NUMERICAL STUDY ON FRACTURE PROPAGATION AND INTERACTION USING CONTINUOUS-DISCONTINUOUS FAILURE METHOD

The pre-existing discontinuous such as fractures have significant influences on the mechanical properties of the rock mass. Understanding the fracture initiation, propagation, interaction, and coalescence mechanisms are critical for characterizing mechanical behaviors of engineering rock mass and evaluating their engineering performance. In this study, a discrete element method is developed on the basis of continuum mechanics models. It is applied and a series of fracture models are established. In these models, the loading conditions and its relationship with the fracture occurrences are considered during numerical simulations. The evolution of fracture propagation and rock failure mechanisms of different fracture models are studied and the fracture propagation and its influence on rock failure characteristics are analyzed. The results show that:(1)The locations of fracture initiation, final coalescence patterns, and damage distributions are influenced by the confining pressures of the models, fracture occurrence, and the angle between fracture orientations and the maximum principal compressive stress. (2)When the weak surface of the fracture is obliquely intersected with the orientation of the maximum principal compressive stress, fracture initiation is more prone to occur at the end of the fracture. These new cracks dominate the coalescence pattern of the rock mass. Conversely, when the weak surface of the fracture is consistent with the orientation of the maximum principal compressive stress, the weak surface of the fracture only passively affects the initiation and propagation of the newly induced fractures and no further propagation or damage are observed during the whole loading process. (3)The increase of the number of pre-existing fractures and the confining pressure of the model could significantly increase the number of internal shear fractures and the degree of failure once the model is failed. The damaged area inside the model shows a slip-line shaped distribution and mainly distributes around the rupture surface, while the damage of the non-ruptured surface area shows a strip-shaped cross distribution. (4)When the weak surface of the fracture is oblique with the orientation of the maximum principal compressive stress, the weaken degree of the strength of the rock model is higher than that at the opposing situation, while the residual strength of the fractured model is the exact opposite.