Research On Law Of Gas Distribution And Migration In Gob In Great Mining Height Face Of Zhao Zhuang Coal Mine

In recent years, with the development of mining technology, the scale of coal mining increases constantly, which leading to a sharp rise of gas emission quantity of working face, the serious gas emission beyond the limit in upper corner of working face,and threatens the security of mining production. Gob gas is the main source of gas emission in working face, So researching and analyzing the law of flow field and gas distribution in gob has a guiding significance to gas prevention of working face and gas drainage of gob.In this paper, according to the actual situation of coal and rock caving in gob of3304 working face in Zhaozhuang Mine, the permeability is set. Simulating and getting pressure distribution of working face via Fluent, the pressure difference of roadway ends of working face is 110 Pa, and it is close to field test data. Then, we simulate the airflow and distribution regulation of gas of two different kinds of gas emission locations, of which uniform emission from the entire goaf region or the upper adjacent layers and fallen coal near floor. After analysis, we get the following conclusions: under the two different circumstances of gas emission source locations, the streamline in working face and gob is almost the same, after through the interface of working face and goaf, the airflow carrying gas in gob flows to tail roadway. When gas pours out from the upper adjacent layer and fallen coal near floor, high concentration of gas that near upper adjacent layer and floor is close to working face, in the vertical direction,Near the gas emission source of the floor and the upper adjacent layer, the distribution of gas concentration has a hook shape, and the gas concentration of the middle part is low; as gas discharge from the entire goaf, high concentration of gas is relatively far from the working face, and gas concentration rises from the bottom to top gradually in vertical direction with obvious stratification, the gas concentration near the roof is higher than 90%.The effect of borehole extracting is also simulated in this paper. Comparing the simulation result and the field test data, we can get the following conclusions: under the two different circumstances of gas emission source locations, the extracting mix amount of the same high level borehole are basically the same and close to the field test data,but the extracting gas quantity are different. The field test data proves correctness ofnumerical simulation parameters.