Numerical simulation and actual measurement analysis of overburden failure height based on PFC

In order to intuitively and clearly grasp the development and evolution of overburden rock fractures in coal mining, determine the failure height of overburden, and conclude the corresponding evolution law, taking Yili mining area as the experimental research object, using discrete element particle flow software PFC^3D to establish the three-dimensional model of numerical simulation, according to the macroscopic parameters measured on site, simulating the damage of the overburden rock in each coal seam when the working face is advanced 160 m, and adopting real-time color TV imaging technology of drilling to fully verify the PFC^3D simulation. The research results show that:the coal seam mining thickness has a positive correlation with the overburden collapse strength, the greater the coal mining thickness, the greater the overburden collapse height, the overburden collapse occurs during the same period, and the collapse intensity increase; PFC^3D simulation shows that the internal fissures in the overburden are mainly vertical fissures, and the inclination angle of the fissures has reached more than 50°, and the fissure development characteristics with a high angle close to the vertical rock layer.