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PROCEEDINGS OFTHE INTERNATIONAL SYMPOSIUM ON OEOTECHNICAL ASPECI'SOF UNDERGROUND CONSTRUCTION IN SOfT OROUND - IS·TOKYO'99TOKYO/JAPAN/19-211ULY 1999

Geotechnical Aspects ofUnderground Constructionin Soft GroundEditedbyO.KusakabeDeptll'tmen/ ofCivil Engineering, Toi,yoInstitute ojTechnolop JapanK.FujitaDepartment ojCivü Engineering. Science University ojTokyo, Chîba, JapanY.MiyazakiObayashi Corporation. Tokyo. Japan

OFFPRINT

A. A. BALKEMA 1ROTTERDAM 1BROOKFIELD 12000

..

The Rotterdam sheet pile wan field test Test setup

D.A.KortGeotechnicaJ Laboratory, Delft University ofTechnology, Netherlands

A.F:vanTolRotterdam Public Works anti Geotéchnical Laboratory & Delft University ofTechnology, Netherlands

A.JonkerCentre for CMl Engineering Research anti Codes, Netherlands

ABSTRACT:The recent devc10pmcntof Eurocodes inthe design prac;ticefot steel sheet pUing bas led te theinitiative for a full scale field test on two steel sheet pi1ewaUs in soft soU.The mam goal.of tbis field test1$to e~ the ~ o(t,wo &cm, sincIe strutted steel sheet pi1ewaD$ wim a Iengtb of 19mdIaad a width of 8 metres. InonewaU apla$tic biaF wül be developed te obtain a tedislnbution of beadinB~ts;the ether waU is composed of double U-piIes te examine the ~ of "obüquc beDding".Pof ·tbisfield test aquestion fortype A ~ was distributed te 50 ~ engineers woddwide.Tbis Paper describes tbesetuPof tbc field test. Tbis test may contnÖllte te a better understaPding of bothplastic design andsheet pi1e design wim double U-sedions and ma)' themore lead te a safer ad moreeconomie design of steel sheet pi1ewaUs.

1 INTRODUCTION

The introduction of Eurocodes in tbc design practiccfor steel sheet piling ma)' .Jead to a .graàua1replacement of natîoua.1 building codes by ODeEuropean Stal1dard.ENV 1993-$(CEN 1997) trellt$,together wim ENV 1997-1 (eEN 1994), tbc designof steel sheet piling. ENV 1993-5 offers thepossibility teintroduce plastic lûnges in the designof steel sheet pile waUs andgives guidance bymeaos of a stepwiseprocedure.If tbc excavation in front of a sheet pile wall is

continue

composed of single aad double U-piles is alsetreated. In case a lack of friction in the drivinginterlocks exists, the sheet piles will oot tully work

D1Ip' .•••

rf f... .. .. .

• ••_ •••~.!' ····-f '~.': ..:.:.;r

rf f.. pIalIc

11 ••••••••• •• - ••!!! ••.... -( ·~.·: ..:èP

10,4= 11 t pIalIc ... r:»:':':~• .... _1~~ ...••.....~ •••:J-....'C~:..:CJ.__ .......•..•........."...Figure I: States of snesses ina sheet pile wallduring anexcavation (Hartmann-Linden 1997)

together in bendm,. which may be c1ear for tbesingle piled wall. However. due te the rotated neutraluis, tbe wall composed of double U-piles might ooton1)'bend out of plaae but also in plane of the wall,This pbeoomenon iscalledoblique bending and caocaese a considerabie loss of strength aod stiffness oftbe sheet pile walt The Netherlands is probably theonly country wbich has severe design rules foroblique bendingof steel $heet pile wali$. In mostother countries the problem of missing interlockfriction for double U·piles is denied. because oblique

537

,.

~~Pipre 2; BeDditlgof Imp and double U-seetions

bendiq bas bardlyever beea observed m practic:e. InlOme couatries even smp U-piles are treated astullycooperatiDg. At tbis moment it is DOt cl_wbether steel sheet pi1ewall dtsiJn istoo expensivein tbe Ned1edandsot·unsafe ia tbe otbercouotries.Large ~fieJd tests on &heet pUe w$lis

~·of.mp U-piles ia Le Havte(HebM etal. 1918)and m Paris(Gipn 1984) proved 10bel all~ve ~. toiavestiptetbe. Ioss of bending~ ••. «0. missiDgintedoct friction. However.dw'bl,tbe ~ofEwoèode3 part , sufficient~ •..was.missiag .fot tbe tIeveIopmeI1t of~ ~ 1:Ules.fot U-seetions.~~pVerise fottbe Geotecbttical '

