Risk Assessment of Water Inrush in Coal Mine through Fault Based on Forchheimer and Non-Darcy Flows

Fault water inrush accident in coal mine construction is a serious hydrogeological disaster, which seriously endangers the safe operation of underground engineering. In the process of mining coal resources in Western China, a large number of serious mine water inrush accidents have occurred. Based on the investigation of geological conditions of fault in the Pingdingshan coal mine, the coupling model of the Darcy laminar flow and Brinkman flow is used to analyze the water inrush mechanism of a fault. On this basis, considering the higher permeability and water inrush rate, the Brinkman flow may not be used to simulate the nonlinear flow mechanism at the fault. Two improved models, the Brinkman equation and Forchheimer equation are used to analyze the mechanism of water inrush. Based on the two-dimensional finite element method, the process of water inrush into the water inrush zone is analyzed. The pressure and velocity nephogram under different conditions and the evolution characteristics of nonDarcy effect influence coefficient of fault water inrush are analyzed through parameter study. Based on the different permeability variation coefficients xi (the ratio of fault permeability kF to aquifer constant permeability kA) and different fluid flow field changes, the Fletcher number and flow rate are compared with the theoretical data.