三峡库区大坡滑坡成因机制分析及稳定性评价

大坡滑坡是三峡库区典型的非涉水覆盖层滑坡，于2017年6月17日发生变形破坏，造成前缘道路中断和多户房屋墙体开裂。为避免后部及前缘区域邻近滑坡群被激活而加剧变形，通过野外地质调查、钻孔勘探、现场监测、室内试验和模型计算，从地质因素和环境因素两方面分析了滑坡的成因机制及触发因素，并考虑人为活动和极端降雨在内的两种工况进行了稳定性评价。结果表明：大坡滑坡属于浅层多级滑面顺层岩质滑坡，该滑坡变形的外因主要是持续性降雨/强降雨和人类活动，库水位升降影响甚微。在水蚀作用下，薄层堆积体下砂岩、砂质页岩及炭质页岩层面的强度弱化是该滑坡变形的主要内因。稳定性计算结果也表明，人类活动促进了滑坡的形成和发育，极端降雨显著降低了滑坡稳定性，在此基础上提出了“抗滑桩板墙+截排水工程”工程治理方案。相关结论对于库区非涉水滑坡的形成机理分析及工程治理具有一定的参考价值。

Mechanism Analysis and Stability Evaluation of Dapo Landslide in the Three Gorges Reservoir Area

The Dapo landslide, a typical non-wading debris landslide in the Three Gorges Reservoir area, occurred locally on June 17, 2017, resulting in road interruption and wall cracking of dozens of households outside the front area. To avoid aggravation of deformation due to activation of adjacent landslide groups in the rear and front area, it is of great practical significance to explore the deformation mechanism and evaluate the stability of the Dapo landslide. According to the field geological survey, borehole exploration, and in-situ monitoring, laboratory tests and model calculation, the genetic mechanism and triggering factors were investigated from geological and environmental aspects. The stability analysis was further carried out under two typical working conditions considering artificially activity and extreme rainfall. The results show that this is a shallow multi-level bedding rock landslide. Continuous heavy rainfall and human activities are the two main external factors affecting the landslide deformation, while the fluctuation of the reservoir water level has little effect. Strength weakening of sandstone, sandy shale, and carbonaceous shale under the thin-layer debris under the action of water erosion is the dominate internal cause of landslide deformation. The stability calculation results show that the formation and development of the landslide is promoted by human activities and devastatingly affected by extreme precipitation. The combined treatment scheme of anti-slide pile sheet wall and interception and drainage system was also recommended. The conclusion remarks in this study have reference significance for the formation mechanism analysis and anti-slide treatment of non-wading landslides in the reservoir area.