Abstract: When rock joints are disturbed by stress waves, the continuous stresses in joint ends change with various degrees of joints. To analyze the relationship between the dynamic change and the incident angle of stress wave, we introduce a combined model of the nonlinear normal normalised constitutive relation and the linear tangential constitutive relation of rock and the corresponding stress wave propagation equation of oblique incident joints in P wave oblique incidence joint. According to the theory of mode-I and mode-II crack-tip stress in fracture mechanics and the displacement field, a formula is obtained for calculating the stress field and displacement field with the change of the velocity of the joint in the combined form. This study investigates the effect of the simulated pulse signal with different incident angles on the simulation of stress and displacement at the end. Stress and displacement fields at the upper and lower ends of the joint present non-symmetric distribution under the oblique incidence of stress wave. With the increase and decrease of vibration velocity of the incident wave particle point, the position of the stress concentration changes. The data of 0.005 m position at the upper and lower sides of the joint end in the model are calculated, the change of joint normal stiffness bringing by the particle velocity of incident wave directly influences the transmission and reflection of stress wave, which leads to the lag of stress and displacement at the end of the joint. The lateral displacement and the incident angle do not change monotonically, but the vertical displacement decreases with the increase of incidence angle.

Key words: nonlinear rock joint, BB model, stress, lag effect