~of ~Uni"".., of Tedmology andtlacnutcb~fotQvn SnllneeritJg &eseatcb andCadet (Cl.Jl) to _date • fuIl scale fieJdtest iaDutch· softsoil widl abisl\poundwater level. In tbistest «he MearCh is .focused 08;

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.. ~porforttWlCe of a ~ pi1ewall witb a plastic~;

.. ttiepedorttWlCe a sheet pRe wallconstructed ofdouble U-sectlons;

- tbesbott-term and tbe long-term performance ofboth sheet pile walls ia soft soit

Por tbis field test a square buildlng pit ofapproximately 121012metre is constructed in wbieb

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\ •••••. Ic I'b .••••• 1QD"

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Figure 3; Layout of tbe sheet pile walls

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two test walls are inc1uded. In order to obtain abenchmart for calculaûoD tools specialmeasurements are foreseen fot a 2-dimensionalpedorttWlCe·of botb test walls.Tbis ,... presents oecessary information to

pedorm a predietioDfor this field test TM Paperdf>scribes«he !ayoutof tbe test site, tbe soUdata, tbe~ details, tbe test sequenceand a possible•__ wbeD dw'blI tbetest tbe plastic ~. isdeveloped. PiaaIlytbe,... motivates tbe questioofor predictions, wbieb bas been distributedto morethan SO specialists in sheet pUewall design.

2 LAYOUT OF TUE TEST SITE

Fipre 3 shows tbe Iayout of tbe sheet pile walls.TM four Walls are instaUedia. all $lmost squareform. wbich sldes of about 12 metre. The top of tbesheet piles is at NAP +1;() m (NAP is Dutch~ltvel) ancltbegreeafield.is at NAP .(U Dl.tbe flOrth. and tbe south walls are test w$lls. In onferto minlmise tbe comer effects on ·tbetest walls, fourbentonite screens have beea instal1ed and fourspecial intetface piles have been developed wbiebare ent over a length of 16 metre.

2.J Hordt waIlTM north wall consists of 10 double pHes ArbedAZ13.Of tbem. 6 foon tbe test wall, 2 tbeinterf'acingpilesAZ13S(see below) and 2 tbe cornerpHes. TM intmonneCting interlocks of tbe doublepiles have been weJdedover tbe fulI length but fottbe driving interlocksae lpecW measures bave been

I9~oooooooooooooooooo\ tol ••• lellilW •••• hoh '1GO 1500-

taken. Tbc sheet pdes have .•been vlbrated toNAP -18 m. On test piles ••At. Mand ASinclinometer tUbeshave heen .l~ Test pile A3 isequipped witb 12 earth press!ieeelis. 4 on theexcavated side and 8 on tberetijnh\g side, and testpile A4 witb 40 vibratins wire (VVI) strain gauges.

2.2 South waU

Tbe test sectkln is formed by 7 double U-pilesLarssen 607K from Hoesch,Hl to H7. Tbcinterlocks ofthe doublepiles ha'vebeen .tded butfor tbe drivins interlocks no spec:ialmeasl1reShavebeen talcen. Tbc lOOGt the sbeetpiles bas beeninstailedatNAP-18mette. On~tpiIesH2, H4 andH6inclinometer tubeshave~welded. Test pileH3 isequîppedwitb 12 earth~ eeUS,4 on theexcavatedside and 8 onthe ~g side and testpileHSwitb 40vibrating w~~ gaup.Tbcsoutb wall is compJetedby 2~ piIes AZl3Sand two·~ piles H8 andH9.

2.3 &st (l1'lI/ west walls

Tbe east andthe west walls are~ formed by 20single· pilesLX32 oom Britisf:l$eel. These piIeshave been .îostalled to NAP-20metre in order tominimise disturt>anceoftbe paijiVe zones of botbtest walls. tbc pilesBS6,B$i4.tJS26 and BS34 areequipped witb inclinometer tubes.

