Multi-physics Coupling Characteristics of Coal Spontaneous Combustion in Goaf

Coal seam mining can cause deformation and fracturing of the overburden in the mining area, creating a channel for fresh air to enter the goaf and triggering the hazard of coal fire. In this paper, a multi-physics coupling model related to heat and mass transfer is established, and the process of coal spontaneous combustion is simulated by COMSOL Multiphysics. By varying oxygen percentage and wind speed at the entrance boundary, the effect of these two factors on the spread of coal fire in the goaf and overlying stratum is analyzed. The simulation data indicate that the special void structure of the goaf and the overburden make a difference to the temperature and gas flow field distribution. In addition, changing these two factors, such as limiting the oxygen content or increasing the wind speed, can delay or inhibit coal combustion.