Test study of mechanical properties and failure characteristics of anchored rock

With rock sample of coal seam roof as matrix and steel wire as bolt, anchored rocks have been experimented by means of uniaxial compression, Brazilian split and pressure-shear test. The results show that: when rock matrix comes up against plastic yielding and certain cracks begin to extend, anchor bolt gradually becomes the main carrier of external load and rock's failure characteristics also change from fragility to ductility. During the process of splitting disk samples, a certain crack in the center of part of samples have no obvious impacts on carrying capacity; its strength increases by 51.1%. A huge penetrating crack turns up in other parts of samples and it quickly loses the carrying capacity; its strength increases by 91.6%. Failure forms of uniaxial compression samples can be divided into two categories. The first is failed with cracks propagating parallel with bolt; and the second is failed with cracks propagating vertically with bolt; the strength of anchored rock increases by 34.6%. In the pressure shear test, the carrying capacity of anchored samples obviously deteriorates once again; and the result shows that its internal friction angle of anchored samples isn't changed while the cohesive force rises by 22.9%.