Research on the Underground Water Inrush Mechanism Based on the Influence of Fault

In underground coal mining, the presence of high-permeability geological faults may cause a large amount of groundwater to suddenly erupt from the aquifer, resulting in undesirable casualties and economic losses. In order to deeply understand the mechanism of underground water inrush caused by typical faults in eastern China, the Zhuxianzhuang Coal Mine was selected as an engineering project case study. The study was analyzed by means of similar-physical experiments and numerical analysis. Research shows the following: (1) Similar-physical experiment results indicate that the evolution process of fault seepage can be divided into five stages: seepage initiation, seepage development, seepage mutation, seepage burst and seepage stability. Seepage types can be summarized as initial pore flow, middle fracture flow, and late channel flow. It is clear that the water pressure, the thickness of aquifuge and the material gradation have an important influence on the seepage characteristics of fault. The migration and loss of particle fillings in fault are the main factors of seepage changes. Under the sustained action of water pressure, the permeability of fault continuously increases, and eventually the fracture flow converts into the channel flow, resulting in the formation of water inrush channels in fault. (2) Numerical simulation results indicate that the failure zone in the floor strata can be divided into mining-induced damage zone, effective water-resisting zone, and fault activation zone, the effective water-resisting zone is the key part of preventing water inrush. Cracks propagation, stress distribution and seepage evolution in the floor strata can be visualized during the formation of the water inrush pathway. Once mining-induced cracks intersect with cracks caused by fault activation, the seepage increases rapidly, and groundwater will flow into the mining face, resulting in water inrush. (3) When mining coal mines with high-permeability faults, the seepage in faults should be regularly monitored, and sufficient attention should be paid to the seepage mutation, which is crucial for accurately assessing the risk of water inrush from fault.