Influence of joint location and connectivity on the shear properties of artificial rock samples with non-persistent planar joints

In this paper, direct shear tests of cement mortar samples with non-persistent planar joints are reported, to study the effects of joint connectivity ratio k (ratio of the length of the planar joint to the length of the specimen) and locations of a planar joint on the shear properties of artificial jointed rock samples. The test results indicate that (a) the shear stress-shear displacement curve of samples with non-persistent planar joint under direct shear stress consists of five stages. (b) For samples with a non-persistent planar joint, when the joint connectivity ratio k remains unchanged, the shear strength of the specimen increases as the distance s between the left end of the planar joint and the left edge of the specimen increases. When the distance s remains constant, the shear strength of the specimens increases with an increase in the joint connectivity ratio k. When both the joint connectivity ratio k and the distance s remain unchanged, the shear strength increases as higher normal stress is applied. (c) For samples with two non-persistent planar joints and constant joint connectivity ratio k, the shear strength increases as the two planar joints, respectively, are at the two ends of specimen, compared to the scenario where the two planar joints are at the middle of the specimen. The results also demonstrate that the proposed fitting model is suitable for characterizing the shear stress-shear displacement of artificial jointed rock specimens where a non-persistent planar joint is present.