Study on Top Coal Weakening Technology of Pre-blasting at Sub-level Caving Mining of Steep and Extremely Thick Coal Seam

Based on the problem of top-coal weakening of sub-level caving mining of steep and extremely thick coal seam of Shenhua Xinjiang energy Co.,Ltd.,Jiangou coal mine,the basic principle of pre-blasting and the equipment and mining technology of no.+564mB3+6 working-face was analyzed by adopted the method of combining the theory analysis and the test of practice.Departures from the practice of the number +564mB3+6 working-face,then the technology of top coal weakening technology of pre-blasting was introduced,and the parameters of this technology was established.The results of industrial test showed that the effect is obvious about the technology of top coal weakening technology of pre-blasting,obvious top-coal deformation and fracture widely,which reduce the effect of mechanical strength and fracture toughness of top-coal,greatly improve the release rate of top-coal,which is benefit to the safe and high-efficient mining of steep and extremely thick coal seam.