Study On Gas Drainage Technology Of High-position Tunnel Of Gengcun Coal Mine

Gas emission increases sharply in goaf,with the increase of mine exploitation intensity and the increase of mine exploitation depth,so the gas concentration in the air-return tunnel and upper corner always overrun,the technology of the high-position tunnel is used to extract the gas in goaf have been used in many mines of China,and that have got good effect.So,it has important guiding significance to govern coal working face gas and goaf fire by confirming the rational sectional area of high-position tunnel,the best extraction location of high-position tunnel and the rational negative extraction pressure of high-position tunnel.The thesis analyzes the air leakage between the working face and the goaf,the gas distribution in goaf and upper corner,the gas quantity drained out by high-position tunnel under different sectional area of high-position tunnel by the simulating software of Fluent,according to the basic knowledge of computational fluid dynamics,and combining porosity distribution of goaf inbreak in Gengcun’s 12220 working face.It is obtained that the influence of sectional area of high-position tunnel on extraction effect,and combining the theory analysis to select the rational sectional area of high-position tunnel is 5m2(width is 2.5m,and height is 2m).It can be analyzed and got the air leakage between the working face and the goaf,the gas distribution in goaf and upper corner,the gas quantity drained out by high-position tunnel when high-position tunnel stays in different positions,then we can confirm the best extraction location of Gengcun’s 12220 working face combining theoretical calculation: the vertical distance that distances from goaf floor is 42 m,the horizontal distance that distances from air-return tunnel is 33 m.In addition,the gas extraction of high-position tunnel has important effect on gas distribution in front of goaf.The airflow field and gas distribution is simulated when high-position tunnel is used to extract the gas in goaf under different extraction negative pressures.The air leakage between the working face and the goaf,the gas distribution in goaf and upper corner,the gas quantity drained out by high-position tunnel are analyzed under different extraction negative pressures of high-position tunnel,then we can confirm the rational negative extraction pressure of high-position tunnel,and some conclusion can help to select rational parameter of high-position tunnel when high-position tunnel is used on other mines.The study shows that the range and volume of air leakage from working face to goaf along the direction of working face length basically remains unchanged with the increase of negative pressure if the extraction negative pressure of high-position tunnel is less than 5kPa,and the range and volume of air-leakage from working face to goaf increases gradually with the increase of negative pressure if the extraction negative pressure is more than 5kPa,the air leaks from the whole length of the working face to goaf when the extraction negative pressure is more than 19 kPa.The gas concentration in upper corner decreases with the increase of negative pressure.The pure gas quantity drained out by high-position tunnel increases with the increase of negative pressure,but the increase range is smaller and smaller.