Abstract: Aiming at the difficulty of regional outburst prevention in closed distance，low permeability and loose outburst coal seams, the outburst prevention technology by comprehensive hydraulic drilling downward through coal seam was proposed. We theoretically analyze the outburst prevention mechanism of this technology. The stress distribution of coal body around different diameters borehole before and after water infusion and wetting was simulated. The results show that released range of borehole increasing with the diameter of hydraulic flushing borehole growing. The released range increases after water infusion and softening under the same diameter condition. Pressure relief effect of increasing diameters is better than water-infusion softening. There is exponential function relationship between the released range and negative reciprocal borehole radius. This outburst prevention technology process was researched. The assessment index system of outburst prevention effect was established. The technology, which has been successfully applied in Qingdong mine, provides a new technical way for regional out-burst prevention in this condition.

Key words:  , borehole downward through coal-seam；comprehensive hydraulic；outburst prevention；process of technology；assessment index system