Institute of Coal Safety and Technology,China Coal Research Institute State Key Laboratory of Coal Efficient
Mining and Clean Uiliation Shanxi Tiandi Wangpo Coal Mining Co.,Ltd.

In order to effectively solve the problem of gas overrun in the upper corner of the working face,combined with the gas emission process of the gob,the W orking face propulsion process,and the air leakage process of the gob,the effective depth and effective area theory of air leakage carrying gas in the gob were establish ed.The number of closed connection roadway of gob behind coal face for gas extraction by buried pipe was according to the limit value of effective depth of air leakage carrying gas in the gob. Fluent software was used to construct the numerical calculation model of air leakage flow field in No.94313 gob of Sihe No. 2 Mine. The param eters of air leakage characteristics in gob were calculated by inversion of the coincidence between the measured results and the numerical simulation results of air volu me and pressure changes.The influence law of advancing speed and air distribution on effective depth and effective area of air leakage carrying gas in gob was analyze d quantitatively. The calculation formula introduces the calculation formula of the daily advance speed and the average air distribution of the actual working face with th e calculation period of 30 d,so that the calculation formula of the effective depth limit value of air leakage carrying gas in the gob has the practicality on the spot. Accord ing to the calculation results of effective depth limit value of air leakage carrying gas in the gob,the number of closed connection roadway of gob behind coal face for ga s extraction by buried pipe was adjusted in real time. During the field application,the effective depth limit value of air leakage carrying gas in gob is142 ~ 236 m,and th e number of lanes is between 2 and 4,and the gas volume fraction of the upper corner is 0. 18% to 0.40%.The study results showed that by optimizing the arrangement of gas drainage in the closed contact roadway of the gob can ensure that the gas in the upper corner does not exceed the limit,reduce the air distribution in the working face,improve the advancing speed of coal face and achieve the purpose of safety,energy saving and production increase.