黄土基岩接触面滑坡滑带土物理力学特性及微观结构

摘要

滑带土抗剪强度取值及微观结构特性对于边坡稳定及防治具有重要意义.以陕西延安地区二庄科滑坡为研究对象,通过剪切试验、扫描电镜及X射线衍射仪等,对典型黄土基岩接触面滑坡滑带土物理力学特性及微观结构进行研究;通过剪切试验得到不同含水率、不同干密度条件下滑带土的抗剪强度参数及其与含水率、干密度之间的相关性函数;通过研究其微观结构及矿物成分,分析了不同干密度、不同垂直压力条件下的土样微观结构.结果表明:随着含水率的减小和干密度的增加,土样的抗剪强度参数均有所提高;黏聚力与含水率呈负指数关系,内摩擦角与含水率呈负线性关系,黏聚力、内摩擦角分别与干密度呈正线性关系;随着垂直压力的增大,孔隙离散指数增大,颗粒离散指数、孔隙(颗粒)平均形态系数、孔隙(颗粒)定向概率熵及孔隙(颗粒)定向分维数均减小;随着干密度的增大,颗粒定向概率熵及颗粒定向分维数均增大.%Shear strength and microstructure characteristics of slip soil are important for the slope stability.Taking Erzhuangke landslide in Yan'an area of Shaanxi as an example,the physical and mechanical properties and microstructures of slip soil of loess bedrock contact landslide were discussed based on the shear test,scanning electron microscope (SEM)and X-ray diffractometer. The shear strength parameters of slip soil under the condition of different moistures and dry densities were obtained through the shear test,and the correlation between the shear strength parameters,moisture and dry density were discussed.According to the mineral composition,the microstructure characteristics of slip soil under the condition of different dry densities and vertical pressures were analyzed.The results show that the shear strength parameters of soil samples increase with the decrease of moisture and the increase of dry density;the relationships of cohesion,internal friction angle with moisture are negative exponent and negative linear, respectively;the relationships of cohesion,internal friction angle with dry density are positive linear;with the increase of vertical pressure,all of the dispersion indexes of particle,and the average shape coefficients,quantitative probabilistic entropy and orientation fractal dimension of porosity (particle)decease;with the increase of dry density,both of quantitative probabilistic entropy and orientation fractal dimension of particle increase.