ABSTRACT
The author has been working on mechanical characteristics of roof before and after fracture since 1984 and established the mechanical model for “Elastic slab and articulated slab structure”. In determining the friction equilibrium between the main roof stratum and fracture blocks, the author used the empirical formula of the rock mass ultimate shearing strength by N. Barton. The weighting caused by the breakage of rock slab (the first weighting, the second breaking span of the main roof and the periodic weighting spans), the breaking strength as well as the support load calculation are deduced from the mechanical model.
