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1、第30卷第1期重庆建筑大学学报Vol.30No.12008年2月JournalofChongqingJianzhuUniversityFeb.2008论土体应力应变关系曲线类型和临界状态11,2周葆春,王靖涛(1.信阳师范学院建筑工程系,河南信阳464000;2.华中科技大学土木工程与力学学院,湖北武汉430074)摘要:为探讨应力历史对土体本构关系的影响,进行了一系列正常固结土和超固结土的排水剪切常规三轴压缩试验,对比具有不同应力历史的土体应力应变关系曲线发现,对于体应变,超固结比是决定性因素,而体应变对固结压力不太敏感。对于抗剪能力,固结压力是决定性因素,超固
2、结比的影响也不可忽略,超固结比决定了是应变强化还是应变软化,且决定了应变软化的程度,但试样最终会达到一个统一的临界状态,具有大体相同的残余强度。根据塑性体应变与塑性剪应变之间的相互作用原理阐明,土体变形过程中,塑性体应变的变化控制了剪切抗力的升降,从而决定了土体应力应变关系曲线的类型;临界状态实际上是一个纯粹剪切变形过程,其中不发生塑性体应变与塑性剪应变之间的相互作用,压硬性、剪胀性、应力路径相关性统统消失,它与以前所经历的应力历史无关。关键词:土体本构关系;临界状态;应力历史;相互作用原理;超固结比;固结压力;应变强化;应变软化中图分类号:TU43文献标志码:A
3、文章编号:100627329(2008)0120063205OntheTypeofStress-strainRelationCurvesandtheCriticalStateforSoils11,2ZHOUBao2chun,WANGJing2tao(1.DepartmentofArchitecturalEngineering,XinyangNormalUniversity,Xinyang464000,P.R.China;2.SchoolofCivilEngineering&Mechanics,HuazhongUniversityofScience&Technolo
4、gy,Wuhan430074,P.R.China)Abstract:Inordertodiscusstheinfluenceofstresshistoryontheconstitutiverelationsforsoils,aseriesofdrainedconventionaltriaxialcompressiontestsfornormallyconsolidatedandoverconsolidatedclayshavebeencarriedout.Itisfoundthroughcomparingthestress-strainrelationcurves
5、underthedifferentstresshistoriesthattheoverconsolidatedratioisthedeterminingfactorforvolumetricstrain.Thevolumetricstrainislesssensitivetoconsolidationpressure,however.Fortheshearcapacity,theconsolidationpressureisthedeterminingfactor,buttheinfluenceoftheoverconsolidatedratiocannotben
6、eglectedsinceitdetermineswhethertherewillbestrainhardeningorstrainsofteningaswellasthegradeofstrainsoftening.Despitethat,thesoilspecimenswillfinallyreachaunifiedcriticalstateandapproximatelythesameresidualstrength.Accordingtotheprincipleofinteractionbetweenplasticvolumetricandshearstr
7、ains,themechanismofgeneratingtwotypesofstress-strainrelationcurvesforclaysisexplained.Itisshownthatthecriticalstateisapureprocessofshearingdeformationinwhichtheinteractionbetweenplasticvolumetricandshearstrainscompletelydisappears.Thecriticalstateisindependentofthepreviousstresshistor
8、y.Key
