IS_1888_1982

8/6/2019 IS_1888_1982

1/13

( Reaffirmed 2002 )

8/6/2019 IS_1888_1982

2/13

IS:1888 - 1982

Indian StandardMETHOD OF LOAD TEST ON SOILS

( Second Revision )Soil Engineering and Rock Mechanics Sectional Committee, BDC 23

ChairmanDR JAGDISH NARAIN

Members

RepresentingUniversity of Roorkee, Roorkee

SFiRI P. D. AoARWAI, Public Works Department, Government ofUttar Pradesh, LucknowDa B. L. DHAWAN ( Afternaie )Da ALAM SINQH University of Jodhpur, JodhpurCHlEB l&arEE~n ( RCD ) Irrigation Department, Government of Punjab,( IPRI ) ChandigarhSHKI P. S. GOSAL ( Alternate )S H R I M. C. DAN~AVATE Concrete Association of India, BombaySRRI N. C. DUC+~AL( Alternate )In personal capacity ( 5 Hungerford Court, 12/,Hungerford Street, Calcutta )SHR IA. G. DMTII MRDR G. S . DHILL~NDIRBXIYOIL Indian Geotechnical Society, New DelhiCentral Soil and Material Research Station,New Delhi

D EP U TY D I RECTO R ( Alternate )DIRECTOR 11~1 Irrigation Department, Government ofUttar Pradesh, Roorkee\ Asia Foundations and Construction (P) Ltd, BombayHR I A. I-1. DIVANJ I

SHIE I A. N J ANCLP, ( Alternate )Dn GOP AL R.YJ .*N Institution of Engineers ( India), Calcutta; a.ldUniversity of Roorkee, RoorkeeSHILI S . GUP T~ Cemindia Company Limited, Bombay

Scar N. V. De-Sousa ( &ernnle )S H R I ASHOK I(. J O I N G. S. Jain & Associates, RoorkeeS H RI VI J AY I L J O I N ( illterrzate )J O I F T DIXACTOR REsEAxif Ministry of Railways( G.E.-I ), RDSO

J OINT DIRXCTOR RESE ARCH( G. E.- I I ) ( ;l l ter n nle )

@ Copyright 1983INDIAN STANDARDS INSTITUTION

This publication is protected under the Indian Coprright Act ( XIV of 1957 ) andreproduction in whole or in part by any means except with written permission of thepublisher shall be deemed to be an infringement of copyright under the said Act.

8/6/2019 IS_1888_1982

3/13

( Continued j?om page 1 )Members Representing

LT-COL V. K. KANITKARSHRI 0. P. MALHOTRASH RI D. R. NARAHARI

Ministry of Defence ( En gineer-in-Chiefs Bra nch )Public Works Depart ment , Chan digar h Administra -tion, ChandigarhCentral Building Research Institute ( CSIR ),Rnorkee

SH RI V. S. AoARWAL ( Alternate )SHRI T. K. N ATRAJ AN Centra l Road Research Institut e ( CSIR 1,New DelhiSHRI RdNJIT SINoH Minist ry of Defen ce ( R & D )SHRI V. B. GHORP ADE ( Alternate )DR G. V. RAO Ind ian Inst itut e of Technology, New DelhiDR K. K. GUPTA ( Alternate )RESEARCH OFFICER ( B & RRL ) Public Works Depart men t, Governm ent of Pu njab,ChandigarhSHRI K. R. SAXEN. En gineering Research Labora tories, Governm ent ofAndhra Pradesh, HyderabadSECRE TARY Cent ra l Board of Irr igation & Power, New Delhi

DEPUTY SECRETARY ( Alternate )SHRI N. SIVACURU Roads Wing ( Ministry of Shippin g an d Tra nsp ort )SH RI P. R. KALRA ( Alternate )SHRJ K. S. SRINI VASAN Nat iona l Bu ildings Organization, New DelhiSHRI SUN IL BERRY ( Alternate )SHRI N. SUBRAMANYAM Karn ata ka En gineer ing Research Station, Govern-ment of Karnata ka, Krishnar ajasagarSUPERTNTENDINCE N a I N E E R Public Works Depart ment , Governm ent Of Tamil

