Mechanism of Water Inrush in Deep Coal Mining Based on Dark Structure

The relationship of “coal-water co-existence” is common in the coalfields of Northern China. It is estimated that the coal resources threatened by the karst groundwater of the Cambrian-Ordovician boundary amount to 900 × 108 T. The mining depth of most of the coalfields of Northern China has exceeded 1000 m, according to the water inrush cases analysis of Northern China coalfields floor, the necessary conditions for water inrush are water filling source and water filling channel, the main water filling source of the deep coal seam is Cambrian-Ordovician boundary karst groundwater underlying the coal seam, and the water filling channels are faults, structural fractures, collapse columns, and mining disturbance fractures, etc. According to the Trajectory Intersection Theory, the main factors affecting the safe mining of deep coal seams are concealed structures, that is unproved structures, such as faults, structural fissures, collapse columns, etc. Three kinds of water inrush geological models of dark structure, such as small fault-fissure, small collapse column-fissure, and small collapse column-small fault-fissure, were established. COMSOL was used to simulate these models, and three kinds of water inrush mechanism models of dark structures in deep coal mining were established.