IS 2911 (Part 1/Sec 2) : 2010 ikby uhao dh fMtkbu vkSj fuekZ.

k -- jhfr lafgrk Hkkx 1 dahV ikby vuqHkkx 2 LoLFkku <fyr dahV dh osfkr ikby Hkkjrh; ekud ( nwljk iqujh{k.k ) Indian Standard DESIGN AND CONSTRUCTION OF PILE FOUNDATIONS -- CODE OF PRACTICE PART 1 CONCRETE PILES Section 2 Bored Cast In-situ Concrete Piles ( Second Revision ) ICS 91.100.30 : 93.020 BIS 2010 BUREAU OF INDIAN STANDARDS MANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG NEW DELHI 110002 May 2011 Price Group 9

Soil and Foundation Engineering Sectional Committee, CED 43 FOREWORD This Indian Standard (Part 1/Sec 2) (Second Revision) was adopted by th e Bureau of Indian Standards, after the draft finalized by the Soil and Foundati on Engineering Sectional Committee had been approved by the Civil Engineering Di vision Council. Piles find application in foundations to transfer loads from a s tructure to competent subsurface strata having adequate load-bearing capacity. T he load transfer mechanism from a pile to the surrounding ground is complicated and is not yet fully understood, although application of piled foundations is in practice over many decades. Broadly, piles transfer axial loads either substant ially by friction along its shaft and/or by the end-bearing. Piles are used wher e either of the above load transfer mechanism is possible depending upon the sub soil stratification at a particular site. Construction of pile foundations requi re a careful choice of piling system depending upon the subsoil conditions, the load characteristics of a structure and the limitations of total settlement, dif ferential settlement and any other special requirement of a project. The install ation of piles demands careful control on position, alignment and depth, and inv olve specialized skill and experience. This standard was originally published in 1964 and included provisions regarding driven cast in-situ piles, precast concr ete piles, bored piles and under-reamed piles including load testing of piles. S ubsequently the portion pertaining to under-reamed pile foundations was deleted and now covered in IS 2911 (Part 3) : 1980 `Code of practice for design and cons truction of pile foundations: Part 3 Under-reamed piles (first revision)'. At th at time it was also decided that the provisions regarding other types of piles s hould also be published separately for ease of reference and to take into accoun t the recent developments in this field. Consequently this standard was revised in 1979 into three sections. Later, in 1984, a new section as (Part 1/Sec 4) was introduced in this part of the standard to cover the provisions of bored precas t concrete piles. The portion relating to load test on piles has been covered in a separate part, namely, IS 2911 (Part 4) : 1984 'Code of practice for design a nd construction of pile foundations: Part 4 Load test on piles'. Accordingly IS 2911 has been published in four parts. The other parts of the standard are: Part 2 Part 3 Part 4 Timber piles Under-reamed piles Load test on piles Other sections of Part 1 are: Section 1 Driven cast in-situ concrete piles Secti on 3 Driven precast concrete piles Section 4 Precast concrete piles in prebored holes It has been felt that the provisions regarding the different types of pile s should be further revised to take into account the recent developments in this field. This revision has been brought out to incorporate these developments. In the present revision following major modifications have been made: a) Definitio ns of various terms have been modified as per the prevailing engineering practic e. b) Minimum diameter of pile has been specified. c) Procedures for calculation of bearing capacity, structural capacity, factor of safety, lateral load capaci ty, overloading, etc, have also been modified to bring them at par with the pres ent practices. (Continued on third cover)

(Continued from second cover ) d) Design parameters with respect to adhesion fac tor, earth pressure coefficient, modulus of subgrade reaction, etc, have been re vised to make them consistence with the outcome of modern research and construct ion practices. e) Minimum grade of concrete to be used in pile foundations has b een revised to M 25. f) Provisions for special use of large diameter bored cast in-situ reinforced cement concrete piles in marine structures have been added. B ored cast in-situ pile is formed within the ground by excavating or boring a hol e within it, with or without the aid of a temporary casing (to keep the hole sta bilized) and subsequently filling it with plain or reinforced concrete. These pi les are particularly applicable in certain subsoil conditions where penetration to a predetermined depth is essential. The recommendations for detailing for ear thquake-resistant construction given in IS 13920 : 1993 `Ductile detailing of re inforced concrete structures subjected to seismic forces -- Code of practice' sh ould be taken into consideration, where applicable (see also IS 4326 : 1993 `Ear thquake resistant design and construction of buildings -- Code of practice'). Th e composition of the Committee responsible for that formulation of this standard is given in Annex G. For the purpose of deciding whether a particular requireme nt of this standard is complied with, the final value, observed or calculated, e xpressing the result of a test or analysis shall be rounded off in accordance wi th IS 2 : 1960 `Rules for rounding off numerical values (revised)'. The number o f significant places retained in the rounded off value should be the same as tha t of the specified value in this standard.

IS 2911 (Part 1/Sec 2) : 2010 Indian Standard DESIGN AND CONSTRUCTION OF PILE FOUNDATIONS -- CODE OF PRACTICE PART 1 CONCRETE PILES Section 2 Bored Cast In-situ Concrete Piles ( Second Revision ) 1 SCOPE 1.1 This standard (Part 1/Sec 2) covers the design and construction of b ored cast in-situ concrete piles which transmit the load to the soil by resistan ce developed either at the pile tip by end-bearing or along the surface of the s haft by friction or by both. 1.2 This standard is not applicable for use of bore d cast in-situ concrete piles for any other purpose, for example, temporary or p ermanent retaining structure. 2 REFERENCES The standards listed in Annex A conta in provisions which through reference in this text, constitute provisions of thi s standard. At the time of publication, the editions indicated were valid. All s tandards are subject to revision and parties to agreements based on this standar d are encouraged to investigate the possibility of applying the most recent edit ions of the standards listed in Annex A. 3 TERMINOLOGY For the purpose of this s tandard, the following definitions shall apply. 3.1 Allowable Load -- The load w hich may be applied to a pile after taking into account its ultimate load capaci ty, group effect, the allowable settlement, negative skin friction and other rel evant loading conditions. 3.2 Anchor Pile -- An anchor pile means a pile meant f or resisting pull or uplift forces. 3.3 Batter Pile (Raker Pile) -- The pile whi ch is installed at an angle to the vertical using temporary casing or permanent liner. 3.4 Bored Cast In-situ Pile -- A pile formed by boring a hole in the grou nd by percussive or rotary method with the use of temporary/permanent casing or drilling mud and subsequently filling the hole with reinforced concrete. 3.5 Cut -off Level -- It is the level where a pile is cut-off to support the pile caps o r beams or any other structural components at that level. 1 3.6 Diameter of Pile s -- Piles of 600 mm or less in diameter are commonly known as small diameter pi les while piles greater than 600 m diameter are called large diameter piles. Min imum pile diameter shall be 450 mm. 3.7 Elastic Displacement -- This is the magn itude of displacement of the pile head during rebound on removal of a given test load. This comprises two components: a) Elastic displacement of the soil partic ipating in the load transfer, and b) Elastic displacement of the pile shaft. 3.8 Factor of Safety -- It is the ratio of the ultimate load capacity of a pile to the safe load on the pile. 3.9 Gross Displacement -- The total movement of the p ile top under a given load. 3.10 Initial Load Test -- A test pile is tested to d etermine the load-carrying capacity of the pile by loading either to its ultimat e load or to twice the estimated safe load. 3.11 Initial Test Pile -- One or mor e piles, which are not working piles, may be installed if required to assess the load-carrying capacity of a pile. These piles are tested either to their ultima te load capacity or to twice the estimated safe load. 3.12 Load Bearing Pile -A pile formed in the ground for transmitting the load of a structure to the soil by the resistance developed at its tip and/or along its surface. It may be form ed either vertically or at an inclination (batter pile) and may be required to r esist uplift forces. If the pile supports the load primarily by resistance devel oped at the pile tip or base it is called `Endbearing pile' and, if primarily by friction along its surface, then `Friction pile'. 3.13 Net Displacement -- The net vertical movement of the pile top after the pile has been subjected to a tes t load and subsequently released. 3.14 Pile Spacing -- The spacing of the piles means the center-to-center distance between adjacent piles.