2.4 Special interface pile$ AZJ3S

As the corners of tbc building pit would have astrong infiuence on the test walls. 4 special interfacepileshave been deve1oped.seeFagure 4. Tbese pUes.consistingofAZ13 sectionsareculover alength of16 mette. In order to prevent w~rleabge into thebuilding pitthe gap bas been co~ witb a 2 mmtbielt VLDPE foU. For a betterdl'ivability of thesepiles 2 mette attbcpiletoe and lmetreat tbc top oftbepile are J:érnaitîedintact andforthe proteetion oftbc foU tbc speçial piles are. plll(l~ in abentonitecolumn wbichteaehes tONAP -US m. Afterdrivingtbe pile is alse cut at tbc top.

t5 Bentordte sereensBehindeach test wall twe bentonite screens havebeen installed. Tbcbentonite screens.arè eomposed()fbentonite-soilcolW1ln$lifSOO-7QOwhicharemixed-in-place witb a hOliowauger rig. The toe ofthecolumns varies from NAP -13Senclose to the testwaU te NAP -3.5 en at 13 metres bebind the testwal1s. Inside tbc building pitthe bentonite screens

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l 'I~Figure 4: Special interfacepiles

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have been left out because of possible seepageduring excavation.

2.6 Struts and walings

Tbc plan of the struts md walings is given in FigureS. Tbc centre line of tbe frame work is at NAP+0.75 m.Tbc stmtsfor the test walls north and southare desi~ in a war that both test wallsactindependendy andare not infiuênCed by tbe othersheet piles. Tbc differencebetweenthe strut fèreesis led to thestiffHE600B struts between theeastand the west wal1s.Thestruts and tbe walings areconstrueted as hinged connections wim sufficientrotarioncapacitybetweenthe sheet pile wal1saad the

Table 1: Struetural data of tbc sheet piles

$ecûQll

AZt3L601K

Ix cm4Jm Wxcm~1m

137244

t970070030

13003220

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Table 2: Summary of soil parameters

Trialtial tests (1=2"') SIiffness pIIl'lIInClm V_tests

Top level Soil Type r•••(kNlm3) c'(kNIm~ •• (0) Bso (MPa) Ic (kNJm3) f,. (peat value)(m-.NAP) (t.NImi

0.5 sand 18 0 30.0 2.0 7000I~ clay, silty 16.6 6.3 29.4 3.5 2000 67.6

sfiabtly sandY5.75 put 10.0 9.3 18.9 2.7 800 65.79.00 put very clayey 10.6 11.8 20.1 3.2 2000 64.310.50 elI)', humous 13.9 7.0 20.0 5.2 37.612.50 clay, sllghlly 16.2 7.4 27.1 6.2 1400 32.8

sandY16.10 clay, highly 12.3 5.0 25.0 10.3 1200 30.7

silty17.00 clay, sIlghlIy 16.2 7.4 27.1 6.2 1000

, sandYio17.50 . sand,siIty, 9.8 37.9 10.0 ooסס1

medium coarse18.50 saad, coarse 20 0 38.0 10.0 ooסס1

~ ~ Tbc strut frame îaclude8 6 pressureeens: 4 eeUs to measm:e tbc Iateral stNt force of tbcIiortb lUId soutb test waUs and two to measure tbcaxiai force in tbc waling of tbcdoubie U test waIL

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3 MATERÎAL ~ARAMETERS

3.1 StiUitural data

Tbc most relevant stmeturai data of tbc sheet pile ispresented in Tabie 1. Siace OM of tbcaims for thisfield tést is to investigate a waU witb a plastic binge,it is important for tbc design tbat tbc failure chanceof tbc north waD is as high as possible, wbicb is ofcourse in contrast witb common designs. Tbereforetbe AZ13 test pi1es have an unusuallow yield stressof about f,=280 N/mm2, wbich results for elastic-plastic stmeturai models in M,,=426 kNmlm'. For tbestmts and walings tbc stiffuess and tbe ultimatestress may he consi.dered as sulflcient high.

3.2 SOUdata

Tbc soil data is obtained from an extensive soilinvestigatiOl1 programme cOl1sisting of common-usedin situ tests, such as CPT's, vaae tests, andpressurerneter tests and laboratory tests,such asoedorneter tests, triaxial compressiOl1 and extensiOl1tests (CUR 1998).In Figure 6 a representative CPT is presentedas

weU as tbe initial water pressures. Tbe soil consistsof a 16.5 rnette nonnally consolidated soft clay-peat-clay stratiflCation. Underneatb, tbe normally

Cooo"'-'- !MP'Iw_ •.••••(1OIlPIl

• • q M g • ••

• • • • • ft ~ M ~Friclloa_

Figure 6: CP'f and piezometric heads

consolidated Pleistocene saad layer is found, wbichis connected to tbe river Maas 2km fartber. Tbcinitial water pressures in tbe different soil layers isdetermined witb 9 piezorneters and 3 open standpipes, A summaty of the most relevant soit data ispresented in Table 2.

