Feasibility Study Of Depressurizing From High Water-Pressure Confined Taiyuan Formation Limestone Aquifer In Chengjiao Coal Mine

Combining with geological and hydrogeological investigation and other basic data of Chengjiao Coal mine,based on the analysis of the water pressure of Taiyuan Formation limestone acquifer, the thickness of the aquifuge and zone destroyed by underground pressure, used the method of water bursting coefficient to assess the water bursting coefficient of 2-2 coal seam floor in Chengjiao coalmine and divided security zone,less danger zone and danger zone; Analysising the water pressure and yield of the leakages to assess the mining risk of 21304 work face which is in the dangerous south area, found that the south side hydrogeological conditions of 21304 work face is more complex and L8 Taiyuan formation is the key water prevention aquifer. The hydraulic connection is confirmed between Taiyuan Formation limestone aquifer and Ordovician limestone aquifer through analysising the water quality.According to the result of water quality tests, tectonics and the recharge intensity, the feasibility of the depressurizing of Taiyuan limestone aquifer of the coalmine seam floor has been assessed. Having collected water samples from the top and floor of the coal seam, analysis and comparison of the results of water quality tests from each section in coalmine, the differences are huge among, whicn means depressurizing of Taiyuan aquifer in 2-2 coal seam is possible from the water quality side; the east、west and south boundary of Yongxia Coalfeild are water-resisting fault, and the north boundary is relative water-resisting fault, which makes Yongxia Coalfield a closed and semi-closed hydrogeological unit, besides, the hydraulic conductivity of most faults is poor according to the hydrogeological investigation, which makes depressurizing possible Macroscopically; Water releasing test showed that the fault fracture zone developments sufficiently and Taiyuan limestone water was closed to Ordovician limestone in hydraulic links, and the recharge is about 200m3/h.According to geophysical prospecting situation safety water pressure、leakages water pressure and yield, divided 21304 work face into 3 sections: rich high-pressured water section, high water pressurer section, poor and low water water pressure section of 21304 work face。Rich high-pressured water section is beside to F20 fault,and the fault fracture zone of this section floor is intensive, the recharge between Taiyuan limestone aquifer and Ordovician limestone aquifer is rich. Visual MODFLOW is utilized to simulate the sepage field of Taiyuan Formation, and forecast effect of depressurizing. Analyzed the possibility to close the drain holes the based on the hydrogeological conditions of 21304 work face to definite the premise of closing the drain holes and thus made the conclusion that the estimated distance is 520m.There are 59 figures,36 tables and 80 references in this paper.