Numerical investigation of the in situ gas explosion fracturing and the enhancement of the penetration in coal seam boreholes

Abstract Permeability enhancement of low permeability coal seams is a key tool in mine gas extraction and utilization. Numerical investigations are used to analyze the geometric parameters drilled cavity effect initial pressure on explosion explore potential original blasting enhancing crack penetration seams. On basis these analyses, changes characteristic body under examined. The results show that maximum tends be close theoretical when L/ Φ 1.67–2.5, mechanical surge velocity wall reaches optimum experimental group 1.67. demonstrate linear positive correlation, increasing former can effectively enhance force applied hole wall. During pressurization stage, cracking range 0.05 m, but duration peak extend cracking. combined stress fields causes elastic energy storage fail radial region wall, regains as increases. fracturing seam borehole before after expanded by 19.6 times, proving situ boreholes improve seepage characteristics increase recovery rate. simulations indicate application permeation technology limited cumulative time pressure. This provides for understanding constraints technology.