Impact of mining-induced fault filling activation on lagging water inrush based on porosity evolution

Coal mine water inrush exhibits high complexity and diversity, with fault-induced water inrush and its seepage-related parameters playing a critical role in evolutionary studies. This study investigates the hysteresis characteristics of fault-induced water inrush using numerical simulation, differing from conventional methods by first simulating stress-damage field evolution to derive porosity variations. These porosity values are then fed back into multi-field coupling simulations (e.g., seepage field analysis). Key findings reveal that porosity evolution significantly influences the time-lag effect of fault-induced water inrush. When incorporated, it induces plastic damage at each stage, altering seepage-related physical properties. Specifically, porosity feedback drives fault-filling body collapse, accumulation, and compaction under coupled seepage-damage conditions. By optimizing damage weakening and water-induced weakening parameters, the model self-interprets hysteresis mechanisms, as evidenced by porosity evolution feedback. The refined simulations better match real-world conditions, improving practical applicability and scientific rigor.