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IS 2911-4 (1985) : Code of practice for design and 
construction of pile foundations^ Part 4: Load test on 
piles [CED 43: Soil and Foundation Engineering] 

Jawaharlal Nehru 
'Step Out From the Old to the New" 

aj^&vi iJii^s:y%K^ isb^^ni^seg 

:<>5&i| mT'5K^5?::5:^>^i»l 


Satyanarayan Gangaram Pitroda 
Invent a New India Using Knowledge 

Bhartrhari — Nitisatakam 
''Knowledge is such a treasure which cannot be stolen" 






IS :2911 ( Part 4) - 1985 

( Reaffirmed 2010) 

Indian Standard 





(First Revision) 

Sixth Reprint JULY 2003 

UDC 624.154.1: 624.042 : 006.76 

O Copyright 1985 


NEW DELHI 110002 

Gr 5 September 1985 

IS I 2911 ( Part 4 ) - 1985 

Indian Standard 





{ First Revision ) 

Foundation Engineering Sectional Committee, BDC 43 

Chairman Representing 

Maj-Gkk Omuiii Sinoji Ministry of Defence 


Col K. p. Asamd ( Alternate to 
Maj-Gcn Ombir Singh ) 

S lilt I D. Anjiah a. p. Engineering Research Laboratories, Hyderabad 

Shri Arji-n' Ri-iHsiHaKANi Cement Corporation of India, New Delhi 

Shri O. S. Srivastava ( Alternate ) 
Dr R. K. BiiANDARi Central Building Research Institute ( CSIR )» 


Shri Chandra Pkakash ( Alternate ) 
Sn»i MAHABtn BiDASAKiA Ferro-Concretc Consultants Pvt Ltd, Indore 

Shri Asiiok Dihasakia ( Alternate ) 
Shri A. K. Chattehjef Gammon India Ltd, Bombav 

Shri A. C. Rov ( Alternate ) 
Chief Exginkkr Calcutta Port Trust, Calcutta 

Shih S. GiHA ( Alternate ) 
Siiui R. K. Da8 GiPTA Simplex Concrete Piles (I) Pvt Ltd, Calcutta 

Shri H. Guha Biswas ( Alternate ) 
Shri A. G. DASTinAU In personal capacity ( 5 Hungt'fo^ Court, 121 Hunger- 

ford Street, Calcutta ) 
Shri V. C. Deshpanpe Pressure Piling Co (1) Pvt Ltd, Bombay 

DiKECTOR Central Soil & Materials Research Station, 

New Delhi 

Deputy Dirfctor ( Alternate ) 
Shri A. H. Divak.u Asia Foundations and Construction Private Limited, 


Shri A. N. Ja^sgle ( Altematt ) 

( Continued on page 2 ) 

® Copyright 1985 


This publication is protected under the Indian CnpyrigHt Aet ( XIV of 1957 ) and 

reproduction in whole or in part by any means exrept with %irritten penninion of the 

publisher shall be deemed to be an infringement of copyright under the said Act. 

18 t 2911 ( Part 4 ) - 1985 

( C$nHnutd fr^m p€g0 1 ) 


Srri a. OaotHAL 
Dr Gopal Rakjan 


Shbi a. K. Mitr\ ( AUematt ) 
Srri Ashojc K. Jain G. S. Jain & Aiioclatef, New Delhi 

Shrx Vijay Ki7mar Jain ( AlUrnatt) 


Stup ComuUanU Limited, Bombay 

Universicy of Roorkee, Roorkee 

Steel Authority of India Ltd, Durgapur 

Joint Director ( Dksign ) 

Sunt Svjtji, Bjcry ( AUsftuHi ) 
Joint Dirbctor Researcji 
( GE )-I 
Joint Director Rrhearch 
( B&S ) ( AUtrnatt ) 
Dr R. K. Katti 
Sbri J. S. KojcLi 

Srri S. R. Kulkarni 

Shri S. Roy ( AUtrnati ) 
Snmi A. P. Mathur 
Srri V. B. Matiivr 
Srri S. Mukhsrjes 

