Research On Solid-Gas Coupling Model And Application Of Boreholes Along Coal Seam For Methane Drainage In Huang Yanhui Coal Mine

Along with the increasing of mining depth of coal mine, the gas disasters are becoming more and more serious. Gas extraction is the fundamental measure to prevention and control gas accident of coal mine in our country, methane drainage can reduce coal seam gas pressure on the one hand, on the other hand can make the coal around boreholes produce cracks or breakage to cause coal relieved. Therefore, The numerical simulation study of it is of great theoretical and practical significance. By using COMSOL Multiphysics numerical simulation software, and based on the 15# coal seam in Huang Yan-hui coal mine as the research background, through theoretical analysis, numerical simulation and field measurement methods, the stress distribution and stress-relief range around boreholes, and borehole extraction gas were studied, and have applied to the field. Then we got following preliminary conclusions:Established the elastoplastic softening model of coal around boreholes, and estimated the calculation formula in different stress area of coal body around borehole. Reveal the boreholes pressure relief range and borehole diameter is linear positive correlation.According to the field test and numerical simulation results, the extracting seam roadways loose circle loose range of 0~8.5m, and the reasonable hole sealing depth of boreholes along coal seam should be between 8.5m~13m.Established the solid-gas coupling model of boreholes along coal seam for methane drainage, and simulating the influence of factors on boreholes extraction, including extraction time, extraction pressure, borehole diameter, depth of coal seam, initial gas pressure and initial permeability.Determined the Huang Yan-hui coal mine 15107 working face the relevant arrangement of bedding drilling parameters. The effective extraction radius of sieve pipe extraction process were 1.5m<reffect<2m, the reasonable spacing of boreholes along coal seam should be range of √2 √2, the limit the extraction time of boreholes along coal seam is about 95 d, the length of boreholes along coal seam is 100 m, and the inclination angle is coal seam dip angle. Field application results show that, boreholes along coal seam for methane drainage can effectively reduce the gas content of coal seam in a short time, and reduce the outburst danger of mining face.