IS 2911 (Part 1/Sec 2) : 2010 3.15 Routine Test Pile -- A pile which is selected for load testing may form a working pile itself, if subjected to routine load t est up to one and 1.5 times the safe load. 3.16 Safe Load -- It is the load deri ved by applying a factor of safety on the ultimate load capacity of the pile or as determined from load test. 3.17 Ultimate Load Capacity -- The maximum load wh ich a pile can carry before failure, that is, when the founding strata fails by shear as evidenced from the load settlement curve or the pile fails as a structu ral member. 3.18 Working Load -- The load assigned to a pile as per design. 3.19 Working Pile -- A pile forming part of the foundation system of a given structu re. 4 NECESSARY INFORMATION 4.1 For the satisfactory design and construction of bored cast in-situ piles the following information would be necessary: a) Site i nvestigation data as laid down under IS 1892. Sections of trial boring, suppleme nted, wherever appropriate, by penetration tests, should incorporate data/ infor mation down to depth sufficiently below the anticipated level of founding of pil es but this should generally be not less than 10 m beyond the pile founding leve l. Adequacy of the bearing strata should be ensured by supplementary tests, if r equired. b) The nature of the soil both around and beneath the proposed pile sho uld be indicated on the basis of appropriate tests of strength, compressibility, etc. Ground water level and artesian conditions, if any, should also be recorde d. Results of chemical tests to ascertain the sulphate, chloride and any other d eleterious chemical content of soil and water should be indicated. c) For piling work in water, as in the case of bridge foundation, data on high flood levels, water level during the working season, maximum depth of scour, etc, and in the c ase of marine construction, data on high and low tide level, corrosive action of chemicals present and data regarding flow of water should be provided. d) The g eneral layout of the structure showing estimated loads and moments at the top of pile caps but excluding the weight of the piles and caps should be provided. Th e top levels of finished pile caps shall also be indicated. 2 e) All transient l oads due to seismic, wind, water current, etc, are to be indicated separately. f ) In soils susceptible to liquefaction during earthquake, appropriate analysis m ay be done to determine the depth of liquefaction and consider the pile depth ac cordingly. 4.2 As far as possible all informations given in 4.1 shall be made av ailable to the agency responsible for the design and/or construction of piles an d/or foundation work. The design details of pile foundation shall give the infor mation necessary for setting out and layout of piles, cut-off levels, finished c ap level, layout and orientation of pile cap in the foundation plan and the safe capacity of each type of pile, etc. 5 EQUIPMENTS AND ACCESSORIES 5.1 The equipm ents and accessories would depend upon the type of bored cast in-situ piles chos en for a job after giving due considerations to the subsoil strata, ground water condition, types of founding material and the required penetration therein. 5.2 Among the commonly used plants, tools and accessories, there exists a large var iety; suitability of which depends on the subsoil condition and manner of operat ion, etc. 5.3 Boring operations are generally done by percussion type rigs or ro tary rigs using direct mud circulation or reverse mud circulation methods to bri ng the cuttings out. In soft layers and loose sands, bailers and chisel method s hould be used with caution to avoid the effect of suction. 5.4 For percussion bo ring using bailer chisel and for rotary rigs, stabilization of bore holes may be done either by circulation or suspended mud. 5.5 Kentledge Dead weight used for applying a test load on a pile. 6 DESIGN CONSIDERATIONS 6.1 General Pile founda tions shall be designed in such a way that the load from the structure can be tr ansmitted to the sub-surface with adequate factor of safety against shear failur e of sub-surface and without causing such settlement (differential or total), wh ich may result in structural damage and/or functional distress under permanent/t ransient loading. The pile shaft should have adequate structural capacity to wit hstand all loads (vertical, axial or otherwise) and moments which are to be tran smitted to the subsoil and shall be designed according to IS 456.

IS 2911 (Part 1/Sec 2) : 2010 6.2 Adjacent Structures 6.2.1 When working near ex isting structures care shall be taken to avoid damage to such structures. IS 297 4 (Part 1) may be used as a guide for studying qualitatively the effect of vibra tion on persons and structures. 6.2.2 In case of deep excavations adjacent to pi les, proper shoring or other suitable arrangement shall be made to guard against undesired lateral movement of soil. 6.3 Pile Capacity The load-carrying capacit y of a pile depends on the properties of the soil in which it is embedded. Axial load from a pile is normally transmitted to the soil through skin friction alon g the shaft and end-bearing at its tip. A horizontal load on a vertical pile is transmitted to the soil primarily by horizontal subgrade reaction generated in t he upper part of the shaft. Lateral load capacity of a single pile depends on th e soil reaction developed and the structural capacity of the shaft under bending . It would be essential to investigate the lateral load capacity of the pile usi ng appropriate values of horizontal subgrade modulus of the soil. 6.3.1 The ulti mate load capacity of a pile should be estimated by means of static formula base d on soil test results. Pile capacity should preferably be confirmed by initial load tests [see IS 2911 (Part 4)]. The settlement of pile obtained at safe load/ working load from load-test results on a single pile shall not be directly used for estimating the settlement of a structure. The settlement may be determined o n the basis of subsoil data and loading details of the structure as a whole usin g the principles of soil mechanics. 6.3.1.1 Vertical load capacity (using static formula) The ultimate load capacity of a single pile may be obtained by using s tatic analysis, the accuracy being dependent on the reliability of the soil prop erties for various strata. When computing capacity by static formula, the shear strength parameters obtained from a limited number of borehole data and laborato ry tests should be supplemented, wherever possible, by in-situ shear strength ob tained from field tests. The two separate static formulae, commonly applicable f or cohesive and non-cohesive soil are indicated in Annex B. Other formula based on static cone penetration test [see IS 4968 (Parts 1, 2 and 3)] and standard pe netration test (see IS 2131) are given in B-3 and B-4. 6.3.2 Uplift Capacity The uplift capacity of a pile is given by sum of the frictional resistance and the weight of the pile 3 (buoyant or total as relevant). The recommended factor of s afety is 3.0 in the absence of any pullout test results and 2.0 with pullout tes t results. Uplift capacity can be obtained from static formula (see Annex B) by ignoring end-bearing but adding weight of the pile (buoyant or total as relevant ). 6.4 Negative Skin Friction or Dragdown Force When a soil stratum, through whi ch a pile shaft has penetrated into an underlying hard stratum, compresses as a result of either it being unconsolidated or it being under a newly placed fill o r as a result of remoulding during installation of the pile, a dragdown force is generated along the pile shaft up to a point in depth where the surrounding soi l does not move downward relative to the pile shaft. Existence of such a phenome non shall be assessed and suitable correction shall be made to the allowable loa d where appropriate. 6.5 Structural Capacity The piles shall have necessary stru ctural strength to transmit the loads imposed on it, ultimately to the soil. Inc ase of uplift, the structural capacity of the pile, that is, under tension shoul d also be considered. 6.5.1 Axial Capacity Where a pile is wholely embedded in t he soil (having an undrained shear strength not less than 0.01 N/mm2), its axial load carrying capacity is not necessarily limited by its strength as a long col umn. Where piles are installed through very weak soils (having an undrained shea r strength less than 0.01 N/mm2), special considerations shall be made to determ ine whether the shaft would behave as a long column or not. If necessary, suitab le reductions shall be made for its structural strength following the normal str uctural principles covering the buckling phenomenon. When the finished pile proj ects above ground level and is not secured against buckling by adequate bracing, the effective length will be governed by the fixity imposed on it by the struct ure it supports and by the nature of the soil into which it is installed. The de pth below the ground surface to the lower point of contraflexure varies with the type of the soil. In good soil the lower point of contraflexure may be taken at a depth of 1 m below ground surface subject to a minimum of 3 times the diamete r of the shaft. In weak soil (undrained shear strength less than 0.01 N/mm2), su

ch as, soft clay or soft silt, this point may be taken at about half the depth o f penetration into such stratum but not more than 3 m or 10 times the diameter o f the shaft whichever is more. The degree of fixity of the position and inclinat ion of the

