THMD Coupling Model for Water-Conducting Fracture Zones of Mines Based on Dual-Porosity Media

The surrounding rock undergoes damage and fracture under the disturbance of mining stress, which can easily form water-conducting fracture zones and cause water-inrush disasters in water-rich mines. Due to the complexity of the media in the water-inrush channel and the coupled environment of various physical fields, the establishment of the seepage model in the water-conducting fracture zones remains a long-term challenge. In this study, the water-inlet part of the fracture zone, dominated by pores and fractures, is simplified as a dual-porosity medium. Then, based on mixture coupling theory, the thermodynamic consistent constitutive model for the dual-porosity media considering stress, damage, heat, and seepage coupling is established using the nonequilibrium thermodynamics method, which is the fully coupled thermal–hydro–mechanical–damage model (THMD). Meanwhile, the dynamic evolution equations of stress, porous matrix porosity, and fracture porosity are derived when multiple physical fields are coupled. Finally, the numerical simulation is conducted with finite-element software to further illustrate the coupling phenomenon in the dual-porosity medium of the water-conducting fracture zone.