(P&D) Nadu, MadrasEXECUTIVE ENGINEER( SMRD ) ( Alternate )SHRI H. C. VERM_~ All Ind ia Man ufactur ers & Dealer s Associat ion,Bombav

SHRI H. K. GUH A ( Alternate )SHHI G. RAMAN, Director Gener al, IS1 (Ex-o&o Member )Director ( Civ En gg )

SfxretarySHRJ K. M. MATHUR

Depu ty Director ( Civ En gg ), IS1

Site Exploration & Investigation for Foundations Subcommittee,BDC 23 : 2Members

SHRI P. D. ACoARWAL Public Works Depar tment , Government ofUttar Pradesh, LucknowSHRI V. S. AooARWAL Centra l Building Research Institut e ( CSIR ),Roorkee

SHRI M. P. J AIN ( Alternate )( Continued on page l2 )

2

8/6/2019 IS_1888_1982

4/13

IS : 1888- 1982

Indian StandardMETHOD OF LOAD TEST ON SOILS

( Second Rev ision )0. FOREWORD

0.1 This Indian Standard (Second Revision ) was adopted by the IndianStandards Institution on 30 November 1982, after the draft finalized bythe Soil Engineering and Rock Mechanics Sectional Committee had beenapproved by the Civil Engineering Division Council.0.2 Visual examination of the soil exposed in suitably located trial pits atthe site, combined with the already established data for different types ofsoils is commonly used for deciding on the safe bearing capacity. Whilethis procedure may be adequate for light or less important structuresunder normal conditions, relevant laboratory tests or field tests areessential in the case of unusual soil types and for all heavy and importantstructures. This standard covers plate load test method for determinationof ultimate bearing capacity of soil in place which assumes that soil stratais reasonably uniform. The load test included in the standard is alsoused to find modulus subgrade reaction useful in the design of raftfoundation -and in the design of pavements.0.3 Plate load test, though useful in obtaining the necessary informationabout the soil with particular reference to design of foundation has somelimitations. The test results reflect only the character of the soil locatedwithin a depth of less than twice the width of the bearing plate. Since thefoundations are generally larger than the test plates, the settlement andshear resistance will depend on the properties of a much thicker stratum.Moreover this method does not give the ultimate settlements particularlyin case of cohesive soils. Thus the results of the test are likely to bemisleading, if the character of the soil changes at shallow depths, whichis not uncommon. A satisfactory load test should, therefore, includeadequate soil exploration ( see IS : 1892-1979* ) with ~due attention beingpaid to any weaker stratum below the level of the footing.0.4 Another~limitationsis the concerning of the effect of size of foundation.For clayey soils the bearing capacity ( from shear consideration ) for alarger foundation is almost the same as that for the smaller test plate.- -__-__

*Code of practice for sub-surface investigation for foundations ( jrsl revision ).3

8/6/2019 IS_1888_1982

5/13

IS a88 - 982But in dense sandy soils the bearing capacity increases with the size ofthe foundation. Thus tests with smaller size plate tend to give conser-vative values in dense sandy soils. Tt may, therefore, be necessary to testwith plates of at least three sizes and the bearing capacity resultsextrapolated for the size of the actual foundation ( minimum dimensionsin the case of rectangular footings ).0.5 This standard was first published in lC62 and subsequently revisedin 1971. In the present revision, the use of apparatus has been generalizedand also specific sizes of plates have been mentioned for the differenttypes of soils, besides incorporating zero correction which was present in1971 version and prescribing log log scale for cohesionless and partiallycohesive soils.0.6 For the purpose of deciding whether a particular requirement of thisstandard is complied with, the final value, observed or calculated,expressing the result of a test or analysis, shall be rounded off in actord-ante with IS : 2-1960*. The ~number of significant places retained in therounded off value should be the same as that of the specified value inthis standard.