Srri T. K. D. Munsi 

Shri M. Iyergar ( Mternate ) 
Shri A. V. S. R. Murtv 
Srri B. K. Partraxy 

National Buildings Organization, New Delhi 
Ministry of Railways ( RDSO ) 

Indian Institute of Technology, Bombay 
Public Works Department, Chandigarh Administra- 
tion, Chanditfarh 
M. N. Dastur & Company PvtXtd, Calcutta 

Central Warehousing Corporation, New Delhi 

McKenzies Ltd, Bombay 

In personal capacity ( £-7(7^ A, Simla Hwu; Neptan 

S$a JUail, Bombay ) 
Engineers India Limited, New Delhi 

Indian Geotechnical Society, New Delhi 
Hindustan Construction Co Ltd, Bombay 
Srri V. M. Madge ( Aiternad ) 
Srri M. R. Purja Cemindia Company Ltd, Bombay 

Shri D. J. Ketkar ( Altirnatt ) 
Shri N. E. V. Raouavan Braithwaite Burn $l Jessop Construction Company 

Ltd, Calcutta 
Dr V. V. S. Rao Nagadi ConsultanU Private Limited, New Delhi 

Dr a. Sarounan College of Engineering, Madras 

Shri S. Bomxinathan- ( Atttrnatt ) 
Srri N. Sivaouru Ministry of Shipping & Transport ( Roads Wing ) 

Shri M. K. Mukrerjes ( Alttrnau ) 
SuFBRiNTENOiNG E N I K £ E H Central Public Works Department, New Delhi 
( Dbsioks ) 
Errcutitr Engineer 
( Designs ) V ( Ali9fnat9 ) 
Dr a. Varadarajan 

Dr R. Kaniraj ( Att$mMi$ ) 
Srri G. Raman, 
Director ( Civ Engg ) 

Indian Institute of Technology, New Delhi 
Director General, ISI ( Ex-offieU Mmhif > 


Shhi K. M. Matrur 
Joint Director ( Civ Engg ), ISI 




IS : 2911 ( Part 4 ) - 1985 CODE OF PRACTICE 




( First Revision ) 

( Page 9, clause 6A.6A ) — Substilulc ihc following for the existing 

*ti.l.6.1 However, routine lest sluill he carried* for a Ccsl load of at 
least equal lo the working load; ihcniaxifnum settlement of the test loading 
in position being not exceeding 25 mm.' 

( BIX" 4) ) 

Reprography Unit, BIS, New Delhi, India 







( First Revision ) 

(Page 6, clause 4 .2 , second line) — Substitute '0.5' for 'one-half. 

(CED 43) 

Reprography Unit, BIS, New Delhi, India 


Indian Standard 





( First Revision ) 


P.l This Indian Standard ( Part 4 ) ( First Revision } was adopted 
by the Indian Standards Institution on 20 February 1985, after the draft 
finalized by the Foundation Engineering Sectional Committee had been 
approved by the Civil Engineering Division Council. 

0.2 Piles find application in foundation to transfer loads from a structure 
to competent subsurface strata having adequate load bearing capacity. 
The load transfer mechanism from a pile to the surrounding ground is 
complicated and could not yet be fully ascertained, although application 
of piled foundations is in practice over many decades. Broadly, piles 
transfer axial loads either substantially by skin friction along its shaft 
or substantially by the end bearing. Piles are used where either of the 
above load transfer mechanism is possible depending upon the subsoil 
stratification at a particular site. Construction of pile foundations require 
a careful choice of piling system depending upon the subsoil conditions, 
the load characteristics of a structure and the limitations cf total settle* 
ment, differential settlement and any other special requirement of a 
project. The installation of piles demands careful control on position, 
alignment, depth and involve specialized skill and experience. 

