha ving a undr ained shear strength not less tha n 0.1 kgf/cm 2 ) its a xialca rr ying cap acity is not limited by its st ren gth a s a long colum n. Wher epiles ar e inst a lled thr ough very weak soils ( ha ving an u ndra ined shea rstr ength less th an 0.1 kgf/cm 2 ) specia l consider at ions sha ll be ma de todetermine whether the shaft would behave as long column or not; if

necessar y suitable reductions sh all be made for its st ru ctu ra l stren gthfollowing the normals tructural principles covering the bucklingph enomenon. When th e finished p ile projects above groun d level an d isnot secured a gainst buckling by a dequa te br acing, th e effective lengthwill be governed by fixity conditions imposed on it by the structure itsupport s an d by the n at ur e of th e soil into which it is inst alled. The depthbelow the gr oun d su rface to th e lower point of cont ra flexur e var ies withth e type of th e soil. A st ra tu m of liquid mu d should be tr ea ted a s if it waswater . The degr ee of fixity of th e posit ion a nd inclina t ion of th e pile topan d t he rest ra int provided by an y bracing sh all be estima ted following

accepted st ru ctu ra l principles. The perm issible str ess sha ll be r educedin a ccorda nce with similar provisions for reinforced concret e colum ns aslaid down in IS : 456-1978*.

5.5.2 Latera l Load Capacity A pile ma y be subjected t o tr an sverseforce from a nu mber of cau ses, such as wind, ear th qua ke, wa ter cur rent ,ear th pr essu re effect of moving vehicles or sh ips, plan t a nd equ ipmen t,etc. The lat era l loa d carr ying capa city of a single pile depends n ot onlyon t he h orizont al su bgrad e modulus of th e sur roun ding soil but also on



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the structural strength of the pile shaft against bending consequentupon a pplicat ion of a la t era l load . While cons idering lat era l load of piles,effect of other coexistent loads including the axial load on the pile,should be ta ken in to cons idera tion for checking th e str uctu ra l capacity

of th e sha ft. A recom men ded met hod for t he det erm ina tion of depth offixity, lateral deflection and maximum bending moment required fordesign is given in Appendix B for fully or partially embedded piles.Oth er a ccept ed met hods, such a s th e met hod of Reese an d Mat lock forfully embedded piles ma y also be used.

NOTE Becau se of limited inform at ion on horizont al m odulus of soil, andrefinemen ts in t he th eoret ical an alysis, it is suggested th at adequa cy of a design ma ybe checked by a n actua l field load test .

5.5.3 R aker Pi les Raker piles ar e norm ally provided where verticalpiles cannot resist the required applied horizontal forces. In the preli-minary design the load on a raker pile is generally considered to beaxial. The distribution of load between raker and vertical piles in agroup may be determined by graphical or analytical methods. Wherenecessary, due consideration should be made for secondary bendinginduced as a result of the pile cap movement, particularly when thecap is rigid. Free-standing raker piles are subjected to bendingmoment s du e to th eir own m ass, or exter na l forces from oth er cau ses.Raker piles embedded in fill or consolidating deposits, may becomelat era lly load ed owing to th e sett lement of th e sur roun ding soil.

5.6 S p a c i n g o f P i le s The cent re-to-cent re spa cing of piles sh ouldbe consider ed from two as pects:

a ) pr actical a spects of inst a lling th e piles, an d

b) th e na tu re of th e load tr an sfer t o th e soil an d possible reductionin t he bea rin g cap acity of a group of piles t her eby.

The choice of the spacing is normally made on semi-empiricalapproach.

5.6.1 In case of piles which a re pr edomina nt ly rest ing on h ar d str at um

and deriving their capacity mainly from end bearing, the spacing willbe governed by the competency of the end bearing strata. Theminimu m spacing in su ch cases, sha ll be 2.5 times t he diam eter of th epile. In case of piles rest ing on rock, th e spa cing of twice t he diam eterof th e pile may be a dopted.

5.6.2 Piles der iving th eir bear ing capa city ma inly from frict ion s ha ll besufficiently apa rt to ensu re t ha t t he zones of soils from wh ich t he pilesderive th eir support do not overlap to such a n extent th at th eir bear ingvalues are reduced. Generally the spacing in such cases shall not be

less tha n t hr ee times the diam eter of th e pile.


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5.6.3 The spacing should not be so close as to cause direct contactbetween two adjacent piles in a group, th e deviat ions at depths ar isingout of the tolerance allowed in the installation. This would mean themin imu m spa cing would, to some ext ent , depend on t he lengt h of piles

installed.

