Crack initiation direction in rock under coupled static and dynamic loads

Considering the scientific understanding of deep rock mass under high crustal stress and dynamic excavating perturbation, the crack initiation and propagation behavior in rock mass under coupled static and dynamic loads are analyzed. Primarily, the crack initiation angle and expansion angle formulas are set forth by use of the fracture mechanics theory. Then, variation of the crack initiation angle under effect of axial static stress, confining stress, axial dynamic stress and crack inclined angle are analyzed graphically based on the given formula. Next, numerical simulations of crack initiation and propagation in rock are conducted using finite element method. The results show that the crack always extends toward the higher stress direction, and the crack initiation angle decreases with the increasing crack inclined angle. The theoretical value and numerical value of initiation angle have good uniformity in general. © 2012 ejge.