Abstract: By using equivalent rock mass (ERM) technique, the rock block and joint are represented by bonded particle model and smooth joint model, respectively. Then, the rock specimen containing two artificial intermittent joints is constructed, and its mechanical characteristics and fracture mechanism are investigated from mesoscopic viewpoint. Meanwhile, combining with lab test result, the suitability and reliability of ERM technique used in the mechanical characteristics research of jointed rock mass are validated by comparative analysis between calculative and experimental data. The main research results are as follows: (1) With the occurrence change of intermittent joint, the macro fractures of specimen can be divided into shear mode, wing tensile mode and mixed mode. However, the tensile micro crack between particles is the main inducement that causes various macro fracture mode. (2) Before the peak compressive strength of specimen, the acoustic emission (AE) events of fracture mainly generate near the tip of intermittent joint and accumulate along the link line between the tips of the two intermittent joints in rock bridge area. In this stage, the number of AE events is less and the fracture magnitude is lower. (3) After the peak compressive strength of specimen, the number of AE events increases rapidly and the fracture magnitude enhances. (4) In different specimens, all the relationships between cumulative number of AE events and fracture magnitude approximately meet Doseresp growth function.

Key words: equivalent rock mass technique, intermittent joint, rock mass, fracture mechanism, meso