Study On Coupling Law Of Mixed Gas Three-dimensional Multi-field In Goaf

Residual coal in goaf easily cause spontaneous combustion, and provide a long-term existence fire source, then easily lead to secondary gas explosion. Taking CH4_, O₂, CO, CO₂ and N₂ constituents in goaf gas-air mixed gas as the research object, on the basis of measurement of gas concentration and temperature in mine goaf, this dissertation has a systematic study on the law of gas flow and heat transfer in goaf pre-and post spontaneous combustion of residual coal by theoretical analysis, experimental verification and numerical simulation. Gas permeability distribution in goaf seepage is summarized in permeability determination experiments. Large-scale goaf gas seepage and heat transfer experiments are practiced and gas concentration distribution, pressure distribution and temperature distribution in goaf seepage are summarized. The space equations of porosity and permeability in the goaf porous media are established, and the 3D goaf physical model is constructed, and the goaf gas mathematical models are improved. And multi-field coupling changed law of gas-air mixed gas 3D seepage field, concentration field and temperature field pre-and post spontaneous combustion of residual coal in goaf have been obtained by discreting mathematical model equations. The numerical simulation results coincide well with experimental results and site observation data. The dissertation has great significance on goaf gas drainage, prevention of residual coal spontaneous combustion and secondary gas explosion.