Study On The Laws Of Dynamic Gas Emission After Coal And Gas Outburst

The prediction or calculation of gas emission when coal and gas outburst are helpful to prevent coal and gas outburst catastrophes and do research on coal and gas outburst by calculating the rate of gas emission after coal and gas outburst. The sources of gas emission were analyzed with field datas. The formulas of throw-out gas emission were derived using the gas desorption law of curshing coal on the base of theoretical analysis in this paper. Dynamic gas emissions of coal seams around the cavity after coal and gas outburst were studied using numerical simulation method based on the theoretical analysis. Then the calculation methods of gas emission after coal and gas outburst were proposed. The main contents are as follows:(1) Field datas of coal and gas outburst catastrophes were widely collected and analyzed. The sources of gas emission were analyzed. And the formulas of throw-out gas emission were derived. The value ranges of parameters such as the quality of throw-out coal when coal and gas outburst, the original pressure of coal seams, the original gas permeability coefficient of coal seams, gas content in coal seams and thickness of coal seams were determined. Simlulation conditions were set for the value ranges of different parameters.(2) The calculation models of dynamic gas emission after coal and gas outburst using numerical simulation software ANSYS were established. Numerical simulation was performed for different conditions. According to simulation results, double logarithm curves of flow dimensionless numbers changing with time criterions were drawn. The results show that: double logarithm curves of flow dimensionless numbers changing with time criterions at different conditions approximately parallel to others and finally coincidence as a diagonal line with the increase of time dimensionless numbers. According to curves of flow dimensionless numbers changing with time criterions, the calculation method and formula on gas emission of coal seams around the outstanding cavity were proposed.(3) The general calculation method and formula on dynamic gas emission when coal and gas outburst were proposed.(4) Parameters of coal and gas outburst catastrophes were back-calculated using calculation method of gas emission after coal and gas outburst combining with field datas of coal and gas outburst catastrophes. And example verifications were performed.