含水率对滑带土抗剪强度的影响

Effect of Moisture Content on Shear Strength of Sliding Zone Soil

雨季公路旁滑坡频发,对人们的生命财产造成威胁.滑带土是滑坡的重要组成部分,其物理力学性质对分析滑坡的形成与发展至关重要,滑带土抗剪强度的研究对滑坡识别与预测具有重要意义.本文以大方县某公路旁滑坡滑带土为研究对象,在滑带土基本物理力学分析基础上,开展不同含水率和不同法向应力的环剪试验,重点分析滑带土在不同含水率下的抗剪强度特性.试验结果表明:滑带土抗剪强度随含水率以较强线性关系衰减,含水率越大,二者之间差值越小;随着试样含水率增加,黏聚力先减小后增大,内摩擦角先增大后减小,且试样含水率未达到塑限及接近液限时,内摩擦角都很小;强降雨条件使土的含水率增加,抗剪强度降低,土颗粒之间摩擦强度降低,导致滑坡发生,且含水率越高,滑坡速度越快.

Landslides occur frequently on the side of highways during the rainy season,posing a threat to people s lives and property.Sliding zone soil is an important part of landslide,and its physical and mechanical properties are very important for the analysis of landslide formation and development,thus the study of shear strength of sliding zone soil is of great significance for landslide identification and prediction.In this paper,taking the landslide soil next to a highway in Dafang County as the research object,on the basis of the basic physical and mechanical analysis of the slip belt soil,the ring shear test with different moisture content and different normal stresses is carried out,and the moisture content is selected with high water content,focusing on the shear strength characteristics of the slip belt soil under different moisture content.The experimental results show that the shear strength of the slip zone soil decays with a strong linear relationship with the moisture content,and the larger the moisture content,the smaller the difference between the two.With the increase of the moisture content of the sample,the cohesion first decreases and then increases,the internal friction angle increases first and then decreases,and the internal friction angle is very small when the moisture content of the sample does not reach the plastic limit and is close to the liquid limit.Heavy rainfall conditions increase the moisture content of the soil,reduce the shear strength,and decrease the friction strength between soil particles,resulting in landslides.The higher the moisture content,the faster the landslide speed.