Sliding phenomena in intermittent rock joint

Rock bridges in rock masses would increase the bearing capacity of Non-persistent discontinuities. In this paper the effect of ratio of rock bridge surface to joint surface, rock bridge shape and number of rock bridge on failure behaviour of intermittent rock joint were investigated. A total of 18 various models with dimensions of 15 cm × 15 cm × 15 cm of plaster specimens were fabricated simulating the open joints possessing rock bridge. The introduced rock bridges have various continuities in shear surface. The area of the rock bridge was 45 cm2 and 90 cm2 out of the total fixed area of 225 cm2 respectively. The fabricated specimens were subjected to shear tests under normal loads of 1 MPa in order to investigate the shear mechanism of rock bridge. The results indicated that the failure pattern and the failure mechanism were affected by two parameters; i.e. the configuration of rock bridge and ratio of rock bridge surface to joint surface. So that increasing in joint in front of the rock bridge changes the shear failure mode to tensile failure mode.