Study on enhanced gas drainage and borehole outburst prevention technology with high pressurized water jet slotting

According to the complicated geological structure,high gas content,low seam permeability coefficient and other occurrence features of Pingdingshan Mining Area,a high pressurized oscillation pulsed water jet was applied to implement the borehole slotting and thus the seam pressure could be released and the seam permeabilit y could be increased in order to enhance the gas drainage capacity purpose.The results showed that the gas drainage volume with the hydraulic slotting borehole could be improved much higher than the conventional borehole. After the slotting conducted,the gas drainage concentration of the neighboring conventional boreholes was increase. dby 1.1 times and 1. 9 times higher than the slotting conducted before. When the high pressurized water jet was applied to the slotting,the average concentration of the g as drainage was seriously increased than the slotting conducted before ,borehole slotting conducted could"activate' the neighboring conventional gas drainage boreholes an d could cause a jumping of the gas drainage concentration. Meanwhile,in order to restrict the borehole outburst phenomenon caused by the hydraulic slotting and to elimin ate the gas overlimit during the mine gateway construction,a borehole outburst prevention device was provided,after the borehole outburst prevention device applied,the hi ghest gas concentration within the mine gateway was reduced from 0.61% to below 0.3%,the total dust concentration was reduced from 75 mg I m3 to about 8 mg I m3 an d the respirable dust concentration was reduced from 20 mg 1 m3 to below 2 mg 1 m3. Thus,the device could not only highly reduce the gas concentration within the mine g ateway and could have an obvious dust control effect.