The Experimental And Numerical Simulation Research Of The Gas Migration Rules In Goaf

Mine gas is one of the main factors threatening mine production safety. Personal casualtyloss and economic loss are most serious and gas disasters prevention is always the key to coalmine safety work. In order to prevent gas disaster, it is necessary to research gas distributionand migration behavior in goaf. Base on physics resemble simulation theory and method andaccording to collapsing characteristic, goaf gas migration experiment system was build usingoriginal three dimensional gas migration experiments system. It also includes controllableperistaltic pump ventilation system, gas injection system, temperature control system and gasconcentration test system. Through resemble simulation of a mine, gas ventilation distributionin goaf were studied and analyzed under different ventilation volume, high temperature andsealing condition. Then, goaf gas migration behavior was got.Using FLUENT software, numerical simulation was done based on goaf gas migrationexperiment system. The simulation results had same trend with the experiments. Theexperiments and simulations results showed when ventilation was positive, gas concentrationincreased with goaf depth increasing along trend, gas concentration increased from inlet airside to return air side along dip and upper concentration was bigger than lower by floatingeffect. Ventilation volume would influence gas concentration distribution. Appropriateventilation volume increasing would reduce gas concentration in shallow goaf effectively andmake leakage air to deep goaf which push high concentration gas to deep goaf. It would alsoreduce concentration difference between inlet and return air and influence gas concentrationin upper goaf. After appearance of heating source, gas in goaf bottom was heated and floatingeffect increased because of increasing temperature. Gas would accumulate in upper goaf andgas concentration distribution was more uneven. When goaf as sealed, gas concentration inshallow goaf increased faster, concentration gradient in all directions disappeared gradually and gas concentration in whole goaf increased and achieved balance finally.