Research on coupling law of gas and coal spontaneous combustion in goaf of high gas mine

In view of problem that current numerical simulation of combined hazards of gas and coal spontaneous combustion in goaf only considers fluid effects, and does not consider influence of other physical fields, multi-field coupling numerical simulation software Comsol-Multiphysics is used to establish coupling model of gas and coal spontaneous combustion in goaf. Distribution law of gas and O2 in stope of working face and goaf is analyzed, and influence of drainage volume and air intake volume on gas concentration in high-level drainage roadway and O2 concentration in floor of goaf is explored to comprehensively determine the optimal drainage volume and air intake volume. The results show that with the increase of drainage volume, gas drainage concentration increases first and then decreases, and the width of oxidation temperature rise zone in goaf has a positive correlation with growth,comprehensively considering gas drainage effect and natural ignition prevention, the optimal drainage volume 90 m3/min is recommended for high-level drainage roadway; with the increase of air intake volume, gas concentration and scalar quantity of the high-level drainage roadway first increase and then decrease, the width of oxidation temperature rise zone on the air intake side of the goaf obviously increases, and the maximum at 109.3 m, the width of oxidation temperature rise zone on the return air side has a small change,comprehensively considering gas drainage effect and natural ignition prevention, the optimal air intake volume at the test face is 1 500 m3/min.