Mechanism and Control of Water Inrush from Separated Roof Layers in the Jurassic Coalfields

Theoretical analysis, numerical simulation, and borehole drilling were used to study the mechanism of four large-scale water inrush events that occurred during the mining of the 1121 working face in the Hongliu coal mine in the Ningdong mine area. We concluded that the working face inrush was induced by water in the bed separations formed by overlying strata movement caused by the mining process. To control such inrushes, the location, size, and hydrogeological properties of the 18 m thick key aquiclude were investigated. We determined that the best time to drain the bed separation water was between when the beds separated and the roof caved, before water inrush occurred. The best place to drain water from was directly above the key aquiclude. These results should be useful for other sites with similar mine conditions.