Research On Flow Field In Goaf And The Determination Of The Reasonable Distance Between Cross-openings Of Fully Mechanized Mining Face In Ping Dingshan Mining Six Ore

With the increase of mining depth of coal seam, the seam gas content is increasing, the problem of gas emission beyond the limit more prominently influences on coal safety production. Gas easily overruns in upper corner and lag roadway. The application of lag roadway and gas drainage has an important significance to eliminate gas overrun in upper corner and control gas of working face. Therefore, researching the law of flow field and gas distribution in gob and determining the reasonable sPacing between tail lane have an important role to reduce coal mine input and ensure coal mine safety production.In this Paper, according to the actual situation of Wu8-22310 working face of the No.6 mine in PingMei Group, mathematical and physical model is established, and the simulation Parameters and boundary conditions are set.Based on the distribution of permeability, we simulate the law of flow field and gas distribution in gob when the distance between tail lane and working face is 10 m and 20 m under extracting in tail lane, then comPare the air of return airway, return air of tail lane, the gas concentration in upper corner and the gas concentration in hysteretic cross-openings to the actual measured data. The simulation results are almost the same to the actual measured data, and it verifies the correctness of the mathematical and physical model, the simulation Parameters and boundary conditions.Based on the verified mathematical physics model, select Parameters and boundary conditions,we simulate the law of flow field and gas distribution in goaf when the distance between hysteretic cross-openings and working face is 10 m,20m,30 m and 40 m under extracting in tail lane and is 10 m,20m and 30 m under no extracting in tail lane, analyzing the results,we get the following concluaions: with the increase of the distance between hysteretic cross-openings and working face, pressure contour in the intake air side is elapsed to the working face along the tend of goaf from mining to deep goaf, distribution of face pressure is 0 – 155 Pa from the intake side to return air side,pressure is around-80 Pa in the middle of gob; Along the strike of goaf, when there are drainage in tail lane and the distance between hysteretic cross- openings lane and working face are 10m、20m、30m、40m respectively, the gas concentration contour line of 5% moves from 112 m to 132 m in the inlet side of goaf. However, when there are no drainage in tail lane and the distance between hysteretic cross-openings lanes and working face are 10m、20m、30m, the gas concentration contour line of 5% moves from 110 m to 124 m in the inlet side of goaf. Along the dip of the goaf, the gas concentration will rise but then drop from the intake side to return air side near the working face, which is mainly caused by air leakage. Take the distance between hysteretic cross- openings lane and working face is 30 m when there are no drainage in tail lane for example, the sPace between 5% gas concentration contour line and working face is 122 m near the intake side, 17 m in middle Part of goaf, while 30 m near the return air side; because of the effect of drainage negative pressure,when the distance between hysteretic cross-openings and working face is 20 m, the gas concentration is between 30%-50%near 43 m in the return air side of gob, when the distance between hysteretic cross-openings and working face is 20 m under extracting in tail lane, the gas concentration is between 40%-50%near 43 m in the return air side of gob, The influence is very small that supporter to gas concentration between the into air side and the middle of gob, but it have a significant imPact to gas concentration in the return air side; Based on the analysis of simulation results and "Coal Mine Safety Regulations" requirement, the text makes reasonable sPacing of cross-openings that is 30 m under extracting in tail lane, the reasonable sPacing of cross-openings that is 10 m under no extracting in tail lane.