Citation

Wang H, Zhao S, Liu J, Xia B, Li S. China Saf. Sci. J. 2020; 30(1): 66-72.

Copyright

(Copyright © 2020, China Occupational Safety and Health Association, Publisher Gai Xue bao)

DOI

10.16265/j.cnki.issn1003-3033.2020.01.011

PMID

unavailable

Abstract

In order to reveal influencing characteristics of vertical penetrating crack on instability and breaking of hard roof, theoretical analysis was conducted on breaking span of such hard roof based on analysis of vertical crack ' s morphology caused by hydraulic fracturing. Then, deformation failure characteristics and damaged area distribution of hard roof were studied by means of numerical simulation. The results show that the breaking span of hard roof is shorter than its initial limited span when open vertical penetrating crack is in certain range. But if crack is closed, two bulks of the hard roof will deflect to crack face and shear slip will take place along it, which makes hard roof easier to break. The tension-compression destructive effect in biting point area of rotary blocks is a main reason for local buckling, greater rotating degree and roof breaking. The smaller normal stiffness coefficient of vertical crack face is, the easier roof breaking will be. Hard roof with open vertical penetrating crack instead of closed one is more likely be deform and break. © 2019 China Safety Science Journal

Language: zh