基于环剪试验的四方碑滑坡滑带土残余强度空间差异性和稳定性分析

水库滑坡因受库水位变化的影响,不同空间位置滑带土的含水率不同,滑带土残余强度也存在空间差异性,使用统一的滑带土残余强度难以准确计算滑坡的稳定性系数。以四方碑滑坡滑带土为研究对象,通过环剪试验分析了不同含水率和不同法向应力作用下滑带土的残余强度特性,结合滑坡渗流模拟结果对滑带土残余强度的空间差异性进行了分区,并计算了在175 m和145 m库水位条件下滑坡的稳定性。结果表明:不同含水率的滑带土试样,其残余强度与法向应力都呈现较好的线性关系,符合Mohr-Coulomb准则;随着滑带土含水率的增加,其残余黏聚力和残余内摩擦角都减小,且滑带土的残余内摩擦角与含水率之间呈现良好的负指数关系;基于滑带土分区的滑坡稳定性计算结果与通过野外调查得到的滑坡稳定性现状相符,说明本文方法具有可靠性。

Spatial Difference of Residual Strength of Sliding Zone Soil and Stability Analysis of Sifangbei Landslide Based on Ring Shear Test

Due to the change of reservoir water level,the moisture content of sliding zone soil in different spatial positions of riverbank landslide is different,and the residual strength of sliding zone soil also has spatial difference.So it is difficult to calculate the safety factor accurately by using unified residual strength.This paper takes sliding zone soil of Sifangbei landslide as an example,analyzes the residual strength characteristics of sliding zone soil under different moisture content and normal stress based on ring shear test,and carries out the spatial zone of the residual strength of sliding zone soil in combination with seepage simulation result,and calculates the safety factor of the landslide under the reservoir water level of 175 m and 145 m.The results show that the residual strength and normal stress of the sliding zone soil samples with different moisture content show a strong linear relationship,which conforms to the Mohr-Coulomb criterion.With the increase of moisture content,both residual cohesion and residual angle of internal friction decrease,and there is a good negative exponential relationship between residual angle of internal friction and moisture content.The calculation result of landslide stability is consistent with the current stability of landslide via field investigation when the spatial difference of sliding zone soil is considered.