IS 2911 (Part 1/Sec 2) : 2010 pile top and the restraints provided by any bracin g shall be estimated following accepted structural principles. The permissible s tress shall be reduced in accordance with similar provision for reinforced concr ete columns as laid down in IS 456. 6.5.2 Lateral Load Capacity A pile may be su bjected to lateral force for a number of causes, such as, wind, earthquake, wate r current, earth pressure, effect of moving vehicles or ships, plant and equipme nt, etc. The lateral load capacity of a single pile depends not only on the hori zontal subgrade modulus of the surrounding soil but also on the structural stren gth of the pile shaft against bending, consequent upon application of a lateral load. While considering lateral load on piles, effect of other co-existent loads , including the axial load on the pile, should be taken into consideration for c hecking the structural capacity of the shaft. A recommended method for the pile analysis under lateral load is given in Annex C. Because of limited information on horizontal subgrade modulus of soil, and pending refinements in the theoretic al analysis, it is suggested that the adequacy of a design should be checked by an actual field load test. In the zone of soil susceptible to liquefaction the l ateral resistance of the soil shall not be considered. 6.5.2.1 Fixed and free he ad conditions A group of three or more pile connected by a rigid pile cap shall be considered to have fixed head condition. Caps for single piles must be interc onnected by grade beams in two directions and for twin piles by grade beams in a line transverse to the common axis of the pair so that the pile head is fixed. In all other conditions the pile shall be taken as free headed. 6.5.3 Raker Pile s Raker piles are normally provided where vertical piles cannot resist the appli ed horizontal forces. Generally the rake will be limited to 1 horizontal to 6 ve rtical. In the preliminary design, the load on a raker pile is generally conside red to be axial. The distribution of load between raker and vertical piles in a group may be determined by graphical or analytical methods. Where necessary, due consideration should be made for secondary bending induced as a result of the p ile cap movement, particularly when the cap is rigid. Free-standing raker piles are subjected to bending moments due to their own weight or external forces from other causes. Raker piles, embedded in fill or consolidating 4 deposits, may be come laterally loaded owing to the settlement of the surrounding soil. In consol idating clay, special precautions, like provision of permanent casing, should be taken for raker piles. 6.6 Spacing of Piles The minimum centre-to-centre spacin g of piles is considered from three aspects, namely, a) practical aspects of ins talling the piles, b) diameter of the pile, and c) nature of the load transfer t o the soil and possible reduction in the load capacity of piles group. NOTE -- In the case of piles of non-circular crosssection, diameter of the circu mscribing circle shall be adopted. 6.6.1 In case of piles founded on hard stratum and deriving their capacity mainl y from end-bearing the minimum spacing shall be 2.5 times the diameter of the ci rcumscribing circle corresponding to the crosssection of the pile shaft. In case of piles resting on rock, the spacing of two times the said diameter may be ado pted. 6.6.2 Piles deriving their load-carrying capacity mainly from friction sha ll be spaced sufficiently apart to ensure that the zones of soils from which the piles derive their support do not overlap to such an extent that their bearing values are reduced. Generally the spacing in such cases shall not be less than 3 times the diameter of the shaft. 6.7 Pile Groups 6.7.1 In order to determine th e load-carrying capacity of a group of piles a number of efficiency equations ar e in use. However, it is difficult to establish the accuracy of these efficiency equations as the behaviour of pile group is dependent on many complex factors. It is desirable to consider each case separately on its own merits. 6.7.2 The lo ad-carrying capacity of a pile group may be equal to or less than the load-carry ing capacity of individual piles multiplied by the number of piles in the group. The former holds true in case of friction piles, cast into progressively stiffe r materials or in end-bearing piles. 6.7.3 In case of piles deriving their suppo rt mainly from friction and connected by a rigid pile cap, the group may be visu alized as a block with the piles embedded within the soil. The ultimate load cap acity of the group may then be obtained by considering block failure taking into

account the frictional capacity along the perimeter of the block and end-bearin g at the bottom of the block using the accepted principles of soil mechanics.

IS 2911 (Part 1/Sec 2) : 2010 6.7.4 When the cap of the pile group is cast direc tly on reasonably firm stratum which supports the piles, it may contribute to th e load-carrying capacity of the group. This additional capacity along with the i ndividual capacity of the piles multiplied by the number of piles in the group s hall not be more than the capacity worked out according to 6.7.3. 6.7.5 When a p ile group is subjected to moment either from superstructure or as a consequence of inaccuracies of installation, the adequacy of the pile group in resisting the applied moment should be checked. In case of a single pile subjected to moment due to lateral loads or eccentric loading, beams may be provided to restrain the pile effectively from lateral or rotational movement. 6.7.6 In case of a struct ure supported on single piles/ group of piles resulting in large variation in th e number of piles from column-to-column it may result in large differential sett lement. Such differential settlement should be either catered for in the structu ral design or it may be suitably reduced by judicious choice of variations in th e actual pile loading. For example, a single pile cap may be loaded to a level h igher than that of the pile in a group in order to achieve reduced differential settlement between two adjacent pile caps supported on a number of piles. 6.8 Fa ctor of Safety 6.8.1 Factor of safety should be chosen after considering, a) the reliability of the calculated value of ultimate load capacity of a pile, b) the types of superstructure and the type of loading, and c) allowable total/differe ntial settlement of the structure. 6.8.2 When the ultimate load capacity is dete rmined from static formula, the factor of safety would depend on the reliability of the formula and the reliability of the subsoil parameters used in the comput ation. The minimum factor of safety on static formula shall be 2.5. The final se lection of a factor of safety shall take into consideration the load settlement characteristics of the structure as a whole at a given site. 6.8.3 Higher value of factor of safety for determining the safe load on piles may be adopted, where , a) settlement is to be limited or unequal settlement avoided, b) large impact or vibrating loads are expected, and c) the properties of the soil may deteriora te with time. 5 6.9 Transient Loading The maximum permissible increase over the safe load of a pile, as arising out of wind loading, is 25 percent. In case of l oads and moments arising out of earthquake effects, the increase of safe load on a single pile may be limited to the provisions contained in IS 1893 (Part 1). F or transient loading arising out of superimposed loads, no increase is allowed. 6.10 Overloading When a pile in a group, designed for a certain safe load is fou nd, during or after execution, to fall just short of the load required to be car ried by it, an overload up to 10 percent of the pile capacity may be allowed on each pile. The total overloading on the group should not, however, be more than 10 percent of the capacity of the group subject to the increase of the load on a ny pile being not more than 25 percent of the allowable load on a single pile. 6 .11 Reinforcement 6.11.1 The design of the reinforcing cage varies depending upo n the installation conditions, the nature of the subsoil and the nature of load to be transmitted by the shaft-axial, or otherwise. The minimum area of longitud inal reinforcement of any type or grade within the pile shaft shall be 0.4 perce nt of the cross-sectional area of the pile shaft. The minimum reinforcement shal l be provided throughout the length of the shaft. 6.11.2 The curtailment of rein forcement along the depth of the pile, in general, depends on the type of loadin g and subsoil strata. In case of piles subject to compressive load only, the des igned quantity of reinforcement may be curtailed at appropriate level according to the design requirements. For piles subjected to uplift load, lateral load and moments, separately or with compressive loads, it would be necessary to provide reinforcement for the full depth of pile. In soft clays or loose sands, or wher e there may be danger to green concrete due to installation of adjacent piles, t he reinforcement should be provided up to the full pile depth, regardless of whe ther or not it is required from uplift and lateral load considerations. However, in all cases, the minimum reinforcement specified in 6.11.1 shall be provided t hroughout the length of the shaft. 6.11.3 Piles shall always be reinforced with a minimum amount of reinforcement as dowels keeping the minimum bond length into the pile shaft below its cut-off level and with adequate projection into the pi le cap, irrespective of design requirements. 6.11.4 Clear cover to all main rein

forcement in pile shaft shall be not less than 50 mm. The laterals of a

IS 2911 (Part 1/Sec 2) : 2010 reinforcing cage may be in the form of links or sp irals. The diameter and spacing of the same is chosen to impart adequate rigidit y of the reinforcing cage during its handling and installations. The minimum dia meter of the links or spirals shall be 8 mm and the spacing of the links or spir als shall be not less than 150 mm. Stiffner rings preferably of 16 mm diameter a t every 1.5 m centre-to-centre should be provided along length of the cage for p roviding rigidity to reinforcement cage. Minimum 6 numbers of vertical bars shal l be used for a circular pile and minimum diameter of vertical bar shall be 12 m m. The clear horizontal spacing between the adjacent vertical bars shall be four times the maximum aggregate size in concrete. If required, the bars can be bund led to maintain such spacing. 6.12 Design of Pile Cap 6.12.1 The pile caps may b e designed by assuming that the load from column is dispersed at 45 from the top of the cap to the mid-depth of the pile cap from the base of the column or pedes tal. The reaction from piles may also be taken to be distributed at 45 from the e dge of the pile, up to the mid-depth of the pile cap. On this basis the maximum bending moment and shear forces should be worked out at critical sections. The m ethod of analysis and allowable stresses should be in accordance with IS 456. 6. 12.2 Pile cap shall be deep enough to allow for necessary anchorage of the colum n and pile reinforcement. 6.12.3 The pile cap should be rigid enough so that the imposed load could be distributed on the piles in a group equitably. 6.12.4 In case of a large cap, where differential settlement may occur between piles under the same cap, due consideration for the consequential moment should be given. 6 .12.5 The clear overhang of the pile cap beyond the outermost pile in the group shall be a minimum of 150 mm. 6.12.6 The cap is generally cast over a 75 mm thic k levelling course of concrete. The clear cover for main reinforcement in the ca p slab shall not be less than 60 mm. 6.12.7 The embedment of pile into cap shoul d be 75 mm. 6.12.8 The design of grade beam if used shall be as given in IS 2911 (Part 3). 7 MATERIALS AND STRESSES 7.1 Cement The cement used shall be any of t he following: 6 a) 33 Grade ordinary conforming to IS 269, Portland cement cemen t cement cement b) 43 Grade ordinary Portland conforming to IS 8112, c) 53 Grade ordinary Portla nd conforming to IS 12269, d) Rapid hardening Portland conforming to IS 8041, e) Portland slag cement conforming to IS 455, f) Portland pozzolana cement (fly ash based) conforming to IS 1489 (Part 1), g) Portland pozzolana cement (calcine d clay based) conforming to IS 1489 (Part 2), h) Hydrophobic cement conforming t o IS 8043, j) Low heat Portland cement conforming to IS 12600, and k) Sulphate r esisting Portland conforming to IS 12330. 7.2 Steel Reinforcement steel shall be any of the following: a) Mild steel and medium tensile steel bars conforming to IS 432 (Part 1), b) High strength deformed conforming to IS 1786, and steel bar s cement c) Structural steel conforming to IS 2062. 7.3 Concrete 7.3.1 Consistency of con crete to be used for bored cast in-situ piles shall be consistent with the metho d of installation of piles. Concrete shall be so designed or chosen as to have a homogeneous mix having a slump/workability consistent with the method of concre ting under the given conditions of pile installation. 7.3.2 The slump should be 150 to 180 mm at the time of pouring. 7.3.3 The minimum grade of concrete to be used for bored piling shall be M 25. For sub aqueous concrete, the requirements specified in IS 456 shall be followed. The minimum cement content shall be 400 k g/m3. However, with proper mix design and use of proper admixture the cement con tent may be reduced but in no case the cement content shall be less than 350 kg/ m3. 7.3.4 For the concrete, water and aggregates specifications laid down in IS 456 shall be followed in general. 7.3.5 The average compressive stress under wor king load should not exceed 25 percent of the specified works cube strength at 2 8 days calculated on the

