| Taking Mengjin mine as the research object,test original coal seam gas content and other parameters(pressure) evaluation the riskof test points.Considering the plastic softening,dilatancy characteristics and rheological characteristics of coal,visco elastic plastic model is built around the coal borehole,the coal body around the borehole stress strain and deformation were studied,determine the different drainage borehole pressure relief range force, different size, different hardness of coal, to provide the basis for rational layout of drainage borehole.Dynamic evolution model of porosity and permeability of coal containing gas,taking the Kozeny-Carman equation as bridge, the solid coupling Darcy law,Langmuir equation, ideal gas equation of state theory of establishing drillingaround the coal gas migration flow model.Analysis software COMSOL numerical simulation of Multiphysics using multiphysical field coupling, different borehole in different geological conditions of gasdrainage radius.Large diameter boreholes were employed and deployed, and the existing regional outburst elimination technology was optimized by the partition layout of boreholes. The outburst elimination effects was investigated in the region where such measures were taken, and it was found that the gas volume drained from a single borehole with a diameter of 113 mm was 1.8 times that of 94 mm. The results indicate that the application of long boreholes with large diameters could eliminate gas outburst danger effectively by predrainage of gas in roadway strips, enhance the development rate, and ensure safety at working face of roadways. |
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