Abstract:

This paper takes the mining of full-mechanized face XV1304 in condition of limestone hard roof in Fenghuangshan coal mine as background, explored the roof structure and mechanical property, researched the roof structure and the roof weighting structure by theoretical calculation and field observation, the result shows: the K2 limestone roof can divide into the lower, the middle and the upper delaminations, the strength of every delamination gradually increased from down to up, the rock mass integrity also gradually raised; the lower rock which about 3.9m thick of roof(the lower delamination is about 1.3m thick, the middle one is about 2.6m thick) falled at random; the upper rock which about 5.21m thick of roof didn’t show typical periodic weighting characteristic, shows pronounced gradual sagging characteristic.

Key words: limestone, hard roof, gradual sagging