Laws of Water Inrush and Prediction Method in Goaf After Water Drainage From Jurassic Coalfield Roof Sandstone Aquifers

To improve the prediction accuracy of the water inflow in the pore fractured sandstone aquifers of the Jurassic Coalfield, the change laws of water bursting in goaf at the stage of recovery are analyzed. Taking the first mining face of 4-1 of a coal mine in Ningdong Majiatan as an example, and the time and space dynamic prediction method of static water storage and dynamic replenishment of roof aquifer in Jurassic coal seam mining process based on the theory of “large well” and “principle of mirror method” is proposed. The prediction formula of water inflow in the working face during recovery process can be used to predict the water inflow more accurately, and provide the basis for the pre-dredging degree of the roof water before the mining, and ensure the safety of mining at the working face threatened by roof water hazards. The water inflow of the first mining face of a mine in the Ningdong Majiagan Mining Area is predicted by the newly proposed prediction method and compared with the observed values. The result shows that the predicted values of the water inrush are in good agreement with the observed values, and the average error is about 10%.