Numerical Simulation of Gas-solid Coupled Field in Gas Drainage Based on the Synchronous Migration Theory

Considering the coal mass deformation and the change of permeability and porosity in the production process of gas drainage,this paper has established the gas-solid coupling dynamic mathematical model of gas drainage,which is based on the synchronous migration theory of coal bed gas seepage diffusion.Taking a mine in Jincheng for example,combined with the characteristics of coal seam occurrence in the mine,and with the aid of Comsol multiphysics software,this paper has carried out numerical simulation.The simulation results show that the effective radius and drainage time of gas extraction accord with the power function relationship;with the increase of embedding depth of coal seam and overburden stress,the permeability and porosity of coalbed decrease,which raises the difficulty of gas drainage.So,to improve the coal seam permeability and porosity is more important compared with to increase gas extraction rate;Suction pressure of the drainage system has little effect on gas extraction.