Simulation Study Of Borehole Pressure Relief Drainage Parameters And Its Application In Kaiyuan Coal Mine

Pressure relief drainage parameters have an important impact on improving coal seam gas drainage rate and guiding mine gas prevention and control work.This paper comprehensively applies theoretical analysis,simulation and actual measurement methods to study the related problems of pressure relief drainage parameters,and systematically study its application.The main results are as follows:(1)Analyze the stress distribution characteristics around the borehole,and obtain the gas drainage borehole loosening zone;and discuss the characteristics of the pores and cracks of the coal seam gas occurrence state and the gas flow characteristics caused by the borehole disturbance.(2)Through the COMSOL numerical simulation analysis,there is a certain positive correlation between the drainage radius and the borehole diameter;after the drainage time is extended,the corresponding drainage radius also continues to increase.The extraction time will have a direct impact on the extent of gas pressure reduction.As the drilling distance increases,the corresponding gas pressure continues to increase and approaches the original gas pressure.(3)The actual measurement was carried out in the air intake lane of the working face of Kaiyuan Coal Mine,and the effect of pressure relief gas drainage was evaluated.The obtained results show that the average gas drainage volume corresponding to the borehole is 0.159m~3/min,and the average gas concentration is 81.2%.When the drainage negative pressure exceeds 10k Pa,the drainage volume of the borehole decreases steadily,so the role of drainage negative pressure in improving the drainage effect is restricted.(4)Based on different methods,tested the effective extraction radius of the coal test site.The statistical analysis of the obtained results shows that the gas pressure of the pressure measuring hole continues to drop during the continuous increase of the drainage time;the coal body with a small distance from the drainage hole enters the effective drainage range faster.