纪以来中国的大型滑坡及其发生机制

263Vol.26No.320073ChineseJournalofRockMechanicsandEngineeringMarch20072006082220061020(50539050)(1963)[e-mail]20(610059)201180%200300mm/d70%3()()P642.22A10006915(2007)03043322LARGE-SCALELANDSLIDESANDTHEIRSLIDINGMECHANISMSINCHINASINCETHE20THCENTURYHUANGRunqiu(NationalProfessionalLaboratoryofGeologicalHazardsPreventionandGeologicalEnvironmentProtectionChengduUniversityofTechnologyChengduSichuan610059China)AbstractThelandslidesoccurfrequentlyinChina.Inparticularlarge-scalelandslidesaredominantandextremelyimportant.InWestChinathelarge-scalelandslidesarenotablefortheirscalecomplexformationmechanismandseriousdestructionwhicharetypicalandrepresentativeintheworld.Datawerecollectedfromsometypicallarge-scalelandslidesoccurredinmainlandofChinasincethe20thcentury.Amongthesecasesninelandslideswerecomprehensivelyanalyzedanddiscussed.Thesecasesrepresentdifferentgeologicalconditionsdifferenttriggeringmechanismsandinducedfactors.Thisstudyshowsthatthefundamentalcauseforlarge-scalelandslideinChinaisduetothetopographicalandgeomorphologicalconditions.About80percentoflarge-scalelandslideswerefoundinthefirstslope-descendingzoneofthemainlandtopographyaroundtheeasternmarginof•434•2007Tibetplateau.Moreoverthisareaisthemostactiveareaoftheplatetectonicactivities.Theintensiveinteractionsbetweentheendogenicandepigeneticgeologicalprocesscauseseriousdynamicchangeofthehighsteepslopewhichareresultedinthedevelopmentoflarge-scalelandslides.Strongearthquakeextremeweatherconditionsandtheglobalclimaticchangearethemaintriggeringfactorsoflarge-scalelandslides.InSouthChinaitiseasytotriggerlarge-scalelandslideswhenstormcauses200300mm/dofheavyrainfall.InNorthwestChinathethawingofthefrozenlayerinspringisthemaincauseoflarge-scalelandslidesinloessregion.Inrecentyearsglobalwarmingcausesthetemperaturetorisesnowlinetoshiftglacierrecessionandglacierlakestocollapse.Thesefactorsarealsothetriggeringfactorsoflarge-scalelandslidesinsomeareas.Inadditionthecausationofmorethan70percentoflarge-scalelandslidesiscloselyrelatedtothehumanactivities.Detailedanalysesofthecasesshowthatthemechanismsoflarge-scalelandslidesinChinaarecomplex.Thelarge-scalelandslidescanbesummarizedintothreetypesrocklandslidessoillandslidesandlandslidesindebris.Thetypicalgeomechanicalmodelsoflarge-scalelandslidesinrocksareshownasfollowingthethreesectionsmodel(i.e.sliding-tensioncracking-shearing)retainingwallcollapsemodelhorizontal-pushingmodelinhorizontalstratalarge-scaletopplingmodelinanti-dipstrataandthecreep-bending-shearingmodeletc..Eachmodelcorrespondstosomespecificrockstructureconditionsanddeformationprocesses.Whenlarge-scalerocklandslidesoccurtheyaregenerallyaccompaniedbythesuddenlybrittlefailureofthelockedsectionalongthepotentialslidingsurface.Thelockedsectionisextremelyimportanttothedeformationcontrolandstabilityoftherockslopewhichisalsothekeyfactorfortheassessmentofslopegeohazardandforthedevelopmentofcontrolmethods.Itisshowninengineeringpracticethatthecorrectunderstandingandusingofgeologicalandmechanicalmodelarethefundamentalkeysforthepreventionoflarge-scalelandslides.Keywordsslopeengineeringlarge-scalelandslidecasestudydevelopmentrulesformationmechanism120(ElNiño)[13][45][610]SN[311][1214]2080()4001000041104173.52104km218.10(2000)19951000[1521][2223][162435]19509(400104m340196310(Vaiont)(2.7108m325002600263.20•435•)[24]198052.8km3[316]19988600104m3200112(75104m3SantaTecla500[25])20192019331965[41516]2080198271983319897199191996619977200042004720200104m32202.1249km56km10341′3201′19338251553X7.5VIII2000km2VI1.4104km2WN216865192511800m170m255m98m7.30107m3[27](1)11933[36]Fig.1LandslidesandrockfallsdistributioninducedbystrongearthquakeatDiexinSongpingbeltin1933[36]4519331091900760m12m10.2103m3/s25008[37]1400m21102425m1400m900m1.5km2170m2.1108m315354050702[38]2.2N•436•200719676891km[3942]1030m1900m1300m1.7km26.8107m35min200m()3050m355175m30km53km6.8108m3200300km(2)2Fig.2Tanggudonglandslidedamanditsbackwaterscope6170800140010km48m30m()20.4m16.6m12.4m6.87m2.86m1730km1.54m5.70104m3/s2.361042.311041.991046.09103m3/s12h()2.319827633.2mm1720001km18020012.5m/s200m1.4km1.6km0.77km21.50107m32.30106m3(3)3(1982)Fig.3JipazilandslideonYangtzeRiverin1982173060040m700m263.20•437•7d8000()1000()0.093.7m30.070.0m0.21.0m68(J3P)EWS(4)[43]4[43]Fig.4PlanofJipazilandslide[43]24h240.9mm1h38.5mm1.70104m3192.41983372283m2080m800m10m3.10107m31min3237400m2100m30352()EW(5)485mm80%791979650mm1982101166mmEWS7386(5)[44]EW7001100mSN11001630m575m1.3km2(6)[45]750m220240m754555()EW250300m5060m2020m2080mNW10510m850mJ3PQdelJ3P0160mQdelN•438•20075[44]()Fig.5PlanofSalemountainlandslideanditsslidingvectordiagram[44](revised)6[45]Fig.6GeologicalprofileofSalemountainlandslide[45]120m(6)[45]120m2.51989710208022160019897222.9mm71088.6mm198979[44]10300m60s12848655m848790m790695m75110mNW47655m210m165m1.801052.0104m3F76(7)F7/m/mNN263.20•439•1234567(IIIIIIIVVVIVIIVIII)SPQ7Fig.7SchematicdiagramofgologicalstructureofXikoulandslide2.619919231810EN30km2300m31820m3000m130m10m4.00106m33min2162522.00105m21200[2728](8)-1820