Study on Mineral Composition and Mechanical Properties of Clayey Slip Soil of Soft Rock Landslide in Shanxi Coal Measures

Purposes For the Shanxi Coal Measures, the slip soil in coal bearing soft rock landslides generally contains a large number of clay minerals, and is a typical slip soil with certain expansibility and is different from the conventional slip soil in mechanical properties. Methods Four typical cases of clayey slip soil in coal bearing soft rock landslides in the Yellow River Basin in Shanxi Province are taken as research objects to reveal the unique mechanical properties. The research methods include X-ray diffraction test, slow shear test, and free expansion rate test. Findings The results show that: 1) The clay minerals of the clayey slip soil are mainly composed of montmorillonite, kaolinite, illite, and chlorite. The percentage contents of montmorillonite mineral quality are 40.95% (for a landslide in Dongshan), 38.30% (for a landslide in Linxian), 34.52% (for a landslide in Xiangning), and 17.65% (for a landslide in Zezhou), respectively. 2) The cohesion and internal friction angle of clayey slip soil show two modes with water content (negative index/negative correlation). The content range of the montmorillonite that affects the regular pattern is 17.65%~34.52%; 3) The attenuation degree of clayey slip soil shear strength shows two correlation with montmorillonite conten (t positive/negative correlation). The critical value of the montmorillonite content that affects the degree of attenuation is 34.52%. Conclusions From the perspective of mineral composition, the attenuation law of clayey slip soil shear strength is expounded and the unique strength property of this kind of slip soil is revealed. This research has certain theoretical significance for further revealing the landslide-induced disaster-causing mechanism of coal bearing soft rock landslides in the Yellow River Basin region.