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1、第30卷第8期北京科技大學學報Vol.30No.82008年8月JournalofUniversityofScienceandTechnologyBeijingAug.2008不同強度巖石的破壞過程及聲發(fā)射數(shù)值模擬王學濱遼寧工程技術(shù)大學力學與工程科學系,阜新123000摘要采用FLAC模擬了初始內(nèi)聚力及內(nèi)摩擦角對具有隨機材料缺陷單軸平面應(yīng)變壓縮巖樣破壞過程及聲發(fā)射的影響;采用編寫的若干FISH函數(shù)規(guī)定隨機缺陷及統(tǒng)計發(fā)生破壞的單元數(shù)目.密實的巖石服從莫爾-庫侖剪破壞與拉破壞復合的破壞準則,破壞之后呈現(xiàn)應(yīng)變軟化-理想塑性
2、行為;缺陷在破壞之后經(jīng)歷理想塑性行為.隨著密實巖石強度參數(shù)的提高,從應(yīng)力峰值到殘余應(yīng)力的應(yīng)力降、軸向應(yīng)變增量提高,貫通試樣的剪切帶出現(xiàn)滯后,試樣內(nèi)部最終發(fā)生破壞的單元數(shù)降低.對于密實巖石強度參數(shù)高的試樣,缺陷全部發(fā)生破壞之后,密實巖石沒有立即發(fā)生破壞;應(yīng)力峰值被達到之后,破壞的單元數(shù)增長不大.在加載過程中,聲發(fā)射數(shù)有顯著增加的三個區(qū)段.區(qū)段1、2及區(qū)段3的絕大部分位于峰前.在區(qū)段3的峰前階段,聲發(fā)射數(shù)的增加源于缺陷的長大、聚結(jié)、傳播和競爭.強度參數(shù)越高,區(qū)段3越長,區(qū)段3的峰值越低.這表明當密實巖石的強度參數(shù)較高時,
3、密實巖石單元破壞相繼發(fā)生,破壞過程持續(xù)得較長.關(guān)鍵詞巖石;破壞過程;內(nèi)聚力;內(nèi)摩擦角;剪切帶;聲發(fā)射;隨機缺陷分類號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
