The Change in the Distribution of the ‘Three Zones’ of Spontaneous Combustion of Coal in a Coal Mine Goaf with a Retained Roadway by Roof Cutting

The roof-cutting and pressure-release (RCPR) mining mode can eliminate coal pillar between the adjacent mining faces by automatically forming roadways, which shows the better mining efficiency and economy than the traditional longwall mining mode. However, this mining mode causes changes in the collapse characteristics of the overlying rock and air leakage in a coal mine goaf, which may influence spontaneous combustion of coal in a coal mine goaf. To study the distribution of the spontaneous coal combustion zone in the coal mine goaf under the RCPR mining mode, the distributions of oxygen concentration and temperature in a coal mine goaf are simulated and analyzed after the simulation verification to reveal the new characteristics of the spontaneous coal combustion zone. The research results show that (1) the spontaneous coal oxidation zone is in the type of letter C, different from the one under the traditional longwall mining mode; (2) the air leakage pathway in the type of letter S causes the unique spontaneous coal oxidation zone, which is different from the air leakage pathway in the type of right parenthesis under the traditional longwall mining mode; (3) a temperature index to divide the spontaneous coal combustion zone is determined by the comparison between the temperature distribution and oxygen concentration distribution.