Optimized design and application of borehole slotting drilling through floor of high outburst seam

In order to solve the blindness problem existed in the floor gas drainage gateway location selection and strata through borehole design during the gas pre-d rainage process with strata through borehole,an optimized analysis was conducted on the space layer relationship between the seam gateway and the floor gas drainage g ateway and the rational layout region of the floor gas drainage gateway was determined. Based on the circumstance,a mathematical model of the borehole length calculatio n was established,integration tactics was provided on concurrent design of the floor gas drainage gateway and gas drainage borehole and the site application was conduct ed in No.12 Mine of Pingdingshan Coal Mine Group. The results showed that with the optimized design,the hydraulic slotting borehole had obvious influences to the surrou nding conventional boreholes. After two weeks of the slotting borehole has drainaged,the gas concentration in 67 %boreholes was obviously increased and was increased b y2 ~ 3 times. The month advance rate of the seam gateway driving was over 100 m and was increased by 1 ~ 1. 5 times than the conventional measures. During the drivin g period,the gas emission of the seam gateway was low and kept below 700 m3 per day. Thus the danger of coal and gas outburst was highly reduced.