中国的强震滑坡：特征及机理(黄润秋)

中国的强震大型滑坡：特征及机理黄润秋成都理工大学地质灾害防治国家重点实验室2012.10.23中国强震震中分布图印度板块菲律宾变快太平洋板块IndiaplatehasbeenpushingEurasianPlatestronglysince3.4MaandresultedinTibetplateauuprisingveryquickly.NowthemovementvelocityofIndiaPlatetowardsEurasianPlateisstill4-5cm/y.IndiaplateTibetplateauEurasianPlateWulumuqiChangchunShenyangNanningTaiwanTheboundaryoflandformelementGuangzhouProvinceLarge-scalelandslidepointTheboundaryofYellowRiver,YangtseRiver,HuaiRivervalley200kmHainanProvinceTaiyuanBeijingXiningFirst-orderstairZhengzhouShanghaWuhanChangshaNanchangGuiyangKunmingXi’anLanzhouYinchuanHuhehaoteLhasaChengduChongqingYangtseRiverJinshaRiverPearlRiverHuaiRiverLantsangNuRiverSecond-orderstairThird-orderstair复杂地形地貌第二阶梯第三阶梯YellowseaSichuanbasinHimalayaMts.HengduanMts.NanjingTibetPlateau第一阶梯(4500m)(500-2000m)(500m)中国地震滑坡分布叠溪1933汶川/2008大渡河/1870S马湖/?印度板块三江/？海源/1920黄河上游/?HaiyuanDingxiGanyechiNanhuaHillJingyuanJingdaiXijiGuyuanHuiningJingningLiupanHillMeizoseismalzoneFailurezoneShanghaiBeijingYinchuan海源地震滑坡，19201920年12月16日，宁夏海源发生8.5级强震，震中烈度12度，地震带200km长，近2万平方公里,强震导致234,117人死亡，50万栋房屋被毁。9度等震线10度等震线11度等震线12度等震线断裂ENWSVIIIIXXXIIXI海源固原西吉晋宁晋远Dingxi天水Ⅺ~ⅫⅩⅨⅧⅨⅦ同威渭河35o36o105o106o等震线滑坡分布区EarthquakelandslideandslidesalongGaojieRiveranditsbrachesRiver&gullyLandslide1kmGaojieRiver由于震级高，地形复杂，且为黄土地区，因而触发了大量的滑坡，其密度达到1个/km2,并形成675个大型滑坡和40个滑坡堰塞湖。IXVIIIXXI~XIIVII规模大,滑面缓、滑速高、滑程远是这次强震滑坡的主要特征，部分黄土滑坡的滑程达到数km。石碑塬滑坡东西向长约1.6km，南北宽1.2~1.5km，滑体平均厚度约14m，滑体体积约为4700万m3，属宽缓巨型土质滑坡，主滑方向260°。滑坡地形坡度平缓，平均坡度约5~8°，前部坡度约2~5°。260°液化区滑坡区2滑坡区12’1’液化区47.0millionsm3固原石碑源滑坡滑坡堆积体总体上陡下缓，后壁无植被覆盖，后壁高度25—35m，坡度约85°，两侧较缓，发育多级阶坎，滑坡后壁多形成不规则的滑坡平台。坡后部形态滑25~35m260°平台260°典型的低角度滑坡35.0millionsm3al+plQ41780176017201700100200300400500600700800900100011001200130014001500160017001800190020002100公路270°公路公路公路撒门河Q3Q2石碑塬滑坡1-1'地质剖面图Q2推测地层界线中更新世离石黄土Q3晚更新世马兰黄土Q4Q4al+plQ4al+pl石碑塬滑坡2-2'地质剖面示意图17801760174017201700100200300400500600700800900100011001200130014001500160017001800公路公路撒门河270°Q2推测地层界线中更新世离石黄土Q3晚更新世马兰黄土Q3Q2Q4del近水平的滑动面上部黄土中部灰白色粉土层中部灰白色粉土层底部砂砾石层黄土:5-10m砂土层:1-2m砂砾石层:2m党家岔滑坡堰塞湖堰塞湖55.0millionsm31#滑坡2#滑坡3#滑坡188019201960200020401840290°安置房区冲沟050100150200250300350400450500550600650700750800850900黄土泥岩推测地层界线18001720滑源区290°流通区330°堆积区原始地形1760LmaxHmaxSourceareaDepositionareaApparentfrictionangle黄土是对地震非常敏感的土！8~1111~146-8Hmax/Lmax0.70.80.91.00.00.10.20.30.40.50.6Hmax/Lmax6543210Mean=0.26681N=32Mean=0.1991N=190HaiyuanearthquakeF.Legros,2002HaiyuanearthquakeF.Legros,2002Frequency(F.Legros,2002)80604020Frequency(Haiyuanearthquake)200大孔隙，可以保持陡边坡，但结构连接非常脆弱，极易在强震作用下溃散，成流态状滑动。