关键词: 特厚煤层, 分层开采, 自燃危险区域, 数值模拟, 氧气体积分数

Abstract:

In order to more effectively and accurately judge the gas concentration field, temperature field, and flow field distribution in the goaf during the mining of extra thick coal seams, and thereby determine the self-ignition risk area for layered mining of extra thick coal seams, taking the 172307 working face of Lingquan mine as an example, numerical simulation technology was used to establish a mathematical model of coal spontaneous combustion in the goaf for layered mining of extra thick coal seams based on the coupling mechanism of multiple fields in the goaf. Combined with the distribution models of coal oxygen consumption rate, heat release intensity, critical oxygen concentration for spontaneous combustion, porosity and permeability, the evolution law of the spontaneous combustion risk zone for layered mining of extra thick coal seams in a stable state was obtained through the simultaneous solution. The results show that in the upper layered goaf, the high oxygen concentration area and the high-temperature area are mainly located near the stop mining line and in the upper part of the intake and return air tunnels, and the main air leakage area is located at the stop mining line. In the composite goaf, the high oxygen concentration area is mainly located on the inlet and return air sides. As it moves towards the deeper part of the goaf, the oxygen concentration shows a decreasing trend. And a local high-temperature zone resembling an ellipse appears at a certain distance from the coal mining face.

Key words: extra-thick coal seam, stratified mining, spontaneous combustion hazard zone, numerical simulation, Oxygen volume fraction