Abstract
Underground fault water inrush is a hydrogeological disaster that frequently occurs in underground mining and tunnel construction projects. Groundwater may pour from an aquifer when disasters occur, and aquifers are typically associated with fractured rock formations. Water inrush accidents are likely to occur when fractured rock masses are encountered during excavation. In this study, Comsol Multiphysics, cross-platform multiphysics field coupling software, was used to simulate the evolution characteristics of water flow in different flow fields of faults and aquifers when water inrush from underground faults occurs. First, the Darcy and Brinkman flow field nonlinear seepage models were used to model the seepage law of water flow in aquifers and faults. Second, the Forchheimer flow field was used to modify the seepage of fluid in fault-broken rocks in the Brinkman flow field. In general, this phenomenon does not meet the applicable conditions of Darcy’s formula. Therefore, the Darcy and Forchheimer flow models were coupled in this study. Simulation results show that flow behavior in an aquifer varies depending on fault permeability. An aquifer near a fault is likely to be affected by non-Darcy flow. That is, the non-Darcy effect zone will either increase or decrease as fault permeability increases or decreases. The fault rupture zone that connects the aquifer and upper roadway of the fault leads to fault water inrush due to the considerably improved permeability of the fractured rock mass.
Highlights
Water inrush is a hydrogeological disaster that frequently occurs in underground mining and tunnel construction projects
Water may flow from aquifers, which are typically associated with fractured rock formations, and may cause problems in the safe operation of underground engineering
When fault permeability was considerably lower than aquifer permeability, i.e., ξ < 0.1, the hydrostatic pressure distribution of the aquifer was uniform due to the relatively low permeability of the fault
Summary
Water inrush is a hydrogeological disaster that frequently occurs in underground mining and tunnel construction projects. In China, north China and south China, several coal mines are being threatened by varying levels of underground fault water inrush. A water inrush accident during tunnel excavation is a dynamic process in which groundwater is poured into a tunnel by an aquifer through a water-conducting fault due to the combined actions of rock disturbance and the pressure release of confined water caused by artificial mining. The purpose of this paper is to establish a suitable seepage model to simulate the flow process of groundwater from aquifer to fault Based on such change, a multifield coupled flow analysis model is established to analyze various changes caused by varying physical quantities that affect the degree of change in water flow. The validity of Brinkman and Forchheimer seepage model in analyzing flow in faults is analyzed in this paper
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