Study Of Mining Face Gas Accumulation And Migration Dynamics Process

China’s coal production is the basis of energy, and China’s coal mine accidents have always occurred, which by gas caused an accident accounts for half of.At the same time, the accident caused serious consequences,which is a big risk to the coal safe production. Because of a lot of gas emission sources in the mining face, it due to gas accident concentrated in this area. The study found that the relationship between gas accident accumulation and migration law in mining face is close, therefore,studying of gas accumulation and migration law can be a good guide for mine practical, it is easier to monitor and surveillance methane and to provide a theoretical basis of controlling the concentration of methane in the mining face.This paper is about the stope gas migration process, which is based on the scholars’ relevant researches. It is the combination of the three scientific methods, theoretical analysis, practical data measurements and FLUENT numerical simulation, and techniques. Gas accumulation and transport dynamic process were studied in this paper, conclusions drew the following:1、Through the establishment of the mathematical model of the gas unit body litering and floating movement in coal roadway, analyzing under airflow the center and top location the gas unit body floating properties.Getting both of the gas unit bodies’ exercise: it is found that the center gas unit body firstly does accelerate upward and forward movement, with the increasing resistance, then slowes down the movement.There is a great relationship between the gas unit body rising height and the initial speed of airflow. Because of the gas unit body near the roof keepes balance in the horizontal and vertical direction, it remains stationary.2、 According to the cell measurement method to divide the area, the site is measured the gas concentration of gob, minig face, coal wall, and then analyzing the field data.At last the gas emission law in the coal face isobtained: along the working incline direction, the concentration distribution of methane in the coal mining face which from inlet side to the return air side is increasing; on the vertical coal wall direction: ① in the ministry of the working face the concentration of gas varies from large to small, and then increases, the shape is "saddle"; ② in the middle of mining face the gas concentration curve firstly decreases rapidly and then rises slowly, and it is lower the gas concentration on the coal wall; ③ in the lower half of mining face, the gas concentration always declines.3 、 With the basis of mine working face, the writer used Gambit software to build the three-dimensional physical model mining face,established the appropriate gas migration conditions, determined the boundary conditions, and at last simulates three different conditions under airflow at different reynolds number in the stope, gas emission at different speeds and mining face at different loft. The simulation results were obtained: ① with the Re increasing: The average wind speed in the stope increases, the gas concentration is reduced accordingly; the impact on the corner gas is larger, the length of two right-angle side of the corner gas accumulation layer is smaller. ② when the gas emission increases, the shapes of gas concentration contour are similar, on the same plane the gas concentration increases in the corresponding position. ③ When the angle increases, the bottom of the gas concentrations are lower, the high gas concentrations are oppiste.