The productive practices and theoretical researches of the fully mechanized sublevel caving mining proved that coal seam strength, crack distributing features and its developing extent are of important effect on topcoal cavability. The influences of crack sets, spacing and the relations betwene cracks' trend and face layout on top - coal recovery have been analysed emphatically in the paper. And according to the viewpoint of which crack distributions determine caving- block feature, and fragment features determine top coal cavability, six kinds of crack distribution ranks being of effect on cavability are proposed and applied in practice. The cracks' coupling technique with face layout should be an effectual technological path of increasing coal drawing rate in fully mechanized sublevel caving mining.
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