6th INTERNATIONAL SYMPOSIUM ON MINE SAFETY SCIENCE AND ENGINEERING

In the process of coal mining, the stress of coal seam is unloaded, which affects the occurrence of disasters. To study the influence of different test conditions on the mechanical and seepage characteristics of loading and unloading gas-bearing coal, conventional triaxial loading and fixed axial unloading confining pressure laboratory and numerical simulation tests on gas-bearing coal were carried out in the paper, analyzing systematically the influence of gas pressure and unloading rate on the energy evolution characteristics and permeability characteristics of gas-bearing coal during the failure process. The results show that with the increase of gas pressure and unloading rate, the peak stress and strain of gas-bearing coal decrease, the expansion point of coal sample appears earlier, and the permeability of coal sample increases. The ratio of elastic strain energy to total energy Ue / U at the peak point and the plastic strain of gas-bearing coal at different failure points increase with the increase of gas pressure and unloading rate. The macroscopic failure form of coal is determined by the degree of crack penetration: the better the internal connectivity of the crack, the wider the failure plastic zone is formed after failure, and the coal sample is dominated by tension-shear composite failure.