Research On The Law Of Gas Outburst Spreading In The Roadway

When coal and gas outburst occur,a large amount of gas carries coal(rock)into the stope space in a short period of time,which can destroy roadway facilities,damage the mine ventilation system,cause suffocation,and may even cause gas explosions and fire accidents.Therefore,it is particularly important to study the law of gas propagation and diffusion in the roadway.In order to in-depth study the propagation and diffusion law of the outburst gas in the roadway,firstly,the formation process of the outburst gas and the propagation and diffusion law were analyzed theoretically.Secondly,based on similar criteria,a visual simulation experiment system for the disaster caused by coal and gas outburst was built,and different experiments were carried out.Finally constructed a numerical analysis model of the outburst gas propagation and diffusion characteristics and carried out simulation calculations.Achieve the following research results:⑴ When the outburst occurs,the high-pressure gas expands rapidly and continuously compresses the air in the roadway to form a protruding shock wave.The air compression zone behind the protruding shock wave is the protruding impact airflow.The migration and diffusion speed of the outburst gas is less than the propagation speed of the outburst impingement gas flow,and the coal-gas two phase flow is closely followed by the outburst impingement gas flow.⑵Gas pressure plays a decisive role in the magnitude of the peak overpressure of the protruding shock wave.Under the same coal loading condition,the peak overpressure of the outburst shock wave is proportional to the gas pressure.The bigger the gas pressure,the bigger the peak of the overpressure of the prominent shock wave,and the bigger the propagation speed of the prominent shock wave;the peak of the overpressure of the prominent shock wave shows an attenuation trend with the increase of the propagation distance,and the presence of obstacles in the roadway will make the attenuation speed of the prominent shock wave slow down.⑶The migration and diffusion of outburst gas in the roadway has roughly gone through two stages: in the first stage,the outburst gas concentration rises sharply to the peak and then rapidly decays.In this stage,the outburst gas is mainly driven and migrated;The decay rate of the outburst gas concentration in the second stage is relatively gentle,and the outburst gas migration is dominated by free diffusion;the continuous desorption of adsorbed gas in the coal has a great influence on the distribution of gas concentration in the roadway.The bigger the gas pressure and coal loading,the bigger the amount of adsorbed gas in the coal body,and the bigger the amount of desorbed gas during outburst,resulting in the bigger the peak of outburst gas concentration in the roadway.