四川5.12地震灾区陈家大院子滑坡形成机理分析与稳定性评价

The Formation Mechanism Analysis and Stability Evaluation of “Chenjiadayuanzi” Landslide in Sichuan 5.12 Earthquake Disaster Area

陈家大院子滑坡位于四川省德阳市什邡市，为一“浅层土质牵引式滑坡”，滑坡体东西宽145m，南北长156m，坡体前、后缘相对高差121m，上覆第四系覆盖物平均5～6m，滑坡体总方量共计约11．3×104m3，主要滑动方向为140°。滑坡下方居住50户共165人，并建有乡村公路、电力、水利等基础设施，潜在经济损失约500万元。2008年“5．12”地震后滑坡体局部出现变形迹象，滑坡体后缘局部出现张裂缝，是诱发滑坡的直接原因”’。后经2009年雨季，由于受到人类工程活动及降雨等多方面因素的影响，滑坡变形迹象进一步加剧，滑坡体后缘拉张裂缝形成贯通，坡体前缘局部部分土体发生滑塌，坡体中部部分树木发生倾倒。本文选取了一条滑坡体主剖面，使用极限平衡法对滑坡体在天然、降水、地震等3种不同工况下的稳定性进行了评价，并对该滑坡体的形成机理进行了分析，为滑坡体后期开展治理工作提供了必要的依据。

＂Chenjiadayuanzi＂ landslide located in Shifang, Deyang City, Sichuan Province, is a retrogressive landslide with shallow soil property. The landslide mass covers an area of 145 m from east to west and 156 m from north to south. The relative elevation is up to 121 m. The average thickness of quaternary sediments is 5-6 m. The total volume of landslide mass is approximately 11.3×104 m3. The main sliding direction is 140°. The below area of landslide includes a settlement with 165 persons, and road, electric power, water conservancy facilities. The potential economic losses are about 5 million yuan. The signs of local deformation appeared after the earthquake on May 12th 2008.The effect of tension fissure in trailing edge of landslide mass was the direct reason for induction of landslide. The deformation intensified due to engineering activities, precipitation and other influence factors after rainy season in 2009, caused the cut-through of tension fissure in the trailing edge. The local sliding occurred in the front edge of landslide mass. The toppled trees were founded in the middle part. This paper mainly discusses the stability evaluation by using limit equilibrium method in different environmental conditions which are respect to nature state, precipitation, earthquake effect, and the formation mechanism analysis of landslide mass, and furthermore, provides the necessary basic information for the landslide remediation.