Laboratory-scale investigation of response characteristics of liquid-filled rock joints with different joint inclinations under dynamic loading

In underground rock engineering, water-bearing faults may be subjected to dynamic loading, resulting in the coupling of hydraulic and dynamic hazards. Understanding the interaction mechanism between the stress waves induced by dynamic loadings and liquid-filled rock joints is therefore crucial. In this study, an auxiliary device for simulating the liquid-filled layer was developed to analyze the dynamic response characteristics of liquid-filled rock joints in laboratory. Granite and polymethyl methacrylate (PMMA) specimens were chosen for testing, and high-amplitude shock waves induced by a split Hopkinson pressure bar (SHPB) were used to produce dynamic loadings. Impact loading tests were conducted on liquid-filled rock joints with different joint inclinations. The energy propagation coefficient and peak liquid pressure were proposed to investigate the energy propagation and attenuation of waves propagating across the joints, as well as the dynamic response characteristics of the liquid in the liquid-filled rock joints. For the inclination angle range considered herein, the experimental results showed that the energy propagation coefficient gently diminished with increasing joint inclination, and smaller coefficient values were obtained for granite specimens compared with PMMA specimens. The peak liquid pressure exhibited a gradually decreasing trend with increasing joint inclination, and the peak pressure for granite specimens was slightly higher than that for PMMA specimens. Overall, this paper may provide a considerably better method for studying liquid-filled rock joints at the laboratory scale, and serves as a guide for interpreting the underlying mechanisms for interactions between stress waves and liquid-filled rock joints.