Experimental Study on Coal Pillar of Roof in Deep Hole Pre-splitting Blasting

The impact load of support is easy to occur in the mining of 31203 fully mechanized mining face under the influence of the isolated pillar of 22# coal in the upper part, the parameters such as single consumption of explosive, charge of single hole, spacing of gun hole and length of sealing hole are determined by calculation to make plans for roof blasting. Blasting effect shows that: after the implementation of the blasting, the roof of 31203 fully mechanized mining face of collapsed in time during the mining, according to the analysis of mine pressure observation data, the first pressure step distance is 43 m, 15 m less than the last working face, the working face support load is normal when the pressure comes, most of the roof caved in time, the concentration of O2, CO, gas and other toxic and harmful gases in the upper corner is normal, step distance of periodic pressure is 12.4 m, the maximum pressure is 46 MPa, and the pressure lasts for 1 cut, the roof of the working face and two lanes collapsed normally. The engineering test shows that the coal pillar on the roof of the deep hole pre-splitting blasting destroys the integrity of the coal pillar, releases part of the pressure, and greatly avoids the accident of the impact load on the working face.