Study On Disposed Methane Drainage Technology Of Close-distance Underlying Protective Seam Mining

Paper summarized the current research of pressure relief scope in under protective mining, relief gas migration and relief gas extraction, analyzed the problems of close under protective mining conditions discharging pressure gas migration rule and discharging pressure gas extraction technology research. To solve these problems, 11223 work face in Jinjia mine mining, actual theoretical analysis , numerical simulation, software development and measurement means of protective mining under pressure relief scope, take the thoroughly studied of relief gas migration rule, gas extraction method choice, and extraction scheme and extraction effect.Using the key strata theory analysis the overlying strata damage rule and fracture development regularity of under protective mined, combining the geological conditions of 22 # protective coal mining in Jinjia. Simulated the vertical displacement distribution rule and the plastic zone by FLAC3D, predicted Jinjia mine after mining under cover the strata discharging pressure range through the simulation results.Theory and data analysis show that the main source of gas is mining seam and mined-out area, found the rule of adjacent relief gas main to mined-out area, mined-out gas main to woke face. Took the gas concentration rule on adjacent layer and woke face through the test of gas concentration on work face.Adopt Fluent simulation the gas migration rule and gas concentration distribution law in mined-out, and analyzes the significance of regularity of relief gas extraction.Take existing gas extraction method into five classified, tunneling area, mining area, prepare area, mined-out area and other areas, took out the gas extraction methods ,summarized the application conditions, technical parameters and application example. On this basis, designed the gas extraction methods choice system use the ACCESS database and.net platform, realized the screening function by extraction method, extraction area, coal thickness, drilling field location conditions and so on.Based on the results of these studies and the design code of gas extraction, propose the design program of close coal group relief gas extraction, combined with the engineering practice of Jinjia, designed the gas extraction solution of 11223 work face, and detection the effect, 77.04% gas extraction rate, 0.36 MPa of the residual gas pressure, 5.19m3/t residual gas content, the results show that the design scientific and reasonable, can achieve gas extraction requirements.