关键词: 侏罗系煤田, 砂岩含水层, 放水性试验, 超前疏放

Abstract: In order to demonstrate the water drainage feasibility of the Baotashan fissured sandstone aquifer at the bottom of the Jurassic coalfield, the water drainage tests were performed using single borehole or multi boreholes in lingxin coal mine located in Ningdong mining area as an example. Then, we analyzed the dynamic variation law of the borehole outflow rate and evaluated the effect and feasibility of water drainage aimed at the bottom aquifer. The test results show that at the initial stage, the borehole discharge is large, and the flowrate gradually decreases and become stable after a week or so. A landing funnel centering on the water discharge borehole is formed when the valve was closed, and the influence radius is large (both greater than 700m), and the water pressure of each borehole is significantly reduced. From single borehole drainage to three boreholes superimposed drainage, the shape of the landing funnel keeps expanding, the influence radius gradually increases, and the water pressure of each borehole decreases gradually. The water inrush coefficient of the coal seam floor calculated by water pressure of FS2, G1 and G2 holes is less than the normal standard (0.1mpa /m) in the water drainage stage using single borehole. The water inrush coefficient of the coal seam floor calculated by the water pressure of FS2, JG, JF, G1 and G2 holes is lower than the normal standard during the period when multi boreholes were used for water drainage. It shows that it is feasible to realize the advance dredging and releasing of the sandstone aquifer located at the bottom of the coal seam through water drainage tests, so as to ensure the safe mining of the working face.