0.3 Pile load test is the most direct method for determining the safe 
loads on piles including its structural capacity with respect to soil in 
which it is installed. It is considered more reliable on account of its 
being ifi'Situ test than the capacities computed by other methods, such as 
static formula, dynamic formulae and penetration test data. There are 
widely varying practices followed for load tests on piles. Particularly, 
the difficulties regarding the establishment of an acceptable criterion, for 
determining the ultimate and safe bearing capacity of piles, and predic* 
ing the pile group behaviour from the test data obtained from individual 
load test on single piles, cannot be under-estimated as the factors 


affecting are many. However, an attempt is made to bring out an unified 
approach to the various aspect of load test on piles. This standard was 
first prepared in 1979, The revised version has been prepared so as to 
give more details in regard to the rate of loading and unloading and the 
details of the situations when the different types of tests are conducted, 

0.4 For the purpose of deciding whether a particular requirement of 
this standard is complied with, the final value, observed or calculated, 
expressing the result of a test or analysis, shall be rounded off in 
accordance with IS : 2-1960*. The number of significant places retained 
in the rounded off value should be the same as that of the specified value 
in this standard. 


1«1 This standard ( Part 4 ) covers the load test on all types of piles cove- 
red in IS : 2911 ( Part 1/Sec 1 )-1979t, IS : 2911 ( Part 1/Sec 2 )-1979J, 
IS : 2911 ( Part 1/Sec 3 )-1979§, IS : 2911 ( Part 1/Sec 4 )-1984!|, IS : 2911 
( Part 2 )-19801f and IS : 2911 ( Part 3 ) 1980** and provides guidelines 
for determinati*m of safe load based on the following types of loadings. 

a) Vertical load test ( compression ), 

b) Lateral load test, and 

c) Pull-out test. 

1.2 Load tests under vibratory loads, moments and other forces and 
sequence of loading under special circumstances like yield load capacity 
of buckling piles are not covered in this standard. 


2«0 For the purpose of this standard, the following definitions shall apply. 

2.1 Cnt*Off Level — The level where the installed pile is cut-off to 
support the pile caps or beams or any other structural components at 
that level. 

*Rule9 for rounding ofT numerical values ( rwisid ). 

tCode of practice for design and construction of pile foundations: Part 1 Concrete 
piles, Section 1 Driven cast in'situ concrete piles (first revision ), 

tCode of practice for design and co»itruction of pile foundations: Part 1 Concrete 
pilest Section 2 Bored cast in*situ concrete piles ( first rmswt ). 

fCode of practice for deugn and construction of pile foundations: Parti Concrete 
piles, Section 3 Driven precast concrete piles {first revision ). 

llCode of practice for design and construction of pile foundations: Part 1 Concrete 
pilet» Section 4 Bored precast concrete piles. 

ICode of practice for design and construction of pile foundatiqns: Part 2 Timber 
piles {first revision ). 

*^Code of practice for design and construction of pile foundations: Part 3 Under- 
reamed piles {first revision). 

IS : 2911 ( Part 4 ) - 1985 

2*2 Datam Bar — A rigid bar placed on immovable supports. 

2.3 Factor of Safety — The ratio of the ultimate load capacity of a 
pile to the safe load of a pile. 

2«4 Initial Test 7- It is carried with a view to determine ultimate load 
capacity and the safe load capacity. 

2*5 Kentledge — Dead-weight used for applying a test load on piles. 

2.6 Net Displacement — Net movement of the pile top from the 
original position after the pile has been subjected to a test load and 
subsequently released. 

2*7 Routine Test — It is carried out on a working pile with a view to 
check whether pile is capable of taking the working load assigned to it. 

2.8 Test Pile *- A pile which is meant for initial test. 

2.9 Total Displacement ( Gross ) — The total movement of the pile 
top under a given load. 

2.10 Total Elastic Displacement — This is magnitude of the 
displacement of the pile due to rebound caused at the top after removal 
of a given test load. This comprises two components as follows: 

a) Elastic displacement of the soil participating in load transfer, 

b) Elastic displacement of the pile shaft. 