5.7 P i le G r o u p i n g In order t o determ ine the bear ing capa city of agroup of piles, a n um ber of efficiency equa tions a re in u se. However, itis very difficult to establish the accuracy of these efficiency equationsas th e beha viour of piles group is dependen t on m any comp lex factors.It is desira ble to cons ider each case sepa ra tely on its own mer it.

5.7.1 The bea rin g capacity of a p ile group m ay be either :

a) equal t o the bea ring capa city of individual piles m ultiplied by th enu mber of piles in t he group , or

b) it may be less.

5.7.2 In case of piles deriving their support mainly from friction andconnected by a pile cap, the group may be visualized to transmit loadto the soil, as if from a column of soil enclosed by the piles. Theultim at e capa city of the gr oup may be compu ted following th is concept,taking into account the frictional capacity along the perimeter of thecolumn of soil as above and the end bearing of the said column usingth e accepted pr inciples of soil mecha nics.

5.7.2.1 When the cap of the pile group is cast directly on reasonably

firm st ra tu m which su pport s the piles it m a y cont ribute t o th e bea ringcapacity of the group. The additional capacity along with theindividua l capacity of th e piles mult iplied by th e nu mber of piles in t hegroup should n ot be more th a n th e capa city work ed out in 5.7.2 .

5.7.3 When a moment is applied on the pile group either from superstructure or as a consequence of unavoidable inaccuracies ofinstallation, the adequacy of the pile group in resisting the appliedmomen t should be checked. In case of a single pile su bjected to momen tsdue to lateral forces or eccentric loading beams may be provided torest ra in t he pile ca p effect ively from lat era l or r ota t iona l movement .

5.7.4 In case of structure supported on single pile/group of piles,resulting into large variation in the number of piles from column tocolumn, it is likely, depending on the type of subsoil supporting thepiles, to result in a high order of differential settlement. Such highorder of differential settlement may be either catered for in thestructural design or it may be suitably reduced by judicious choice ofvariations in the actual pile loadings. For example, a single piles capma y be loaded t o a level higher th a n t ha t of a pile in a group in order t oachieve redu ced differen tia l settlem ent between t wo adjacent pile cap s

supp ort ed on d ifferen t nu mber of piles.


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5 .8 Fa c to r o f Sa f e ty an d Sa fe Lo ad

5.8.1 Fa ctor of sa fety should be judiciously chosen after consider ing:

a ) th e r eliability of t he va lue of ultim at e load ca pacity of a pile,

b) th e type of superstr uctur e an d t he t ype of loading, an d

c) allowable tota l/differen t ial sett lement of t he st ru ctu re.

5.8.2 The ultimate load capacity may be obtained wheneverpra cticable, from a loa d t est (initia l) [ see IS : 2911 (Pa rt 4)-1984* ].

5.8.3 When t he u ltima te load capa city is comput ed from st at ic form ulathe factor of safety would depend on the reliability of the formuladepending on a particular site and locality and the reliability of thesubsoil parameters employed in such computation. The minimum

factor of safety on static formula shall be 2.5. The final selection offactor of safety shall take into consideration the load settlementcha ra cter istics of th e str uctur e as a whole at a given site.

5.8.4 Factors of safety for assessing safe load on piles from load testdat a should be increased in un favour able conditions where:

a) sett lemen t is to be limited or u nequa l sett lement a voided as inth e case of accur a tely aligned m echiner y or a supers tr uctur e withfragile finishings,

b) large impact or vibra ting loads a re expected,

c) th e properties of th e soil ma y be expected to deter iora t e withtime, an d

d) the live load on a st ru ctu re car ried by friction piles is a consider -able port ion of t he t ota l load a nd a pproxima tes to th e dead load inits duration.

5.9 T r a n s ie n t L oa d i n g The ma ximu m perm issible increase overth e sa fe load of a pile as a rising out of wind loa ding, is 25 per cent . Incase of loads and moments arising out of earthquake effects, the

increase of safeload on a single pile may be limited to the provisionscontained in IS : 1893-1975. For transient loading arising out ofsuper imposed loads no increa se may be genera lly allowed.

5.10 O v e r l oa d i n g When a pile in a group, designed for a cert ainsafe load is found, during or after execution, to fall just short of theload required to be carried by it, an overload up to 10 percent of thepile capacity ma y be allowed on each pile. The t ota l overloa ding on t he

*Code of pra ctice for design a nd const ru ction of pile found at ions : Pa rt 4 Load t est onpiles (first revis ion ).

Criteria for earth quake r esista nt design of stru ctur es ( th ird revision ).


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group s hould not be more th an 10 percent of t he capa city of th e groupand not more than 40 percent of the allowable load on a single pile.This is su bject to th e increase of t he load on a ny pile not exceeding 10percent of its capacity.

5.11 L ift i n g a n d H a n d l in g S t r e s s e s Stresses induced by bendingin t he cross section of a pr ecast pile dur ing liftin g an d ha ndling ma y beestimated just as for any reinforced concrete section in accordancewith relevant provisions of IS : 456-1978*. The calculations withregard to moments depending on the method of support duringhandling will be as given below. Excessive whippiness in handlingprecast pile ma y gener ally be avoided by limiting t he length of pile to ama ximu m of 50 times the least width .

whereW= ma ss of pile in kg, and

L = length in metres.

During hoisting the pile will be suspended at one point near thehead and the bending moment will be the least when it is pulled in adist ance of 0.293L , and th e value of bending moment will be:

5.12 R e i n fo r c e m e n t The longitu dinal reinforcemen t sh all be

provided in for the entire length preferably of high yield strength towithst an d th e han dling stresses to the extent t o meet r equirement asgiven in 5.11 . All the main longitudinal bars shall be of the samelength. The area of the main longitudinal reinforcement of any typean d grad e sha ll not be less th an 0.4 percent of th e cross section a rea ofthe piles or as required to cater for handling stresses whichever isgreat er. The lat era l reinforcemen t sha ll be links or spirals prefera blyof not less th an 6 mm diam eter bar s. The cover of concret e over a ll th ereinforcement including bending wire should not be less than 40 mm,but wh ere th e piles ar e exposed to th e sea wat er or water ha ving oth er

*Code of practice for plain an d r einforced concret e ( thirdrevision ).

N um ber of Poin ts

of Pick Up

Location of Point of S upport from

and in T erm s of Length of Pilefor Min im um Mom ents

Bendin g Mom ent

to be Allowed forDesign

One 0.293 L

Two 0.207 L

Three0.145L , th e middle point

will be at t he cent re

W L

23.3-----------

W L

46.6-----------

W L

95---------

W L

23.3-----------


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corrosive contents the cover should be no where less than 50 mm. Athin gauge sheathing pipe of approximately 40 mm diameter may beattached to the reinforcement cage, in case of solid piles, to form thecent ra l duct for pu mping grout to th e bott om of th e bore.

5 .13 Des ign o f P i le Ca p

5.13.1 The pile caps ma y be designed by assum ing th at th e load fromcolumn is dispersed a t 45 from the t op of th e cap u p to the m id-depthof the pile cap from the base of the column or pedestal. The reactionfrom piles may also be taken to be distributed at 45 from the edge ofthe pile, up to the mid-depth of the pile cap. On this basis themaximum bending moment and shear forces should be worked out atcritical sections. The methods of analysis and allowable stressesshould be in a ccord a nce with IS : 456-1978*.

5.13.2 Pile cap shall be deep enough to allow for necessary anchorageof th e colum n a nd pile reinforcemen t.

5.13.3 The pile cap should normally be rigid enough so that theimposed load could be distr ibut ed on th e piles in a group equita bly.

5.13.4 In case of a large cap, where differential settlement may beimposed between piles u nder th e sam e cap, due considera tion for th econsequ ent ial momen ts sh ould be given.

5.13.5 The clear overha ng of th e pile cap beyond th e out erm ost pile inth e group sh all norma lly be 100 to 150 mm depend ing upon t he pile size.

5.13.6 The cap is genera lly cas t over a 75 mm th ick levelling cour se ofconcrete. The clear cover for main reinforcement in the cap slab shallnot be less tha n 60 mm .

5.13.7 The pile should project 50 m m into th e cap concret e.

5.14 The design of grade beams if used shall be as given in IS : 2911(Par t 3)-1980.

6. MATER IALS

6.1 C em e n t The cement used sha ll conform to the requiremen ts of

IS : 269-1976, IS : 455-1976, IS : 8041-1978 | | , IS : 1489-1976, andIS : 6909-1973** as t he case may be.

*Code of practice for plain an d r einforced concret e ( th ird revision ).Code of practice for design and construction of pile foundations : Part 3 Under-

ream ed pile founda tions ( fi rs t revis ion ).Specificat ion for ordina ry a nd low h eat Portlan d cement ( th ird revision ).Specificat ion for P ortla nd s lag cemen t ( third revision ).| | Specificat ion for r apid h ar dening P ort land cement (fi rs t rev is ion ). Specifica t ion for Port la nd-pozzola na cem en t ( second revision ).

