Experimental research on the directional hole-forming and delivering explosion in long-borehole of top-coal

According to the characters of hard-thick coal seam in Xiagou mine,a test was carried out to analyse the technique of the directional hole-forming and the projectile filling in long-borehole of the top-coal,which provides the technical support for the top-coal avianize.The technique has the generalization and application value for top-coal avianize under the same geological conditions.