三峡库区典型顺斜向岩质滑坡变形破坏特征及失稳机制分析

Deformation characteristics and failure mechanism of large-scale obliquely dip rock landslide in the Three Gorges Reservoir Region

近年来,三峡库区城集镇开发区顺斜向岩质滑坡失稳破坏现象时有发生,研究顺斜向岩质滑坡的变形破坏特征及失稳机制对防治此类滑坡具有重要意义。本文以巫山县白杨湾滑坡为例,通过现场踏勘、钻探和多种监测手段,对这一典型顺斜向岩质滑坡的变形破坏特征及失稳机制进行了深入研究。此滑坡所处地层为巴东组第二段泥岩,岩体破碎,地下水较丰富。滑坡岩层向右边界倾斜,右边界受断层控制,断层面与岩层面相交切割形成楔形体顺斜向滑移。滑坡体积约320×10^(4) m^(3),滑动方向与岩层倾向夹角60°。受坡脚开挖和坡体建筑荷载等人类工程活动的影响,滑坡于2019年7月开始出现显著变形,滑坡中部的位移速率达到2~5 mm/d。2019年9月中旬,滑坡前部设置应急抗滑桩后,滑坡变形开始减缓至0~0.5 mm/d。白杨湾滑坡对城集镇开发区金科城造成巨大威胁,建议采取"搬迁避让+工程治理+专业监测"的防治对策。本文的研究成果对指导三峡库区顺斜向岩质滑坡防治和人工开挖诱发滑坡的防治具有重要借鉴意义。

In recent years,the tangential rock landslides occurred frequently in the urban area of the Three Gorges Reservoir region.Therefore,it is of great significance to study the deformation and failure characteristics and failure mechanism for the prevention and control of the tangential rock landslides.In this paper,taking the Baiyangwan landslide in Wushan Town as a case study,the deformation characteristics and failure mechanism are studied in detail,by field investigation,drilling works and in-situ comprehensive monitoring systerm.The stratum of the landslide is mudstone in the second member of the Badong Formation,with abundant groundwater and broken rock mass.The rock layer incline to the right boundary,which is cut by a fault,and the multi-layered weak interlayer forms a multi-stage slip zone.Therefore,wedge-shaped sliding surface was easily developed.The volume of the landslide is about 320×10^(4) m^(3),and the angle between the sliding direction and the rock formation attitude is 60°.Affected by human engineering activities,such as slope excavation and construction loading,the significant deformation began in July 2019,and the displacement velocities in the middle part reached to 2~5 mm/day.In September2019,the emergency anti-slide pile project was set at the toe part of the landslide,after that the deforamtion velocities of the landslide slow down to 0~0.5 mm/day.The Baiyangwan landslide seriously threaten to the Jinke community,and the prevention and control measures of"relocation avoidance+project management+professional monitoring"were recommended to adopt to the landslide.The research results of this paper are of great significance for guiding the prevention of tangential rock landslides in the Three Gorges reservoir area and landslides induced by excavation.