Multi-physics Field Coupling Simulation Study on Spontaneous Combustion in Goaf Considering Gas Extraction

To address the collaborative prevention and control challenges of compound disasters involving gas and coal spontaneous combustion in goaf areas of high-gas mines, this study establishes a multi-physics coupled numerical model based on Darcy’s law of seepage and Fick’s law of diffusion. The model incorporates the source term from residual coal gas desorption and the sink term from extraction outlets, enabling systematic simulation of the dynamic evolution of the seepage field, gas concentration field, and temperature field within the goaf.Through numerical simulation and parameter optimization, the optimal collaborative control parameters were determined as an extraction outlet located 45 meters from the working face and an extraction negative pressure of -6Pa. Implementation of this scheme reduces gas concentration at the upper corner of the working face by 62.3%, maintains a stable gas concentration of 5.6% at the extraction point, and keeps the solid temperature field in the goaf below the critical threshold for coal spontaneous combustion.