2.11 Ultimate Load Capacity — The maximum load which a pile or 
pile shaft can carry before failure of ground ( when the soil fails by shear 
as evidenced from the load settlement curves ) or failure of pile. 

2«12 Safe Load -- It is a load on a pile derived by applying a factor of 
safety on ultimate load capacity of pile as determined by load test. 

2.13 Working Load — The load assigned to a pile acobrding to design. 

2.14 Working Pile — A pile forming part of foundation of a structural 
system which may be used for routine load test. 


3.1 The following information is necessary for pile(8) on which test is 

a) Pile type including material and reinforcement details, group of 
piles, if any; 

b) Method of driving with driving record or installation; 

c) Pile depth(s) and details of cro8S*section(s}; 


IS 1 2911 ( Part 4 ) • IMS 

d) Type of test desired; 

e) Layout or the pile(s) — space available around and position in 
the group for single pile test; 

f ) Depth of water table and soil strata details with soil test results; 

g) Safe load and ultimate load capacity, and the niethod(s} on 
which based; 

h) Availability and provision of type of piles or anchors or kentledge 
for reaction; 

j) Nature of loading/loading plan with a particularly mention of 
pile(8} which may be free standing when scour is expected; and 

k) Any other information concerning planning and conducting the 
tests including the relevant past experience concerning similar 



4*0 There are two types of tests for each type of loading (that is, vertical, 
lateral and pullout ), namely, initial and routine test. 

4.1 biltisil Teat — This test is required for one or more of the 
following purposes. This is done in case of important and/or major 
projects and number of tests may be one or more depending upon the 
number of piles required. 

NoTB — In case specific information about strata and past guiding experience is 
not available, ttiere should be a minimum of two tesu, 

a) Determination of ultimate load capacities and arrival at safe 
load by application of factor of safety, 

b) To provide guidelines for setting up the limits of acceptance for 
routine tests, 

c) To study the effect of piling on adjacent existing structures and 
take decision for the suitability of type of piles to be used, 

d) To get an idea of suitability of piling system, and 

e) To have a check on calculated load by dynamic or static 

4.2 Roatisie Teat — This test is required for one or more of the 
following^ purposes. The number of tests may generally be one*hsdf 
percent of the toul number of piles required. The number of the test 
may be increased up to 2 percent in a particular case depending upon 
nature, type of structure and strata condition: 

a) One of the criteria to determine the safe load of the pile; 

b) Checking safe load and extent of safety for the specific functional 
requirement of the pile at working load; and 



c) Detection of any unusual performance contrary to the findings 
of the initial test, if carried out. 


5.1 Pile test may be carried out on a 5ingle pile or a group of piles as 
required. In case pf pile groups, caps will be provided such that the 
required conditions ^f actual use are fulfilled. 

5.2 Generally the load application and deflection observation will be 
made at the pile top. 

5J3 In particular cases where upper part of pile is likely to be exposed 
later on due to scour, dredging or otherwise then capacity contributed 
by that portion of the pile during load test shall be duly accounted for. 
The pile groups in these conditions shall be tested without their cap 
resting on the ground. 

5*4 The test should be carried out at cut-off level wherever practicable, 
otherwise suitable allowance shall be made in the interpretation of the 
test results/test load if the test is not carried out at cut-off level. 


CI Gesieral — In this type of test, compression load is applied to the 
pile top by means of a hydraulic jack against rolled steel joist or suitable 
load frame capable of providing reaction and the settlement is recorded 
by suitably positioned dial gauges. Maintained load method as given 
in 6*2 should be used for determination of safe load. Howev cv, for 
specific requirements cyclic and CRP methods, which are alternate 
methods, may be used as mentioned in 6.3 and 6A. The general require- 
ments applicable for these three methods are given frosn 6.L1 to 6«1.6, 
unless otherwise specified. 

