Evaluation of mixed-mode Ⅰ-Ⅱ stress intensity factors of rock utilizing digital image correlation method

A method for determining the mixed-mode Ⅰ-Ⅱ stress intensity factors and crack tip position of rock specimens by the digital image correlation method is proposed. The notched semicircular disk rock specimen under three-point bending is used in the rock fracture tests, the displacement field around the crack tip is measured by the digital image correlation method, and nonlinear displacement field equations with unknown parameters are solved by the nonlinear method. The characters of rock specimen fracture and crack propagation are studied based on the analysis of stress intensity factors and crack extension length. The experimental results show that the mixed-mode Ⅰ-Ⅱ stress intensity factors and crack tip position of rock can be evaluated accurately from the displacement components by the proposed method.