| The permeability of coal seam is an important parameter for the the gas extraction and gas outburst control. However, most of the coal seams are low-permeability in China. Therefore, it is a good technology to provide the technical support for increasing the permeability of low-gas- permeability coal seam by shocking with high-pressure air.In this paper,the laws of gas flow and seepage in the coal seam o are understood in the theory, and it provides an important theoretical foundation for the technology of increasing the gas extraction by drilling with high-pressure air. Based on the percolation theory of porous media and combining the gas pressure change after shocking the coal seam with high-pressure air, the solid-gas coupled mathematical model is presented for the flow in the coal seam. By applying the software COMSOL Multiphysics, the numerical simulation is computed and analyzed for the gas pressure evolution owing to shocking the coal seam by the high-pressure air under the different pressure values and strata pressure. And the computed results are analyzed and the data are coped with by employing the software Tecplot.The computed results show that the distribution range of gas pressure increases with increasing the value of high-pressure air to shock the coal seam. The greater action is shocked for coal seam near to the free face, but it has a little effect on the deepen coal seam. And the change of strata pressure has an effect on the pressure distribution after shocking the coal seam with high-pressure air... |
