Abstract: Based on moment tensor theory, P-T diagram method and T-k diagram method, the fracture parameters and their evolution such as spatial position, fracture azimuth, fracture types, stress state and moment magnitude were analyzed to reveal the rock failure mechanism of triaxial compression under the condition of different confining pressure with a large number of acoustic emission (AE) data in the process of generation, propagation and coalescence of cracks simulated by Particle Flow Code. The results have shown that：1) The rock fracture azimuth is influenced by the loading direction and the joint orientation. When the joint orientation and the loading direction are in a certain angle, the principal compressive stress components are gradually distributed around with the joint orientation corresponding location of the P-T diagram. 2) The proportion of linear tension fracture decreases as the angle between joint and Z-axial increases. The proportion of linear shear fracture, mixed fracture and double couple shear fracture increases as the angle between joint and Z-axial increases. 3) The tensile fracture is mainly distributed in the joint plane, and its energy is lower. The shear fracture and mixed fracture type is mainly distributed in the intersecting line of joint plane and free face; and its energy is higher. In conclusion, the rock fracture mechanism and its macroscopic evolution rule can be effective grasped with the moment tensor theory, P-T diagram method and T-k diagram method. These methods provide a new technical measure for the stability analysis of rock mass and its development trend, which is an effective supplement to the traditional analysis method.

Key words: jointed rock, acoustic emission, moment tensor, fracture type, fracture azimuth