Viscoelastic Stress Wave Propagation in Rock Masses with Inclined Joints

Roadways, slopes, foundations, chambers, and other engineered rock structures are all subject to dynamic disturbances that can threaten their stability. Clarifying the propagation characteristics of stress waves across discontinuities in jointed rock masses is a necessary step in ensuring engineering stability. Stress waves show clear amplitude attenuation and waveform dispersion when propagating through discontinuous rock media, reflecting their viscoelasticity. In this study, a sandstone rod is used as a stress-wave medium for impact experiments and numerical simulations conducted to investigate the propagation of viscoelastic stress waves through joints with different dip angles under finite-boundary conditions. The sandstone rod generates viscoelastic stress waves with an approximately sharp triangular envelope, which markedly differs from the elastic waves observed in steel rods. As the joint dip angle increases from 30° to 90°, the reflection coefficient exhibits an increase–decrease–increase trend under the combined influence of the intermediate joint and the upper and lower boundaries, whereas the transmission coefficient shows a decrease–increase trend. Inclined joints alter the propagation path of viscoelastic stress waves in the finite-boundary medium, thereby affecting the transmission and reflection coefficient trends. Frequency-domain analysis of the transmitted waves indicates that the coupled effects of viscoelasticity and jointing reduce the dominant frequency of stress waves; this reduction grows more pronounced as the joint dip angle decreases, leading to stronger attenuation of high-frequency components. These results may provide a sound theoretical basis for the anti-dynamic-disturbance design of natural jointed rock masses.