PAGE\*MERGEFORMAT17外文翻译StabilityofSlopes1.1IntroductionGravitationalandseepageforcestendtocauseinstabilityinnaturalslopes,inslopesofembankmentsandearthdams.ThemostimportanttypesofslopefailurearcillustratedinFig.1.1.Inrotationalslipstheshapeofthefailuresurfaceinsectionmaybeacircularareoranon-circularcurve.Ingeneral,circularslipsareassociatedwithhomogeneoussoilconditionsandnon-circularslipswithnon-homogeneousconditions.Translationalandcompoundslipsoccurwheretheformoffailuresurfaceisinfluencedbythepresenceofanadjacentstratumisatarelativelyshallowdepthbellowthesurfaceoftheslope:thefailuresurfacetendstobeplaneandroughlyparalleltotheslope.Compoundslipsusuallyoccurwheretheadjacentstratumisatgreaterdepth,thefailuresurfaceconsistingofcurvedandplanesections.Figure1.1TypeofslopefailureInpractice,limitingequilibriummethodsareusedintheanalysisofslopestability.Itisconsideredthatfailureisonthepointofoccurringalonganassumedoraknownfailuresurface.Theshearstrengthrequiredtomaintainaconditionofthelimitingequilibriumiscomparedwiththeavailableshearstrengthofthesoil,givingtheaveragefactorsafetyalongthefailuresurface.Theproblemisconsideredintwodimensions,conditionsofplanestrainbeingassumed.Ithasbeenshownthattwo-dimensionalanalysisgivesaconservativeresultforafailureonathree-dimensional(dish-shaped)surface.Figure1.2Theu=0analysis1.2AnalysisfortheCaseofu=0Theanalysis,intermoftotalstress,coversthecaseofafully-saturatedclayunderundrainedconditions,i.e.fortheconditionimmediatelyafterconstruction.Onlymomentequilibriumisconsideredintheanalysis.Insection,thepotentialfailuresurfaceisassumedtobeacirclearc.Atrialfailuresurface(centreO,radiusandlengthLa)isshowninFig1.2.Potentialinstabilityisduetothetotalweightofthesoilmass(Wperunitlength)abovethefailuresurface.Forequilibriumtheshearstrengthwhichmustbemobilizedalongthefailuresurfaceisexpressedas:m==whereFisthefactorofsafetywithrespecttoshearstrength.EquationmomentaboutO:Wd=LarF=(1.1)Themomentsofanyadditionalforcesmustbetakenintoaccou