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TEST SEQUBNCE

efoce tbc start of tbc test,me ~leld level was, a leve! of NAP -1;6 m. In ordClrtomake tbc testte accessible for tbe CPT and bpl'erias, craaes andtber constJ:'tlÇÛ(meqtltpment, tbc •• site was filledI'St with OAmetre dry sand aDd.••~ ffiled llpto Iletre·sand in total. The test is ~ in 4 ~.

tagel

!ter constrUCtioo of tbc sheet .pile walIs, tbcmtOtlite screeas andtbc .stmtframe, a dry(Cilvationisexecutedto NAP 4m; bath soit andllter are removedto tbis JevekTbeexcavatiool~t is simated as much aspossible bebind meIStwaU.

'age 2

l1ewater'in me excavatiOtlis ~toNAP -l.S Dlld tbc excavatiOtl is subsequeatty h1creased.to avel ofNAP-7 111. During tbc~vtWOQ ••. wateJ'vel is kept at NAP -1.S 111.

age 3)wering the water level to NAP·S. Dl in S steps.te lntennediate steps are NAP ·2.~m..NAP -3-'m,I\P 4.0 m,NAP 4.5 Dl andNAP~S.O Dl. AfterdJeird Stepto NAP 4 an evaluationstep is iDtroduced.on:IetCO ·assessmecritical f~lOad of me north111.

'Jge4

aintainingtbc fmal water' level of stage 3 for ariod of 6 months.

!ring allstage5 measurementsarec.ried out fromûch me action effects can be derîved, such asera} and transverse walt displàcements, strotI'Cês.bendins moments and earth pressures, Ammary of tile activities with acumulative timelJe is given in TabJe 3.

EXECUTION OF THE TEST

Ie of tbc difficulties of tbc .desip. is thattbc testtbc wan with a plastic hinge isadestructive testd tbcrefure not tree from danpr.Moreover. the'lering of tbc water level isa lOad COtltro1leddng procedure, whereas tbc pl$Sûc mnge bas a

Table 3: Test sequcnce

IlO. aetivity time

U SQdau· te NAP·1.25m 0l.2 saad·sill te NAP -0.65 m 1252 slleet.piIodriYÎlti 2963.1 dry .cw:avatioate NAP 4.0 m 3313.2 mi WiCJl· water te NAP -I.S m 335•• excaYllÛOlluader·WII« te NAP -7.0 m 3405.1 ~ ••• ~ te NAP -2.5 til 3425.2 I~ water level te NAP -3.5 m 3455.3 ~ w•.. ~ te NAP 4.0 m 3465.4 evllhraáoDoftest data5.5~w •• ~ te NAP 4.5 m 3555.6 ·lowermJwater level te NAP -5.0 m 3596lo1l •• tmnpcrf~

...- álIme&er

lIlnIl

RotaIioII of top sbeeI piIe wd (rad]1

o +---+--+---1i. ·11.2J .3Jt •••1.,

-6

-1

1.•..FJgllFe7: Rotationof tbc sheet pile around tbcstrut due totbc lowering of tbc water leve!

softening behaviour due to tbc oombinatioo ofyieldingand Iocal buckling (Van Toland Kort.991). Consequendy, if tbc Iowering of the waterlevel in front of tbc sheet pile walt iscontinued aftel'yielding in dJe ultimate libre occurs (sec Fipre I>,Dot only theplastic mnge is developed, but also tbcresistance of this plastic hingedecreases, which maycause asudden and unpredictable deve10pmentof thesecondpiastic binp.In order la COtltrolthe execution of the test, the

water level is lowered withaspeed of 10 cm perbour. The formation of the plastic moge will beobserved in real time wim a tittmeter, wmchmeasures·the tilt of !he sheetpile ·cWseto the st.I:Uts,and a piezometer \\'bieb· measures tbc water levelinside thebuilding pit: a sudden tilt ofthe sheet piein compari$Otl wit1l the water head inside thebuildinspit indicates tbc formation of tbc plastichinge. sec Fipre 7.

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6 PREDICl'ION QUESTION

The interest ofpredietions in geotecbnka1engineering is elttensive1y discussed by Lambe(1973). Von Wolffersdorff (1997) Otganized (also incooperation wim tbc CUR) a fI.lU~scalefield test andinclU

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