**Specification for super-sulphated cement.


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6.2 S t e e l Reinforcement steel shall conform to IS : 432 (Pa rt 1)-1982*, IS : 1786-1985 or IS : 226-1975.

6 .3 Con cr e t e

6.3.1 Mat erials a nd met hod of ma nu factur e for cement concrete sh a ll ingeneral be in accordance with the relevant requirements given inIS : 456-1978. The st resses in concrete due t o workin g load a nd du ringha ndling, pitching a nd dr iving of th e pile should not exceed th an t hosestipulat ed in IS : 456-1978 according to th e grade of concrete used an dha ving due r egard t o th e age of piles a t t he t ime of ha ndling.

6.3.2 The gra de of concret e should be preferably not less th an M25.

6.3.3 For the concrete, water and aggregates specifications laid downin IS : 456-1978 sha ll be followed in genera l. Nat ur al r oun ded sh ingle

of appropriate size may also be used as coarse aggregate. It helps togive high slump with less water-cement ratio. For tremie concretingaggregat es ha ving nominal size more th an 20 mm should not be used.

7. WOR KMANSH IP

7.1 As far as possible in-situ extensions shall be avoided. The castingyard for all concrete piles should preferably be so arranged that theycan be lifted directly from their beds and transported to the pilingframe with a minimum of handling. The casting yard should have awell-drained surface to prevent excessive or uneven settlement due tosoftening dur ing ma nu fa ctu re a nd curing.

7.2 As far as practicable each longitudinal reinforcement shall be inone len gth. In cases wh ere joint s in r einforcing bar s can not be a voided,the joints in bars shall be staggered. The hoops and links forreinforcement sha ll fit t ight ly against longitudina l bars an d be boun dto them by welding or by tying with mild steel wire, the free ends ofwhich should be turned into the interior of the pile. The longitudinalbars m ay be held apart by tempora ry or perman ent spreader forks notmore than 1.5 m apart. The reinforcement shall be checked fortight ness a nd position imm ediat ely before concret ing.

7.3 C a s t i n g a n d C u r in g7.3.1 The piles should be cast in a continuous operation from end toend of each pile. The concret e sh ould be t horoughly compacted againstth e form s a nd ar oun d t he r einforcement by mean s of imm ersion an d/orshu tt er vibra tors. The faces of th e pile including th ose exposed at th e

*Specification for mild steel and medium tensile steel bars and hard drawn steelwires for concrete r einforcement: Pa rt 1 Mild st eel and m edium t ensile steel bars ( thirdrevision ).

Specification for high strength deformed steel bars and wires for concretereinforcement ( th ird revision ).

Specificat ion for str uctur al st eel (sta nda rd qua lity) (fi ft h revis ion ).Code of practice for plain an d r einforced concret e ( thirdrevision ).


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top of pile should be dense as far as possible. Immediately oncompletion of the casting the top surface should be finished levelwithout excessive trowelling. Care should be taken to ensure thatvibration from adjoining works does not effect the previously placedconcret e for p iles du rin g th e set tin g period.

7.3.1.1 All shuttering shall be placed on firm supports capable ofwith sta nding th e loads of shu tt ering, wet concrete a nd in cident al loadof workm en, so th at cast piles a re st ra ight a nd free from deform at ions.The sh ut ter ing sha ll be coa ted with oil on t he ins ide face.

7.3.2 Though from consideration of speed and economy precastconcret e piles will have t o be placed with t he lea st possible delay a ftercast ing, it sha ll be kept in mind th at a t horough curing and ha rden ing

is necessary before the piles are placed and proper schedule to takeca re of th is sha ll be decided for th e opera tions of ca stin g, st acking a ndplacing. The m ost im port a nt factors effectin g th e time of cur ing ar e th emethod of curing, weather during hardening, probable hardness ofplacing and t he m eth od of lifting a nd pit chin g.

7.3.4 Before the operation of handling the piles, the minimum periodscounted from the time of casting as given in IS : 456-1978* shall befollowed.

7.4 S o r t i n g a n d H a n d l in g

7.4.1 Piles sh all be stored on firm groun d free from liability to un equa lsubsidence or set tlem ent un der t he m as s of th e sta ck of piles. The pilessha ll be placed on timber su pport s which a re t ru ly level an d spaced soas to avoid undue bending in the piles. The support shall be verticallyone a bove the other . Spaces sha ll be left r oun d th e piles to enable th emto be lifted without difficult y. The order of st acking sh all be such t ha tthe older piles can be withdrawn for placing without disturbing thenewer piles. Separate stacks shall be provided for different lengths ofpiles. Wherever curing is needed during storage, arrangements shall

be made to enable the piles to be watered if weather conditions sorequire. For detailed precautions with regard to curing operationsreference ma y be made to IS : 456-1978*.