IS 2911 (Part 1/Sec 2) : 2010 total cross-sectional area of the pile. Where the casing of the pile is permanent, of adequate thickness and of suitable shape, th e allowable compressive stress may be increased. 7.4 Drilling Mud (Bentonite) Th e drilling mud to be used for stabilizing the borehole in bored piling work shou ld conform to the requirements given in Annex D. 8 WORKMANSHIP 8.1 Control of Pi ling Installation 8.1.1 Bored cast in-situ piles should be installed by installa tion technique, covering, a) the manner of borehole stabilization, that is, use of casing and/or use of drilling mud; b) manner of concreting which shall be by use of tremie; and c) choice of boring tools in order to permit satisfactory ins tallation of a pile at a given site. Detailed information about the subsoil cond itions is essential to determine the installation technique. 8.1.2 Control of Al ignment Piles shall be installed as accurately as possible according to the desi gn and drawings either vertically or to the specified batter. Greater care shoul d be exercised in respect of installation of single piles or piles in two-pile g roups. As a guide, an angular deviation of 1.5 percent in alignment for vertical piles and a deviation of 4 percent for raker piles should not be exceeded. Pile s should not deviate more than 75 mm or D/6 whichever is less (75 mm or D/10 whi chever is more in case of piles having diameter more than 600 mm) from their des igned positions at the working level. In the case of single pile under a column the positional deviation should not be more than 50 mm or D/6 whichever is less (10 mm in case of piles having diameter more than 600 mm). Greater tolerance may be prescribed for piles cast over water and for raking piles. For piles to be c ut-off at a substantial depth below the working level, the design shall provide for the worst combination of the above tolerances in position and inclination. I n case of piles deviating beyond these limits and to such an extent that the res ulting eccentricity can not be taken care of by redesign of the pile cap or pile ties, the piles shall be replaced or supplemented by additional piles. In case of piles, with non-circular cross-section `D' should be taken as the dimensions of pile, along which the deviation is computed. In such cases the permissible de viation in each direction should be 7 different depending upon the dimension of the pile along that direction. 8.1.3 A minimum length of two metres of temporary casing shall be provided for each bored pile. Additional length of temporary ca sing may be used depending on the condition of the strata, ground water level, e tc. 8.1.4 In subsurfaces comprising of loose fill, soft marine clay, presence of aggressive ground water, tidal effect or in adverse subsoil conditions like loo se bouldary zones/voids, etc, and in marine condition, piles may be formed using permanent liner upto the firm strata. 8.1.5 For marine piles, see Annex E . 8.2 Use of Drilling Mud 8.2.1 In case a borehole is stabilized by use of drilling m ud, the specific gravity of the mud suspension should be determined at regular i ntervals by a suitable slurry sampler. Consistency of the drilling mud shall be controlled throughout the boring as well as concreting operations in order to ke ep the hole stabilized as well as to avoid concrete getting mixed up with the th icker suspension of the mud. 8.2.2 The concreting operations should not be taken up when the specific gravity of bottom slurry is more than 1.12. The slurry sho uld be maintained at 1.5 m above the ground water level. 8.3 Cleaning of Borehol e 8.3.1 If a borehole is stabilized by drilling mud, the bottom of the hole shal l be cleaned of all loose and undesirable materials before commencement of concr eting in the following manner: a) Boring done with normal bailor and chisel with temporary/permanent liner -- First heavier material to be removed with cleaning tools, such as, bailor and then reinforcement cage and tremie pipe to be lowere d. Flushing then to be continued with water/drilling fluid under pressure throug h tremie pipe. b) Boring done with bentonite slurry -- Procedure given in (a) ab ove to be followed. However, flushing shall be done with fresh bentonite slurry. c) Boring done by rotary drilling rigs -- Cleaning bucket attached to the kelly shall be used for cleaning the bore. Wherever bentonite slurry is used, after u sing cleaning bucket, the bore shall be flushed with fresh bentonite slurry.

IS 2911 (Part 1/Sec 2) : 2010 In case of flushing with water or bentonite slurry , the pump capacity shall be suitably decided depending on depth and diameter of bore so that sufficient pressure is built to lift the material up along with th e fluid. Flushing should be continued till coarse materials cease to come out wi th the overflowing fluid. The finer materials will normally remain suspended in the fluid but they do not pose any problem. Alternatively, air lift technique ma y be used for cleaning of bore hole, if required. 8.4 Tremie Concreting Concreti ng for bored piles shall be done by tremie method. The following requirements ar e particularly to be followed for tremie concrete work: a) The concrete should b e coherent, rich in cement (not less than 400 kg/m3) and of slump between 150-18 0 mm; b) The tremie should be water-tight throughout its length and have a hoppe r attached to its head by a water-tight connection; c) The tremie pipe should be large enough in relation to the size of the aggregate. For 25 mm down aggregate , the tremie pipe should have a diameter not less than 200 mm. For 20 mm down ag gregate, tremie pipe should be of diameter not less than 150 mm. All piling abov e 600 mm diameter piles, should, however preferably be done with 200 mm diameter tremie pipe; d) A steel plate or a ball is placed at the bottom of the hopper a nd the hopper is filled with concrete. The first charge of concrete is sent down the tremie by removal of this plate or ball. Additional concrete is then added into the hopper and by surging action is pushed down the tremie and into the pil e bore to the bottom of the pile. Theoretically, a small part of the first charg e which gets contaminated is supposed to be the top of the rising concrete withi n the bore; e) The tremie pipe should always be kept full of concrete and should always remain at least one meter into the concrete in the bore hole with adequa te margin against accidental withdrawal of tremie pipes; f) The pile should be c oncreted wholly by tremie and the method of deposition should not be changed mid way to prevent laitance from being entrapped within the pile; g) All tremie pipe s should be cleaned before and after use; and h) A sliding plug of polystrene or similar material lighter than water and approved by the Engineer-in-charge or h is representative 8 shall be placed in the tremie pipe to prevent direct contact between the first charge of concrete in the tremie and the bentonite slurry. 8. 4.1 Normally concreting of the piles should be uninterrupted. In exceptional cas es of interruption of concreting, it shall be resumed within 1 or 2 h, but the t remie shall not be taken out of the concrete. Instead it shall be raised and low ered from time-totime to prevent the concrete around the tremie from setting. 8. 4.2 In case of withdrawal of tremie out of the concrete, either accidentally or to remove a choke in the tremie, the tremie may be introduced 60 cm to 100 cm in the old concrete and concreting resumed as mentioned in 8.4.1 . The fresh concr ete will emerge out of the tremie displacing the laitance and scum and prevent i mpregnation or laitance of scum in the fresh concrete. 8.4.3 The top of concrete in a pile shall be brought above the cut-off level to permit removal of all lai tance and weak concrete before capping and to ensure good concrete at the cut-of f level. The reinforcing cages shall be left with adequate protruding length abo ve cut-off level for proper embedment into the pile cap. 8.4.4 Where cut-off lev el is less than 2.5 m below the ground level, concrete shall be cast to a minimu m of 600 mm above cut-off level. For each additional 0.3 m increase in cut-off l evel below the working level, additional coverage of minimum 50 mm shall be allo wed. Higher allowance may be necessary depending on the length of the pile. When concrete is placed by tremie method, concrete shall be cast up to the ground le vel to permit overflow of concrete for visual inspection or to a minimum of one metre above cut-off level. In the circumstances where cut-off level is below gro und water level, the need to maintain a pressure on the unset concrete equal to or greater than water pressure should be observed and accordingly length of extr a concrete above cut-off level shall be determined. 8.5 Defective Pile 8.5.1 In case, defective piles are formed, they shall be left in place. Additional piles as necessary shall be provided. 8.5.2 Any deviation from the designed location, alignment or load capacity of a pile shall be noted and adequate measures taken well before the concreting of the pile cap and plinth beams. 8.5.3 While removin g excess concrete or laitance above the cut-off level chipping by manual or pneu matic tools shall be permitted seven days after pile casting. Before, chipping/b

