强震触发黄土滑坡流滑机理的试验研究——以宁夏党家岔滑坡为例  

EXPERIMENTAL STUDY ON MECHANISM OF FLOW SLIDE OF LOESS LANDSLIDES TRIGGERED BY STRONG EARTHQUAKE——A CASE STUDY IN DANGJIACHA,NINGXIA PROVINCE

作　　者：张晓超[1] 裴向军[1] 张茂省[2] 孙萍萍[2] 贾俊[1,2] ZHANG Xiaochao;PEI Xiangjun;ZHANG Maosheng;SUN Pingping;JIA Jun(State Key Laboratory of Geohazard Prevention and Geoenvironment Protection,Chengdu University of Technology,Chengdu 610059;Xi’an Center of China Geological Survey,Xi’an 710054)

机构地区：[1]地质灾害防治与地质环境保护国家重点实验室(成都理工大学),成都610059 [2]中国地质调查局西安地质调查中心,西安710054

出　　处：《工程地质学报》2018年第5期1219-1226,共8页Journal of Engineering Geology

基　　金：国家自然科学基金(41702335);国家自然科学基金重大项目(41790445);中国地调局地质调查项目(DD20089270)资助

摘　　要：针对地震触发低角度、长距离流态化黄土滑坡的问题,以1920年宁夏海原大地震触发的西吉县党家岔滑坡为典型案例,开展较为详细的现场勘查与工程地质测绘工作,并结合室内试验研究,揭示了党家岔滑坡特殊的形成机制及运动特征。结果表明:在强震过程中,马兰黄土的原始结构遭到摧毁性的破坏,上层非饱和黄土震裂损伤,后缘拉裂,底部潜在滑带的高饱和黄土层内超孔隙水压力骤增,并产生明显液化,强度骤减,塑性变形急剧累积,剪切面逐渐贯通;之后坡体在地震力水平抛射作用下,高速启动,几个滑块先后沿着295°、300°、80°方向滑向中间沟槽,然后碰撞变向顺沟而下;液化层呈泥流状向前运移,表现为典型的"剪切稀化"流体,达到极低的稳态强度和表观动力黏度,浮拖上部滑体产生低角度、长距离运移,冲出沟口后受到对面山体阻挡,转向沿着堡玉沟往下游侧扩离,整个滑程长达3 km。研究成果有助于深入认识强震条件下流态化滑坡的形成机制,对于防控黄土地区地质灾害具有一定的参考价值和指导意义。This paper aims at the problem of low angle and long distance fluidized loess landslide triggered by earthquake.It takes the Dangjiacha landslide as a typical example.It was triggered by Haiyuan Earthquake in 1920.A detailed field investigation and indoor research are carried out for the Dangjiacha landslide.After comprehensive analysis,it reveals the genetic mechanism and movement characteristic of Dangjiacha landslide.In the earthquake process,the original structure of Ma Lan loess was destroyed destructively.The upper unsaturated loess was damaged in tension with the seismic shaking.Edge cracked,excess pore water pressure was accumulated in saturated zone.The saturated loess was liquefied and plastic deformation had accumulated.The shear surface gradually transfixed.Under the seismic horizontal ejection,the slope collapsed in high-speed.Three sliders slid to the middle groove,along the direction of 295 degree,300 degree and 80 degree to the north respectively.Then they turned down the ditch with collision.Liquefied layer flowed forward like mudslides,showing a typical"the shear-thinning fluid”,with extremely low steady-state strength and very low apparent dynamic viscosity coefficient.The upper loess floated with low angle and long distance movement,finally rushed out the valley,then turning along Bao Yu Gou to downstream for the mountain barrier.The displacement was up to 3￣￣km.The results have important reference value or guiding significance for further understanding the formation mechanism of fluidized loess landslide under strong earthquake conditions and preventing geological disasters triggered by earthquake liquefaction in loess area.

关 键 词：党家岔滑坡 黄土液化 稳态强度 剪切稀化 表观动力黏度 

分 类 号：P642.22[天文地球—工程地质学]