1. SCOPEi.1This standard lays down the method for conducting load test forestimation of bearing capacity of soils and its settlement.2. TERMINOLOGY2.1 For the purpose of this standard, the definitions given in 18 : 280%1972t and IS : 6403-1981$ shall apply.3. APPARATU3.1 Loading platform truss of sufficient size and properly designedmembers soas to estimate load reaction Tor conducting the test shall beused. The typical set up used for gravity loading is given in Fig. 1, forieaction loading in Fig. 2 and for loading truss in Fig. 3.3.2 Hydraulic jack of required capacity with properly calibrated loadmeasuring device, such as pressure gauge, electronic load cell, or proving,ring shall be used.3.3 Bearing P lates - Circular or square bearing plates of mild steel,not less than 25 mm in thickness and varyingin size from 300 to 750 mm

*Rules for rounding off numerical values ( revised ).$Glossary of terms and symbols relating to soil engineering ( jirst revision ).$Code of practice for determintaion of allowable bearing pressure on shallowfoundations ( first reuision ) .

4

8/6/2019 IS_1888_1982

6/13

WOODEN JOISTS OFSUITABLE SIZE WOODEN PLANKS

WOODEN JOISTS0F SUITABLE SIZE

15 cm # LOADING COLUMN(WITH PLUM BOB ARRAN

LE IRON STAKESODEN GUIDE JOISTS

TEST PLATE

NOTE - Ctamp could also be at 2ower level.FIG. 1 TYP ICAL SET UP FOR GRAVITY LOADING PLATFORM

6ALL AND SOCKARRANGEMENHEAD ROOM FORPERSON TO -SITAND OBSERVE

IF NECESSARYNOTE Dial gauge ixturemay be on the form clam p also.

FIG. 2 TYP ICAL SET UP I;OR REACTION LOADING PLATFORM

8/6/2019 IS_1888_1982

7/13

CROSS BARCHANNELSPIKEH.,,,RSf I-J

FIG. 3 TYP ICAL SET UP FOR LOADING TRUSS

8/6/2019 IS_1888_1982

8/13

IS : 1888- 1982with chequered or grooved bottom ( see Fig. 4 ), provided with handlesfor convenient setting and centre marked. As an alternative, cast in-situor precast concrete blocks may be used with depths not less than two-third the width.

All dimensions in millimetres.FIG. 4 DETAILS OF CHEQUERS OR GROOVES

3.4 S e t t l e m e n t R e c o r d i ng D e v i c e - Dial gauges with 25 mm travel,capable of measuring settlement to an accuracy of 0.01 mm.3.5 D a t u m B e a m o r R o d - Beam or rod of sufficient strength capableof maintaining straightness when fitted on two independent supportsfitted with arms or magnetic bases for holding dial gauges.3.6 M i s c e l l a ne ous A ppa r a t u s - A ball and socket arrangement,loading columns, steel shims, wooden blocks, collar, reaction girder withcradles for independent fitting to the reaction platform as necessary to theparticular set up.4. PROCEDURE4.1 Se lec t ion of Locat ion - The locations for load test shall be basedon exploratory borings, and unless otherwise desired, shall be conductedat an elevation of the proposed fouridation level under the worst estimatedconditions. In case the water table is within the depth equal to thewidth of the test plate, the test shall be conducted at water table level.In case water table is higher than the test level, it shall be lowered to thetest level and maintained by pumping through a sump, away from thetest plate, however, for the soils like cohesionless silt and fine sand whichcannot be drained by pumping from the sump, the test level shall also bewater table level.4.2 T e s t P i t - The pits, usually at the foundation level, having ingeneral normally of width equal to five times the test plate or block, shallhave a carefully levelled and cleaned bottom at the foundation level;protected against clisturbance or changes in natural formation.4.3 D e a d L oa d - The dead load of all equipment used, such as balland socket, steel plate, loading column, jack, etc, shall be recorded priorto application of load increment.

