Abstract:There is a landslide at an elevation of 150m on the north slope of the Yangjialing mining area, which has caused significant damage and deformation to safety production. The landslide rock belongs to the Gufeng Formation shale. In order to explore the macroscopic and microscopic failure mechanisms of the rock, using X-ray powder diffraction, scanning electron microscopy, MTS816 electro-hydraulic servo control testing machine to study it. The experimental results show that the shale in the study area is mainly composed of detrital mineral quartz and clay mineral illite, a small amount of chlorite and kaolinite, and the rocks have a certain degree of water absorption; The whole interior of siliceous shale is flaky structure, containing pores with a diameter of approximately 0.61~4.01μm,and primary cracks with a length of approximately 1.09~2.95μm. Under uniaxial compression, the compressive strength and elastic modulus of rocks increase exponentially with the increase of loading rate. At low loading rates, shale has a significant yield stage and the failure mode is brittle tensile failure; Under triaxial compression, the average compressive strength of shale decreased by 15.31% to 20.40%, and the cohesion decreased by about 16.57%. Confining pressure can improve the compressive strength of saturated shale, which mainly occurs brittle shear failure with a failure angle of about 67.38°; The damage strength and peak strain of rocks are most significantly affected by confining pressure, and the sensitivity of their strength to confining pressure is in the order of damage strength＞peak strength＞initiation strength. The research results indicate that the mineral composition and microstructure of shale in the study area may be the main reasons inducing its macroscopic failure.