€•14 Pnparalion of Pile Head — The pile head should be chipped off 
to natural horizontal plane till sound concrete is met. ' The projecting 
reinforcement should be cut off or bent suitably and the top finished 
smooth and level with plaster of Paris or similar synthetic material where 
required. A bearing plate with a hole at the centre should be placed on 
the head of the pile for the jacks to rest. 

f.1.2 Application of Load — ( Not applicable to CRP method. ) The 
test should be carried out by applying; a series of vertical downward 
incremental load each increment being of about 20 percent of safe load 
on the pile. For testing of raker piles it is essential that loading is along 
the axis. 

IS t 2911 ( Part 4 ) - 1985 

6.1.3 Reaction — The reaction may be obtained from the following: 

a) Kentledge placed on a platform supported clear of the test pile. 
In case of load test below under^-pinned structure, the existing 
structure if having adequate weight and suitable construction 
may serve as kentledge. The centre of gravity of the kentledge 
should generally be on the axis of the pile and the load applied 
by the jack should also be coaxial with this pile. 

b) Anchor piles with centre-to-centre distance with the test pile not 
less than 3 times the test pile shaft diameter subject to minimum 
of 2 m. If the anchor piles are permanent working piles, it 
should be ensured that their residual uplift is within limits. Care 
should be exercised to ensure that the datum bar supports are 
not affected by heaving up of the soil. 

c) Rock anchors with distance from the nearest edge of the piles at 
rock level being 2 times the test pile shaft diameter or 1*5 m 
whichever is greater. The reaction to be made available for the test should be 
25 percent more than the final test load proposed to be applied. 

6.1.4 Settlement — ( Not Applicable for CRP Test. ) Settlement shall be 
recorded with minimum 2 dial gauges for single pile and 4 dial gauges of 
0*01 mm sensitivity for groups, each positioned at equal distance around 
the piles and normally held by datum bars resting on immovable supports 
at a distance of 3 D ( subject to minimum of 1*5 m ) from the edge of 
the piles, where D is the pile stem diameter of circular piles or diameter 
of the circumscribing circle in the case of square or non-circular piles. 

6.1.5 The safe load on single pile for the initial test should be least of 
the following: 

a) Two-thirds of the final load at which the total displacement 
attains a value of 12 mm unless otherwise required in a given 
case on the basis of nature and type of structure in which case, 
the safe load should be corresponding to the stated total displace- 
ment permissible. 

b) 50 percent of the final load at which the total displacement 
equal 10 percent of the pile diameter in case of uniform diameter 
piles and 7*5 percent of bulb diameter in case of under-reamed 
piles. However routine test shall be carried for a test load of at least 
one and half times the working load; the maximum settlement of test 
loading in position being not exceeding 12 mm. 



6«1.6 The safe load on groups of piles for initial test shall be least of^ 
the following: 

a) Final load at which the total displacement attains a value of 
25 mm unless otherwise required in a given case on the basis of 
nature and type of structure, and 

b) Two-thirds of the final load at which the total displacement 
attains a value of 40 mm. However routine test shall be carried as in the 

maximum settlement not exceeding 25 mm. 

6.2 Maintained Load Method — This is applicable for both initial 
and routine test. In this method application of increment of test load 
and taking of measurement or displacement in each stage of loading is 
maintained till rate of displacement of the pile top is either 0*1 mm in 
first 30 minutes or 0*2 mm in first one hour or till 2 h whichever occur 
first. If the limit of permissible displacement as given in 6.1.5 or 6.1.6 
is not exceeded, testing of pile is not required to be continued further. 
The test load shall be maintained for 24 h. 

6.3 Cyclic Method — This method is used in case of initial test to find 
out separately skin friction and point bearing load on single piles 
of uniform diameter. The procedure as given in Appendix A or by 
instrumentation may be used. 

6.4 CRP Method — This method which is used for initial test is 
generally considered to be more suitable for determining ultimate bear- 
ing capacity than the maintained load test but the load/deflection 
characteristics are quite difierent from those of the maintained load test 
and cannot be used to predict settlement of the pile under working load 
condition). This method should not be included in routine test. The 
procedure is given in Appendix B. 