7.4.2 Care shall be taken at all stages of transporting, lifting andhandling of the piles that they are not damaged or cracked. Duringtransportation, the piles shall be supported at the appropriate liftingholes provided for the purposes. If the piles are put down temporarilyafter being lifted, t hey sh all be pla ced on t res tles of blocks locat ed a tth e liftin g point s.



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7 .5 Co n t r o l o f P i le I n s t a ll a t i o n

7.5.1 Bored precast piles sh all be cons tr ucted by suit able choice of borin gand installation techniques; covering the manner of soil stabilization,

th a t is, us e of ca sing a nd /or u se of dr illing mu d and choice of borin g toolsin order to permit a satisfactory installation of a pile at a given site.Su fficient deta iled inform at ion about th e subsoil cond itions is essent ialto predeterm ine th e deta ils of th e insta llat ion technique. The bott om endof th e pile sha ll have proper ar ra ngement s for clean ing an d grout ing.

7.5.2 Control of Alignm ent Piles sha ll be insta lled as accur at ely aspossible according to the designs and drawings either vertically or tothe specified batter. Greater care should be exercised in respect ofinstallation of single pile or piles in two pile groups. As a guide, forvertical piles a devia tion of 1.5 per cent an d for ra ker piles a deviat ion

of 4 percent sh ould n ot be norm ally exceeded a lth ough in special casesa closer tolerance may be necessary. Piles should not deviate moretha n 75 mm or D/6 which ever is less (75 mm or D/10 which ever is morein case of piles having diameter more than 600 mm) from theirdesigned positions a t t he work ing level. In t he case of a single pile in acolumn t he positiona l tolerance should not be more th an 50 mm or D/6whichever is less (100 mm in case of piles having diameter more than600 mm). Greater tolerance may be prescribed for piles driven overwat er a nd for ra king piles. For piles to be cut off a t a substa nt ial depth(below ground level) or height (above ground level), the design should

provide for the worst combination of the above tolerance in positionand inclination. In case of piles deviating beyond these limits and tosuch an extent that the resulting eccentricity cannot be taken care ofby a redesign of t he p ile cap of pile ties, th e piles should be r eplaced orsupplemented by one or more additional piles. In case of piles, withnon-circular cross section D sh ould be ta ken a s th e dimen sions of th epile, along which the deviation is computed. In such cases thepermissible deviation in each direction should be different dependingupon the dimension of t he pile a long t ha t direction.

7.6 F lu s h i n g The cent ra l duct/hole shall be conn ected t o a suita ble

pump and water drilling fluid allowed to flow through the bottom ofth e pile rem oving loose ma ter ial.

7.7 G r o u t in g San d an d cement grout m ixed with water in a h ighspeed collidal m ixer is t o be fed int o the pile with a grout pu mp of suit-able capa city conn ected t o th e cent ra l duct th rough a manifold. A groutof sand and cement with additives as necessary, of strength not lessthan 1 : 2 cement and sand ( see also Note under 1.1 ) suitable forpumping into the annulus, may also be used. The temporary casingher e used sh all be removed in st ages with th e rise of th e level of grout .

After final removal of the temporary casing, the grout level shall bebrought up to the t op by pour ing in additiona l grout a s r equired.


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7.8 Defec t i v e P i le In case, defect ive piles a re form ed, th ey sh a ll beremoved or left in place whichever is convenient without affectingperformance of the adjacent piles or the cap as a whole. Additionalpiles sha ll be provided to replace them .

7.9 Any deviation from the designed location alignment or loadcapa city of a ny pile shall be noted an d adequa te m easu res t a ken wellbefore the concreting of the pile cap and plinth beam if the deviationsar e beyond th e prem issible limit.

7 .10 Re cor d in g o f Da ta

7.10.1 A competent inspector shall be present to record the necessaryinformation during installation of piles and the data to be recordedsha ll include:

a) th e sequence of inst a llat ion of piles in a group;b) th e dimensions of th e pile including t he r einforcemen t deta ils a nd

ma rk of th e pile;

c) the depth placed;

d) cu t off level/work ing level; a nd

e) an y other importa nt observation.

7.10.2 Typica l dat a sheet for facility of recordin g piling da ta a re shownin Appendix C.

7 .1 1 S t r i p p in g P i le Hea d s7.11.1 The concrete should be str ipped to a level such t ha t t he r ema in-ing concrete of a pile will project minimum 50 mm into the pile cap.The effect of this projection on the position of any reinforcement in thepile cap sh ould be consider ed in design. The p ile r einforcemen t shouldbe left with adequate projecting length above the cut off level forproper embedment into the pile cap. Exposing such length should bedone carefully to avoid shattering or otherwise damaging the rest ofthe pile. Any cracked or defective concrete should be cut away andma de good with new concret e pr operly bond ed t o the old.

