In view of the geological characteristics of large gas emission, medium coal seam permeability and obvious gas supply in adjacent layers in B51302 fully mechanized caving face of No.8 well in Sikeshu Coal Mine of Wusu, the applicability and gas extraction effect of combined extraction technology of bedding pre-drainage and goaf under thick coal seam conditions are studied. A three-dimensional combined extraction technology is constructed, which is mainly based on bedding borehole pre-drainage, supplemented by directional high-level long borehole and goaf buried pipe, and the working face is divided into three extraction evaluation units. The desorption gas content and residual gas content of 54 measuring points were measured on site. The results show that the residual gas content of the working face after pre-drainage is reduced to 0.79 ~ 1.84 m3/t, and the desorption gas content is 0.12 ~ 1.17 m3/t ; the absolute gas emission during the mining period is predicted to be 8.51 m3/min, the maximum gas concentration of the return air flow is 0.21%, and the wind speed is 1.06 m/s. The extraction technology significantly reduces the gas content of the coal seam in the working face and realizes the ' balance of extraction and mining ', which can provide technical reference and engineering basis for gas control in thick coal seam working face under similar geological conditions.
