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18218(2):12412819994ChineseJournalofRockMechanicsandEngineeringApril,1999()(12DEVP)2Graham,,,,O344.612,Bjerrum22Graham(e2quivalenttime),(12DElasticVisco2Plastic,12DEVP),2,Bjerrum1967,[1],,2,Bjerrum,Graham1989Bjerrum,,,6,[2],Graham[3],,[4,5],/,,1,20mm,,1020min,(z2t)1020min21,,[2,3](),ez=ez0+mez(1):ez,z,ez0,me(1)1Fig.1Equivalenttime,referencetimelineandelasticline1998119,19981228:,,,/2,meepz=epz0+mep(z-z0)(2):epz;epz0z0,z=z0,epz=epz0;mepepz0,z0mep,:tpz=Vlnt0+tet0(3):/Vt0,,(3)tet,(3)te=0,i(i+1),,t(i+1),1(i+1),te=0,te=t0,(3),/Vt0[2,3],,/V,(),(3),(i+1)dtpzdte=V1t0+te=V1t0+t(4),()(i+1)(i+1),1,,(i+1)?Bjerrum22Grahamte[2,3],()(i+1)(i+1),(i+1)dtpzdte=V1t0+te(5)((5)),2,1i,,i2196.2kPa()196.2kPa()2(a),,(),/Vt0(,),,iii,(3)(5)(5),idtpzdtei=V1t0,,idtpzdtei=V1t0+teiidtpzdteidtpzdtei,tei0,z=epz0+mep(z-z0)+Vlnt0+tet0(6)(6)te,,(a)(b)2Fig.2Creepunderinitialloadingandreloadingdezdtpz:dz=dez+dtpz=medz+Ûtpzdt(7)(1),dez=medzdtpzdtpz=ÛtpzdtÛtpz,(5),(6),tete=t0expz-epz0-mep(z-z0)/V-t0(8)(8)(5),ÛtpzÛtpz=V1t0+te=Vt0exp-[z-epz0-mep(z-z0)]/V(9)(9)(7),521182.dzdt=medzdt+Vt0exp-[z-epz0-mep(z-z0)]/V(10),,(10),1,/V=0,(10)(10),/V=0,dzdt=medzdt,(1)(6),/V=0,z=epz0+mep(z-z0),(2)/V=0,,,[2,3][3],/V0,(10)(1)(2)3,me(1)/2,(3)/Vt0epz0,mepz01,(i+1),(i+1)(z(i+1)z(i+1)),,(2),z0=z(i+1)epz0=z(i+1),1,,(i+1)(i+2),t(i+2)(i+1)z(i+1),z(i+1)(i+1)(i+1),(1),(i+1)z(i+2)z(i+2),z(i+2)z(i+2)(i+2)te,(i+2)(8)te,(i+2)=t0expz(i+2)-epz0-mep(z(i+2)-z0)/V-t0(11)(i+2)(i+2)t,(i+2)te,(i+2)te,(i+2)=te,(i+2)+t=t0expz(i+2)-epz0-mep(z(i+2)-z0)/V-t0+t(12)(11)(6),(i+2)z(i+2)z(i+2)=epz0+mep(z(i+2)-z0)+Vlnt0+te,(i+2)t0(13)(12)te,(i+2)(13)z(i+2)=epz0+mep(z(i+2)-z0)+Vlntt0+expz(i+2)-epz0-mep(z(i+2)-z0)/V(14)t(i+2)z(i+2),z(i+2),mep,mep,42Graham2Graham,2(),:ez=ez0+Vlnzu(15):u,ez0,V=1+e0(e0)/V(15)/2,/V(2),:ez0=epz0+Vlnzz0(16)z=z0,epz=epz0z0epz0/Vepz2lnzz03[2,3](3),Ûz=VÛzz+Vt0exp[-(z-epz0)V]zz0/(17)2Graham(12DEVP),,,,24hCc,/Cr,Cezczc6:Crln(10),Ccln(10),epz0=zc,z0=zc,Celn(10),t0=t24(18)V=1+e0621199952Graham3(17)23,2Graham(,)[2](a)(b)(Backebolclay)[6]3,[2]Fig.3Stress2strainrelationshipsunderconstantrateofstrain,comparisonofcomputedandmeasuredresults[2]62196.2kPa()(t1)196.2kPa()(t2)(,t1t2),2(a),196.2kPa(),t=(t1+t2),2(b),,43=3.6MPa,q=1-3=21.5MPa262h,q=0,15h,q=21.5MPa[7]4,,4,,,4,3=3.6MPaq=1-3=21.5MPa,262hq=0(15h),q=21.5MPa[7]Fig.4Verticalcreepstrainversustimeinhours,confiningpressure3=3.6MPaandderiatorstressq=1-3=21.5MPa,262hafterinitialloadingcreep,thespecimenwasunloadedtoq=0in15h;continueingcreepafterreloadingtoq=21.5MPa[7]7(12DEVP)2Graham[2,3],,,(12DEVP)[4,5],721182.(q=0)(17)(evolutionlaw)1BjerrumL.SeventhRankineLecture:EngineeringgeologyofNorwegiannormally2consolidatedmarineclaysasrelatedtosettlementofbuildings.Geotechnique,1967,17(2):811182YinJH,GrahamJ.Viscouselasticplasticmodellingofone2dimensionaltimedependentbehaviourofclays.CanadianGeotech.J.,1989,26:1992093YinJH,GrahamJ.Equivalenttimesandelasticvisco2plasticmodellingoftime2dependentstress2strainbehaviourofclays.CanadianGeotech.J.,1994,31:42524YinJH,GrahamJ.Elasticvisco2plasticmodellingofone2dimentionalconsolidation.Geotechnique,1996,46(3):5155275YinJH,GrahamJ,ClarkJI,etal.Modellingunanticipatedporewaterpressuresinsoftclays.CanadianGeotech.J.,1994,31:7737786SallforsG.Preconsolidationpressureofsoft,high2plasticclays[Ph.D.the2sis].Sweden:ChalmersUniversityofTechnology,19757YangCH,DaemenJJK,YinJH.Experimentalinvestigationofcreepbehaviorofsaltrock.AcceptedbyInt.JournalofRockMechanicsandMiningSciences,1999EQUIVALENTTIMEANDELASTICVISCO2PLASTICMODELLINGOFGEOMATERIALSYinJianhua(DepartmentofCivil&StructuralEngineering,TheHongKongPolytechnicUniversity,HongKong)AbstractTheconceptsofequivalenttime,referencetimelineetc.areintroducedandasimpleone2dimensionalelasticvisco2plasticmodel(12DEVP)isderived.YinandGrahams12DEVPmodelanditsverificationarealsointroduced.Thecreepdataofamarineclayandasoftsaltrockareusedtoexaminetheloading2historyindependenceofequivalenttimeandcreepstrainrate.Itisshownthatthegeneral12DEVPmodelwillapproachtotheelasticlineandthereferencetimeline(e2lastic2plasticline)whenthecreepparameter/Vapprochestozero.Keywordscreep,elasticvisco2plasticity,constitutiveequations,geomaterials,19988,16,336,49.7,42,66,4ViziCAD,199312,16,43,68ViziCAD,,,,,,,,,,,NURB,8211999