Research on the Influence of the Position Change of High Drainage Roadway on the Gas Distribution Law in Goaf

In order to study the application of high drainage roadway in goaf gas extraction and gas control in upper corner, and explore the influence of high drainage roadway extraction position on gas distribution law in goaf. Taking 15302 fully mechanized top coal caving face of Liyang Coal Mine as the research object, the gas distribution was simulated by using Fluent numerical simulation software when the goaf without extracted and when the roadway was extracted at different extraction positions. By compared the data of gas extraction concentration and gas concentration in the upper corner, analyzed the gas extraction effect of high-drainage roadway at different extraction positions. Combining the simulation results with the actual field, designed a suitable high-drainage roadway extraction scheme, and used the field measured data to verify. The results showed that the gas extraction concentration in high drainage roadway increased with the increase of the vertical height between the extraction location and the roof, and increased first and then decreased with the increase of the horizontal distance from the return air roadway. The gas concentration in the upper corner decreased first and then increased with the increase of vertical distance and horizontal distance; The theoretical optimal extraction position was the vertical distance of 30 m, the horizontal distance of 32 m, and the gas concentration at the corners of the working face was within 0.19%. The designed extraction position was 40 m vertical and 35 m horizontal, and the gas concentration at the corners of the working face was maintained at 0.63%~0.65%. Reasonable high drainage roadway extraction position can not only effectively solve the problem of gas over-limit at the corner of the working face, but also help to improve the gas extraction efficiency in the goaf.