7.12 L e n g t h e n i n g P i le s Where a pile is to ha ve an other lengthcast on to it before or during placing the longitudinal reinforcementshould preferably be jointed by full penetration butt welding. Theconcret e a t th e top of t he origina l pile sh ould be cut down to expose n otless th an 200 mm of th e bars. The bar s should be held accur at ely andrigidly in position during welding. Where facilities at site areinsufficient to make good butt welding practicable the joint may bema de by lappin g. The r einforcemen t a t t he h ead of t he pile will need t obe exposed for a distan ce of 40 times th e bar dia met er a nd t he n ew bars

overlapped for t his dista nce. If th e bond s a re lap ped, spot welding sha llbe done. As an alt ern at ive special bolt a nd n ut joint s ma y be provided.


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A P P E N D I X A

( Clause 5.3.1.1 )

LOAD CARR YI NG CAP ACI TY STATI C FOR MULA

A-1. P ILE S IN GR ANULAR SO ILS

A-1.1 The ultimate bearing capacity ( Qu ) of piles in granular soils isgiven by th e following formula:

where

NOTE 1 Nr factor can be t ak en for gener al sh ear failure as per IS : 6403-1981*NOTE 2 Nq factor will depend, ap ar t from na tu re of soil on th e type of pile a nd itsmethod of construction, for bored piles, the value ofNq corresponding to angle ofshearing r esistan ce ar e given in F ig. 1. This is based on Bereza nt seu s curve for D/Bof 20 up to = 35 an d Vesics cur ves beyond = 35.

NOTE 3 The earth pressure coefficient Kdepends on t he n atu re of soil strata , typeof pile and its method of construction. For bored piles in loose medium sands, Kvalues between 1 and 2 should be used.

Ap = cross-sectiona l ar ea of pile toe in in cm2

;D = stem diam eter in cm;

= effective un it weight of soil at pile toe in k gf/cm3;

PD = effective overbur den p ressu re a t p ile toe in k gf/cm2;

Nr and Nq = bearing capa city factors depen ding upon t he a ngle ofint ern a l friction at toe;

sum ma tion for n layers in wh ich pile is ins ta lled;

K= coefficient of ear th pressu re;

PDi = effective overbur den pr essu re in kg/cm2 for the i t h layerwhere i var ies from l to n ;

= a ngle of wall friction between pile a nd s oil, in d egrees( ma y be taken equal to ); a nd

A si = sur face area of pile stem in cm2 in the ith layer where

i var ies from l to n .

*Code of practice for determination of bearing capacity of shallow foundations ( first

revision ) .


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F IG 1 BEARING CAPACITY F ACTORNqFOR BORED P ILES


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NOTE 4 The an gle of wall friction ma y be taken equal to an gle of shea r resista nceof soil.

NOTE 5 In working out pile capa cities using sta tic form ula, for piles longer t ha n 15to 20 pile diam eter, m aximum effective overburden at th e pile tip should corr espond

to pile length equ al to 15 to 20 diamet ers.

A-2 . P ILES IN COH ESIVE S OILS

A-2.1 The ultimate bearing capacity of piles ( Qu ) in cohesive soil isgiven by t he following:

Qu = Ap.Nc. Cp + . C.As

where

NOTE 1 The following values of ma y be tak en depen ding upon th e consisten cy ofth e soils:

NOTE 2 (a) Stat ic form ula m ay be used as a guide only for bear ing capa city

estima te. Better r elian ce may be put on load t eat on piles.

(b) For workin g out safe load a m inimum factor of safety 2.5 should be used on t heultima te bearing capacity estima ted by stat ic form ulae.

NOTE 3 ma y be ta ken to vary from 0.5 to 0.3 depending upon t he consisten cy ofthe soil. Higher values of up to one may be used for softer soils, provided the soil isnot sen sitive.

A-2.2 When full static penetration data is available for the entiredepth, the following correlations may be used as a guide for thedeter min a tion of sha ft r esista nce of a pile.

Ap = cross sectiona l area of pile toe in cm2

,Nc = bear ing capa city factor usua lly ta ken as 9,

Cp = avera ge cohesion a t pile tip in kg/cm2,

= reduction factor ,

C = avera ge cohesion th roughout t he length of pile inkg/cm2, an d

As = surface area of pile shaft in cm2.

