Optimization of precise extraction parameters in high-drainage roadway based on nonlinear permeability model

High-drainage roadway extraction working face and fracture zone pressure relief gas is an important means for coal seam group gas control. In order to further improve the gas extraction effect of high-drainage roadway and achieve precise extraction,based on the masonry beam theory and the "O" ring theory,this paper establishes a non-linear permeability model of the gob,so as to establish a simulation model that is more in line with the actual situation and improve the accuracy of the numerical simulation results. And apply it to the fluent simulation software to simulate and analyze the influence of the high-drainage roadway on the three-dimensional gas flow field in the gob under different suction pressure,vertical distance and horizontal distance,and then propose the optimized technical parameters of high-drainage roadway precise drainage. The results show that along the gob trend,the permeability on both sides of the air inlet and return roadway is large,and the resistance coefficient is small. Along the gob,as the working face moves away,the permeability gradually decreases,and basically remains in the compaction stable area stable; Affected by wind current and high-drainage drainage,the gas concentration on the side of the air inlet roadway is low,while the gas concentration on the side of the return airway is relatively high. The gas concentration distribution contour in the gob shows an "outward convex" distribution; When the horizontal distance of the roadway is 32 m,the vertical distance is 30 m,and the suction pressure is 15 kPa,the high-drainage roadway has the best drainage effect,which can effectively reduce the upper corner gas concentration; the gas drainage effect of the high-drainage roadway is measured on site the gas concentration in the upper corner verifies the accuracy of the simulation results. The research results can provide a theoretical basis for the precise mining of high gas coal seams and the optimization of high-drainage roadway parameters.