Simulation research on the mechanism of water inrush from fractured floor under the dynamic load induced by roof caving: taking the Xinji Second Coal Mine as an example

Abstract

The deformation and failure modes of the fractured floor are very complicated, under the coupled action of the dynamic and static stress superposition disturbance as well as the seepage field induced by high strength deep mining. Currently, there are not enough researches on the mechanism of water inrushes from the fractured floor under the action of dynamic and static stress superposition disturbance in deep parts. In this paper, the background was the geological conditions of Xinji Second Coal Mine No.1 coal seam, which is located in Huainan of Anhui Province in China. This paper was based on the results of the 3D seismic exploration for small faults in the field floor, and the roof carving over great extent was taken as the typical dynamic disturbance inducement. The FLAC program was applied in this paper, and the non-linear dynamic module and the seepage module of the software were coupled to simulate the activation and re-development process of the floor fracture under the dynamic load caused by roof caving. The evolution law of the water inrush from floor fractures under the action of dynamic and static stress superposition disturbance was studied. From the aspects of the stress, plastic failure zones, pore water pressure lifting height, the fracture seepage velocity, the dynamic load strength, and the confined water pressure of the fractured floor model, this paper analyzed the activation and re-development process of the floor fracture under the dynamic load caused by roof caving and the formation mechanism of the water-flowing channel. The results revealed the mechanism of the secondary failure of the floor fracture caused by roof caving, and provided the theoretical basis and calculation methods for predicting the water inrush from floor fractures in high strength deep mining.