击实粘性土断裂韧度KIC的试验研究

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1、第24卷第21期岩石力学与工程学报Vol.24No.212005年11月ChineseJournalofRockMechanicsandEngineeringNov.，2005击实粘性土断裂韧度KIC的试验研究王俊杰，朱俊高(河海大学岩土工程科学研究所，江苏南京210098)摘要：用线弹性断裂力学理论，研究土体中裂缝的产生和扩展过程的可行性已经为很多学者所认可，但对土体断裂韧度断裂韧度KIC的测试方法尚未形成共识。标准的三点弯曲试验中，土梁可能仅在自重作用下就发生断裂破坏，即使不发生这种试验前的断裂破坏，由于试样自重与断裂荷载相比是不可忽略的，试样自重对试验结果也存在较大影响。首先对标准三点弯

2、曲试验方法进行了改进，研制了适于测试土体断裂参数的测试仪，并用其对某堆石坝心墙料的室内击实试样进行了断裂韧度KIC的测试，论证了线弹性断裂力学的适用性，研究了试样干密度和试验含水量对断裂韧度KIC的影响。关键词：土力学；线弹性断裂力学；断裂韧度；三点弯曲试验；土体断裂试验仪；干密度；含水量中图分类号：TU47文献标识码：A文章编号：1000–6915(2005)21–3972–06LABORATORYSTUDYONFRACTURETOUGHNESSKICOFCOMPACTEDCLAYWANGJun-jie，ZHUJun-gao(InstituteofGeotechnicalResearch，H

3、ohaiUniversity，Nanjing210098，China)Abstract：Itiswidelyacceptedthatthelinearelasticfracturemechanics(LEFM)canbeusedtoinvestigatetheinductionandpropagationofcracksinsoil，especiallyforover-consolidatedandhardclay，butnomethodisacknowledgedtobeperfecttodeterminefracturetoughnessKICofsoilinlaboratory.Inco

4、nventionalthree-pointbendingbeamtest，thesingleedgecrackedbeam(SECB)maybefracturedonlyduetogravityitself.Evenifnofracturefailureofspecimenoccursbeforetest，theinfluenceofthegravityofthespecimenontestresultscannotbeignoredbecauseitisnotlittleenoughcomparedwithfractureload.Inthisstudy，animprovedmethodof

5、three-pointbendingbeamloadingtestissuggested，whichcanavoidthefracturefailurebeforetestandremovetheinfluenceofthegravityofthespecimenbecausetheloadingdirectionishorizontal.Basedontheimprovedmethod，anapparatustodeterminefracturetoughnessKICofsoilisdeveloped.Theapparatusdoeshaveverysimplestructure，buti

6、tsoperationisveryeasyanditstestresultisreasonableenough.Usingtheimprovedtestingmethodandthenewapparatus，thefracturetoughnessKICofcompactedclaywhichisusedtobuildthecorewallofahighrock-filldaminWestChinaisinvestigated.ThereasonabilityofLEFMusedtodescribethecharacteristicsoftheclayinthecourseoffracture

7、failureistestified.TheinfluencesofdrydensityandwatercontentintestingofspecimenonKICarealsoinvestigated.Forthespecimenswhicharemadeunderthesamewatercontent，thevaluesofKICincreasewiththeincreaseofthedry