Columnar jointed rock mass (CJRM), Joint interface stress, Interface mechanics, Crack initiation stress, Fracture behaviors, Engineering geology. Rock mechanics. Soil mechanics. Underground construction, TA703-712

For a special geological structure of columnar jointed rock mass (CJRM), its mechanical properties are strongly affected by the columnar joints. To describe the fracture behaviors of CJRM using the basic theories of interface mechanics for composite materials, the interface stresses of the vertical and horizontal joints, which are the two primary joints in the CJRM under triaxial compression, are studied, and their mathematical expressions are derived based on the superposition principle. Based on the obtained interface stresses of the vertical and horizontal joints in the CJRM, the crack initiation of the joint interface in the CJRM is studied using the maximum circumferential stress theory in fracture mechanics. Moreover, based on this investigation, the fracture behaviors of CJRM are analyzed. According to the results of similar material physical model tests for the CJRM, the theoretical study is verified. Finally, the influence of the mechanical parameters of the CJRM on the joint interface stress is discussed comprehensively.