Consistency N Value Value of

Soft to very soft

Medium

Stiff

St iff to ha rd

< 4

4 to 8

8 t o 15

> 15

0.7

0.5

0.4

0.3


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where

qc = sta tic point resistan ce, an d

fs = local side friction.

For non-homogeneous soils th e ultima te point bea rin g capa city ma ybe calculat ed u sing t he following rela tions hips:

where

A-2.3 The correlation between standard penetration test value N andstatic point resistance qc given below may be used for working thesha ft r esista nce an d skin friction of piles.

Type of S oil Local S ide Friction,fs

Clays and peat s where qc < 10


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A P P E N D I X B

( Clause 5.5.2 )

DET ER MINATION OF D EP TH OF F IXITY, LATE RALDE F LECTION AND MAXIMUM MOMEN T OF LATER ALLY

L O AD E D P I L E S

B-1. DETE RMI NATI ON OF LATER AL DEF LECTI ON AT THE

P I L E H E AD AN D D E P T H O F F I XI T Y

B-1.1 The long flexible pile, fully or pa rt ially embedded, is tr eat ed a s acan tilever fixed a t s ome d epth below th e groun d level ( see Fig. 2 ).

F IG. 2 DETERMINATIONOF DEPTH F IXITY

B-1.2 Determ ine th e depth of fixity an d h ence the equivalent length ofth e can tilever u sing th e plots given in F ig. 2.

where

a nd R ( K1 and K2 are constants given in

Tables 1 and 2 below, E is t he Youngs m odulus of the pile

material in kg/cm 2 and I is th e momen t of iner tia of th e pile

cross-section in cm 4).

NOTE Fig. 2 is valid for long flexible piles wher e th e embedded len gthL e is 4R or 4T .

T 5E I

K1-------= 4

E I

K2-------=


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B-1.3 Knowing the length of the equivalent cantilever the pile headdeflection ( Y ) sha ll be com put ed u sing th e following equa tions:

where Q is the lat era l load in kg.

B-2. DET ER MINATION O F MAXIMUM MOMENT IN TH E P ILE

B-2.1 The fixed end moment (MF ) of the equivalent cantilever ishigher th an t he actua l ma ximum moment (M ) of the p ile. The a ctu alma ximu m moment is obta ined by multiplying th e fixed end m omen t ofthe equivalent cantilever by a reduction factor, m given in Fig. 3. Thefixed end momen t of th e equivalent can tilever is given by:

The actua l ma ximu m m oment (M ) = m (MF ).

T AB LE 1 VAL UE S O F C ON ST AN T K1 (kg/cm3)

( Clause B-1.2 )

VALUE

Dry Submerged

Loose sand

Medium sa nd

Dense sand

0.260

0.775

2.075

0.146

0.525

1.245

Very loose sand underrepea ted loading ornorm ally loadin g clays

0.040

T AB LE 2 VAL UE S O F C ON ST AN T K2 (kg/cm2)

( Clause B-1.2 )

UNCONFINED COMPRESSIVESTRENGTH IN kg/cm2

VALUE

0.2 to 0.4

1 to 2

2 to 4

More tha n 4

7.75

48.80

97.75

195.50

( cm )

...for free h ead pile

...for fixed h ea d pile

MF = Q (L1 +L f) ...for free head pile

...for fixed h ea d pile

Y Q L 1( L F )+3

3E I----------------------------------=

Q L 1( L F )+

3

12E I----------------------------------=

Q L 1 L f+( )

2-------------------------------=


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F IG . 3 DETERMINATION OF REDUCTION F ACTORSFORCOMPUTATIONOF MAXIMUM MOMENTIN P ILE


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A P P E N D I X C

( Clause 7.10.2 )

DATA SHE ET S

Site..............................................................................................................

Title.............................................................................................................

Date of enquiry...........................................................................................

Da te pilin g commen ced..............................................................................

Actua l or a nt icipa ted da t e for complet ion of piling work ..........................

Number of p ile..................................................

TEST P I LE DATA

Pile: Pile t est commenced.........................................

P ile t est completed............................................

P ile t yp e: ...........................................................................(Men t ion pr opr ieta ry syst em, if an y)...............

P ile specifica t ion:

Shape..............................................................

Size Sh aft...................t oe..........................

Rein forcement .......No......dia for.......(depth).......................................................................)

Sequ en ce of piling( for Gr ou ps ):

Fr om centr e towards t he per iphery or fromperiphery towar ds the cent re

Concret e: Mix ra tio 1:................: ...........by volume/massor st ren gth a fter ............da ys ..............kgf/cm2

Qua nt ity of cement per m 3: .............................Extr a cement a dded if an y:

Det a ils of dr illing m ud if us ed: ..................................................................

