Study On Techniques Of Improving Falling Ability Of Highly Tough Coal At Longwall Top-coal Caving

Increasing recovery rate of top-coal is one of key problem in studying long wall top-coal caving. A great deal of practicing long wall top-coal caving indicates that recovering rate of top-coal difficultly broken is on the low side, so improving falling ability of top-coal difficultly broken and increasing recovery rate of top-coal is a problem urgently dealed with. There is a sort of highly tough coal which compression strength is low and comes into being big distortion before breakage. The mechanism and method to improve falling ability of top-coal difficult is deeply studied in the article during the process of studying this kind of coal seam.The article brings forward guide line to judge highly tough coal on the basis of experiment and data state method, and uses software of FLAC to analyze the characteristic of highly tough top-coal. According to technology which can improve falling ability of top-coal difficultly broken and the characteristic of highly tough top-coal broken, the article put forward a measure of deep-hole blast to improve falling ability of highly tough top-coal . The radius of fracture zone and cracked zone can be calculated by theory of blasting, and blasting effectiveness of different blasting project can be analyzed and simulated by the software of LS-DYNA. It is indicated that improving falling ability of highly tough top-coal by deep-hole blast is efficacious by the fieldwork at Ciyaobao mine in Lingzhou.