Computer simulation of gas pressure and drainage radius for dense boreholes gas pre-drainage in outburst coal seam

The computer simulation technique has been widely applied to the mine disaster control field. In this paper, we discuss the use of dense borehole pre-drainage technology as a preventive measure for coal and gas outburst. In order to enhance the pre-drainage efficiency and rationally arrange the borehole, the solid-gas coupled RFPA^2D-Gas software is used to study the variation regularity in gas pressure and drainage radius under different conditions. These include the coal seam permeability coefficient, the space between boreholes, the borehole diameter, the gas content coefficient and the pre-drainage time. In conclusion, if a large permeability coefficient, a large borehole diameter, a small space between boreholes and a small content coefficient are used in the coal seam, then the reduction in gas pressure and drainage radius will be large. In this case, the shortest pre-drainage time is required in order to avoid the outburst danger in the coal seam. If the pre-drainage time is extended, both gas pressure reduction and drainage radius increase.