In the mining process of high gas mining area, the gas emission from goaf is large, which leads to the gas overrun in the upper corner of the working face, and affects the safe mining of the mine. This paper studies the differential drainage of the upper corner gas by high-level directional long borehole, and then solves the problem of gas control in the upper corner. Taking a fully mechanized mining face as the research object, this paper analyzes the theoretical parameters of the overlying strata failure of the working face, and according to the production practice, the high position directional long drilling layer is arranged differently, and the influence of high position directional drilling on gas drainage effect in different layers is analyzed, and the best location in different distance and height area is obtained to guide the actual production work. The research results show that the differential drainage method of high position directional long borehole can effectively control the gas overrun in upper corner of fully mechanized mining face in thick coal seam.
To prevent coal mine water disasters, the main objective of this study is to predict the water enrichment of the main aquifer in a coal mine of China that has been threatened by water inrush. The prediction is carried out using a geographic information system (GIS) and a coupled analytic hierarchy process (AHP) and entropy model. The flushing fluid consumption, burnt rock distribution, sand–shale ratio, and lithology structure index were determined as the main factors controlling the water enrichment of the aquifer. A thematic map of these main factors was constructed using the spatial data analysis functions of GIS and the data from a total of 146 drilling columns and field investigation. The weights of these controlling factors were calculated using the coupled model. A prediction map of the water enrichment of the aquifer was then developed by overlaying the thematic map with the weights of each controlling factor. The degree of water enrichment was finally divided into four levels for easy interpretation, where Level I denotes the highest water enrichment and poses the greatest threat of water disaster.
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