reaking the pile top,

IS 2911 (Part 1/Sec 2) : 2010 a 40 mm deep groove shall be made manually all rou nd the pile at the required cut-off level. 8.5.4 After concreting the actual qua ntity of concrete shall be compared with the average obtained from observations made in the case of a few piles already cast. If the actual quantity is found to be considerably less, the matter should be investigated and appropriate measure s taken. 8.6 Recording of Data 8.6.1 A daily site record shall be maintained for the installation of piles and shall essentially contain the following informati on: a) Sequence of installation of piles in a group; b) Number and dimension of the pile, including the reinforcement details and mark of the pile; c) Depth bor ed (including depth in soft/hard rock); d) Time taken for boring, concreting and empty boring, chiseling and whether the pile is wet or dry; e) Cut-off level/ w orking level; f) Sample bore log in the initial stage or when major variation oc cur; g) When drilling mud is used, specific gravity of the fresh supply and cont aminated mud in the bore hole before concreting shall be recorded regularly; and h) Any other important observation. 8.6.2 Typical data sheet for facility of re cording pilling data is shown in Annex F. ANNEX A (Clause 2) LIST OF REFERRED INDIAN STANDARDS IS No. 269 : 1989 Title Ordinary Portland ceme nt, 33 grade -- Specification (fourth revision) Specification for mild steel and medium tensile steel bars and hard-drawn steel wire for concrete reinforcement: Part 1 Mild steel and medium tensile steel bars (third revision) Portland slag cement -- Specification (fourth revision) Plain and reinforced concrete-- Code o f practice (fourth revision ) Portland-pozzolana cement -- Specification: Fly as h based (third revision) Calcined clay based (third revision) Specification for high strength deformed steel bars and wires for concrete reinforcement (third re vision) Code of practice for sub-surface investigations for foundations (first r evision) Criteria for earthquake resistant design of structures: Part 1 General provisions and buildings (fifth revision) 9 IS No. 2062 : 2006 Title Hot rolled low, medium and high tensile structural steel (sixth revision) Method for standa rd penetration test for soils (first revision) Method of test for soils: Part 5 Determination of liquid and plastic limit (second revision) Code of practice for design and construction of pile foundations: Under-reamed piles (first revision ) Load test on piles (first revision) Code of practice for design and constructi on of machine foundations: Part 1 Foundation for reciprocating type machines (se cond revision) Code of practice for planning and design of ports and harbours: S ite investigation (first revision) Earth pressures (first revision) Loading (fir st revision) General design (second revision) Layout and requirements requiremen ts functional 432 (Part 1) : 1982 2131 : 1981 2720 (Part 5) : 1985 2911 (Part 3) : 1980 (Part 4) : 1985 2974 (Part 1) : 1982 455 : 1989 456 : 2000 1489 (Part 1) : 1991 (Part 2) : 1991 1786 : 1985 4651 (Part 1) : 1974 (Part 2) : 1989 (Part 3) : 1974 (Part 4) : 1989 (Part 5) : 1980 4968 1892 : 1979 1893 (Part 1) : 2002 Method for sub-surface sounding for soils:

IS 2911 (Part 1/Sec 2) : 2010 IS No. (Part 1) : 1976 Title Dynamic method using 50 mm cone without bentonite slurry (first revision) Dynamic method using cone a nd bentonite slurry (first revision) Static cone penetration test ( first revisi on) Code of practice for determination of bearing capacity of shallow foundation s (first revision) Rapid hardening Portland cement -- Specification (second revi sion) IS No. 8043 : 1991 8112 : 1989 12269 : 1987 12330 : 1988 12600 : 1989 Titl e Hydrophobic Portland cement-- Specification (second revision) 43 grade ordinar y Portland cement -- Specification (first revision ) Specification for 53 grade ordinary Portland cement Specification for sulphate resisting Portland cement Po rtland cement, low heat -- Specification (Part 2) : 1976 (Part 3) : 1976 6403 : 1981 8041 : 1990 ANNEX B (Clauses 6.3.1.1 and 6.3.2) LOAD-CARRYING CAPACITY OF PILES -- STATIC ANALYSIS B-1 PILES IN GRANULAR SOILS T he ultimate load capacity (Qu) of piles, in kN, in granular soils is given by th e following formula: PDi = effective overburden pressure for the ith layer, in k N/m2; i = angle of wall friction between pile and soil for the ith layer; and As i = surface area of pile shaft in the ith layer, in m2. NOTES 1 N factor can be taken for general shear failure according to IS 6403. 2 Nq factor will depend on the nature of soil, type of pile, the L/B ratio and its method of construction. The values applicable for bored piles are given in Fig. 1. 3 Ki, the earth pressure coefficient depends on the nature of soil strata, t ype of pile, spacing of pile and its method of construction. For driven piles in loose to dense sand with varying between 30 and 40, Ki values in the range of 1 to 1.5 may be used. 4 , the angle of wall friction may be taken equal to the f riction angle of the soil around the pile stem. 5 In working out pile capacity b y static formula, the maximum effective overburden at the pile tip should corres pond to the critical depth, which may be taken as 15 times the diameter of the p ile shaft for 30 and increasing to 20 times for 40 . 6 For piles passing thro ugh cohesive strata and terminating in a granular stratum, a penetration of at l east twice the diameter of the pile shaft should be given into the granular stra tum. Qu = Ap ( D N N + PD N q ) + n Di tan i Asi ... (1) i =1 K i P The first term gives end-bearing resistance and the second term gives skin frict ion resistance. where Ap = cross-sectional area of pile tip, in m2; D = diameter of pile shaft, in m; = effective unit weight of the soil at pile tip, in kN/m3 ; N = bearing capacity factors depending upon and Nq the angle of internal frict ion, at pile tip; PD = effective overburden pressure at pile tip, in kN/m2 (see Note 5); n i =1 = summation for layers 1 to n in which pile is installed and which contri bute to positive skin friction; Ki = coefficient of earth pressure applicable for the ith layer (see Note 3); 10

IS 2911 (Part 1/Sec 2) : 2010 FIG. 1 BEARING CAPACITY FACTOR, Nq FOR BORED PILES B-2 PILES IN COHESIVE SOILS T he ultimate load capacity (Qu) of piles, in kN, in cohesive soils is given by th e following formula: NOTE -- The value of adhesion factor, i depends on the undrained shear strength of the clay and may be obtained from Fig. 2. Qu = Ap istance ctional s 9; cp n Nc cp + n ...(2) i =1 i ci Asi The first term gives the end-bearing res and the second term gives the skin friction resistance. where = cross-se area of pile tip, in m2; Ap Nc = bearing capacity factor, may be taken a = average cohesion at pile tip, in kN/m2; i =1

= summation for layers 1 to n in which the pile is installed and which contribut e to positive skin friction; = adhesion factor for the ith layer depending on th e consistency of soil, (see Note); = average cohesion for the i th layer, in kN/ m2; and = surface area of pile shaft in the ith layer, in m2. 11 i ci Asi FIG. 2 VARIATION OF WITH Cu

