Feasibility of Modifying Coal Pillars to Prevent Sand Flow Under a Thick Loose Layer of Sediment and Thin Bedrock

摘要

This paper focuses on the first work face under a thick loose layer of sediment and thin bedrock in the No. 8 Mining District of the Baodian Coal Mine in the Yanzhou mining area of China. Due to mining, the hydrogeological conditions in the aquifers at the bottom of the thick, loose sediment layers have been greatly changed in the shallow areas in this area. The main problem is a low-pressure, water-rich aquifer. However, this problem could be remedied by modifying the coal pillars to prevent sand flow instead of water seepage. To do so, measurements of the first work face were obtained from drilling data, and the stress distribution and plastic zone were determined by examining the mining of the upper part of the no. 3 coal seam using FLAC(3D) numerical analysis software. The simulated results were also compared with the empirically calculated results. Comprehensive analysis indicates that modifying the coal pillars from preventing water seepage or inrush to preventing sand flow appears feasible, and provides an important reference for increasing mining areas and recovery of coal resources.