加卸载围压条件下岩石峰后力学特性试验分析-(5504)

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1、重庆大学硕士学位论文II英文摘要ABSTRACTInordertogivefullplayofthebearingcapacityofrockmasstomaintainstabilityinundergroundengineering,torevealtheevolutionofplasticzoneinrockmassandtodooptimumdesignforsupportoftherockengineering,itisnecessaryforscholarstostudythepost-peakresidualstrengthso

2、frock.Byconductingaseriesofconfiningpressureuninstall-recoverytestatthephaseofresidualstrengthsofrock,westudythemechanicalcharacteristicsofrockintheresidualphase.Wesimulatethepost-peakslidingfrictiondeformationofrockwithsinglestructureplaneandtheinterlayerslidingfrictiondef

3、ormationcharacteristicsinthelayeredsurroundingrockwhentunneling.Themainresearchcontentsandresultsofthispaperareasfollows:(1)Theresidualstrengthofrockareaffectedbythepeakstrengthandtheconfiningpressure,andtheresidualstrengthismoresensitivetothelowconfiningpressure.Thereasoni

4、sthereislittlecontactbetweenfractureplanesatlowconfiningpressure,andtheinteractionforceissmall.Withtheincreaseofconfiningpressure,thecontactareabetweenfractureplanesincrease,thestress-strainrelationshipalsochangefrombrittlestressdroptoplasticslip.Itismainlytheprocessofcohes

5、ionlosingfromthepeakstrengthtotheresidualstrengthforshaleandthereductionofinternalfrictionangleisverysmall.(2)Intheloadingandunloadingconfiningpressuretestattheresidualstageofrock,theeffectofunloadingconfiningpressureonthemechanicalcharacteristicsattheresidualstageforrockha

6、vethesameruleinthethreetestplans(manytimesunloading-manytimesloadingconfiningpressuretest,manytimesunloading-onceloadingconfiningpressuretestandcyclicloadingandunloadingtest):Inthestageofinitialresidualwelimittheaxialdisplacement,whentheconfiningpressureisunloadedwithunifor

7、mspeed,thecorrespondingaxialstressdecreasedhomogeneously;aftertheconfiningpressurereachstable,weappliedaxialdisplacementloadandtheaxialstresskeepessentiallystable,Theaxialstress-strainrelationshippresentplasticdeformationfeatures.(3)Loadingconfiningpressurealsohassameaffect

8、rulesinthethreetestplans:theaxialstress-straincurvecanbedividedintothreestages,the