IS 2911 (Part 1/Sec 2) : 2010 B-3 USE OF STATIC CONE PENETRATION DATA B-3.1 When full static cone penetration data are available for the entire depth, the follo wing correlation may be used as a guide for the determination of ultimate load c apacity of a pile. B-3.2 Ultimate end bearing resistance (qu), in kN/m2, may be obtained as: qc0 + qc1 + qc2 2 qu = 2 where qc0 = average static cone resistance over a depth of 2D below the pile tip, in kN/m2; qc1 = minimum static cone resi stance over the same 2D below the pile tip, in kN/m2; qc2 = average of the envel ope of minimum static cone resistance values over the length of pile of 8D above the pile tip, in kN/m2; and D = diameter of pile shaft. B-3.3 Ultimate skin fri ction resistance can be approximated to local side friction (fs), in kN/m2, obta ined from static cone resistance as given in Table 1. Table 1 Side Friction for Different Types of Soil Sl No. (1) i) ii) iii) iv) v) Type of Soil (2) qc less than 1 000 kN/m2 Clay Sil ty clay and silty sand Sand Coarse sand and gravel q c = cone resistance, in kN/ m . 2 B-4 USE OF STANDARD PENETRATION TEST DATA FOR COHESIONLESS SOIL B-4.1 The correl ation suggested by Meyerhof using standard penetration resistance, N in saturate d cohesionless soil to estimate the ultimate load capacity of bored pile is give n below. The ultimate load capacity of pile (Qu), in kN, is given as: Qu = 13 N N As L Ap + 0.50 B ...(3) The first term gives end-bearing resistance and the second term gives frictional resistance. where N = average N value at pile tip; L = length of penetration of pile in the bearing strata, in m; B = diameter or minimum width of pile in m; A p = cross-sectional area of pile tip, in m2; N = average N along the pile shaft; and As = surface area of pile shaft, in m2. NOTE -- The end-bearing resistance should not exceed 130 NAp . Local Side Friction, fs kN/m2 (3) q c /30 < fs < qc /10 qc /25 < fs < 2 qc /25 q c /100 < fs < qc /25 q c /100 < fs < qc /50 q c /100 < fs < qc /150 B-4.2 For non-plastic silt or very fine sand the equation has been modified as: N As L Ap + ...(4) 0.60 B The meaning of all terms is same as for equation 3. Qu = 10 N B-5 FACTOR OF SAFETY The minimum factor of safety for arriving at the safe pile capacity from the ultimate load capacity obtained by using static formulae shall be 2.5. B-6 PILES IN STRATIFIED SOIL In stratified soil/C- soil, the ultimate l oad capacity of piles should be determined by calculating the skin friction and end-bearing in different strata by using appropriate expressions given in B-1 an d B-2. B-7 PILES IN HARD ROCK When the crushing strength of the rock is more tha n characteristic strength of pile concrete, the rock should be deemed as hard ro ck. Piles resting directly on hard rock may be loaded to their safe structural c apacity. B-8 PILES IN WEATHERED/SOFT ROCK For pile founded in weathered/soft roc k different empirical approaches are used to arrive at the socket length necessa ry for utilizing the full structural capacity of the pile. 12 B-3.4 The correlation between standard penetration resistance, N (blows/30 cm) a nd static cone resistance, qc, in kN/m2 as given in Table 2 may be used for work ing out the end-bearing resistance and skin friction resistance of piles. This c orrelation should only be taken as a guide and should preferably be established for a given site as they can substantially vary with the grain size, Atterberg l

imits, water table, etc. Table 2 Co-relation Between N and qc for Different Type s of Soil Sl No. (1) i) ii) iii) iv) v) Type of Soil (2) Clay Silts, sandy silts and sligh tly cohesive silt-sand mixtures Clean fine to medium sand and slightly silty san d Coarse sand and sands with little gravel Sandy gravel and gravel q c/ N (3) 15 0-200 200-250 300-400 500-600 800-1 000

IS 2911 (Part 1/Sec 2) : 2010 Since it is difficult to collect cores in weathere d/soft rocks, the method suggested by Cole and Stroud using `N' values is more w idely used. The allowable load on the pile, Qa, in kN, by this approach, is give n by: N c = bearing capacity factor taken as 9; Fs = factor of safety usually ta ken as 3; = 0.9 (recommended value); cu2 = average shear strength of rock in th e socketed length of pile, in kN/m2 (see Fig 3); B = minimum width of pile shaft (diameter in case of circular piles), in m; and L = socket length of pile, in m . NOTE -- For N 60, the stratum is to be treated as weathered rock rather than so il. B2 BL Qa = cu1 Nc . 4F + cu2 . F s s where cu1 = shear strength of rock below the base of the pile, in kN/m2 (see Fig . 3); NOTE -- Standard penetration test may not be practicable for N values greater th an 200. In such cases, design may be done on the basis of shear strength of rock . FIG. 3 CONSISTENCY AND SHEAR STRENGTH OF WEATHERED ROCK 13

IS 2911 (Part 1/Sec 2) : 2010 ANNEX C (Clause 6.5.2) ANALYSIS OF LATERALLY LOADED PILES C-1 GENERAL C-1.1 The ultimate resistance of a vertical pile to a lateral load and the deflection of the pile as the load bui lds up to its ultimate value are complex matters involving the interaction betwe en a semi-rigid structural element and soil which deforms partly elastically and partly plastically. The failure mechanisms of an infinitely long pile and that of a short rigid pile are different. The failure mechanisms also differ for a re strained and unrestrained pile head conditions. Because of the complexity of the problem only a procedure for an approximate solution, that is, adequate in most of the cases is presented here. Situations that need a rigorous analysis shall be dealt with accordingly. C-1.2 The first step is to determine, if the pile wil l behave as a short rigid unit or as an infinitely long flexible member. This is done by calculating the stiffness factor R or T for the particular combination of pile and soil. Having calculated the stiffness factor, the criteria for behav iour as a short rigid pile or as a long elastic pile are related to the embedded length L of the pile. The depth from the ground surface to the point of virtual fixity is then calculated and used in the conventional elastic analysis for est imating the lateral deflection and bending moment. C-2 STIFFNESS FACTORS C-2.1 T he lateral soil resistance for granular soils and normally consolidated clays wh ich have varying soil modulus is modelled according to the equation: p y = h z (1) i) ii) iii) iv) v) Soft Medium stiff Stiff Very stiff Hard (2) Table 3 Modulus of Subgrade Reaction for Granular Soils, h, in kN/m3 (Clause C2.1) Sl No. (1) i) ii) iii) iv) Soil Type N (Blows/30 cm) (3) 0-4 4-10 10-35 > 35 (4) < 0.4 0.4-2.5 2.5-7.5 7.5-20.0 Range of h kN/m3 10 3 Dry (2) Very loose sand Lo ose sand Medium sand Dense sand Submerged (5) < 0.2 0.2-1.4 1.4-5.0 5.0-12.0 NOTE -- The h values may be interpolated for intermediate standard penetration v alues, N. C-2.2 The lateral soil resistance for preloaded clays with constant soil modulus is modelled according to the equation: p y =K where k1 0.3 1.5 B where k 1 is Terzaghi's modulus of subgrade reaction as determined from load deflection measurements on a 30 cm square plate and B is the width of the pile (diameter in case of circular piles). The recommended values of k1 are given in Table 4. K = Table 4 Modulus of Subgrade Reaction for Cohesive Soil, k1, in kN/m3 Sl No. Soil Consistency Unconfined Compression Strength, qu kN/m2 (3) 25-50 50-1 00 100-200 200-400 > 400 Range of k1 kN/m3 10 3 (4) 4.5-9.0 9.0-18.0 18.0-36.0 36.0-72.0 >72.0 where p = lateral soil reaction per unit length of pile at depth z below ground level; y = lateral pile deflection; and h = modulus of subgrade reaction for whi ch the recommended values are given in Table 3. 14 NOTE -- For q u less than 25, k1 may be taken as zero, which implies that there is no lateral resistance. C-2.3 Stiffness Factors C-2.3.1 For Piles in Sand and Normally Loaded Clays Stif fness factor T, in m = 5

EI h

IS 2911 (Part 1/Sec 2) : 2010 where E = Young's modulus of pile material, in MN/ m2; I = moment of inertia of the pile crosssection, in m4; and = modulus of sub grade reaction, in MN/m3 h (see Table 3). C-2.3.2 For Piles in Preloaded Clays S tiffness factor R, in m = where E = Young's modulus of pile material, in MN/m2; I = moment of inertia of the pile crosssection, in m4; K = 4 Table 5 Criteria for Behaviour of Pile Based on its Embedded Length (Clause C-3) Sl No. Type of Pile Behaviour Relation of Embedded Length with Stiffness Factor Linearly Increasing (3) L 2T L 4T Constant (4) L 2R L 3.5 R (1) i) (2) Short (rigid) pile Long (elastic) pile EI KB ii) NOTE -- The intermediate L shall indicate a case between rigid pile behaviour an d elastic pile behaviour. C-4 DEFLECTION AND MOMENTS IN LONG ELASTIC PILES C-4.1 Equivalent cantilever app roach gives a simple procedure for obtaining the deflections and moments due to relatively small lateral loads. This requires the determination of depth of virt ual fixity, zf. The depth to the point of fixity may be read from the plots give n in Fig. 4. e is the effective eccentricity of the point of load application ob tained either by converting the moment to an equivalent horizontal load or by ac tual position of the horizontal load application. R and T are the stiffness fact ors described earlier. k1 0.3 (see Table 4 for values of k1, in 1.5 B MN/m3); and B = width of pile shaft (diameter in case of circular piles), in m. C-3 CRITERIA FOR SHORT RIGID PILES AND LONG ELASTIC PILES Having calculated the stiffness fa ctor T or R , the criteria for behaviour as a short rigid pile or as a long elas tic pile are related to the embedded length L as given in Table 5. FIG. 4 DEPTH OF FIXITY 15

IS 2911 (Part 1/Sec 2) : 2010 C-4.2 The pile head deflection, y shall be compute d using the following equations: Deflection, y = H e + zf 3 EI b b g g 3 103 ...for free head pile e = cantilever length above ground/bed to the point of load application, in m. C -4.3 The fixed end moment of the pile for the equivalent cantilever may be deter mined from the following expressions: Fixed end moment, M F = H e + zf Deflection, y = H e + zf 12 EI 3 a f 103 ...for fixed head pile Fixed end moment, M F = where H = lateral load, in kN; y = deflection of pile head, in mm; E = Young's m odulus of pile material, in kN/m2; I = moment of inertia of the pile cross-secti on, in m4; zf = depth to point of fixity, in m; and H e + zf 2 ...for fixed head pile a ...for free head pile f The fixed head moment, MF of the equivalent cantilever is higher than the actual maximum moment M in the pile. The actual maximum moment may be obtained by mult iplying the fixed end moment of the equivalent cantilever by a reduction factor, m, given in Fig. 5. 5A For Free Head Pile 5B For Fixed Head Pile FIG. 5 DETERMINATION OF REDUCTION FACTORS FOR COMPUTATION OF MAXIMUM MOMENT IN P ILE 16

