Experimental Study On Influencing Factors Of Coal And Gas Outburst

Coal and gas outburst is an extremely complex dynamic phenomena in the processof coal mine exploitation, and for the mechanism of its occurrence, the combined effecthypothesis is generally agreed by the domestic and foreign scholars, namely coal andgas outburst is the result of the combined effect of the ground stress, gas and thephysical and mechanical properties of coal. Based on this hypothesis, after themeasurement of the basic physical and mechanical parameters of briquette, physicalsimulation experiments were conducted by coal and gas outburst simulation test devicewhich is independently researched and developed by the State Key Laboratory for CoalMine Disaster Dynamics and Control, Chongqing University, and the PCI-2acousticemission system which is produced by the acoustics and physics company of the UnitedState. This experiment simulates the influence on coal and gas outburst under differentstress in load relief zone belonged to ground stress factor, different moisture contentbelonged to coal’s physical mechanics properties factor and different adsorption gasbelonged to gas factor. This experiment studied the gas pressure, the coal temperature,the acoustic emission characteristics, the outburst strength, the sorting and crushing ofpulverized coal. There are the main results:1) In the process of charging gas into the coal, the coal temperature increases withthe increase of the gas pressure. The coal temperature increases less when stress in loadrelief zone and coal’s moisture content increase, and when the absorption gets weaker.Among the three factors, the absorption of gas charged into coal effect most, then is themoisture content of coal, stress in load relief zone is the weakest. When outburst occurs,gas pressure decreases quickly, coal temperature drops suddenly. The changes of coaltemperature have nothing to do with the stress in load relief zone almost. But the coaltemperature drops less when coal’s moisture content increases and when the chargedgases’ absorption gets weaker. And the absorption has more obvious effect on the coaltemperature changes after outburst than coal’s moisture;2) Coal acoustic emissioncharacteristics are related to the amount of change in coal temperature. The acousticemission Hit rate in peak and cumulative Hit number increase when the amount ofchange in coal temperature increase under different stress, moisture content andabsorption in the process of experiments. And stress in load relief zone, coal moisturecontent, gas absorption have a stronger and stronger effect on acoustic emission Hit rate and cumulative Hit number;3) The outburst has a more obvious crushing effect on thepulverized coal when stress in load relief zone increases, coal moisture content dropsand the outburst gets stronger. The outburst gets weaker as the gases charged into coalare He,CO2, CH4in turn and the crushing effect on the pulverized coal gets weakerwhen outburst occurs between coal and CH4,CO2,He respectively. And among thosethree factors, coal moisture content situation, gas absorption and stress in load reliefzone have a weaker and weaker effect on outburst strength and the crushing effect ofpulverized coal.