Application of Flooded Water Jet Rotary Slotting Technology to Gateway Driving in Outburst Seam

Abstract：Due to the available outburst prevention measures for the outburst seam consumed a long time and could not meet the requirements of the seam gateway driving, a flooded water jet was applied to the rotary slotting of seam. Thus the length of the surrounding pressure released zone was highly increased, the coal mass structure （including the pore and fracture structure and stress status ） were changed, the time of the outburst prevention measures was reduced and the seam gateway driving speed was improved. The paper had a study on the pressure released and permeability improvement mechanism by the flooded water jet rotary slotting. The hydraulic parameters affected to the jet rotary slotting performances were theoretically inferred. The jet pressure and nozzle diameter numerical scope suitable for the seam gateway driving were calculated. The optimized rotary speed of the nozzle when the Protodyakonov coefficient was 0. 8 was determined with the indoor experiments. The site test results of the driving face in the air returning gateway of a mine in Pingdingshan Coal Mining Group showed that the effective influence radius of the flooded water jet rotary slotting technology would be 2. 5 times of the single pilot borehole. The borehole numbers of the water jet slotting could be reduced by 70% , the month advanced rate of the seam gateway driving could improved by 83% and the performance efficiency could be remarkably improved.