Reseach On Gas Extraction Parameters Optimization Based On Multi-Physics Coupling

On the basis of studying the problem of gas drainage parameters determination, pore structure parameters, gas adsorption constant, mechanical parameters, permeability and other parameters of different metamorphism degree and destructive types coal were tested; visco-elastic-plastic model of coal considering plastic softening and dilatancy was established; the expressions of stress, displacement, pore size and pressure relief range were obtained; the relief range and borehole aperture variation of borehole in hard and soft coal seam were comparatively analyzed; and rapid decay of drainage concentration of soft seam borehole was explained; the hydro-mechanical coupling model considering rheological properties, permeability dynamics and adsorption characteristics was established; the gas drainage radius, reasonable sealing depth, reasonable drainage time were numerically determined; big quality coal samples’efficient gas adsorption-desorption experiment system with temperature control function was developed; the determination method of gas content critical value was drawn up; the critical value of gas content are determined taking Longshan anthracite and Wan lean coal for example. Research results in the determination of hydraulic punching hole space indicate that the model is reasonable and reliable.