7.1 The test may be carried out by introducing a hydraulic jack with 
gauge between two piles or pile groups under test or the reaction may 
be suitably obtained otherwise. If it is conducted by jack located bet- 
ween two piles or groups, the full load imposed by the jack shall be 
taken as the lateral resistance of each pile or group. The loading should 
be applied in increments of about 20 percent of the estimated safe 

7.2 The next increment should be applied after the rate of displacement 
is nearer to 0*1 mm per 30 minutes. 

7.3 Displacements shall be read by using at least two dial gauges of 
00 1 mm sensitivity (s$e Fig. 1 ) spaced at 30 cm and kept horizontally 


€110 abovte the other on the test pile and the diiplacement interpolated at 
cut-off level from similar triangles where cut*oiF level is unapproachable 
and for approachable cut-off level, however, one dial gauge placed 
diametrically opposite to the jack shall directly measure the displacement. 
Where, it is not possible to locate one of the dial gauges in the line of 
the jack axes, then two dial gauges may be kept at a distance of 30 cm 
at a suitable height and the displacement interpolated at load point from 
similar triangles. 

Nora •— Ons of the methodi for kstpiag dial gauge on pile nirfsc« is to chip off 
uneven concrete on the tide of the pile eno to fix a piece of gleii 20 to 30 mm iquere. 
The dial fsuget tips shall rest on the eentral portion of the glass phite. 



Fig. 1 PosiTtoff OF DAtrm BAa SupPOKTs 

7.4 The safe lateral load on the pile shall be taken as the least of the 

a) Fifty percent of the fnal load at which the total displacement 
increases to 12 mm; 

b) Final load at which the total di^lacement corresponds to 5 mm; 

c) Load corresponding to any other specified displacement as per 
performance requiremems. 

Nora — The displacement is at the cut-off level of the pile. 


18 f 2911 ( Ptert 4 ) - IMS 

7.5 Pile groups shall be tested under conditions as per actual use in the 
structure as far as possible. 


8.1 Uplift force may preferably be applied by means of hydraulic jack(s) 
with gauge using a suitable pull out set up. 

Note •— Ont of tlic methocii for pull out tsstt thftt may be uied is where hydraulic 
jack is made to rest on rolled steel joitc(s) resting on two supports on the ground. 
' The jack reacts against e frame attached to the top of the test pile such that when 
the jack is operated, the pile gets pulled up and the reaction is transferred to the 
ground through the supports which are at least 2*5 /> away from the test pile 
periphery ( where D is pile stem diameter of circular piles or diameter of the 
circumscribing circle in the case of square piles ). The framework can be attached 
to the pill* top with the reinforcement bars which may be threaded or to which 
threaded bolts may be welded. As an alternative it is sometimes preferable to use 
.1 central rod designed to take pile load and embedded centrally in the pile to a 
length equal to the bond length load required. It will have threads at top for fixing 
it to the framework. For larger loads the mimber of rods may have to be more and 
depending on the set-up these may be put in a line or in any other symmetrical 
p.ittern. For routine tests, the framework is normally attached to the reinforcing 
bars but a tentral rod may also be used in case the upper portion of the pile is 
required to be Iniilt up. 

8.2 The test pile shall have adequate steel to withstand pulling. In 
some cases, in order to allow for neck tension in a pull out test, it may be 
necessary to provide additional reinforcement in the piles to be tested. 

8.3 The pull out load incitements and consequent displacement readings 
shall be read as in the case of vertical load test. 

8.4 The safe load shall be taken as the least of the following: 

a) Two*thirds of the load at which the total displacement is 12 mm 
or the load corresponding to a specified permissible uplift, and 

b) Half of the load at which the load-displacement curve shows a 
clear break ( downward trend ). 

8.5 The initial test shall be carried out up to twice the estimated safe 
load or until the load displacement curve shows a clear break ( down- 
ward trend }• 

8«€ Routine test shall be carried out to one-and-a-half times the estimated 
safe load or 12 mm total displacement whichever is earlier. 


