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1、第30卷第8期北京科技大学学报Vol.30No.82008年8月JournalofUniversityofScienceandTechnologyBeijingAug.2008不同强度岩石的破坏过程及声发射数值模拟王学滨辽宁工程技术大学力学与工程科学系,阜新123000摘要采用FLAC模拟了初始内聚力及内摩擦角对具有随机材料缺陷单轴平面应变压缩岩样破坏过程及声发射的影响;采用编写的若干FISH函数规定随机缺陷及统计发生破坏的单元数目.密实的岩石服从莫尔-库仑剪破坏与拉破坏复合的破坏准则,破坏之后呈现应变软化-理想塑性
2、行为;缺陷在破坏之后经历理想塑性行为.随着密实岩石强度参数的提高,从应力峰值到残余应力的应力降、轴向应变增量提高,贯通试样的剪切带出现滞后,试样内部最终发生破坏的单元数降低.对于密实岩石强度参数高的试样,缺陷全部发生破坏之后,密实岩石没有立即发生破坏;应力峰值被达到之后,破坏的单元数增长不大.在加载过程中,声发射数有显著增加的三个区段.区段1、2及区段3的绝大部分位于峰前.在区段3的峰前阶段,声发射数的增加源于缺陷的长大、聚结、传播和竞争.强度参数越高,区段3越长,区段3的峰值越低.这表明当密实岩石的强度参数较高时,
3、密实岩石单元破坏相继发生,破坏过程持续得较长.关键词岩石;破坏过程;内聚力;内摩擦角;剪切带;声发射;随机缺陷分类号TU452NumericalsimulationoffailureprocessesandacousticemissionsofrockspecimenswithdifferentstrengthsWANGXuebinDepartmentofMechanicsandEngineeringSciences,LiaoningTechnicalUniversity,Fuxin123000,ChinaABSTR
4、ACTForrockspecimenswithinitiallyrandommaterialimperfectionsinuniaxialplanestraincompression,theeffectsofini2tialcohesionandinternalfrictionangleonthefailureprocessesweremodeledusingFLAC.FISHfunctionswereusedtogenerateran2domimperfectionsandtorememberthenumberof
5、failedelements.Fortheintactrockexhibitingthelinearstrain2softeningbehaviorbeyondtheoccurrenceoffailureandthentheidealplasticbehavior,thefailurecriterionisacompositeMohr2Coulombcriterionwithtensioncut2off.Theimperfectionundergoestheidealplasticbehaviorbeyondtheo
6、ccurrenceoffailure.Asthestrengthparameters(initialcohesionandinternalfrictionangle)increase,thestressdropandincrementalaxialstrainfromthepeakstresstotheresidualstressincrease;theoccurrenceofshearfracturesintersectingthespecimenislaterandthefinalnumberofyieldede
7、lementsdecreases.Fortheintactrockwithhigherstrengthparameters,afterallimperfectionsfailitdoesnotfailimmediately;instead,whentheaxialstressreachesacertainvalueitstartstoyieldandtheincreaseinthenumberoffailedelementsislessapparentbeyondthepeakstress.Intheloadingp
8、rocess,theacousticemissionsareapparentinthreestages.Thefirststage,thesecondstageandamajorityofthethirdstageappearatpre2peak.Priortothepeakstressandinthethirdstage,theincreas
