三峡水库区严家坡滑坡成因分析及稳定性评价

三峡水库区地质条件复杂，是我国地质灾害的多发区及重灾区。严家坡滑坡位于奉节县内，距三峡大坝158km，滑坡在整体上被3条冲沟分为东、西两个滑坡，地貌上两滑坡均呈缓倾斜坡，平面上呈扇形，两侧有冲沟围切，后侧具圈椅状拉张裂缝，前缘剪出口部位弧形特征明显。勘察发现：两个滑坡均存在3级滑带，第1级滑带位于松散堆积物与碎裂岩体接触部位；第2级滑带位于碎裂岩体与块裂层状岩体接触部位；第3级滑带位于块裂层状岩体与完整基岩接触部位。严家坡滑坡由较坚硬的泥质灰岩、灰岩及相对软弱的泥灰岩组成，软弱的泥灰岩及薄层泥岩等力学性质较差，抗风化能力弱，多破碎，甚至形成软弱夹层。岩体中裂隙产状较陡，其中一组裂隙近其中直立，为地下水提供了良好的通道，同时与较软的岩层易贯通，破坏岩体的整体稳定性。严家坡滑坡不但规模大，而且复杂。于文章详细介绍了三峡库区奉节县严家坡滑坡的结构及变形特征，对滑坡的成因及影响因素进行了分析，用不同的方法对几种工况进行计算与比较，评价其稳定性并提出一些可行的防治措施及建议。

Causes analysis and the stability assessment of Yanjiapo Landslide in the Three Gorges Reservoir area

The geological conditions of Three Gorges Reservoir area are very complex, where geological calamities happen frequently. Yanjiapo landslide is located in Fengjie county, which is distant from the Three Gorges Reservoir Dam about 158 kilometers. Yanjiapo landslide is divided to east one and west one by three gullies.The two landslides present gently acclivous, with the plane of fan-shape, cut by three gullies at the peripheries, chair-shape tensile fractures in the rear, and curve-shape feature in the front. Through survey three sliding zones are found in each landslide, the first sliding zone locates between loose accumulation and cracked rock mass, the second locates between cracked rock mass and block-cracked rock mass, and the third locates between block-cracked rock mass and sound rock mass. Yanjiapo landslide is composed of solid marl and relatively weak marlite, and the mechanical properties of weak marlite and slight mudstone are worse, whose anti-weathering ability is very weak, more over, some strata became weak intercalated layers. Middle-steep fissures distribute in the rock mass, and one group of fissures is nearly erect, which forms a good channel for groundwater and easily connects with weak srata, resulting in destroying the whole stability of rock mass. In sum, Yanjiapo landslide is not only large but also complex, so this paper analyses the characteristics of structure and deformation of the landslide in detail. Meanwhile, the mechanism and causes of deformation are also discussed, At last, the paper uses different methods to calculate and contrast several operating conditions. Some constructive measures and advices are put foreword, the stability of the landslide is evaluated and useful experiences for other similar landslides in the Three Gorges Reservoir area are presented in this paper.