9.1 The pile test data essentially concemi three variables, namely, load, 
displacement and time. These are to be recorded sequentially for the 
tests under consideration and recorded in a suitable tabular form along 
with the information about the pile. 


IS s 2911 ( Part 4 ) « 1985 

9.2 The data may be suitably presented by curves drawn between the 
variables and safe loads shown on the graphs. Load displacement curve 
should be an essential part of presentation. 


( Clause 6.3 ) 


A-Ll Alternate loading and unloading shall be carried out at each stage 
as in 6.I.2 and each loading stage shall be maintained as in 6.2 and each 
unloading stage shall be maintained for at least 15 minutes and the sub- 
sequent elastic rebound in the pile should be measured accurately by 
dial gauges as in 6.L4. The test may be continued up to 50 percent 
over the safe load. 


A-2.1 Graphical Method 

A-2«l.l The analysis shall be done as explained in Fig. 2. 

A-2.1.2 Assuming that there is no compression in the pile, plot a graph 
relating total elastic recovery and load at the pile top. 

A-2«l«3 Draw a straight line parallel to the straight portion of curve 
I to divide the load into two parts and thereby obtained approximate 
values of point resistance and skin friction. 

A*2«M From the approximate value of skin friction^ and knowing the 
loads on top of pile, compute the elastic compression of the pile corres- 
ponding to these loads, by the following formula: 

^ AE 


A "" elastic compression of pile in cm, 
T «• load on pile t6p in kgf, 
F » frictional reiistance in kgf» 
L «i length of the pile in cm, 
A » cross«8ectional area of the pile in cm*, and 
E >■ modulus of elasticity of the pile material in kgf/cm*. 


IS t 2911 ( Part 4 ) - 1»S5 

















Fio. 2 

Analysis of Cyclic Load Test Data for Separation of 
Skin Friction and Point Resistance 


18 t 2fll ( Part 4 ) • IMS 

( The value should normally be measured from an exposed portion 
of pile stem by means of compressometer during the load test itself. ) 

A«2*1.5 Obtain values of tlie elastic compression of the subgrade by 
subtracting the elastic compression of the pile from the total elastic 
recovery of pile» and plot the graph relating these new values to the 
corresponding loads on pile top. When elastic compression of the sub* 
grade works out negative, the negative value shall be ignored until the 
value is positive. 

A*2«l«6 Repeat the procedures given in A*2.1«9 to obtain new values 
of skin friction. 

A-2«l«7 The process of further approximations covered in A*2«l«6 may 
be repeated further to any desired extent, but usually the third curve 
would give sufficiently accurate values for skin friction for practical 

A-2.2 Aaalytlcml Method 

A-2.2.1 From straight line portion of curve ( set Fig. 2 ) calculate the 
value of constant from the equation ( 1 ). 


m ^^ '— (1) 



m » a constant; 
A» «• change in total elastic settlement of pile top = ( 5 — 5 ), 

in cm; 
At «» change in applied load « ( Tb — T* ) in kgf; 
L '■=' length of pile in cm; 
A "• cross-sectional area of pile in cm*; 
E ^ elastic modulus of the material of the pile in kgf/cm'; 

T a- load on pile top in kgf. 

A«2«2.2 Calculate the corrected settlement for different load increment 
by equation ( 2 ). 

S^mT (2) 


S » corrected settlement in cm, and 
T --= total load on pile top in kgf. 


18 t 2911 ( Part 4 ) • 1985 

A-UU3 Knowing value of m and S compute skin friction and point 
bearing by solving simultaneous equation ( 3 ) and ( 4 ). 

T'.P + F (3) 



P mm point bearing in kgf, and 
F skin friction* in kgf. 


