Numerical Simulation And Prediction Of Karst Water Dewatering Flow In Pingyu 1st Coal Mine, Henan Province

The 1st mine of the Pingyu Coal and Power Company is mainly working on 2₁ and 2₃ coal. The Carboniferous thin limestone and Cambrian thick limestone are distributed in the coal seam floor, with developed karst fissures, rich karst water and high confined water head. So, it's a threat to mining seam in the process of coal mining. So far, The mine has occurred four Water inrush accidents, leading to the mine inundation or mining area inundation. With the depth of mining increasing, the pressure of karst water working on the coal seam floor increases, and the risk of water-inrush also increases.Based on lots of relative literature and the hydro-geological information of the past years, this paper analyzes the geological and hydrogeological conditions of Ping Yu 1st mine. In order to understand the Cambrian karst water recharge,discharge and runoff conditions of Ping Yu mine field, a dewatering test has been done. According to the information of the drainage test, this paper used correlation analysis method to predict the mine water inflow under the conditions of dewatering in the future. On the basis of the drainage test data, the simulation model of groundwater flow will be established by using Visual Modflow to predict karst water flow field in the case of water discharge increasing.The stability and reliability of the model is proved by model verification and parameter estimation, and the model fits the hydrogeological conditions of Ping Yu 1st mine. Based on the predicted results, with further increase of mine water discharge, groundwater will be in a state of negative equilibrium, and karst water level will continue to decline, causing the formation of depression cones as the center of the third mining area and well rehabilitation's water drainage hole. When the mine warter discharge is 4880m³/h,central cone's level will drop to -50m or so after one year.