Research on the activation and water inrush catastrophe of mining-induced fault filling body based on the evolution of porosity

The mechanism of fault water inrush exhibits distinct phased characteristics, and the related parameters of the stress-damage field and seepage field of the fault should also undergo significant phased evolution. To explore the fault structure activation characteristics in fault water inrush, this paper analyzes the evolution of fault water inrush using numerical simulation. Unlike previous computational studies that input predetermined parameters, this simulation derives porosity evolution through the evolution of the stress-damage field and numerically feeds the results back into subsequent multi-field coupling simulations, such as the seepage field. The research results indicate that during the evolution of fault water inrush, the porosity evolution derived from the stress-damage field exhibits highly distinct phased characteristics. When the porosity evolution feedback is incorporated, the various stages of damage evolution significantly alter the physical properties related to the seepage field. The permeability undergoes a notable cliff-like difference in evolution with the occurrence of complete plastic failure, and subsequently tends to decline smoothly and stably. By optimizing and improving the relevant calculation formulas for seepage evolution and incorporating them into the simulation, it is found that the phased interactive response of damage-seepage evolution characteristics is more pronounced after optimizing the feedback of parameters such as porosity evolution. The simulation results are more consistent with actual conditions.