There Is No Key Strata Reducing Waterproof Coal Pillar Mining Under Ⅰ Classes Water Bodies

According to the huge waste of the upper part coal resources, a reasonable height of coal pillar must be researched, thus a reasonable mining in excess coal pillar can be made.The Xisan mining area Pansan mine is mining under thick unconsolidated layers. Its unconsolidated layers of cenozoic erathem is368.6-442.95m in buried depth, with the average depth of about421.38m. The Coal Seam13-1is covered by a rich water-bearing bottom aquifer, so the safety mining is confronted with huge threat. This paper made a study on the reduction of coal seam13-1’s waterproof pillar of the Xisan mining area Pansan mine.At first, its engineering geological condition、hydrogeological condition、Quaternary unconsolidated layers and especially the middle aquifuge and the lower aquifer were analyzed.And the related parameters of pumping test were analysised too. The results showed that the losses bed of cenozoic erathem was a middle water abundance aquifer, and the water mining level for class I water. Second, the overlying strata’s mechanical parameters were obtained by soil mechanics test and the height of water flowing fractured zone and caving zone with the changing depth of propulsion by FLACK-3D. At last, a reasonable height of waterproof pillar and pick up height of extracting coal face were determined by making a comparison research on the differences of height of water flowing fractured zone obtained from empirical formula、analogy、Numerical Simulation and BP Neural Network. Compared with the original waterproof pillar, its height reduced15.0m. Than the upper part coal resources of working face was liberated. And it provided evidence for shallow mining of coal seam13-1of Xisan mining area.