基于监测成果与变形特征的滑坡成因分析

Cause Analysis of Landsides Based on Monitoring Results and Deformation Characteristics

基于罗家坪滑坡详细的地质结构勘察和现场调查结果,结合库区蓄水、降雨情况与滑坡变形监测资料,揭示了滑坡滑动带特征,分析了滑坡体在蓄水后的变形响应,提出了承压水模型,并通过承压水模型分析其变形特征及机理。分析表明:蓄水是滑坡的诱因,降雨是滑坡的动力条件。蓄水后,地下水位升高,前缘部分滑体及危岩体处于浸润线以下,发生软化及塑性变形,滑体抗滑力减小,造成滑坡启动,前缘的塑性变形同时造成危岩体的变形协调。滑坡复活,后缘产生裂缝,降雨造成滑带底部产生承压水,降雨越大,承压水越大,且主要集中在滑体中下部。在承压水与滑坡自重增大的作用下,滑坡前缘变形速率与大小均大于滑坡后缘。持续降雨对于滑坡的影响大于暴雨情况对于滑坡的影响。

Based on the analysis of the monitoring data of water storage,rainfall conditions and deformation,detailed geological structural investigation was carried out to research the relationship between the curves of displacement-depth and geological characteristic. The confined water model of bedding rock landslide was put forward to explain the deformation behavior. The research showed that the water storage is the cause of landside,and the rainfall is the motivation of landside. The groundwater level is rising during water storage,but parts of the sliding surface and soil deposits at the toe of landslide under the groundwater level cause the latter becoming soft. The resistance force decreases due to plastic deformation and viscous. The compatibility of deformation of dangerous rock body may occur by plastic deformation. The confined water turns out during the rainfall and water impoundment,the heavier the rainfall the higher the pressure head will be,and the pressure is concerned at the lower part of landside. As a result of confined water and its own weight,the deformation rate and deformation size of the toe area are larger than the heel area. The landside is more dangerous in persistent rain than heavy rains.