| 汶川八级地震地质灾害研究 |
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| 引用本文： | 殷跃平.汶川八级地震地质灾害研究[J].工程地质学报(英文版),2008,16(4):433-444. |
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| 作者姓名： | 殷跃平 |
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| 作者单位： | 中国地质调查局 北京 100037 |
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| 摘 要： | 汶川地震触发了15000多处滑坡、崩塌、泥石流,估计直接造成2万人死亡。地质灾害隐患点达10000余多处,以崩塌体增加最为显著,反映出地震对山区高陡斜坡的影响差异性非常大,在山顶上的放大作用非常显著。通过综合分析堰塞湖库容、滑坡坝高以及坝体物质组成和结构,对地震形成的33处坝高大于10m的滑坡堰塞湖进行了评估,划分出极高、高、中和低4种溃决危险。汶川地震滑坡滑床往往不具连续平整的滑面,尖点撞击是极震区滑坡的一大共性,可以分为勺型滑床、凸型滑床和阶型滑床等类型。据实地调查,滑坡附近震毁建筑物垂向震动非常明显,具有地震抛掷撞击崩裂高速滑流三阶段特征。在高速滑流中,发生3种效应:(1)高速气垫效应,滑坡体由较大块石和土构成,具有一定厚度,飞行行程可达1~3km;(2)碎屑流效应,撞击粉碎的土石呈流动状态,特别是含水丰富时,形成长程流滑;(3)铲刮效应,巨大撞击力导致下部岩体崩裂,形成新滑坡、崩塌,但是,其厚度不大,滑床起伏不平。本文以北川城西滑坡和青川东河口滑坡为例,分析了地震滑坡高速远程滑动及成灾机理。北川县城城西滑坡导致1600人被埋死亡,数百间房屋被毁,是汶川地震触发的最严重的滑坡灾难,举世罕见。青川东河口滑坡碎屑流是汶川地震触发的较为典型的高速远程复合型滑坡,滑程约2400m,高速碎屑流冲抵清江河左岸,形成滑坡坝,致使7个村庄被埋,约400人死亡。
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| 关 键 词： | 汶川地震 滑坡 堰塞湖 高速远程 |
| 收稿时间： | 2008-07-20 |
RESEARCHES ON THE GEO-HAZARDS TRIGGERED BY WENCHUAN EARTHQUAKE,SICHUAN |
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| YIN Yueping.RESEARCHES ON THE GEO-HAZARDS TRIGGERED BY WENCHUAN EARTHQUAKE,SICHUAN[J].Journal of Engineering Geology,2008,16(4):433-444. |
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| Authors: | YIN Yueping |
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| Institution: | China Geological Survey, Beijing 100037 |
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| Abstract: | Wenchuan Earthquake triggered landslides,rock collapses and debris flows at more than 15000 sites,which directly caused about 20,000 fatalities.There are more than 10,000 sites of potential geo-hazards,where an increase in slope collapses is mostly noticeable,which shows the earthquake has substantially abnormal actions on steep slopes in the mountains.In particular,the amplifications at mountain peaks is extremely evident.A comprehensive analysis of quake lake volumes,landslide dam heights and their debris compositions and structures was carried out.An assessment on the 33 landslide dames of dam heights great than 10 m formed by the earthquake was further conducted.Consequently,the landslide dams were classified into four types of the dam burst potential : extremely high,high,intermediate and low.The sliding beds of the landslides induced by the earthquake usually have non-continuous flat sliding beds."Sharp point collision" is a common and major characteristic.The sliding beds can be classified into spoon-shaped,raised-shaped and staircase-shaped.Site investigations demonstrate that the vertical vibrations in buildings destroyed by the earthquake adjacent to the landslides were evident.The landslides have three stages: throwing out of ground shocking,collision and collapsing and broken,and high-speed sliding flow.During the high-speed sliding flow,three effects were occurring:(1) high-speed air-bed effect,landslide debris were comprised with larger rock blocks and soils,had enough thickness and the flying distance of 1 to 3 km.(2) Broken debris flow effect,collision broken soils and rocks were in a flowing state,especially they contained abundant water,forming long distance flow sliding.(3) Shovel and scraping,huge collision forces induced collapse of rocks at lower portion,which formed new landslides and collapses,however,their thicknesses are not large and the sliding beds were non-smooth and irregular.The two landslides at western Beichuan county and Dongheko of Qingchuan county were analyzed in detail.They are used as examples to analyze the mechanism of the high speed and long distance sliding and hazard formation of earthquake landslides.The landslide at western Beichuan county buried 1,600 people and destroyed several hundreds houses and buildings,which is the severest landslide disaster triggered by the earthquake and is a rear event in the world.The Donghekou landslide at Qingchuan: Debris flow is a typical high speed and long distance landslide triggered by the earthquake.Its distrace is about 2,400 m.Its high-speed debris flew to the left bank of Qingjiang river and formed landslide dam,resulted 7 villages buried and about 400 fatalities. |
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| Keywords: | Wenchuan earthquake Landslide Quake lakes High-speed Long distance |
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