7

8/6/2019 IS_1888_1982

9/13

IS : 1888 - 19824.4 Size a n d S h a p e o f P la t e - Except in case of road problems andcircular footing;, square plates may be adopted. For clayey and siltysoils and for loose to medium dense sandy soils with N < 15, a 450 mmsquare plate or concrete blocks shall be used. In the case of dense sandyor gravelly soils ( 15 < N < 30 ) three plates of sizes 300 mm to 750 mmshall be used depending upon practical considerations of reaction loadingand maximum grain size. The side of the plate shall be at least fourtimes the maximum size of the soil particles present at the test location.

NOTE - N is the standard penetration resistance value determined in accordancewith IS : 2131-l%l*.4.5 T e s t A r r a n g e m e n t

4.5.1 The loading platform shall be supported by suitable means atleast 2.5 m from the test area with a height of 1 m or more above thebottom of the pit to provide sufficient working space. No support ofloading platform should be located within a distance of 3.5 times size oftest plate from its centre.4.5.2 The test plate shall be placed over a fine sand layer of maximumthickness 5 mm, so that the centre of plate coincides with the centre ofreaction girder/beam, with the help of a plumb and bob and horizontallylevelled by a spirit level to avoid eccentric loading. The hydraulic jackshould be centrally placed over the plate with the loading column inbetween the jack and reaction beam so as to transfer load to the plate.A ball and socket arrangement shall be inserted to keep the direction of

the load vertical throughout the test. A minimum seating pressure of70 g/cm2 shall be applied and removed before starting the load test.4.5.3 The two supports of the reference beam or datum rod shall beplaced over firm ground, fixed with minimum two dial gauges resting atdiametrically opposite ends of the plates. The dial gauges shall be soarranged that settlement is measured continuously without any resettingin between.

4.6 L o a d I n c r e m e n t s - Apply the load to soil in cumulative equalincrements up to 1 kg/cm2 or one-fifth of the estimated ultimate bearingcapacity, whichever is less. The load is applied without impact,fluctuation or eccentricity and in case of hydraulic jack load is measuredover the pressure gauge, attached to the pumping unit kept over thep i t , away from the testing plate through extending pressure pipes.4.7 S e t t le m e n t a n d O b s er v a t i o n - Settlements should. be observedfor each increment of load after an interval of 1, 2.25, 4, 6.25, 9, 16 and

*Method for standard penetration test for soils (.first revision ).8

8/6/2019 IS_1888_1982

10/13

IS : 1888 - 198225 min and thereafter at hourly intervals to the nearest 0.02 mm. Incase of clayey soils the time settlement curve shall be plotted at eachload stage and load shall be increased to the next stage either when thecurve indicates that the settlement has exceeded 70 to 80 percent of theprobable ultimate settlement at that stage or at the end of 24 hour period.For soils other than clayey soils each load increment shall be kept for notless than one hour or up to a time when the rate of settlement getsappreciably reduced to a value of 0.02 mm/min. The next increment ofload shall then be applied and the observations repeated. The test shallbe continued till, a settlement of 25 m m u n d e r n o r m a l c i r c u m s t a n c e s o r50 mm in special cases such as dense gravel, gravel and sand mixture, isobtained or till failure occurs, whichever is earlier. Alternatively wheresettlement does not reach 25 mm, the test should be continued to at leasttwo times the estimated design pressure. If needed, rebound observa-tions may be taken while releasing the load.5. DETE RMINATION OF ULTIMATE BEARING CAPACITY/

SAFE BEARING P RE SSURE/SETTLEMENT5 .1 Sh a p e of t h e Lo a d /Se t t l e m e n t C u r v e - A load settlement curveshall be plotted out to arithmetic scale. From this load settlement curvethe zero correction which is given by the inter-section of the early straightlines or the nearly straightline part of the curves with zero deadline shallbe determined and subtracted from the settlement readings to allow forthe perfect seating of the bearing plate and other causes.

