An Investigation on the Bursting Liability of Oxidized Coal and the Coupling Mechanism of Rock Burst and Spontaneous Combustion

After rock burst and spontaneous combustion, a coal seam is exposed, and this form of compound disaster shows new characteristics. Therefore, basic research on oxidized coal is important to the theoretical research and prevention of compound disasters. Based on temperature-programmed and mechanical experiments and the first law of thermodynamics, as the degree of the oxidation of coal increases, the volume expands slightly and then shrinks, and the mass, density and wave speed decrease. Raw coal and 70 ℃ oxidized coal have a strong impact, 135 ℃ oxidized coal and 200 ℃ oxidized coal have a weak periodic impact, and 265 ℃ oxidized coal has no impact. Additionally, wave velocity is positively correlated with compressive strength and the elastic strain energy index but is negatively correlated with the dynamic fracture duration. Compressive strength is positively correlated with the elastic strain energy index and negatively correlated with the dynamic fracture duration. As the degree of oxidation increases, the post-peak dissipated energy release of coal changes from linear to stepped, and its release intensity basically corresponds to the results of bursting liability. Finally, high stress is likely to cause coal fractures to develop, thereby inducing the spontaneous combustion of coal. Spontaneous coal combustion further weakens the bursting liability of coal, but the danger of rock burst increases significantly.