IS 2911 (Part 1/Sec 2) : 2010 ANNEX D (Clause 7.4) REQUIREMENTS OF DRILLING MUD (BENTONITE) D-1 PROPERTIES The bentonite suspension used in bore holes is basically a clay of montmorillonite group having exchange able sodium cations. Because of the presence of sodium cations, bentonite on dis persion will break down into small plate like particles having a negative charge on the surfaces and positive charge on the edges. When the dispersion is left t o stand undisturbed, the particles become oriented building up a mechanical stru cture of its own. This mechanical structure held by electrical bonds is observed as a thin jelly like mass or membrane. When the jelly is agitated, the weak ele ctrical bonds are broken and the suspension becomes fluid again. D-2 FUNCTIONS D -2.1 The action of bentonite in stabilizing the sides of bore holes is primarily due to thixotropic property of bentonite. The thixotropic property of bentonite suspension permits the material to have the consistency of a fluid when introdu ced into a trench or hole. When left undisturbed it forms a jelly like membrane on the borehole wall and when agitated it becomes a fluid again. D-2.2 In the ca se of a granular soil, the bentonite suspension penetrations into sides under po sitive pressure and after a while forms a jelly. The bentonite suspension then g ets deposited on the sides of the hole and makes the surface impervious and impa rts a plastering effect. In impervious clay, the bentonite does not penetrate in to the soil, but deposits only as thin film on the surface of hole. Under such c ondition, stability is derived from the hydrostatic head of the suspension. D-3 REQUIREMENTS The bentonite powder and bentonite suspension used for piling work shall satisfy the following requirements: a) The liquid limit of bentonite when tested in accordance with IS 2720 (Part 5) shall be 400 percent or more. b) The bentonite suspension shall be made by mixing it with fresh water using a pump fo r circulation. The density of the freshly prepared bentonite suspension shall be between 1.03 and 1.10 g/ml depending upon the pile dimensions and the type of s oil in which the pile is to be bored. The density of bentonite after contaminati on with deleterious material in the bore hole may rise up to 1.25 g/ml. This sho uld be brought down to at least 1.12 g/ml by flushing before concreting. c) The marsh viscosity of bentonite suspension when tested by a marsh cone shall be bet ween 30 to 60 stoke; in special cases it may be allowed up to 90 s. d) The pH va lue of the bentonite suspension shall be between 9 and 11.5. ANNEX E (Clause 8.1.5) SPECIAL USE OF LARGE DIAMETER BORED CAST IN-SITU RCC PILES IN MARINE STRUCTURES E-1 Because of the economy and availability of easy technology, large diameter b ore cast in-situ piles are widely used in marine structures in India. In similar conditions, steel piles are generally preferred in western countries. This cast in-situ piles require certain special attention which are needed to be consider ed in design and construction. E-2 CONSTRUCTION ASPECT E-2.1 Generally, permanen t mild steel liner is provided for the pile cut-off level to certain depth below bed level. This liner shall be of sufficient rigidity. This should be ensured b y selecting suitable thickness of plate. 17 E-2.2 Piles installed using movable or fixed platform or jack up barge are generally within acceptable tolerance. Sp ecial care shall be taken when piles are installed from floating barge subjected to tide, water current or wave forces. E-2.3 As per present practice, pile hole s are bored with bailer and chisel operated by a winch or using rotary rigs. Sin ce bentonite mud solution is used for the unlined bored depth for stability, utm ost care shall be taken about the quality of bentonite (or other stabilization) slurry. Bentonite should be of approved quality and to be mixed with potable wat er. Mechanical mixing system shall be used.

IS 2911 (Part 1/Sec 2) : 2010 E-2.4 After completion of boring in a pile hole, f lushing with bentonite fluid or air flushing shall be done. Time for reinforceme nt cage lowering shall be kept to minimum and early start of concreting shall be ensured. E-2.5 High grade concrete (minimum M 30 but preferably higher grades) shall be adopted. Cement content, workability and setting time of concrete shall be maintained as per IS 456 to ensure good health of concrete during constructi on and also during its serviceability period. Pumped concrete, transported from automatic batching plant using transit mixture are preferred in concreting work. E-3 DESIGN ASPECT E-3.1 Marine piles are subjected to large horizontal forces g enerated from wave, seismic wind, water current, berthing of ship, mooring pull, etc. Pile members are to be designed for axial force with moments and shear. Ad equate cover to reinforcement (75 mm generally provided) shall be ensured. E-3.2 Long-term serviceability condition shall be checked as per provision of IS 4651 (Part 4). Calculated crack width to be kept as per the provision of IS 4651 (Pa rt 4). For splash zone subjected to tidal variation special care is to be taken and relevant provision of IS 456 shall be adopted. Generally large deflection is allowed for such long cantilever marine piles and relevant provision of IS 456 and IS 4651 (Parts 1 to 5) are to be followed. E-3.3 When piles are subjected to extremely large horizontal force due to wave and current forces special design incorporating analysis of pile, model analysis, etc, may be adopted. E-3.4 When very soft marine clay or loose sand exists at bed level, it should be checked fo r potential liquefaction during earthquake. ANNEX F (Clause 8.6.2) DATA SHEET Site ................................................................ ................................................................................ .......................... Title ............................................... ................................................................................ .......................................... Date of enquiry ..................... ................................................................................ ................................................. Date piling commenced ........ ................................................................................ ................................................. Actual or anticipated date for completion of piling work ..................................................... ............................ Number of pile .................................... ................................................................................ .................................... TEST PILE DATA Pile: Pile test commenced .. ................................................................................ ..................... Pile test completed ...................................... ................................................................... Pile type: . ................................................................................ ........................................................ (Mention proprietary sy stem, if any) .................................................................. .......... Shape -- Round/Square Pile specification: Size -- Shaft ............. ......................................... Tip .................................. .................... Reinforcement ................ No. ........................ ..... dia for ....................................(depth) ...................... ................................................................................ ................................... Sequence of piling: (for Groups) From centre towards the periphery or from periphery towards the centre 18

IS 2911 (Part 1/Sec 2) : 2010 Concrete : Mix ratio 1: .......................... ....................................................... by volume/weight or stre ngth after .................. days ............................................. ............................... N/mm2 Quantity of cement/m3: ................... ............................................................................... Extra cement added, if any: .................................................... ...................................... Details of drilling mud used: ........... ................................................................................ ..................................... Time taken for concreting: ............... ................................................................................ .................................... Quantity of concrete -- Actual: ........... ................................................................................ ................................. Theoretical: ................................. ................................................................................ ... Test loading: Maintained load/Cyclic loading/C.R.P ......................... ...................................................................... ......... ................................................................................ ................................................ Capacity of jack .............. ................................................................................ ...................................... If anchor piles used, give .............. ...... No., Length ............................................................. .............. Distance of test pile from nearest anchor pile .................. .................................................................. Test pile and anchor piles were/were not working piles. Method of Taking Observations: Dial g auges/Engineers level .......................................................... ....................................................... Reduced level of pile ti p .............................................................................. ........................................ General Remarks: ...................... ................................................................................ ........................................................................... .... ................................................................................ ................................................................................ ............. .................................................................. ................................................................................ ............................... ................................................ ................................................................................ ................................................. .............................. ................................................................................ ................................................................... Special Diff iculties Encountered: .......................................................... ................................................................................ ....................................... ........................................ ................................................................................ ......................................................... ...................... ................................................................................ ........................................................................... Resu lts: Working load specified for the test pile .................................. ..................................................................... Settlement specified for the test pile ................................................... ......................................................... Settlement specified f or the structure ............................................................... ............................................ Working load accepted for a single pile as a result of the test ................................................... ............... ................................................................ ................................................................................ .......................... ..................................................... ................................................................................ ..................................... .......................................... ................................................................................ ................................................ 19

