英语翻译-植被模型对边坡稳定性的影响

河北工程大学本科毕业设计英语翻译译文题目MODELLINGTHEEFFECTSOFVEGETATIONONSTABILITYOFSLOPES植被模型对边坡稳定性的影响姓名专业勘查技术与工程班级学号指导老师指导教师职称教授2013年6月12日MODELLINGTHEEFFECTSOFVEGETATIONONSTABILITYOFSLOPESSUMMARYITISWELLUNDERSTOODTHATVEGETATIONINFLUENCESSLOPESTABILITYINTWOWAYSTHROUGHHYDROLOGICALEFFECTSANDMECHANICALEFFECTSHYDROLOGICALEFFECTSINVOLVETHEREMOVALOFSOILWATERBYEVAPOTRANSPIRATIONTHROUGHVEGETATION,WHICHLEADTOANINCREASEINSOILSUCTIONORAREDUCTIONINPOREWATERPRESSURE,HENCE,ANINCREASEINTHESOILSHEARSTRENGTHTHESHEARSTRENGTHOFTHESOILISALSOINCREASEDTHROUGHTHEMECHANICALEFFECTSOFTHEPLANTROOTMATRIXSYSTEMTHEDENSITYOFTHEROOTSWITHINTHESOILMASSANDTHEROOTTENSILESTRENGTHCONTRIBUTETOTHEABILITYOFTHESOILSTORESISTSHEARSTRESSTHEEFFECTSOFSOILSUCTIONANDROOTREINFORCEMENTHASBEENQUANTIFIEDASANINCREASEINAPPARENTSOILCOHESIONTHISPAPERINVESTIGATESTHEEFFECTSOFVEGETATIONONTHESTABILITYOFSLOPESUSINGTHEFINITEELEMENTMETHODTWOKEYVEGETATIONDEPENDENTPARAMETERSHAVEBEENINCORPORATEDINTHEFINITEELEMENTSLOPESTABILITYANALYSIS,NAMELY,APPARENTROOTCOHESIONCRANDDEPTHOFROOTZONEHRPARAMETRICSTUDIESWEREPERFORMEDTOASSESSTHESENSITIVITYOFTHESTABILITYOFASLOPETOTHEVARIATIONINTHEKEYVEGETATIONANDSOILPARAMETERSRESULTSSHOWTHATVEGETATIONPLAYSANIMPORTANTROLEINSTABILIZINGSHALLOWSEATEDFAILUREOFSLOPES,ANDSIGNIFICANTLYAFFECTSSTABILITYINTRODUCTIONSLOPEINSTABILITYISONEOFTHEMAJORPROBLEMSINGEOTECHNICALENGINEERINGWHEREDISASTERS,LIKELOSSOFLIFEANDPROPERTY,DOOCCURTHEMAJORITYOFTHESESLOPEFAILURESAREOFVEGETATEDORFORESTEDNATURALSLOPESANATURALSLOPEISDIFFERENTFROMANEMBANKMENTORAMANMADESLOPEINTHATTHEEFFECTSOFVEGETATIONANDSOILVARIABILITYPLAYANIMPORTANTROLEINTHEIRSTABILITYTHEEFFECTSOFVEGETATIONONTHESTABILITYOFSLOPESAREWELLRECOGNIZEDVEGETATIONAFFECTSSLOPESTABILITYTHROUGHMODIFICATIONOFTHESOILWATERREGIME,WHICHINTURNCAUSESAVARIATIONINSOILSUCTIONORPOREPRESSUREVEGETATIONCANALSOENHANCETHESTABILITYOFASLOPEBYROOTREINFORCEMENTWUETAL1979INVESTIGATEDTHESTABILITYOFSLOPESBEFOREANDAFTERREMOVALOFFORESTCOVERANDCONCLUDEDTHATTHESHEARSTRENGTHCONTRIBUTEDBYTREEROOTSISIMPORTANTTOTHESTABILITYOFSLOPESTHESTUDYINDICATEDTHATVEGETATIONCOULDCONTRIBUTESHEARSTRENGTHTOTHESLOPESTHROUGHROOTREINFORCEMENTWUETAL1979SHOWEDTHATSLOPEFAILUREWOULDHAVEOCCURREDIFTHEEFFECTSOFVEGETATIONWERENOTTAKENINTOACCOUNTINSLOPESTABILITYANALYSESNATURALSLOPESARESUBJECTEDTOINHERENTVARIABILITYBOTHINTHESOILANDTHEVEGETATIONITISUNLIKELYTHATTHEUNDERLYINGSOILPROFILESOFNATURALSLOPESARECOMPLETELYUNIFORMORHOMOGENOUSEVENWITHINAHOMOGENOUSSOILLAYER,SOILPROPERTIESTENDTOVARYFROMPOINTTOPOINTVANMARCKE,1977THEGROWTHOFVEGETATIONISSENSITIVETOENVIRONMENTALCONDITIONSANDCHANGESTYPICALLYDIFFERENTTYPESOFVEGETATIONGROWONANATURALSLOPE,SUCHASAMIXTUREOFGRASSES,HERBS,SCRUBSANDTREESTHEIRDIFFERENCESINSIZEANDPHYSICALPROPERTIESWILLAFFECTTHESLOPESTABILITYINDIFFERENTWAYSTHEREFORE,THEUSEOFASINGLEINPUTVALUEFORTHEVEGETATIONDEPENDENTPARAMETERSINANALYSESISBESTVIEWEDASAFIRSTAPPROXIMATIONOFTHEFIELDCONDITIONSTHISPAPERINVESTIGATESTHEEFFECTSOFVEGETATIONONTHESTABILITYOFSLOPESUSINGTHEFINITEELEMENTMETHODTHEFINITEELEMENTMETHODALLOWSTHEEXTENTOFTHEVEGETATIONEFFECTSTOBEDEFINEDBYTHEUSERDUETOTHENATUREOFTHEMETHODWHERESLOPEGEOMETRYISDICRETISEDINTOSMALLELEMENTSTOLIMITTHESCOPEOFTHISPAPER,ONLYTHEEFFECTSOFROOTREINFORCEMENTAREINCORPORATEDINTHESLOPESTABILITYANALYSISTHEVARIABILITYINTHEVEGETATIONANDSOILPROPERTIESARENOTCONSIDEREDINTHISPAPERA21HOMOGENOUSSLOPEANGLEOFINCLINATION2657ISUSEDTOINVESTIGATETHEEFFECTSOFVEGETATIONONSLOPESTABILITYTWOKEYVEGETATIONDEPENDENTPARAMETERSAREINCORPORATEDINTHEFINITEELEMENTSLOPESTABILITYANALYSIS,NAMELY,APPARENTROOTCOHESIONCRANDDEPTHOFROOTZONEHRPARAMETRICSTUDIESWEREPERFORMEDTOASSESSTHESENSITIVITYOFTHESTABILITYOFTHESLOPETOTHEVARIATIONINTHEKEYVEGETATIONANDSOILPARAMETERSPREVIOUSANALYSESOFTHEEFFECTSOFVEGETATIONONSLOPESTABILITYMODELOFROOTREINFORCEMENTFORTHEPASTTHREEDECADES,RESEARCHHASFOCUSEDONUTILIZINGPLANTROOTREINFORCEMENTTOSTABILIZESLOPESTHEABILITYOFPLANTROOTSTOSTRENGTHENASOILMASSISWELLKNOWNTHEINCLUSIONOFPLANTROOTSWITHHIGHTENSILESTRENGTHINCREASESTHECONFININGSTRESSINTHESOILMASSBYITSCLOSELYSPACEDROOTMATRIXSYSTEMTHESOILMASSISBOUNDTOGETHERBYTHEPLANTROOTSANDTHESHEARSTRENGTHISINCREASEDBYTHISEFFECTTHECONTRIBUTIONOFROOTREINFORCEMENTTOSHEARSTRENGTHISCONSIDEREDTOHAVETHECHARACTERISTICSOFCOHESIONWUETAL,1979WUETAL1979PROPOSEDASIMPLIFIEDPERPENDICULARROOTMODELTOQUANTIFYTHEINCREASEDSHEARSTRENGTHOFSOILDUETOROOTREINFORCEMENTTHEINCREASEINSHEARSTRENGTHOFTHESOIL,SR,WASEXPRESSEDBYTHEFOLLOWINGRELATIONSHIPSRTRCOSTANSIN1WHERESRSHEARSTRENGTHINCREASEFROMROOTREINFORCEMENT,TRAVERAGETENSILESTRENGTHOFROOTPERUNITAREAOFSOIL,ANGLEOFSHEARROTATION,ANDFRICTIONANGLESINCETHEMECHANICALEFFECTOFPLANTROOTSISTOINCREASETHECOHESIVENESSOFTHESOILMASS,SRCANBECONSIDEREDASEQUIVALENTTOANAPPARENTCOHESIONOFTHESOIL,KNOWNASAPPARENTROOTCOHESIONCRTYPICALVALUESOFAPPARENTROOTCOHESIONCRRANGEFROM1KPATO175KPACOPPINANDRICHARDS,1990THESEVALUESWEREOBTAINEDFROMTHESTUDIESOFSEVERALINVESTIGATORSUSINGDIFFERENTTECHNIQUESINCLUDINGBACKANALYSIS,DIRECTSHEARTESTS,ROOTDENSITYINFORMATIONCOMBINEDWITHVERTICALROOTMODELEQUATIONS,ANDBACKANALYSISCOMBINEDWITHROOTDENSITYINFORMATIONTHEVALUESOFAPPARENTROOTCOHESIONCRAREDEPENDENTONTHETYPEOFVEGETATIONANDINSITUSOILCONDITIONSPREVIOUSSLOPESTABILITYANALYSESWUETAL1979INCORPORATEDTHEEFFECTSOFVEGETATIONINSLOPESTABILITYANALYSISBYUSINGCONVENTIONALLIMITEQUILIBRIUMMETHODINLIMITEQUILIBRIUMMETHODS,THESHEARSTRENGTHOFTHESOILALONGAPOTENTIALSLIPSURFACEISASSUMEDTOBEFULLYMOBILIZEDATTHEPOINTOFFAILURETHEMOHRCOULOMBEQUATIONISUSEDTODESCRIBETHESHEARSTRENGTHOFTHESOILCUTAN2BYINCORPORATINGTHEEFFECTOFROOTREINFORCEMENT,EQUATION2BECOMESCCRUTAN3WUETAL1979INCORPORATEDTHEAPPARENTROOTCOHESIONCRINTHEIRINFINITESLOPEANALYSISANDFOUNDANINCREASEINTHEFACTOROFSAFETYFOSFORSOMESLOPESTHERESULTSINDICATEDTHATTREEROOTSIMPROVEDTHESTABILITYOFFORESTEDSLOPESTHEREHAVEBEENNOPUBLISHEDSTUDIESUSINGNUMERICALFORMULATIONSTOANALYZEROOTREINFORCEMENTEFFECTSTHEPRESENTSTUDYEMPLOYSNUMERICALANALYSISWHICHALLOWSLIMITINGTHEEXTENTOFTHEROOTZONEBYASSIGNINGDIFFERENTVALUESOFAPPARENTROOTCOHESIONCRTOTHEROOTZONE,ITSSIGNIFICANCEONTHEFOSISEVALUATEDDESCRIPTIONOFNUMERICALSTUDYUSEDTOMODELVEGETATIONEFFECTSINTHEPRESENTSTUDY,THEEFFECTOFVEGETATIONONTHESTABILITYOFSLOPESHASBEENINVESTIGATEDUSINGTHEFINITEELEMENTMETHODTHEDISCRETISATIONPROCESSOFTHEFINITEELEMENTMETHODBREAKSDOWNTHESLOPEGEOMETRYINTOSMALLELEMENTSANDTHISFACILITATESTHEINCORPORATIONOFTHEEFFECTSOFVEGETATIONINTHESLOPESTABILITYANALYSISTHEEFFECTSOFVEGETATIONARETAKENINTOACCOUNTINTHESLOPESTABILITYANALYSISBYMODIFYINGTHESOILPROPERTIESOFTHEINDIVIDUALSOILELEMENTTHATISAFFECTEDBYVEGETATIONFOREXAMPLE,THESOILELEMENTSINTHETOPLAYEROFTHESLOPECANHAVEAHIGHERCOHESIONVALUEDUETOTHEADDITIONALAPPARENTCOHESIONFROMROOTREINFORCEMENTVARIATIONOFSOILSUCTIONCAUSEDBYVEGETATIONCANALSOBEINCORPORATEDINTHEFINITEELEMENTANALYSISTHEFLEXIBILITYINLOCATINGTHEVEGETATIONAFFECTEDELEMENTSMEANSTHATTHEVARIABLEANDRANDOMNATUREOFVEGETATIONCANBEMODELEDEFFECTIVELYINTHISPAPER,THEWORKISLIMITEDTOTHEEFFECTSOFROOTREINFORCEMENTONTHESTABILITYOFSLOPESTHEFINITEELEMENTMODELTHEFINITEELEMENTMODELINTHEPRESENTSTUDYASSUMES2DIMENSIONALPLANESTRAINCONDITIONSTHEPROGRAMUSEDINTHISSTUDYWASDEVELOPEDBYSMITHANDGRIFFITHS1998ANDITUSESEIGHTNODDEDQUADRILATERALELEMENTSANELASTOPLASTICMODELWITHMOHRCOULOMBFAILURECRITERIONISASSUMEDTHISPROGRAMHASBEENUSEDTOANALYZESEVERALSLOPESTABILITYPROBLEMSINCLUDINGTHEINFLUENCEOFLAYERINGANDFREESURFACEONSLOPEANDDAMSTABILITYGRIFFITHSANDLANE,1999THEPROGRAMCOMPUTESTHEFACTOROFSAFETYFOSOFTHESLOPEBYUSINGTHENONCONVERGENCESOLUTION,COUPLEDWITHASUDDENINCREASEINNODALDISPLACEMENTSASANINDICATIONOFFAILURECONDITIONSGRIFFITHSANDLANE,1999INTHISSTUDY,A21HOMOGENOUSSLOPE2657WITHAHEIGHTOF10METRESISUSEDTOINVESTIGATETHEEFFECTSOFVEGETATIONONTHESTABILITYOFASLOPE,ASSHOWNINFIGURE1THESOILPROPERTIESAREASFOLLOWS25C020KN/M3TWOADDITIONALVEGETATIONDEPENDENTPARAMETERSUSEDINTHESLOPESTABILITYANALYSISAREAPPARENTROOTCOHESIONCRANDDEPTHOFROOTZONEHRAPPARENTROOTCOHESIONCRISTHEAPPARENTSOILCOHESIONCAUSEDBYTHEPLANTROOTMATRIXSYSTEMTHEDEPTHOFTHEROOTZONEHRISDEFINEDASTHEEFFECTIVEDISTANCEBEYONDWHICHPLANTROOTSCAUSELITTLEORNOEFFECTSONTHESOILSHEARSTRENGTHTWOSCENARIOSARECONSIDERED1VEGETATIONCONFINEDTOTHESLOPESURFACEONLYAND2VEGETATIONEXTENDINGOVERTHEENTIREGROUNDSURFACEPARAMETRICSTUDIESAREPERFORMEDTOASSESSTHESENSITIVITYOFTHESTABILITYOFTHESLOPETOTHEVARIATIONINKEYVEGETATIONDEPENDENTPARAMETERSFIGURE1MESHFORA21HOMOGENOUSSLOPEWITHASLOPEANGLEOF2657,25,C0RESULTSOFANALYSESSLOPEWITHOUTVEGETATIONEFFECTSC0,CR0THESTABILITYOFTHE21HOMOGENOUSSLOPEWITHOUTVEGETATIONWASANALYSEDUSINGBOTHTHEFINITEELEMENTMETHODANDTHELIMITEQUILIBRIUMMETHODTHELIMITEQUILIBRIUMMETHODWASPERFORMEDUSINGTHEGGUSTABILITYPROGRAMBU,1999WHEREBISHOPSSIMPLIFIEDMETHODOFSLICESWASADOPTEDTHERESULTSOFTHEANALYSESARESUMMARISEDINTABLE1TABLE1FACTOROFSAFETYFORTHESLOPEUSINGDIFFERENTMETHODSMETHODFOSFINITEELEMENTMETHOD095LIMITEQUILIBRIUMMETHOD093THERESULTSINTABLE1SHOWTHATBOTHMETHODSGIVECOMPARABLERESULTS,ALTHOUGHTHELIMITEQUILIBRIUMMETHODGIVESASLIGHTLYLOWERVALUECOMPAREDTOTHEFINITEELEMENTMETHODFIGURE2SHOWSTHEDEFORMEDFINITEELEMENTMESHOFTHESLOPEATFAILURE,ANDTHECORRESPONDINGFOS095ITCANBEOBSERVEDTHATTHEFAILUREMECHANISMISASHALLOWPLANARFAILURETHEFAILUREOCCURSWITHINTHEFIRSTTWOLAYERSOFTHEELEMENTS,EXTENDINGTO2METERSBELOWTHESLOPESURFACEFIGURE2DEFORMEDMESHATFAILUREFORTHESLOPEWITHC0SLOPEWITHVEGETATIONEFFECTSC0,CR5KPA,HR1MCASE1VEGETATIONCONFINEDTOTHESLOPESURFACEONLYTHEFIRSTCASEINVOLVESASCENARIOWHEREVEGETATIONGROWSONTHESLOPESURFACEONLYTHEHORIZONTALGROUNDSURFACES,ONTHESLOPEITSELFASWELLASBEYONDTHESLOPETOE,ARENOTCOVEREDBYVEGETATIONTHEEFFECTOFROOTREINFORCEMENTISCONSIDEREDBYUSINGAPPARENTROOTCOHESIONCROF5KPATHEDEPTHOFROOTZONEHRISCONSIDEREDTOBE1METREACCORDINGLY,THEZONEMODELLEDWITHTHEADDITIONALROOTSTRENGTHISCONFINEDTOTHEFIRSTLAYEROFTHEFINITEELEMENTSBENEATHTHESLOPESURFACETHUS,THEFIRSTLAYEROFELEMENTSINTHEFINITEELEMENTMODEL,SHOWNASSHADEDINFIGURE3,HASAHIGHERVALUEOFSOILCOHESIONCOMPAREDTOALLOTHERELEMENTSINTHEFINITEELEMENTMESHTHESLOPESTABILITYANALYSISGAVEARESULTOFFOS097THEDEFORMEDMESHOFTHESLOPEATFAILUREISSHOWNINFIGURE3SINCETHESLOPEISPROTECTEDBYVEGETATIONONTHESLOPESURFACEONLY,FAILUREWAS,INTHISCASE,INITIATEDFROMTHESLOPETOEELEMENTTAFAILURESLIPSURFACETHENDEVELOPEDALONGTHESOILLAYERBENEATHTHEROOTZONE,ASTHISSOILLAYERISTHETOPOFTHEWEAKZONEINTHESLOPEAFTERINTRODUCINGAROOTZONEALTHOUGHTHEINCREMENTINTHEFOSISSMALL,ITCANBENOTEDFROMFIGURE3THATTHECRITICALSLIPSURFACEHASBEENSHIFTEDDEEPERBELOWTHEGROUNDSURFACE,BEINGLOCATEDBETWEENTHESECONDANDTHIRDLAYERSOFTHEFINITEELEMENTSTHESHALLOWPLANARFAILUREATTHESLOPESURFACEISNOLONGERCRITICAL,BECAUSEOFTHEPRESENTOFTHEROOTZONEWHENTHESLOPETOEELEMENTELEMENTTINFIGURE3ISTREATEDASAVEGETATEDSOILELEMENTASSIGNEDHIGHERAPPARENTCOHESION,THEFOSFORTHESLOPEINCREASESTO102THISSHOWSTHATTOEFAILUREISTHECRITICALFAILUREMECHANISMFORTHECASEWHEREVEGETATIONISCONFINEDTOTHESLOPESURFACEONLYTHEINCREASEINTHEFOSISNOTSIGNIFICANTIFTHESLOPETOEISNOTVEGETATEDTHEREFORE,THEEXTENTOFTHEROOTZONETOTHESLOPETOEREGIONISANIMPORTANTFACTORTOBECONSIDEREDWHENVEGETATIONISUSEDTOIMPROVETHESTABILITYOFASLOPEFIGURE3DEFORMEDMESHATFAILUREFORTHESLOPEWITHVEGETATIONONSLOPESURFACEONLYC0,CR5KPA,HR1MCASE2VEGETATIONEXTENDINGOVERTHEENTIREGROUNDSURFACEAMORECOMMONSCENARIOINNATURALSLOPESISTHECASEWHEREVEGETATIONGROWSEVERYWHEREONTHEGROUNDSURFACE,WHICHEXTENDSFROMTHEUPPERSLOPEREGIONTOTHESLOPETOESIMILARLY,ANAPPARENTROOTCOHESIONOF5KPAANDDEPTHOFROOTZONEOF1METREWEREADOPTEDINTHISCASE,THEROOTREINFORCEMENTEFFECTEXTENDSEVERYWHEREONTHEGROUNDSURFACEINTHEFINITEELEMENTMODEL,ASSHOWNINFIGURE4THEFINITEELEMENTANALYSISYIELDEDAFOS103,SHOWINGASIGNIFICANTINCREASEDUETOTHEPRESENCEOFTHEROOTZONELOCATEDEVERYWHEREONTHEGROUNDSURFACETHESLOPETHATWASINITIALLYUNSAFEFOS095ISNOWMARGINALLYSAFEFOS1DUETOTHEROOTREINFORCEMENTEFFECTSTHEDEFORMEDMESHOFTHESLOPEISSHOWNINFIGURE4ITISNOTEDTHATTHECRITICALSLIPSURFACEISNOLONGERPLANARBUTISCIRCULARFIGURE4DEFORMEDMESHFORTHESLOPEWITHVEGETATIONEXTENDINGOVERTHEENTIREGROUNDSURFACEC0,CR5KPA,HR1MTHEABOVEEXAMPLESHAVESHOWNTHATROOTREINFORCEMENTCANIMPROVETHESTABILITYOFASLOPEBYINCORPORATINGTHEAPPARENTROOTCOHESIONINTHEROOTZONEOFTHESLOPE,THEFOSOFTHESLOPEISINCREASEDTHECONTRIBUTIONOFROOTREINFORCEMENTTOTHESTABILITYOFSLOPEISSIGNIFICANTREFERRINGTOTHE21HOMOGENOUSSLOPEINTHEABOVEEXAMPLES,THISSLOPEWOULDBEUNSTABLEIFTHEEFFECTOFVEGETATIONISNOTTAKENINTOACCOUNTINREALITY,THEREAREMANYSLOPESTHATWOULDFAIL,BASEDONTHESTABILITYANALYSISUSINGTHEFIELDORLABORATORYSOILDATA,BUTREMAININTACTFORALONGPERIODOFTIMEACASEINPOINTISTHETHREDBOLANDSLIDEHAND,2000THEPRESENCEOFVEGETATIONONSUCHSLOPESISCLEARLYONEOFTHEMAJORCONTRIBUTIONSTOTHESTABILITYOFTHESESLOPESPARAMETRICSTUDIESPARAMETRICSTUDIESWEREPERFORMEDFORARANGEOFTHEVEGETATIONANDSOILPARAMETERSTHEAPPARENTROOTCOHESIONCRWASVARIEDOVERTHEFOLLOWINGRANGE0CR20KPA4THREEVALUESOFDEPTHOFROOTZONEHRWEREUSED,NAMELYHR1M,2M,3M5FORTHESOILPROPERTIES,ONLYTHEEFFECTIVECOHESIONCWASVARIEDTHEVALUESOFEFFECTIVECOHESIONCCONSIDEREDWEREASFOLLOWSC1KPA,2KPA,3KPA,4KPA,5KPA6THERESULTSOFTHEPARAMETRICSTUDIESARESUMMARISEDINFIGURE5TO7FIGURE5SHOWSTHEVARIATIONOFTHEVALUESOFFOSWITHTHEAPPARENTROOTCOHESIONCRWHEREC0ANDVEGETATIONISCONFINEDTOTHESLOPESURFACEONLYTWOSETSOFRESULTSAREPRESENTEDINTHISFIGURETHEBROKENLINESREPRESENTTHERESULTSFORTHECASEWHEREVEGETATIONISCONFINEDTOTHESLOPESURFACEONLY,WITHOUTEXTENDINGTOTHESLOPETOETHESOLIDLINESARETHERESULTSFORTHECASEWHERETHESLOPETOEELEMENTELEMENTTINFIGURE3ISASSUMEDTOBEAFFECTEDBYVEGETATIONGENERALLY,THEVALUESOFFOSINCREASEWHENAPPARENTROOTCOHESIONCRINCREASESFORTHECASEWHERETHESLOPETOEISNOTPROTECTEDBYVEGETATION,THEFOSINCREASESSLIGHTLYINITIALLY,BUTDROPSTOALOWERVALUEAFTERREACHINGAMAXIMUMVALUEOFFOSTHEFOSREMAINSCONSTANTREGARDLESSOFANYINCREASEINTHEAPPARENTROOTCOHESIONFORACOHESIONLESSSOILSLOPEC0,THEFAILUREMECHANISMISASHALLOWPLANARFAILURETHISFAILUREMECHANISMISPREVENTEDWHENPLANTROOTSAREPRESENTASTHEAPPARENTROOTCOHESIONINCREASES,THECRITICALSLIPSURFACESHIFTSDEEPERBELOWTHEGROUNDSURFACEWHENTHECRITICALSLIPSURFACEISBEYONDTHEEXTENTOFTHEROOTZONE,ANYINCREASESINAPPARENTROOTCOHESIONDONOTLEADTOANINCREASEINFOSFORTHESLOPESINCETHESLOPETOEISNOTPROTECTEDBYVEGETATION,THISREGIONISTHEWEAKZONE,ANDASTHEAPPARENTROOTCOHESIONINTHEROOTZONEINCREASES,FAILUREISINITIATEDFROMTHISREGIONTHISEVENTUALLYTRIGGERSFAILUREDUETOADIFFERENTMECHANISMTOEFAILUREWHENTHESLOPETOEISPROTECTEDBYVEGETATION,THEFOSINCREASESASTHEAPPARENTROOTCOHESIONINCREASESTHEREFORE,THESLOPETOEAPPEARSTOBETHEMOSTCRITICALREGIONWHEREVEGETATIONNEEDSTOBECONSIDEREDINSLOPESTABILISATIONTHUS,INORDERTOENSUREIMPROVEDSTABILITYOFASLOPEUSINGVEGETATION,THEROOTZONENEEDSTOEXTENDBEYONDTHETOEREGIONFIGURE5VARIATIONOFFOSFORTHECASEWHEREVEGETATIONISCONFINEDTOTHESLOPESURFACEONLYC0FIGURE6SHOWSTHEVARIATIONOFTHEVALUESOFFOSWITHTHEROOTCOHESIONCRWHEREC0ANDVEGETATIONEXTENDSENTIRELYOVERTHEGROUNDSURFACE,INCLUDINGTHEUPPERSLOPE,SLOPESURFACEANDSLOPETOETHEFOSINCREASESASTHEAPPARENTROOTCOHESIONCRINCREASESITISNOTEDTHAT,WHENTHEENTIRESLOPEISPROTECTEDBYVEGETATION,THEEFFECTSONFOSARESIGNIFICANTFOREXAMPLE,WHENHR1MTHEFOSISINCREASEDBY26FORCR20KPATHEINCREASEISEVENMORESIGNIFICANTWITHADEEPERROOTZONEHIGHERHR,ASSHOWNINFIGURE6FIGURE6VARIATIONOFFOSFORTHECASEWITHVEGETATIONEXTENDINGOVERTHEENTIREGROUNDSURFACEC0FIGURE7SHOWSTHEVARIATIONOFTHEFOSWITHTHEDIMENSIONLESSPARAMETERCR/CFORTHECASEWHERETHEEFFECTIVECOHESIONOFTHESOILC1KPA,2KPA,3KPA,4KPA,5KPATHEANALYSESWEREPERFORMEDFORTHECASEWHEREVEGETATIONEXTENDSEVERYWHEREONTHEGROUNDSURFACEANDHR1MTHEANALYSISWASTERMINATEDATCR20KPAFOREACHVALUEOFCITISWORTHWHILETONOTETHATTHEINCREASEINTHEFOSISMORESIGNIFICANTFORASLOPEWITHALOWEFFECTIVECOHESIONC1KPACOMPAREDWITHASLOPEWITHAHIGHEFFECTIVECOHESIONC5KPAEXAMINATIONOFTHEDEFORMEDMESHESSHOWEDTHAT,INTHECASEOFSLOPESWITHHIGHERVALUESOFEFFECTIVECOHESIONC,FAILUREOCCURREDALONGADEEPSEATEDROTATIONALSLIPSURFACETHISIMPLIESTHATVEGETATIONHASLESSOFANEFFECTONDEEPSEATEDFAILURESWHENTHEDEPTHOFROOTZONEHRISSHALLOWFIGURE7VARIATIONOFFOSFORTHECASEWITHVEGETATIONEXTENDINGOVERTHEENTIREGROUNDSURFACEC0,HR1MFUTUREWORKBYINCORPORATINGTHEEFFECTSOFROOTREINFORCEMENTINSLOPESTABILITYANALYSIS,SIGNIFICANTINFLUENCEONTHESTABILITYOFSLOPESHASBEENOBSERVEDTOMODELANATURALSLOPEMOREACCURATELY,THEINFLUENCEOFSOILSUCTIONANDSOILVARIABILITYSHOULDBETAKENINTOACCOUNTTHISWORKWILLBECARRIEDOUTINTHISONGOINGRESEARCHPROJECT,INPARTICULAR,TOINCORPORATEVARIABILITYOFTHEVEGETATIONANDSOILPROPERTIESWITHINTHEFINITEELEMENTFRAMEWORKSUMMARYANDCONCLUSIONSVEGETATIONPLAYSANIMPORTANTROLEINTHESTABILITYOFSLOPESROOTREINFORCEMENTHASBEENCONSIDEREDASANINCREASEINAPPARENTSOILCOHESIONTHEAPPARENTROOTCOHESIONCRHASBEENINCORPORATEDINTHESLOPESTABILITYANALYSISUSINGTHEFINITEELEMENTMETHODTHEEXTENTOFTHEVEGETATIONEFFECTSHASBEENCHARACTERISEDBYTHEDEPTHOFROOTZONEHRTHESTABILITYOFASLOPEISSENSITIVETOBOTHTHEAPPARENTROOTCOHESIONCRANDDEPTHOFROOTZONEHRTHESTABILITYOFSLOPESISIMPROVEDWITHANINCREASEINTHEVALUESOFCRANDHRINADDITION,RESULTSSHOWEDTHATTHEIMPROVEMENTINFOSFORASLOPEWITHVEGETATIONCOVEROVERTHEENTIREGROUNDSURFACEISHIGHERCOMPAREDWITHVEGETATIONCOVERONTHESLOPESURFACEALONETHESTUDYHASALSOSHOWNTHATTHEEFFECTSOFVEGETATIONAREMORESIGNIFICANTINSLOPESWITHLOWVALUESOFEFFECTIVECOHESIONWHERESHALLOWPLANARFAILURESARELIKELYTOOCCURCORRESPONDINGLY,VEGETATIONHASLESSOFANEFFECTONDEEPSEATEDFAILURE植被模型对边坡稳定性的影响摘要据了解，植被在两个方面影响边坡稳定水文效应和机械效应。水文效应包括通过植被土壤水分蒸散，从而导致土壤吸力的增加或者孔隙水压力的减少，因此，增加了土的抗剪强度。通过植物的根矩阵系统的力学效应，也增加了土壤的抗剪强度。在土体内根密度和根抗拉强度也有助于增加土壤的抵抗剪切能力。土壤吸力和根钢筋的影响在表现土壤凝聚力方面已经量化。本文利用有限元法分析植被在斜坡稳定性方面的影响。两个关键的植被参数已被纳入有限元边坡稳定分析中，即明显的根凝聚力（CR）和根区的深度（HR）。对由植被和土壤参数变化引起斜坡稳定性的灵敏性进行了参数研究评价，结果表明，植被在斜坡浅层失稳中起着重要作用，并且显著影响其稳定性。引言边坡失稳灾害时岩土工程中的主要问题之一，它的发生也会造成生命和财产的损失。这些失稳的边坡大多数是植被或森林覆盖的天然斜坡。天然斜坡和与河堤或者人工斜坡是不同的，植被和土壤变异在它们的稳定性方面起着重要作用。植被对斜坡稳定性的影响是众所周知的。植被通过改变土壤水分构成的改变来影响斜坡的稳定性，这反过来又导致土壤吸力或空隙压力的变化。植被也可以通过根加固来提高斜坡的稳定性。WUETAL1979对移除植被前后斜坡的稳定性进行调查，得出结论，树根提供的抗剪强度对斜坡的稳定性是至关重要的。研究表明，植被可以通过根钢筋提高坡体的抗剪强度。WUETAL1979表示，如果在边坡稳定性分析中不考虑植被的影响，边坡则可能发生失稳。天然斜坡受制于土壤和植被固有的变异性。这就使得天然斜坡的底层土壤坡面不能完全一致或者同质。即使是在一个相同土质的土层，土壤的性质从点到点也是变化的（VANMARCKE，1977年）。植被的生长对环境状况和变化非常敏感。通常不同类型的植被生长于一种天然的斜坡上，如牧草，药材，灌木和树木等。这些不同植物的大小和物理性的不同都会导致对斜坡稳定有不同的影响。因此使用单一为分析植被参数的输入值最好看作是原始条件下的近似值。本文利用有限元方法对植被影响斜坡稳定性进行调查。有限元法允许用户将斜坡几何分成小分子的方法来确定植被对斜坡稳定性影响的程度。由于本文篇幅的限制，本文只将根钢筋的影响纳入边坡稳定分析，不考虑植被和土壤性质的变化。21同质坡（倾角2657角）用于研究植被对边坡稳定性的影响。两个关键的植被参数被纳入有限元边坡稳定性分析，即明显的根凝聚力（CR）和根区的深度（HR）。同时对由植被和土壤参数变化引起斜坡稳定性的灵敏性进行了参数研究评价。植被对边坡稳定性影响的前期分析根筋模型在过去的三十年中，研究集中在利用植物根系加固稳定斜坡。植物根系的能力来加强土壤稳固是众所周知的。有高抗拉强度的植物根系能利用其密集的根矩阵系统来提高土体的强度。土体质量与植物根系是紧密联