重庆小南海地震崩滑体的基本特征及形成机制研究  

BASIC CHARACTERISTICS AND FORMATION MECHANISM OF COLLAPSED AND SLIDED DEBRIS MASS INDUCED BY XIAONANHAI EARTHQUAKE IN CHONGQING CITY

作　　者：崔芳鹏[1,2] 胡瑞林[1] 张明[1,2] 许强[2] 陈晓岚 韩应军[4] 

机构地区：[1]中国科学院工程地质力学重点实验室,北京100029 [2]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 [3]重庆市地科工程勘察设计院,重庆400700 [4]河南理工大学高职学院,焦作454000

出　　处：《工程地质学报》2009年第2期167-174,共8页Journal of Engineering Geology

基　　金：“十一五"国家科技支撑计划项目(2006BAC04B02);地质灾害防治国家重点实验室”科技减灾,重建家园"专项科研资助项目(DZKJ-0807)

摘　　要：通过对重庆小南海地震崩滑堆积体进行野外地质调查和工程地质勘察等相关工作，阐述了该崩滑堆积体的基本特征和形成机制，认为其形成过程经历了“风化剥蚀-震荡抛射-崩滑堆积-堵江成湖”4个阶段，其岩体破坏形式为高度破裂或严重高度破裂状态，其岩体破坏过程以崩塌为主，滑动为辅。研究发现，小南海地震崩滑堆积体的最终形成是受地震构造运动及应力、岩体构造、地形地貌及地震波作用等因素综合作用的结果：（1）该区NE向黔江逆滑（右行）断裂与NNW向仰头山逆滑（左行）断层形成的“X”型地震构造组合及轴向呈NWW向的构造压应力使小南海断块内部发生张滑（左行）破裂而导致6^1／4级地震发生；（2）该区呈“X”形展布的3组主要构造节理是崩滑体发育的物质基础，大、小垮岩在地震波作用下最终发生了向山体临空面（约145°～155°方向）的各自崩滑；（3）从崩滑堆积体中发现的灰岩块石证明崩滑体原始地层中曾含二叠系栖霞组和茅口组灰岩，这为恢复崩滑前山体地形提供了直接证据；（4）崩滑体中堆积岩块直径分布区域沿约150°方向自WN到ES依次递减，间接证明了地震时崩滑体抛洒方向为约150°方向，且大、小垮岩分别形成堆积区，交叉堆积部分较少。This paper presents the field geological investigation, engineering geological exploration and other related studies on the collapsed and slided debris mass induced by the Xiaonanhai Earthquake in Chongqing,city. Basic characteristics and formation mechanism of the debris mass are elaborated. It is held that the forming process of the mass consists of four steps ： namely weathering and denudation, shocking and projecting, collapse - slide accumulating and dammed lake formation. Collapses rather than landslides appeared in process of rock mass fracturing and rock blocks in accumulation body are quite and even more fragmental. Research shows that the mass is a result of comprehensive actions including seismotectonic moving and stress field, rock mass structure, topography and geomorphology, and seismic wave. First of all, the left lateral tensile - slip fracture in Xiaonanhai fault block was induced by X - shaped seismotectonic combination. It consists of the NE trending right lateral Qianjiang reverse - slip fracture and the NNW trending left lateral Yangtoushan reverse - slip fault. The NWW trending axially tectonic compression resulted in the M61/4 earthquake. Secondly, the rock mass near both Dakuayan and Xiaokuayan with three groups of tectonic joints forming X -shape collapsed respectively towards their free faces, at about 145°- 155°direction. Thirdly, the limestone rubbles discovered in the collapse -slide mass prove that mountain body before moving contains limestone belong Qixia and Maokou formations during the Permian period. This discovery provides the evidence for restoring mountain body before its collapse - slide. Finally, the diameter of rock blocks in accumulation body decreases from northwest to southeast along 150° direction. I It proves indirectly that the direction of rock mass ejecting is along 150° direction. What＇s more, the collapse -slide masses from mountain body near Dakuayan and Xiaokuayan form their accumulation bodies, respectively. Therefore their overlapping part is small.

关 键 词：小南海 地震崩滑体 基本特征 形成机制 

分 类 号：P642.2[天文地球—工程地质学]