Tim e taken for concret ing: ........................................................................

Qu ant it y of concrete Actual: .................................................................

Th eoret ical: .........................................................


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Test load ing:

.....................................................................................................................

Capacity of jack...........................................................................................

If anchor piles used, give........................No., Length................................Dist ance of tes t pile from nea rest anchor p ile...........................................

Test pile an d an chor piles were/were n ot workin g piles.

Meth od of ta king observat ions :

Dia l ga uges/En gineer s level.......................................................................

Reduced level of pile toe.............................................................................

Genera l Remar ks:

.....................................................................................................................

.....................................................................................................................

.....................................................................................................................

.....................................................................................................................

.....................................................................................................................

Special difficulties encountered:

.............................................................................................................

.............................................................................................................

.............................................................................................................

Results:

Working load specified for the test pile.............................................

Set t lemen t specified for the t est pile.................................................

Set t lemen t specified for the s t ructu re...............................................

Work ing load accepted for a single pile as a r esu lt of the t est .........

.............................................................................................................

.............................................................................................................

Work ing load in a group of piles a ccepted as a resu lt of th e t est .....

.............................................................................................................

.............................................................................................................

Gen era l descript ion of t he st ru ctur e to be founded on piles.............

.............................................................................................................

.............................................................................................................

.............................................................................................................

.............................................................................................................

.............................................................................................................


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28

Name of the constructing agency..........................................................

................................................................................................................

Name of per son condu ctin g the t est ......................................................

................................................................................................................

Na me of t he pa rt y for whom the t est was conducted............................

................................................................................................................

BORE -HOLE LOG

1. Sit e of bore h ole rela t ive to test pile posit ion ........................................

................................................................................................................

2. NOTE If no bore hole, give best availa ble groun d condit ions.......................................

.............................................................................................................................................

.............................................................................................................................................

SoilProperties

S oil Description ReducedLevel

SoilLegen d

DepthBelow

G.L.

Thicknessof

Strata

Position of thetoe of pile to beindicted th us

Standing groundwater level indi-cat ed thu s

METHOD OF SI TE I NVESTI GATI ON

Tria l pit/post-hole a uger /sh ell an d au ger boring/percussion/probing/wash borings/mud-rotary drilling/core-drilling/shot drilling/su bsu r face soun ding by cones or st a nda rd sa mpler.............................

................................................................................................................

................................................................................................................

NOTE Gra phs, showing th e following relations, sha ll be prepar ed and a ddedt o t h e r ep or t :

1) Load vs Time

2) Sett lement vs Load


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( Contin ued from page 2 )

P ile Foun da tions Subcomm itt ee, BDC 43 : 5

Convener R epresen ting

SHRI M. D. TAMBEKAR In personal capacity ( Pradeep Villa, 92 KotnisPath, Mahim , Bombay

Mem bers

SHRI CHANDRA P RAKASH Central Building Research Institute (CSIR),Roorkee

SHRI K. G. GARG (Alt ern ate )

SHRI A. GHOSHAL Stup Consultant s Ltd, Bombay

SHRI M. I YENGARSHRI J . K. BAGCHI (Alt ern ate )

En gineers In dia Ltd, New Delhi

SHRI P. K. J AIN Un iversity of Roorkee, Roork eeSHRI A. N. J ANGLE Asia Foundations and Construction Pvt Ltd,

Bombay

J OINT DIRECTOR R E SE ARCH (GE)-II, RDS O

Minist ry of Railways

DY DIRECTOR RESEARCH (GE)-III, RDSO (Alt ern ate )

SHRI B. K. P ANTHAKYSHRI P. V. NAIK (Alt ern ate )

Hindu sta n Constru ction Co Ltd, Bombay

SHRI M. R. P UNJA Cemindia Co Ltd, Bombay

SHRI B. RUSTOMJEE Pile Foundations Construction Co (I) Pvt Ltd,Calcutta

SHRI S. C. BOS E (Alt ernate )

SUPERINTENDING E NGIN E E R(DESIGNS)

Centr al Public Works Depar tm ent , New Delhi

EXECUTIVE ENGINEER (DESIGNS) V(Altern at e )


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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

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This Indian Sta ndard has been developed by Technical Comm ittee : BDC 43

Am e n d m e n t s I s s u e d S i n c e P u b l i c a t i o nAm e n d No. Da t e o f I s su e

Amd. No. 1 October 1987

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2911 1 4+CONCRETE+PILES+Bored+Precast+Concrete+Piles

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