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时间:2018-11-04
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1、附录1外文翻译原文3.2Elasticmodels3.2.1AnisotropyAnisotropicmaterialhasthesamepropertiesinalldirections—wecannotdis-tinguishanyonedirectionfromanyother.Samplestakenoutofthegroundwithanyorientationwouldbehaveidentically.However,weknowthatsoilshavebeendepositedinsomeway—forexample,sedimentarysoilswill
2、knowabouttheverticaldirectionofgravitationaldeposition.Theremayinadditionbeseasonalvariationsintherateofdepositionsothatthesoilcontainsmoreorlessmarkedlayersofslightlydifferentgrainsizeand/orplasticity.Thescaleoflayeringmaybesuffcientlysmallthatwedonotwishtotrytodistinguishseparatematerials
3、,butthelayeringtogetherwiththedirectionaldepositionmayneverthelessbesuffcienttomodifytheproperiesofthesoilindifferentdirections—inotherwordstocauseittobeanisotropic.Wecanwritethestiffnessrelationshipbetweenelasticstrainincrementandstressincrementcompactlyaswhereisthestiffnessmatrixandhencei
4、sthecompliancematrix.Foracompletelygeneralanisotropicelasticmaterialwhereeachlettera,b,...is,inprinciple,anindependentelasticpropertyandthenecessarysymmetryofthesti?nessmatrixfortheelasticmaterialhasreducedthemaximumnumberofindependentpropertiesto21.Assoonastherearematerialsymmetriesthenthe
5、numberofindependentelasticpropertiesfalls(Crampin,1981).Forexample,formonoclinicsymmetry(zsymmetryplane)thecompliancematrixhastheform:andhasthirteenelasticconstants.Orthorhombicsymmetry(distinctx,yandzsymmetryplanes)givesnineconstants:whereascubicsymmetry(identicalx,yandzsymmetryplanes,toge
6、therwithplanesjoiningoppositesidesofacube)givesonlythreeconstants:Figure3.9:Independentmodesofshearingforcross-anisotropicmaterialIfweaddthefurtherrequirementthatandsetand,thenwerecovertheisotropicelasticcompliancematrixof(3.1).Thoughitisobviouslyconvenientifgeotechnicalmaterialshavecertain
7、fabricsymmetrieswhichconferareductioninthenumberofindependentelasticproperties,ithastobeexpectedthatingeneralmaterialswhichhavebeenpushedaroundbytectonicforces,byice,orbymanwillnotpossessanyofthesesymmetriesand,insofarastheyhaveadomainofelasticresponse,w
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