中国地震滑坡分布海源/1920叠溪1933汶川/2008大渡河/1870S马湖/?印度板块三江At14:28,onMay122008,Ms8.0EarthquakeoccurredatLongmenMountain,westofSichuanBasin.HighMagnitude:Ms8.0,Shallowfocus：14km,LongSurfacerupture：240km,Longduration:120sGeologicalenvironmentisveryfragile①TheS-NcompressingofthesetwoplatesandtheuprisingofTibetplateauresultsinthemassofTibetPlatedmovingtowardeastandsoutheastalongaseriousbigactivefaults.CentroidMomentTensorSolution:Songpan-GanziplatethrustontheLongmenMountainalongthecentrefault—Yinxiu-BeichuanfaultwithN30EdirectionandthenlateraldisplacementtowardsNEalongit.Theepicenterdepthisonly10-20km.汶川-茂县断裂都江堰-安县断裂龙门山Songpan-GanziPlate震级高，震源浅43,842/62,000个滑坡FootwallHangingwall上盘效应hangingwallfootwallYingxiu-BeichuanFaultJiangyou-GuanxianFaultDistancefromtheco-seismicfault(m)NumberoflandslidesFootwallHangingwall映秀方向效应平行断层方向垂直断层方向顺坡背坡…..RiverboundaryRiveryS|idedimuonoflargescalelandslide1lI1.M\'lIorlll'l'\..rc;制.lUJIrtll'I'f\ÞLh.u...dC.。但Þ.I....翩翩帽Ir....lcui.FootwallHangingwall1993M6.9FinisterreEarthquake1999M6.9Chi-ChiEarthquake0510152025300.20.41.00.80.6HighLD/km21.2VeryhighlowerDistance(km)moderatehigh42.7778.9488.1894.3110066.981008060402001200102030Distancefromthefaults（km）HazardnumberpercentzThemostsensitiverangeis0to10km,67%landslidesdistributesinit..Fault距离效应3.5-6/km2锁固段效应—TherearehighlyconcentrationoflandslidesatseveralstaggeredandtransitionalpartsalongYingxiu-BeichuanFault.Wecallthisphenomenonas“Lockedsegmenteffect”.112largescalelandslides：A.Yinxiusection；B.Xiayudongsection；C.Hongbai—Chaping；D.Leigu—Chenjiaba；E.Nanba—Donghekou。河流水系效应震后YingxiuXuankouBaihuaYinxingCaopoMianchiYingxiuXuankouBaihuaYinxingCaopoMianchi10.11020304097.879.539.81200506070DegreeofslopeHazardnumberpercent100100806040200滑坡密度的坡度分布20-50坡度效应87%的滑坡出现在地形坡度20~50度的范围之内。Slopegrade(°)10-2020-3030-4040-5050Area(km2)5632.6714603.3713984.805048.27913.14Hazardnumber928271636311678200Hazardpercent10.1429.6739.6718.332.19Sensitivity（spot/km2)0.160.190.260.330.22滑坡区堆积区滑出口滑塌区堆积区Slipout堆积位置宽谷峡谷1500m滑坡位置Mostlandslidesoccurredontheupperpartofavalleyandtheslopechangeplaceofstrathshapeoftherivertogorges,wheregenerallyisstrongunloadingandhighlybroken,微地貌效应planationsurface峡谷宽谷孤立地形单薄山脊lgVHmax/Lmax0.450.400.350.300.257.57.06.56.030002500200010001500V(104m3)5000Hmax/Lmax5.5SourceareaHmax/Lmax=-0.086lgV+0.939(R2=0.531)0.550.500.450.400.350.300.25Hmax/Lmax=-0.037lnV+0.939(R2=0.530)ApparentfrictionangleDepositionareaLmaxHmax大“失距”特征0.60.50.40.30.20.10.0Hmax/Lmax1210864N=20220FrequencyMean=0.2076N