Study On Water Level Change In Confined Aquifer And Deformation And Failure Law Of Overlying Strata Caused By Coal Mining

In order to study on water level change in confined aquifer and movement and failure lawof overlying strata caused by coal mining, the paper studied theoretically water level change lawcaused by mining in confined aquifer. According to strata movement and overlying strata failuretheory of coal mining and percolation theory, discussed the mechanical mechanism of the waterlevel change in confined aquifer formed by the function of crack leak water and deformationcompressive stress using percolation theory. Based on this, the mathematical models to calculatewater level change which were based on the formulas of groundwater stable and unstable wellflow were established. Combined with the measured data of hydrology condition of N1S2coalface under Santaizi reservoir in Daping Coal Mine, the mathematical model was verified. Theresults showed that the groundwater unstable motion mathematical model could well predictwater level change caused by mining in confined aquifer. Meanwhile, the paper studiedoverlying strata movement and failure law caused by coal mining under existing the upperconfined aquifer by using FLAC3Dfinite difference software. The overlying strata failure fielddistribution law was obtained under different working position and different pore pressure. It canbe seen that the failure height and range of overlying strata would increase with the propulsion ofcoal face, but when the coal face advanced a certain distance, the failure height of overlyingstrata increased no longer and that with the increase of pore pressure, the failure height and rangeof overlying strata would increase, but when the pore pressure increased a certain value, theplastic zone would extend from aquifer, then it would connect with water flowing fractured zone,coal face would inrush water finally. The results of the research could provide the theory basisfor the roof water-inrush prevention and cure.