Research On Advance Deep Hole Loose Blasting Technology In Coal Seam Thick Hard Roof

The thin coal seam thick hard roof due to it has high resisitant destructive ultimate strength. Can forming large acreage hanging arch after coal mining.can't naturalism caving in short period Length of span before the first roof caving in thin coal seam thick hard roof is in common hard roo,2 to 3 times; Length of span before periodic caving in common hard roof is in common hard roof,3 to 4 times.Once roof caving,it will cause serious damage.And because height of coal mining machine greater than height of coal seam,so when it working.drill can not cut the roof rock.So how to reduce length of span in thin coal seam thick hard roof,simultance satisfy the condition of coal mining machine working.This problem impact safety production in thin coal seam thick hard roof working face,o it must be solved,For that reason,this paper research and study on advance deep hole loose blasting techology in thin coal seam thick hard roof.First,compared different conditions of stress and strain under loading of rock in dynamic-static state.and loading rate impact on rock strength.simultaneously,the author discused the characteristics of rock's dynamic failure by blast wave and stress wave.and gases generated from explosives impact on rock,as well as expansion and generation law of crack in blast hole rock.Secondly,through deep analysis for caving pace of common hard roof,proposed rock beam and rock slab model based on elastic-plastic theory.and deduce simplified calculation method for length of span before the first roof caving and periodic caving by rock beam and rock slab model.Determine hard roof should use rock slab model,but thin coal seam thick hard roof not conform to plate theory,so thin coal seam thick hard roof should use rock beam model. Then, analyse the thin coal seam thick hard roof by Ansys software.as compared with theoretical arithmetic value.then propose the method of prevent thin coal seam thick hard roof. suddenly caving.Finally,optimum design of blasting parameters on base theory. Determine blast hole diameter,depth.space length, stemming length and charge calculation and other blasting parameters.Though work field of advance deep hole loose blasting test inⅡ646 working face of zhuzhuang coal mine. Determine the suitable blast parameters for the work field,On the basis of obtain desirable blasting effect and economic interestthe achievements of this thesis can be useful reference for the similar situation.