( Clause 6.4 ) 


B-l.l The load shall be measured by means of pressure of 001 mm 
sensitivity load gauge. The penetration ( deflection ) should be measured 
by means of dial gauges held by a datum bar resting on immovable supports * 
at a distance of at least 3 D ( subject to a minimum of 1 *5 m ) away from 
the rest pile edge where D is defined in 6.I.5. One of the dial gauges 
will be selected for conducting the test. With continuous application of 
pressure on the pile top by operating of the jack, a person watches the 
rate of settlement of the dial gauge against a stop watch held in his hand 
and directs the pump operator to pump faster or slower or at the same 
rate as needed to maintain the prescribed rate of settlement say at every 
0*25 mm settlement, he gives an indication to take readings. Immedia- 
tely, other persons record the pressure gauge readings and other dial 
gauge readings. The pump supplying the jack may be hand or 
mechanically operated. For force up to 200 ton hand pumping is con- 
venient. If a mechanical pump is used, it should, for preference, have 
an 'infinite variable* delivery, controlled either by a bleed valve or a 
variable speed drive. 

B-1.2 The jack should be operated to cause the pile to penetrate at 
uniform rate which may be controlled by checking the time taken for 
small increments of pMMrtration and adjiittiiif the pumping rate accord- 
ingly. Readings of time, poattration aad load should be taken at 
sufficiently close intervals to give adtquale control of the rate of penetra- 
tion. A rate of pen«tration of about 0*75 mm per minute is suitable for 
predominantly friction pUet. For prodhHUinantly dnd-bnring piles in 
•and or gravel, rate of ponelratioai of TS mm per minute may be used. 



Tho rate of penetration, if steady, may be half or twice these values 
without signiGcantly affecting the results. The test should be carried 
out for the penetration more than 10 percent of the diameter of the 
pile base. 

B"1.3 As the test proceeds a curve between load and penetration should 
be drawn to determine when the ultimate load capacity has been 


B^l The curve of load versus penetration in the case of a predominantly 
firiction pile will represent either a peak and the subsequent downward 
trendy or a peak and then almost a straight line, as shown in Fig. 3A. 
The peak load marked A in Fig. 3A will represent the ultimate load 
capacity of pile. 

II-2.2 In the case of predominantly end-bearing pile the curve will be 
similar to that shown in Fig. 3B and the ultimate load capacity may be 
taken as the load corresponding to the penetration equal to 10 percent 
of the diameter of the pile base. 





$ 10 15 20 2S 


3A Predominantly Friction Piles 

30 3S 


IS : 2911 ( P«rc 4 ) - 1985 


' 120 





§ 80 






125 250 375 500 

62.5 750 

3B Predominantly End Bearing Piles 
Fio. 3 Load vs Penetration Curve in CRP Test 


IS 1 2911 ( Part 4 ) - 1985 

( C^niinuid ft mi pag$ 2 ) 

Pile Foundations Subcommittee, BDC 43 : 5 

SiiRi M. D. Tamrkkaii 
Pradtep Villa* 92 Kotnts Path Mahim, Bombay 

Mimkers Hiprismling 

SKRiCKANpitA Prakash Central Building Research Institute ( CSIR )» 

SifRt K. G. Garo ( AUimaU ) 
Srri a. Grcnimal Stup Consultants Limited, Bombay 

Skri Nf. Itbnoar Engineers India Limited, New Delhi 

SJfRi J. K. Bagchi ( AUiffmh ) 
Shri p. K. J aim University of Roorkee, Roorkee 

SitRi A. N. jAiroLS Asia Foundations and Construction Private Limited, 

JOfMT DiiiRCTOR RK8BARCII Ministry of Railways ( RDSO ) 
( GE HI 
Dbpcty Dirsctor Resbarcii 
Srri B. K. Parthaky Hindustan Construction Company Limited, Bombay 

Shri P. V. Nair ( Alttn^li ) 
Srri M . R. Pi7RJA Cemindia Company Limited, Bombay 

Srri D. J. Krtkar ( AiUmait ) 
Srri B. Rustomibk Pile Foundations Construction Company ( India ) 

Private Limited, Calcutta 
Srri S. C. Boar ( Aiunuti ) 
SuPRRiRTBRDixo ExoiSfKER Central Public Works Department, New Delhi 
( Drhions ) 


( DKSiQNa ) V ( AUerMti ) 



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