Division method of coal spontaneous combustion zone in multi-layer goafs based on fracture development law

Abstract

In order to accurately divide the risk range of coal spontaneous combustion in multiple goafs of shallow buried deep coal seam group and take effective prevention and control measures, based on the porous medium seepage equation and oxygen volume fraction equilibrium equation, the mathematical model is established by using particle flow discrete element software PFC, and the development law of fracture channel under the influence of repeated mining is studied. The results show that 78 % of the floor cracks are distributed in the range of 20 m of the boundary of mined-out area. The porosity distribution in the upper part of the mining space continues to expand with the advance of the working face, and maintains a slender shape. The areas with large porosity are still distributed above, behind and near the working face. According to the calculation results and the mining process, the danger range of the goaf area of the 1203 working surface is divided into serious air leakage danger area, general air leakage danger area, weak air leakage danger area and difficult air leakage danger area.

Keywords

• fracture development
• mathematical model
• shallow coal seam group
• multi-layer goafs
• porosity
• spontaneous combustion hazard