Research On Law Of Gas Distribution And Migration In Gob Under The Extracting Condition Of High Level Borehole

In recent years with the increasing of mining depth and accelerating of mining speed, they cause increasing of gas emission quantity in working face. Gas emission of working face includes gas emission of coal wall and coal mining as well as gob, and Gas from gob is the main source of gas emission of working face. Therefore, researching the law of gas distribution and gas entrainment in gob under the extracting condition of high level borehole has an important significance to gas prevention of working face.In this paper according to the actual situation of coal and rock caving in gob of 3304 working face in Zhaozhuang Mine, Simulating and getting the pressure difference of roadway ends of working face is 115 Pa via Fluent, it is close to field test data. On this basis analysis gas concentration in the upper and the tail of working face of U+L-shaped ventilation mode without extracting. The results of the study show that, gas concentration in the upper of working face of U+L-shaped ventilation mode without extracting is 0.31%, which is far lower than the safety regulation of coal mine, it solves gas emission beyond the limit. Gas concentration in the tail lane of working face is 2.7%, which is more than the regulation. Therefore, researching the law of gas distribution in gob under the extracting condition of high level borehole is indispensable.Simulating and researching the law of gas distribution in gob when elevation of high level borehole was ranging from 20°、25°、30°、35°via Fluent, analyzing the situation of high level borehole extracting, we get the following conclusions: all gas concentration of gob on the plane of Z=3m are up to 40% when elevation of borehole is different, the gas distribution in gob is basically identical; the elevation of borehole is 30°and the angle of borehole is 25°when it has best effect of extracting,extracting gas quantity was 2.06m3/min. field test data shows that the elevation and angle respectively are 30°、27°, the two are basically identical, the field test data proves correctness of numerical simulation.