Determination of shear strength and three-dimensional Yield srength for the Hock-Brown criterion.pdf

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1、RockMech.RockEngng.(2005)38(4),299327DOI10.1007/s00603-005-0056-5DeterminationofShearStrengthandThree-dimensionalYieldStrengthfortheHoek-BrownCriterionByS.D.PriestSchoolofNaturalandBuiltEnvironments,UniversityofSouthAustralia,MawsonLakes,AustraliaReceivedOctober26,2004;acceptedJanuary27,

2、2005PublishedonlineMay2,2005#Springer-Verlag2005SummaryMostcurrentlyusedtechniquesforanalysingthestabilityofnearsurfacestructures,suchasrockslopes,arebasedontheapplicationoftheeffectiveCoulombshearstrengthparameterscohesionc0,andtheangleoffriction0onsomeknownoranticipatedshearsurfacesub

3、jectedtoaneffectivenormalstress0.Themostwidelyusedofthesetechniquesarethevariantsofnthemethodofslicesandrelatedupperboundtechniques.IftheHoek-Browncriterionistobeusedtomodelthestrengthofnearsurfacefracturedrocks,itisnecessarytodetermineequivalentCoulombshearstrengthparametersforthespeci

4、fiedlevelofeffectivenormalstress.CalculationoftheequivalentCoulombparametersfortheHoek-Browncriterionforcaseswhena6¼0:5isnotastraightforwardmatter.Asimpleprocedureforcalculatingin-stantaneousvaluesofc0and0hasbeendevelopedbasedonspreadsheetcalculationsandtheiiapplicationofanumericaloptimi

5、sationroutine.Thisprocedurecanalsobeappliedtocalcu-latingtheHoek-Brownenvelopeplottedinshearstress=normalstressspace.Asimpleclosedformsolutionforc0andtan0hasalsobeendevelopedforthespecialcasewhena¼1.Aiithree-dimensionalversionoftheHoek-BrowncriterionhasbeendevelopedbycombiningitwiththeD

6、rucker-Pragercriterion.Thisnewyieldcriterionhasbeenimplementedbynumer-icalsolutionofthegoverningequations.Asimplificationofthisthree-dimensionalyieldcriterionhasbeendevelopedbyintroducinganintermediateprincipalstressweightingfactor.Comparisonwithpublishedresultsdemonstratesthatthissimplifi

7、edcriterionhasthecapacitytomodeltheresultsoftruetriaxialtestsforarangeofdifferentrocktypesoverawiderangeofstresslevels.Thenewthree-dimensionalyieldcriterionhastheadvantagethatitsinputparameterscanbedeterminedfromroutineuniaxialcompressiontestsandmineralogicalexamination.K