5.1.1 Four typical curves are shown in Fig. 5. Curve A is typical forloose to medium cohesionless soil; it is a straightline in the earlier stagesbut flattens out after some time, but there is no clear point of failureCurve B is for cohesive soil; it may not be quite straight in the earlypart and leans towards settlemCnt axis as the settlement increases. Forpartially cohesive soils curve C possessing the characteristics of both thecurves il and B is obtained while curve D i s purely for dense cohesionlesssoils.5.2 From the corre~cted load settlement curves no difficulty should beexperienced in arriving at the ultimate bearing capacity in case of densecohesionless soils or cohesive soils ( see Fig . 5 , curves D and B ) a s t h efailure is well defined. But in the case of Curves A and C where yieldpoint is not well defined settlements shall be plotted as abcissa againstcorresponding load intensities as ordinate, both to logarithmic scales ( seeFig. 6 ), which give two straightlines, the inter-section of which shall beconsidered as yield value of soil.5.3 From Fig. 5 the safe bearing pressure for medium and dense sandscould be read, corresponding to a settlement ( S, ), which shall be

9

8/6/2019 IS_1888_1982

11/13

IS:1888-1982ULTIMATE BEARINGCAPACITY ,

N(A) LOOSE TO MEDIUMSOIL COHESIONLESS SOIL

FIG. 5 LOAD SETTLEMENTCURVEScalculated as under ( St taken as permissible settlement of footing ( seeIS : 1904-1978 ):

1(Bp + 0.3) 2Sr = s, BP ( B + 0.3 > IwhereB = the size of footing in m,BP = size of test plate in m,S, = settlement of test plate in m, andSt = settlement of footing in m.

From this formula total settlement of footing ( Sr ) is calculatedtaking Sp as observed total settlement of plate.6. REPORT6.1 The continuous listing of all time, load and settlement data, for eachtest shall be recorded with details of test elevation, natural water table,profile of test pit, size of bearing pIate and irregularity, i f any, in routineprocedure.6.2 It is necessary to excavate soil below the test plate to a depth equalto twice the dimension of the plate so as to examine and record the sub-soil profile.

..____*Code of practice for structural safety of buildings :revision ) . Shallow foundations ( second10

8/6/2019 IS_1888_1982

12/13

Da SETTLEMENT

o-5 1 5 10 50Settlement in mmFIG. 6 LOAD SETTLEMENTCURVE

( Lot -LOG SCALE )

8/6/2019 IS_1888_1982

13/13

IS : 1888 - 1982( Continued from page 2 )

Members RepresentingDRALAM SUCH* University of Jodhpur, JodhpurDIRECTOR Central SoilNew Delhi & Material Research Station,

DIWUTY Drn~~~ox ( CSMRS ) ( Alternate )E x E c u T I v E E N c I N E E n Central Public Works Department, New Delhi( DESIGNS ) VE x E c TJ T I v E E N a I N R E n Public Works Department, Government of(SM&RD) Tamil Nadu, MadrasEXECUTIVE ENGINEER ( CD ) ( AlternateTOINT DIREC~COR RESEAILCH Ministry of Railways ( G.E.-II ) RDSODEPUTY DJRECT~R ( G.E.-II )RDSO ( Altermzle

SHRI M. D. Nara Associated Instruments Manufacturers (I) Pvt Ltd,New DelhiPROF T. S. N.~GARAJ ( Alternate )SHRI T. K. NATIEJAN Central Road Research Institute ( CSIR ), New DelhiLT-COL I(. M. S. SAnASI Engineer-in-Chiefs Branch ( Ministry of Dt,fence )SHRI A. K. ClI_4TURVEDI ( ~h%Ut~ )SHRI S. K. SHOM~ Geological Survey of India, Calcutta

SHRI P. N. M~XTA ( Alternate)SHRI N. SIVAoUaU Roads Wing ( Ministry of Shipping and Transport )SHKI P. K. THOMAS ( Alternate )SUPERINT~NIJINO EN~INREIL ( IC ), Irrigation Department, Government of Maharashtra,NAUPUR Bombay

*Acted as Convener.12