Investigation of stress wave transmission across a nonlinearly jointed complex rock mass

The authors studied wave transmission across an unfilled linearly jointed complex rock mass (the wave impedances on the two sides of the joint are different). (Fan et al., 2018) 1 This paper further presents an investigation of stress wave transmission across a natural filled jointed complex rock mass, which behaves nonlinearly. In this study, the conventional characteristic method is modified. The expression of the particle velocity of a stress wave propagating through a complex rock mass across a nonlinearly deforming joint is established. The particle velocity transmission coefficient and energy transmission coefficient are obtained. The nonlinear effects of the frequency and amplitude of the incident wave, initial stiffness of the joint and wave impedance ratio of the complex rock mass on the particle velocity transmission and energy transmission are discussed. The results show that the particle velocity transmission coefficient and energy transmission coefficient are closely related to the incident wave, initial joint stiffness and wave impedance ratio. The particle velocity transmission coefficient increases with increasing nonlinear coefficient of the joint. It is noted that for the “soft-to-hard” rock mass, the particle velocity transmission coefficient is always smaller than 1.0, while for the “hard-to-soft” rock mass, it can exceed 1.0. However, the energy transmission coefficient is always smaller than 1.0 for both the “soft-to-hard” rock mass and the “hard-to-soft” rock mass.