土木工程岩土工程裂隙岩体毕业论文中英文资料对照外文翻译文献综述文档格式.docx

土木工程岩土工程裂隙岩体毕业论文中英文资料对照外文翻译文献综述文档格式.docx

《土木工程岩土工程裂隙岩体毕业论文中英文资料对照外文翻译文献综述文档格式.docx》由会员分享，可在线阅读，更多相关《土木工程岩土工程裂隙岩体毕业论文中英文资料对照外文翻译文献综述文档格式.docx（14页珍藏版）》请在冰豆网上搜索。

Introduction

Itiscommonlyacknowledgedthatrockmassesalwaysdisplaydiscontinuoussurfacesofvarioussizesandorientations,usuallyreferredtoasfracturesorjoints.Sincethelatterhavemuchpoorermechanicalcharacteristicsthantherockmaterial,theyplayadecisiveroleintheoverallbehaviorofrockstructures,whosedeformationaswellasfailurepatternsaremainlygovernedbythoseofthejoints.Itfollowsthat,fromageomechanicalengineeringstandpoint,designmethodsofstructuresinvolvingjointedrockmasses,mustabsolutelyaccountforsuch‘‘weakness’’surfacesintheiranalysis.

Themoststraightforwardwayofdealingwiththissituationistotreatthejointedrockmassasanassemblageofpiecesofintactrockmaterialinmutualinteractionthroughtheseparatingjointinterfaces.Manydesign-orientedmethodsrelatingtothiskindofapproachhavebeendevelopedinthepastdecades,amongthem,thewell-known‘‘blocktheory,’’whichattemptstoidentifypoten-

tiallyunstablelumpsofrockfromgeometricalandkinematicalconsiderations（GoodmanandShi1985;

Warburton1987;

Goodman1995）.Oneshouldalsoquotethewidelyuseddistinctelementmethod,originatingfromtheworksofCundallandcoauthors（CundallandStrack1979;

Cundall1988）,whichmakesuseofanexplicitfinite-differencenumericalschemeforcomputingthedisplacementsoftheblocksconsideredasrigidordeformablebodies.Inthiscontext,attentionisprimarilyfocusedontheformulationofrealisticmodels

fordescribingthejointbehavior.

Sincethepreviouslymentioneddirectapproachisbecominghighlycomplex,andthennumericallyuntractable,assoonasaverylargenumberofblocksisinvolved,itseemsadvisabletolookforalternativemethodssuchasthosederivedfromtheconceptofhomogenization.Actually,suchaconceptisalreadypartiallyconveyedinanempiricalfashionbythefamousHoekandBrown’scriterion（HoekandBrown1980;

Hoek1983）.Itstemsfromtheintuitiveideathatfromamacroscopicpointofview,arockmassintersectedbyaregularnetworkofjointsurfaces,maybeperceivedasahomogeneouscontinuum.Furthermore,owingtotheexistenceofjointpreferentialorientations,oneshouldexpectsuchahomogenizedmaterialtoexhibitanisotropicproperties.

Theobjectiveofthepresentpaperistoderivearigorousformulationforthefailurecriterionofajointedrockmassasahomogenizedmedium,fromtheknowledgeofthejointsandrockmaterialrespectivecriteria.Intheparticularsituationwheretwomutuallyorthogonaljointsetsareconsidered,aclosed-formexpressionisobtained,givingclearevidenceoftherelatedstrengthanisotropy.Acomparisonisperformedonanillustrativeexamplebetweentheresultsproducedbythehomogenizationmethod,makinguseofthepreviouslydetermined

14

criterion,andthoseobtainedbymeansofacomputercodebasedonthedistinctelementmethod.Itisshownthat,whilebothmethodsleadtoalmostidenticalresultsforadenselyfracturedrockmass,a‘‘size’’or‘‘scaleeffect’’isobservedinthecaseofalimitednumberofjoints.Thesecondpartofthepaperisthendevotedtoproposingamethodwhichattemptstocapturesuchascaleeffect,whilestilltakingadvantageofahomogenizationtechnique.ThisisachievedbyresortingtoamicropolarorCosseratcontinuumdescriptionofthefracturedrockmass,throughthederivationofageneralizedmacroscopicfailureconditionexpressedintermsofstressesandcouplestresses.Theimplementationofthismodelisfinallyillustratedonasimpleexample,showinghowitmayactuallyaccountforsuchascaleeffect.

ProblemStatementandPrincipleofHomogenizationApproach

Theproblemunderconsiderationisthatofafoundation（bridgepierorabutment）restinguponafracturedbedrock（Fig.1）,whosebearing

capacityneedstobeevaluatedfromtheknowledgeofthestrengthcapacitiesoftherockmatrixandthejointinterfaces.Thefailureconditionoftheformerwillbeexpressedthrough

theclassicalMohr-CoulombconditionexpressedbymeansofthecohesionCm

andthe

frictionangle m.Notethattensilestresseswillbecountedpositivethroughoutthepaper.

Likewise,thejointswillbemodeledasplaneinterfaces（representedbylinesinthefigure’splane）.Theirstrengthpropertiesaredescribedbymeansofaconditioninvolvingthestressvectorofcomponents（σ,τ）actingatanypointofthoseinterfaces

Accordingtotheyielddesign（orlimitanalysis）reasoning,theabovestructurewillremainsafeunderagivenverticalloadQ（forceperunitlengthalongtheOzaxis）,ifonecanexhibitthroughouttherockmassastressdistributionwhichsatisfiestheequilibriumequationsalongwiththestressboundaryconditions,whilecomplyingwit