Abstract: Based on the issues of roof collapse in fault zones, roof elastic thick outrigger mechanical models in normal fault zone and reverse fault zone are established; the roof stress distribution law is researched; and the roof collapse mechanisms under different roof pressures, different support strengths, different span-depth ratios, etc. are analyzed according to the Mohr-Coulomb failure criterion. Theoretical analysis shows that the maximum effective shear stress of roof thick outrigger increases with the growth of span-depth ratio; and it presents three different kinds of fracture modes with the increasing of span-depth ratio; support strength should be enhanced in the roadway crossed faults; surface protection effect should be enhanced near normal fault plane. According to the theoretical analysis, pressure relief anchor box beam support system is put forward to apply to fault zones, by which roof is supported opportunely and forcefully; and the effect of first anti-pressure, then pressure relief, at last anti-pressure is implemented; and the support system works effectively; the self-bearing ability of surrounding rock is put into full play. The mechanism research conclusion is applied to the support scheme in similar fault zones of the mine; and it prevents roof collapse accidents effectively, so as to prove that the conclusion of theoretical analysis is correct.

Key words: coal roadway, fault zone, roof, fracture mechanism, mechanical model, box supporting beam