汶川地震触发大光包巨型滑坡基本特征及形成机理分析_百度

工程地质学报 1004—9665/2008/16(6JD730—12

汶川地震触发大光包巨型滑坡基本特征及形成机理分析

黄润秋裴向军李天斌

(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610059

摘要大光包一红洞子沟巨型滑坡是汶川地震触发的最大规模滑坡,其体积达7.42亿Ⅱ13,堰塞坝高达690m,是我国已知的最大规模地震滑坡和最高的滑坡堰塞坝,也是目前全世界已知的为数不多的几个方量在5亿tll3以上的超大规模滑坡之一。其高达690m的滑坡堰塞坝为目前世界最高的滑坡坝。滑坡位于发震断层上盘,距发震断裂——映秀一北川断裂不足 7hn。震前斜坡为三面切割的孤立型山脊,相对高差达1500m;斜坡岩层走向与坡面近于垂直,层面延展性极好,构成滑动面形成的基础。调查和分析表明,斜坡的临空条件和贯通性好的灰岩层面是滑坡产生的基础;而高强度和长持时强震地面运动是导致滑坡产生的根本因素。滑坡产生的机理和过程可分为以下4个阶段:即坡体震裂、松弛和解体阶段、高速溃滑阶段、震动堆积阶段、二次抛射和碎屑流堆积阶段。失稳高速下滑的坡体,形成了沿主滑方向长4.2kin,宽2.2kin的堆积体,高速流动的碎屑流越过下游侧风波岩山脊,沿红洞子沟形成了长1km的碎屑流堆积区。

关键词大光包滑坡形成机制溃滑震动堆积

中图分类号:P642.22文献标识码:A

BASIC CHARACTERISTICS AND FoRMATION MECHANISM oF THE LARGEST SCALE LANDSLIDE AT DAGUNGBAO OCCURRED DUIUNG THE WENCHUAN EARTHQUAKE

HUANG Runqiu PEI Xiangjun LI Tianbin

(State Key laboratory of Geo-Hazard Prevention and Geo-Environment Protection.Chengdu University of Technology-Chengdu 6113059 Abstract The landslide

at Daguangbao and Hongdongzigou site is the largest among all landslides occurred during the Wenchuan Earthquake.Its volume is up to 742Mm3-and its debris dam height reaches 690m.So it is also the most largest scale landslide triggered by earthquake among all investigated landslides in China.Additionally,it has the highest debris dam originating from landslide in China.It is even one of a few super large—scale landshdes known all over the world。whose individual volume iS over 500Mm3.The debris dam formed by this landslide can be the hi【ghest around the world.The landslide is located on the upper plate of the Causative Fault.It is nearly 7 km away from the triggering seismic fracture of Yingxiu—beichuan fault.The slope was an isolated ridge before the Earthquake.itg the ridge had its 3sides cut.Its height difference reaches 1500

m.The strike of clinothen was a1. most vertical to the slope surface.the clinothen had perfect extension.They composed together the basic conditions of sliding surface formation.Our investigation and analysis show that the free surface conditions of the slope and the surface connectivity of limestone bedding plane were the base of landslide

formation.And the ground movement re— suited from the intensive quaking with large intensity and long duration Was the radical triggering factor of the land・

・收稿R期:2008一ll一10;收到修改稿Ft期:2008—12一lO.

基金项目:本项r作获国家自然科学基金汶川地震灾后调查辛任基会资助(编号:40841009.

第一作者简介:黄润秋,主要从事工程地质和岩土工程方面的教学与研究工

作.Email:************.cn

16(6 黄润秋等:汶川地震触发大光包巨型滑坡基本特征及形成机理分析

slide.The mechanism and process of the landslide could be divided into 4stages ag follows:(athe stage of slope body shatter-relaxation and disintegration,(bthe stage of hish speed sliding-9ctIle stage of accumulation with shock-and(dthe stage of the second