Crack Propagation and Acoustic Emission Characteristics of Boreholes in Gas Drainage in Soft Coal Seams
To study the influence of borehole angle and gas pressure on crack propagation dur-ing gas extraction,this study utilized a self-developed solid-gas coupled physical similar simula-tion experimental platform to monitor the effect of the borehole angle and gas pressure on acous-tic emission energy,counts,and events under constant pressure and closed conditions.The re-sults show that the acoustic emission signals during the drilling of gas extraction boreholes can be divided into three periods:development period,growth period,and attenuation period.As the borehole angle increases from 0° to 30°,the cumulative energy increases by 437.3％,cumulative counts by 540.2％,and event numbers by 80.9％.When the gas pressure increases from 0.13 MPa to 0.50 MPa,the cumulative energy increases by 140.4％and the cumulative counts by 231.6％,while the event numbers remains relatively constant.The distribution of cracks around the borehole changes from the concentrated distribution in the middle area to the concen-trated distribution in the lower part of the middle area,with fewer cracks in the front and upper part of the boreholes.
万方数据
维普
