Study and application of hydraulic slotting construction technique with downward passed through . strata borehole

According to the poor effect of a soft seam pressure released, improved permeability and gas drainage with a conventional downward drilling passed thr ough strata borehole, a hydraulic slotting matched equipment was optimized for the downward drilling through strata borehole. The paper had a study on the hydraulic S lotting construction process and technique of the downward drilling borehole and the water and cutting discharging technique with " air blowing in group and row" for the downward drilling borehole. In No.1672 ( 1) transportation gateway of Pansan Mine, an effect investigation was conducted on 60 downward passed through strata hydr aulic slotting boreholes. The application results showed that after the hydraulic slotting completed, an equivalent diameter of the borehole at the seam section was incre ased to 370 mm and the coal wall exposed area of the borehole was 2.3 times larger than the borehole without a slotting. The pure gas drainage volume from 100 boreh oles with the hydraulic slotting was 0.5 ~ 0.7 m3/min and was 70% higher than the pure gas drainage volume from 100 boreholes without slotting. The water and cutting discharging of the downward borehole drilling with " air blowing in group and row" could effectively discharge the coal ( rock) cutting and water in the boreholes by the h ydraulic slotting, could provide a favorable condition to the borehole gas drainage and could provide an effective means to the gas drainage and the mine pressure bum p elimination in the mine downward borehole strip zone with the hydraulic sloting technology of the downward passed through strata borehole.