摘要
西藏昌都市江达县波罗乡白格村分别在2018年10月11日和11月3日发生两次滑坡灾害,堵塞金沙江干流并形成堰塞湖,导致重大经济损失。为研究其成因,通过现场调查、钻孔取样和地下水流速测量发现,此次滑坡是该区域特殊的工程地质与水文地质联合作用下"新模式"的结果。研究表明:该滑坡处于羌塘地体和松潘-甘孜褶皱带之间的金沙江缝合带上,其后缘发育波罗-木协断裂,在此断裂作用下形成的波贡沟增加了研究区地下水的渗流;研究区主要出露地层为三叠系侵入的蛇纹岩和元古界雄松群片麻岩,钻孔资料显示坡顶地面45 m深度以下均为强风化蛇纹岩,岩体极为破碎,为滑坡地下水的赋存提供有利条件,并与下盘片麻岩隔水层结合,形成了侵入接触带蓄水构造和风化壳蓄水构造;白格滑坡的坡脚处于金沙江凹岸处,在河谷强烈下蚀、凹岸侧蚀以及滑坡体自身重力作用下易发生倾倒弯曲拉裂变形;波贡沟水流长期渗入滑坡体,降低土体的抗剪强度和有效应力,使蛇纹岩地层逐渐演化成蠕滑带,在2018年极端降雨事件的触发下导致白格滑坡的发生。
Clarifying the characteristics of engineering geology and hydrogeology is beneficial to better understand the formation mechanism of landslide disaster and take targeted prevention and control measures.Two landslides have occurred in Baige Village on October 11 and November 3,2018,respectively,blocking the main flow of the Jinsha River and forming a barrier lake,causing a great economic damage.In order to better understand the cause of landslide formation and avoid the recurrence of such disasters,the Baige landslide in Jinsha River was taken as the research object to carry out the field investigation and the geological background analysis.The results show that the landslide is located in the Jinsha River suture zone between the Qiangtangterrane and the Songpan-Ganzi fold belt,and the Boluo-Muxie fault is developed at its rear edge.Simultaneously,the formation of Bogong Gully formed under this fault increases the seepage of groundwater in the study area.The main outcrops in the study area are the Triassic serpentinite and the Proterozoic male pine group gneiss and the borehole data show that the serpentine strata are strongly weathered and the rock masses are extremely broken,which provides favorable conditions for the occurrence of landslide groundwater that contributes the landslide.In addition,the serpentine strata combine with the gneiss that acts as a water-barrier layer in footwall to forming the water storage structure of intrusive contact zone and weathered crust.The slope of the Baige landslide is located on the concave bank of the Jinsha River,which is prone to toppling,bending and cracking deformation due to the strong erosion of the valley,the side erosion of the concave bank and the gravity of the landslide body.The water in Bogong Gully has been infiltrating into the landslide body for a long time,reducing the shear strength and effective stress of the soil,and gradually transforming the serpentine strata into a creep zone,which leads to the occurrence of Baige landslide under the trigger of the extreme rainfall event in 2018.It is pointed out that further risk management measures should include strengthening the depth of geological exploration and increasing the construction of drainage measures based on existing prevention and control.
作者
钟政
陈宁生
倪华勇
刘恩龙
韩征
ZHONG Zheng;CHEN Ning-sheng;NI Hua-yong;LIU En-long;HAN Zheng(Key Lab of Mountain Hazards and Surface Processes,Institute of Mountain Hazards and Environment,Chinese Academy of Sciences,Chengdu 610041,China;Kunming University of Science and Technology,Kunming 650093,China;Academy of Plateau Science and Sustainability,Xining 810016,China;Chengdu Center,China Geological Survey,Chengdu 610081,China;State Key Laboratory of Hydraulics and Mountain River Engineering,College of Water Resources and Hydropower,Sichuan University,Chengdu 610065,China;School of Civil Engineering,Central South University,Changsha 410075,China)
出处
《科学技术与工程》
北大核心
2021年第13期5262-5269,共8页
Science Technology and Engineering
基金
国家自然科学基金面上项目(41671112)
国家自然科学基金国际(地区)合作与交流项目(41861134008)
四川科技计划项目重点研发计划(18ZDYF0329)。
关键词
金沙江
白格滑坡
工程地质
水文地质
Jinsha River
Baige landslide
engineering geology
hydrogeology
