Numerical simulation of progressive failure law of thick-hard rock strata in the upper coal seam

Abstract

The thick-hard rock strata (THRS) are widely distributed among coal-bearing strata. In the process of coal mining, the strong dynamic load will be produced after the THRS are broken, which will lead to dynamic disasters such as mine earthquake, rock burst and so on. Therefore, revealing the breaking law of THRS is helpful to prevent and control the dynamic disasters. This paper constructed the mechanical model of THRS based on thick plate theory and obtained the breaking distance of THRS, which is applied to Yangliu Coal Mine. And we constructed the numerical stratigraphic model and analyzed the caving characteristics, the changing rules of displacement and stress of THRS under different advancing distances. Then the above results are verified by the change of hydraulic support resistance. The research shows that the critical instability distance of THRS overlying the coal seam #10 in Yangliu Coal Mine was 296.4 m. Based on the numerical simulation, the displacement and stress of the main THRS increased greatly at the position of 250-300 m, and occurred a large-scale collapse. The hydraulic support resistance of the working face increased sharply and microseismic energy is released rapidly when the mining reached about 330 m, the reliability of the theoretical analysis and numerical simulation were verified by the engineering tests.