IS 2911 (Part 1/Sec 2) : 2010 Working load in a group of piles accepted as a res ult of the test ............................................................. .. ................................................................................ ................................................................................ ........ ....................................................................... ................................................................................ ................... General description of the structure to be founded on piles ..................................................................... .......... ................................................................................ ................................................................................ ....... ........................................................................ ................................................................................ ......................... ...................................................... ................................................................................ ........................................... .................................... ................................................................................ ............................................................. .................. ................................................................................ ............................................................................... ................................................................................ ................................................................................ ................. Name of the constructing agency .............................. ................................................................................ ........... .................................................................... ................................................................................ ............................. Name of person conducting the test ............... ................................................................................ ..................... .......................................................... ................................................................................ ....................................... Name of the party for whom the test was conducted ...................................................................... ................... ............................................................ ................................................................................ ..................................... BORE-HOLE LOG 1. Site of bore hole relativ e to test pile position ........................................................ ..................................... .......................................... ................................................................................ ................................................ 2. If no bore hole, give best a vailable ground conditions ..................................................... ........................ ....................................................... ................................................................................ ................................... ............................................ ................................................................................ .............................................. Soil Properties Soil Description Position of the tip of pile to be indicated thus Standing ground Water level ind icated thus METHOD OF SITE INVESTIGATION Trial pit/Post-hole auger/Shell and aug er boring/Percussion/Probing/Wash borings/Mud-rotary drilling/Coredrilling/Shot drilling/Sub-surface sounding by cones or Standard sampler ..................... ................................................................................ ............................................................................. .. ................................................................................ ................................................................................ ................ NOTE -- Graphs, showing the following relations, shall be prepared and added to the report: a) Load vs Time, and b) Settlement vs Load. Reduced Level Soil Legend

Depth Thickness Below Ground Level of Strata 20

IS 2911 (Part 1/Sec 2) : 2010 ANNEX G (Foreword) COMMITTEE COMPOSITION Soil and Foundation Engineering Sectional Committee, CED 4 3 Organization In personal capacity (188/90, Prince Anwar Shah Road, Kolkatta 7000 45) A.P. Engineering Research Laboratories, Hyderabad AFCONS Infrastructure Limi ted, Mumbai Central Board of Irrigation & Power, New Delhi Central Building Rese arch Institute, Roorkee Central Electricity Authority, New Delhi Central Public Works Department, New Delhi Central Road Research Institute, New Delhi Central S oil & Materials Research Station, New Delhi Engineer-in-Chief's Branch, New Delh i Engineers India Limited, New Delhi F. S. Engineers Pvt Limited, Chennai Gammon India Limited, Mumbai Ground Engineering Limited, New Delhi Gujarat Engineering Research Institute, Vadodara Indian Geotechnical Society, New Delhi Indian Inst itute of Science, Bangalore Indian Institute of Technology, Chennai Indian Insti tute of Technology, New Delhi Indian Institute of Technology, Mumbai Indian Inst itute of Technology, Roorkee Indian Society of Earthquake Technology, Uttarancha l ITD Cementation India Ltd, Kolkata M.N. Dastur & Company (P) Ltd, Kolkata M/s Cengrs Geotechnical Pvt Limited, New Delhi Ministry of Surface Transport, New De lhi Mumbai Port Trust, Mumbai Nagadi Consultants Pvt Limited, New Delhi National Thermal Power Corporation Limited, Noida Representative(s) DR N. S OM ( Chairma n ) SHRI P. SIVAKANTHAM S HRI P. JOHN VICTOR ( Alternate ) SHRI A. D. LONDHE S H RI V. S. KULKARNI ( Alternate) DIRECTOR SHRI Y. P ANDEY S HRI R. DHARMRAJU (Alte rnate) DIRECTOR (TCD) DEPUTY DIRECTOR (TCD) (Alternate) SUPERINTENDING ENGINEER (DESIGN) EXECUTIVE ENGINEER (DESIGN-V) (Alternate) SHRI SUDHIR MATHUR SHRI VASAN T G. HAVANGI ( Alternate) SHRI S. K. BABBAR S HRI D. N. BERA ( Alternate ) SHRI J. B. S HARMA S HRI N. K. JAIN ( Alternate ) SHRI T. BALRAJ S HRI S. D EBNATH ( Alternate) DR A. VERGHESE C HUMMAR DR N. V. N AYAK S HRI S. PATTIWAR (Alternate) SHRI ASHOK KUMAR JAIN SHRI NEERAJ KUMAR J AIN (Alternate) DIRECTOR S HRI J. K. P ATEL ( Alternate) SECRETARY PROF A. SRIDHARAN PROF S. R. GHANDI DR A. VARADARA JAN DR R. KANIRAJ (Alternate ) SHRI G. VENKATACHALAM PROF M. N. VILADKAR DR MAHE NDRA SINGH ( Alternate) REPRESENTATIVE SHRI P. S. S ENGUPTA S HRI MANISH KUMAR ( Alternate) DIRECTOR-CIVIL STRUCTURAL S HRI S. N. PAL (Alternate ) SHRI S ANJAY G UPTA SHRI RAVI SUNDARAM (Alternate) SHRI A. K. B ANERJEE SHRI S ATISH KUMAR (A lternate) SHRIMATI R. S. H ARDIKAR S HRI A. J. L OKHANDE (Alternate) DR V. V. S. R AO SHRI N. SANTOSH RAO ( Alternate) DR D. N. NARESH S HRI B. V. R. S HARMA (A lternate) 21

IS 2911 (Part 1/Sec 2) : 2010 Organization Pile Foundation Constructions Co (I) Pvt Limited, Kolkata Safe Ente rprises, Mumbai School of Planning and Architecture, New Delhi Simplex Infrastru ctures Limited, Chennai The Pressure Piling Co (I) Pvt Limited, Mumbai Universit y of Jodhpur, Jodhpur BIS Directorate General Representative(s) SHRI B. P. GUHA NIYOGI S HRI S. BHOWMIK ( Alternate) SHRI VIKRAM S INGH R AO SHRI S URYAVEER S I NGH RAO ( Alternate) PROF V. THIRIVENGADAM SHRI SHANKAR GUHA S HRI S. RAY ( Alte rnate) SHRI V. C. DESHPANDE SHRI P USHKAR V. D ESHPANDE (Alternate) SHRI G. R. C HOWDHARY SHRI A. K. S AINI, Scientist `F' & Head (CED) [Representing Director Ge neral (Ex-officio)] Member Secretary SHRIMATI MADHURIMA MADHAV Scientist `B' (CE D), BIS Pile and Deep Foundations Subcommittee, CED 43 : 5 In personal capacity (Satya Avenue, 2nd Cross Street, Janganatha Puram, Velacher y, Chennai 600042 ) AFCONS Infrastructure Ltd, Mumbai Association of Piling Spec ialists (India), Mumbai Central Building Research Institute, Roorkee Central Pub lic Works Department, New Delhi Engineer-in-Chief's Branch, New Delhi Engineers India Limited, New Delhi Gammon India Limited, Mumbai Ground Engineering Limited , New Delhi Indian Geotechnical Society, New Delhi Indian Institute of Technolog y, Chennai Indian Institute of Technology, Roorkee Indian Roads Congress, New De lhi ITD Cementation India Limited, Kolkata M/s Cengrs Geotechnical Pvt Limited, New Delhi Ministry of Shipping, Road Transport and Highways, New Delhi National Thermal Power Corporation, Noida Pile Foundation Constructions Co (I) Pvt Limite d, Kolkata Research, Designs & Standards Organization, Lucknow Simplex Infrastru ctures Limited, Chennai Structural Engineering Research Centre, Chennai TCE Cons ulting Engineers Limited, Mumbai Victoria-Jubilee Technical Institute, Mumbai SH RI M URLI I YENGAR (Convener) SHRI A. N. J ANGLE SHRI V. T. GANPULE SHRI M ADHUK AR L ODHAVIA (Alternate) SHRI R. DHARAMRAJU S HRI A. K. S HARMA ( Alternate) SUP ERINTENDING ENGINEER (DESIGN) EXECUTIVE E NGINEER (DESIGN D IVISION V) (Alternat e) DIRECTOR GENERAL OF WORKS DR ATUL NANDA S HRI SANJAY K UMAR ( Alternate) DR N . V. N AYAK S HRI R. K. MALHOTRA (Alternate ) SHRI ASHOK KUMAR JAIN SHRI NEERAJ KUMAR J AIN (Alternate) DR S ATYENDRA MITTAL DR K. R AJAGOPAL (Alternate) DR S. R. GANDHI DR A. BHOOMINATHAN (Alternate) DR G. RAMASAMY SHRI A. K. B ANERJEE S H RI I. K. P ANDEY ( Alternate ) SHRI M ANISH KUMAR SHRI P ARTHO S. S ENGUPTA ( Al ternate) SHRI S ANJAY G UPTA SHRI RAVI S UNDURAM (Alternate) SHRI V. K. SINHA SH RI R. R. M AURYA S HRI V. V. S. RAMDAS ( Alternate) SHRI B. P. GUHA NIYOGI S HRI S. BHOWMIK ( Alternate) DIRECTOR (B&S) DIRECTOR GE (Alternate ) SHRI SHANKAR GU HA S HRI S. RAY (Alternate) SHRI N. GOPALAKRISHNAN DR K. RAMANJANEYULU (Alternat e) SHRI C. K. RAVINDRANATHAN S HRI S. M. PALERKAR ( Alternate) REPRESENTATIVE 22

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