芦山地震触发大岩崩滑坡碎屑流特征与运动过程

摘要： “4·20”芦山强烈地震次生地质灾害以崩塌、落石为主，滑坡较不发育，且规模小.但在天全县老场乡大庙村大岩崩却形成了地震灾区唯一一处大规模滑坡：在地震作用下，沿大岩崩单薄山脊两侧各约35.2万和42.0万 m3的强风化白云质灰岩岩体高位、高速滑出，分别沿两侧高速运动，左、右侧沿途分别滑行约504和740 m后与各自主沟道形成撞击爬坡，在春尖窝沟左岸和干沟头主沟右岸爬高分别约35和26 m.随后又各自顺沟而下（沿春尖窝沟滑行763 m，沿干沟头沟滑行409 m），并在干沟头沟撞击点下游409 m处交汇，交汇后由于坡道较缓运动约223 m后停止，在主沟和春尖窝沟各形成8 000和600 m3的小堰塞湖，沿沟因无保护对象而未造成人员和财产损失.在对滑坡现场进行详细地质调查的基础上，结合现场测绘、勘探等手段，对大岩崩滑坡体的基本特征进行了较深入的研究，对滑坡发生及成灾原因进行了初步分析.结果表明，滑源区陡峭单薄山脊的地形条件、风化破碎的白云质灰岩岩体和有利的结构面组合是滑坡发生的基本条件；芦山7.0级地震对滑源区的震动效应是滑坡发生的直接诱因.

关键词： “4·20”芦山地震；大岩崩滑坡；远程滑坡碎屑流；运动机理

中图分类号： P642.22； P642.23文献标志码： ADebris Flow Characteristics and Movement Process

of Dayanbeng Landslide in Tianquan County

Triggered by “4·20” Lushan EarthquakeHU Xiewen1，2，GU Chengzhuang1，NIU Yanbo1，LIANG Jingxuan1，

PAN Cong1，WU Jianli1，LIN Jinhui1，CHEN Dingcai3

（1. School of Geosciences and Environmental Engineering， Southwest Jiaotong University， Chengdu 610031， China； 2. Aseismic Engineering Technology Key Laboratory of Sichuan Province， Southwest Jiaotong University， Chengdu 610031， China； 3. Chengdu Geoinvestigation Institute of Sichuan Metallurgy Geoexploration Bureau， Chengdu 610203， China）

Abstract：The secondary geological disasters triggered by “4·20” Lushan strong earthquake were dominated by rockfalls rather than landslides， and their scales were not large. However， there was a largescale landslide in Damiao Village， Laochang Township， Tianquan County， the only largescale landslide in the disaster area. There were about 35.2×104 and 42.0×104 m3 strongly weathered dolomitic limestone sliding out quickly from high places along both sides of thin ridge in Dayanbeng mountain， moving along grooves on both sides with a high speed， then sliding about 504 and 740 m respectively along the left and right ditches， hitting with their main channels and climbing about 35 and 26 m respectively in the left bank of Chunjianwo ditch and the right bank of Gangoutou main ditch. Afterwards they slid about 763 and 409 m respectively and intersected 409 m away from the impact point in Gangoutou ditch， then they slid about 223 m because of gentle slopes to form two small dammed lakes with volumes of 8 000 and 600 m3， causing no casualties and property loss because of no inhabitants along the ditch. On the basis of detailed geological survey and combining with field mapping， prospecting and other means， the basic features of Dayanbeng landslide were researched thoroughly， and the causes of the landslide were analysed preliminarily. The research result shows that the thin ridge， weathered dolomitic limestone and favorable structures are the basic conditions of the landslide， and vibration effect of “4·20” Lushan earthquake is the direct cause of the landslide.