Research And Application Of Small Diameter Deep And Shallow Hole-blasting In Working Face With Large Mining Height In Roof Pre-splitting

In the process of coal production, hard roof often exist in differentworking face. If we do not take effective safety measures, it will bring thedifferent safety problems. The most serious damage is the roof in a largearea pressure: because of roof with mining and caving which will produce alarge area of vacant, along with the working face advancing, it brings alarge area of vacant roof caving. The sudden release of energy accumulatedin the coal body, will produce coal ejection and highlight the seriousrock-burst phenomenon. Roof falling in a large area, the gravity will have agreat impact on the working surface and the damage bracket in a large area.Roof suddenly falling at the same time, the vacant air is instant extrusion,will form a storm, produce destruction of the roadway, turn over thetramcar, damage the wind bridge or closed wall.In view of the situation of hard roof exists in large mining height fullymechanized working face, other similar conditions of working face (4304working face,4305working face) were also take the measures ofpre-splitting blasting of hard roof, but the treatment effect is not ideal. Therefore this article unifies the other working face blasting method ofChangping Mine, summarizes the other working face blasting technology,put forward a method for forced caving fully mechanized face with hardroof.Through collecting the data of Changping Coal Mine, this articleexperimented No.3coal seam roof, comparative analysis of other fullymechanized working face strata occurrence, it brings a full understandingto working face roof condition.By using the basic theory of the roof pre-splitting blasting, this articlefurther analysis of the functions of hallow hole blasting and deep holeblasting in roof pre-splitting process. Based on the blasting method of otherworking face and combined with the actual conditions of4307workingface, it brought the determination of main parameters of pre-splittingblasting.Through summing up the roof pre-splitting blasting experience of the4304working face and the4305working face, combining the blastingtechnology of4304working face and4305working face, this articleovercame the deficiencies of blasting technique method in4304and4305working face. It put forward a kind of reasonable roof pre-splitting blastingmethod--the small aperture shallow and deep hole blasting technology, usepre-splitting blasting method in hard roof of4307working face,do acomprehensive analysis of the blasting effect after blasting.It focus oncomparative analysis of the roof of working face pressure before and afterpre-splitting blasting, the working resistance of support before and after thepre-splitting blasting and the gas concentration before and afterpre-splitting blasting. Analysis on the blasting method is reasonable, andprovide a reference guide for mining working face, which exists hard roof, with large mining height in mining area.