Study On Gas Migration Law And Prevention Technology In Gob Area Of W Type Ventilation Face

China is a major consumer of coal as the main energy source.With the expansion of coal mining scale,improvement of mining technology and equipment and improvement of production,after the coal mine enters deep mining,the gas pressure and gas content of the mine increase rapidly,resulting in mine disaster.More and more serious.Especially the mine gas disaster seriously restricts the safe production of coal mines.Therefore,studying the distribution law of gas migration in goaf is of great significance to the prevention and control of mine gasBased on the field data of 3111S working face in Longtan Coal Mine of Sichuan Province this paper theoretically analyzes the plastic failure occurred in the overlying strata of 3111S goaf after being affected by mining,and theoretically divides the "three horizontal zones" and vertical three zones".Based on the collection of on-site data,FLAC3D software was used to simulate the calculation of the height of the fall zone and the fracture zone.The theoretical calculation,numerical simulation and field measurement data obtained the heights of the fall zone and the fracture zone were 9.65m and 66.55m respectively,which was 3111SW type.The theoretical basis for gas drainage in ventilation and gob area is providedAccording to the on-site data of the 3111S working face,the FLUENT numerical simulation was carried out on the working face using the gas migration law of the W-type ventilation goaf in two directions,and the distribution law of gas concentration in the goaf was obtained.Under the condition of the same total air volume,the two air inlets are studied in the case of different air volume ratios of 1:1,2:1 and 3:2,and the gas migration law of the goaf is studied.When the air ratio of the two inlets is 1:1,the air leakage in the goaf is the least,the gas concentration in the return air passage is the smallest,and the ventilation effect is the best.At the same time,the gas accumulation area is determined,and the gas enrichment zone is within the range of 35?40 m above the top surface of the working face.This area is an ideal area for gas drainage.Aiming at the problem of gas overrun in the goaf of Longtan Mine,the technical measures for prevention and control and engineering practice are proposed.The average extraction concentration is 30.4%and the pure amount is 2.56m3/min,accounting for 49%of the total extraction.The highest concentration of gas in the backwind road corner is controlled below 0.7%,which solves the problem of gas overrun in the W-type ventilation goaf in the 3111S fully mechanized mining face of Longtan Mine,and achieves the goal of safe production.