Abstract
Abstract 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 non-Darcy effect influence coefficient of fault water inrush are analyzed through parameter study. Based on the different permeability variation coefficients ξ (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.
Highlights
With the focus of traffic infrastructure construction gradually shifting to the central and western mountainous areas and karst areas, coal mine and underground engineering construction often face the baptism of complex structures, great changes in geological environment, and many disasters and accidents [1]
According to an incomplete statistics, nearly 80% of the major safety accidents in underground engineering construction, such as traffic and hydropower, are caused by water inrush disasters and improper disposal, which lead to heavy casualties, economic losses, and delay of construction period, and even force the coal mine to stop or change its route
It is useful to determine whether the Forchheimer effect is included in the numerical simulation of the fluid flow in porous media [34,35,36,37,38]
Summary
With the focus of traffic infrastructure construction gradually shifting to the central and western mountainous areas and karst areas, coal mine and underground engineering construction often face the baptism of complex structures, great changes in geological environment, and many disasters and accidents [1]. The seepage of water gushing fluid in fractured rock mass has nonlinear characteristics It is of great theoretical and practical significance to reveal the mechanism of water inrush and the reasonable prediction of water inrush. The failure of rock mass structure after mining (especially fault fracture zone and collapse column) leads to the increase of fracture size and sudden change of fluid velocity It makes the Reynolds number far greater than 10, showing Forchheimer-type and nonDarcy-type seepage characteristics. Under the influence of mining stress, when it is collapse column, fault fracture zone, or surrounding rock failure area, its main structure is composed of the broken rock mass, which belongs to a porous medium with a large gap. I p, ð6Þ where the k0 is the initial permeability of rock element, cf is the compressibility coefficient, and σii/3 is the average total stress
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