汶川地震诱发文家沟巨型滑坡-碎屑流基本特征及成因机制初步分析  

BASIC CHARACTERISTICS AND PRELIMINARY MECHANISM ANALYSIS OF LARGE SCALE ROCKSLIDE-STURZSTROM AT WENJIAGOU TRIGGERED BY WENCHUAN EARTHQUAKE

作　　者：黄河清[1] 赵其华[1] 

机构地区：[1]成都理工大学地质灾害防治与地质环境保护国家重点实验室,成都61059

出　　处：《工程地质学报》2010年第2期168-177,共10页Journal of Engineering Geology

基　　金：国家自然科学基金项目"台风引发斜坡地质灾害机理研究(面上项目;编号:40772177)"资助

摘　　要：2008年5月12日,汶川M8.0地震在四川省绵竹市清平乡文家沟内诱发一巨型滑坡。通过现场调查得知,滑坡前后缘高差455m,厚度20~30m,滑面为基岩层面,初始方量2.750×107m3。滑体在运动中转化为碎屑流。滑坡-碎屑流总的水平运动距离为4022m,垂直运动距离为1443m,遗留的堆积物体积达5×107m3。滑坡距映秀—北川断裂仅3.6km,位于其下盘,地震烈度达X I度。滑坡导致文家沟中48人遇害,并形成一条完整的地震次生地质灾害链。初步分析表明滑坡启动速度快,滑坡向碎屑流转化过程明显、地点明确。碎屑流运动过程复杂,伴有强烈的＂气垫效应＂和＂前缘气浪冲击效应＂。作者认为,文家沟滑坡的高启动速度是长持时强烈地震动作用的结果,与山体的猛烈碰撞是导致滑体解体并转化为碎屑流的原因。On 12th May,2008,the M8.0 Wenchuan Earthquake induced a rockslide-sturzstrom at Wenjiagou valley in Qingping County,Mianzhu City,Sichuan Province,P.R.China.The field survey indicated that the height of rockslide source area is 455 m,the thickness is 20～30 m,and the rockslide mass that the initial volume is 2.750×107 m3 slipped.The rockslide-mass slipped among the bedding surface,and the total motion distance is 4022 m in horizontal,and 1443 m in vertical.The rockslide mass left 5×107m3 debris in the valley.The distance between rockslide source area and seismogenic fault named Yingxiu-Beichuan Fault,is only 3.6 km.The rockslide is located in the fault＇s footwall.The earthquake intensity of rockslide source area is XI.The disaster event formed a complete chain of earthquake-induced geohazards and killed 48 local people.The preliminary analysis showed that rockslide startup speed was very high.The process and position of the transformation of rockslide to sturzstrom is clear.The accompanied air cushion effect and front air-blast effect,the sturzstrom-mass motion processing were complex.In this event,it is authors＇ opinion that long duration strong earthquake is the immediate cause of very high startup speed of slipping mass.And that the mass crashed into a hill in the valley caused rockslide mass transformed into sturzstrom.

关 键 词：地震 滑坡 碎屑流 成因机制 地质灾害链 

分 类 号：P642.22[天文地球—工程地质学]