Permeability Improvement Gas Drainage Technology with Deep Borehole Accumulated Energy Hydraulic Blasting of Low Permeability Seam

According to the problems of low gas drainage rate in high gassy and low permeability seam and poor blasting effect of a conventional deep borehole,a deep borehole permeability improvement technology with the accumulated hydraulic blasting was provided and four key technologies for permeability improvement with deep borehole accumulated hydraulic blasting were analyzed,including the borehole with directional vertical drilling,overlong distance explosive transportation,double grouts consolidated borehole sealing and forward detonation with double detonators and double primacords. The site trial in No. 41 seam of Dongbaouei Mine showed that compared to the conventional borehole blasting,the deep borehole accumulated energy hydraulic blasting could make the seam permeability coefficient increased by four times,the gas drainage rate increased by 15%,the gas reduced from 1. 28 ~ 2. 12 MPa to 0. 47 ~ 0. 63 MPa,the gas content of the seam reduced to 4. 8 ~ 5. 8 m3/t,the advancing rate of the coal mining face increased by 45% and the deep borehole accumulated energy hydraulic blasting technology could provide an effective technical access to improve the gas drainage rate of the low permeability seam.