Experimental study on top coal's failure law of extremely thick seam's mining face

摘要

Based on similar analog experiments on top coal's displacement, the extremely thick coal seam mined in 21121 fully mechanized top caving longwall working face of Qianqiu mine, is studied in detail. It can be found that top coal above support is classifie I as the roofs rotation action layer and short beam structure layer and support action layer. Also it can be found that the thicker of top coal, the three layers are more clear. What's important, the mechanic model of the short beam layer which is vital to successful top mining is built and studied, which can do great benefit to extremely thick coal seams' high efficient mining.