摘要
2008年5.12汶川地震由于其超常的地震动力,触发了数百处大型滑坡灾害。本文以遥感解译所获取的汶川地震区112处面积大于50000m2大型滑坡的基本信息为基础,结合代表性大型滑坡实例的现场调绘,对汶川地震诱发大型滑坡的发育分布规律进行了较系统的研究。结果表明,汶川地震大型滑坡分布除表现出与汶川地震诱发区域性地质灾害类似的分布规律之外,因主要源于发震断层瞬间大幅度错动的直接地震动力引发的大型滑坡,其发育分布及滑动、运动方式还表现出自身的特点,具体可归结为以下几种效应:(1)距离效应:约80%的大型滑坡集中分布于发震断裂地表破裂带两侧5km的范围内,距离越远,滑坡分布数量越少;(2)锁固段效应:汶川地震诱发的大型滑坡主要集中分布在与发震断裂的交叉、错列、转换部位及NE段末端等5个集中区段。其中,红白-茶坪段是大型滑坡最为集中发育段,不仅滑坡数量多,而且规模大,汶川地震诱发的最大两处滑坡均分布于此段。其次为断裂NE段末端的南坝-东河口段,该段大型滑坡密集发育,东河口滑坡和窝前滑坡等大型滑坡均出露于此段;(3)上下盘效应:绝大多数(>70%)大型滑坡都位于活动断裂的上盘,存在明显的"上下盘效应;"(4)方向效应:在与发震断裂带近于垂直的沟谷斜坡中,在地震波传播的背坡面一侧的滑坡发育密度明显大于迎坡面一侧,存在"背坡面效应"。同时,大型滑坡的滑动及运动方向还与各区段断层的错动方向有一定的相关性。在断层活动以右旋走滑为主的青川境内,有相当数量的滑坡表现出向NE方向滑动和运动的特点。
Due to its unusually strong seismic shaking,the＂5·12＂Wenchuan Earthquake in 2008 induced hundreds of large-scale landslides.This paper is based on the interpreted data about 112 landslides,each of which has a plane area greater than 50,000m^2.It also uses the field investigation of representative large-scale landslides.It further conducts a systematic analysis on the distribution regularities of these large-scale landslides.It is suggested that the large-scale landslides not only show the distribution rules similar to those associated with the general landslides induced by Wenchuan Earthquake,but also present unique features in the distribution as well as sliding and moving ways.The occurrences of the large-scale landslides are usually attributed to the direct seismic forces resulting from the horizontal displacements of seismic faults.The distribution rules of large-scale landslides induced by Wenchuan Earthquake can be summarized as follows：（1）distance effect： about 80% large-scale landslides are distributed within the range of 5km from the Yinxiu-Beichuan fault（i.e.,seismic fault ruptures）.The farther the distance is,the lower the number of landslides is.（2） Locked segment effect： the large-scale landslides are mainly distributed in the five concentration zones closely related with the crossing,staggering and transforming section as well as the end of NE section of the seismic fault.The most concentrated zone is Hongbai-Chaping segment,where many large-scale landslides and the two largest landslides were induced by Wenchuan Earthquake.The second concentrated zone is Nanba-Donghekou segment at the NE end of the seismic fault,where the well-known Donghekou Landslide and Woqian Landslide are located.（3）Hanging wall effect： a vast majority of large-scale landslides（70%） are located in the hanging wall of the seismic fault,showing a clear＂Hanging wall effect＂.（4）Direction effect： in the valley slopes almost perpendicular to the seismic fault,the number of large scale lands
出处
《工程地质学报》
CSCD
北大核心
2010年第6期818-826,共9页
Journal of Engineering Geology
基金
国家重点基础研究发展计划课题(2008CB425801)
教育部创新团队发展计划课题(IRT0812)
地质灾害防治与地质环境保护国家重点实验室自主研究课题
关键词
汶川地震
大型滑坡
分布规律
方向效应
锁固段效应
＂5·12＂Wenchuan earthquake
Large-scale landslide
Distribution rule
Directional effect
Locked segment effect
