Stress wave transmission across a filled joint with different loading/unloading behavior

This paper presents a theoretical study of stress wave propagation across a rock joint with different loading/unloading behavior. Two Bandis–Barton (B–B) models are introduced to describe the stress–closure relationships of a rock joint under loading and unloading situations, respectively. A characteristics method is proposed to investigate the stress wave transmission. Amplitude-dependence and frequency-dependence of unloading effect on the energy transmission are analyzed. The unloading effect on stress waves with different waveforms and stress waves with multiple pluses are evaluated. The results show that the characteristics method can be used to investigate the wave propagation across a rock joint with different loading/unloading behavior. The effect of unloading behavior on energy transmission is amplitude- and frequency-dependent. The stress wave with a rectangular waveform is less influenced by the unloading behavior than the stress waves with other waveforms. Unloading behavior has a significant effect on the energy transmission for the stress wave with both single pulse and multiple pulses. However, unloading behavior has an effect on the wave attenuation provided that the time interval of multiple pulses stress wave is sufficiently small.

► Wave propagation across a joint with different loading/unloading paths is studied.
► The amplitude- and frequency-dependence of unloading behavior is analyzed.
► The rectangular wave is found to be less influenced by the unloading behavior.
► Unloading influences the energy transmission of both single and multiple pulses.
► Unloading influences wave attenuation when time interval between pulses is small.