Dynamic failure characteristics of primary coal-rock combination under hydrostatic pressure

The surrounding rock of deep roadway is weak and the fissures are developed. Under the influence of mining disturbance, it is easy to cause dynamic disasters and the overall instability failure of coal rock combination is one of key factors inducing disasters. In order to explore the dynamic damage characteristics of the primary combined coal rock body under impact load, with the help of the split Hopkinson pressure bar and high-speed camera, raw coal, artificial combination and primary combination of coal rock are studied. Based on different hydrostatic pressure and strain rate conditions, this study explores the dynamic stress-strain, crack evolution and fracture fractal characteristics of coal rock and explores the deformation and failure characteristics of coal rock using macroscopic fracture fractal and microscopic electron microscope scanning. The study shows that ① the dynamic stress-strain of raw coal, artificial combination and primary combination of coal rock is significantly nonlinear and the plast