Development and Experimental Application of a Novel Instrumentation for Investigating Shear-Seepage Coupling Behavior in Rock Joints Under Dynamic and Static Loading

To investigate the shear behavior and failure mechanisms of rock joints under coupled seepage and complex random vibrations， a rock joint shear-seepage testing system capable of simulating seismic excitation was developed. The apparatus comprises four primary subsystems: a main loading frame， a servo control system， a servo hydraulic power unit， and a seepage monitoring and control system. It can apply dynamic loading with frequencies up to 50 Hz and supports user-defined waveforms in three channels that can be operated in either synchronous or asynchronous modes; multiple controllable boundary conditions， including stress， stiffness， and displacement， can be imposed. The apparatus enables coupled dynamic shear-seepage tests on rock joints， with fluid pressures up to 1.2 MPa， and features interchangeable shear boxes of various sizes to satisfy research needs related to the size effect of joint dynamic shear behavior. This study details the testing system and rigorously verifies its advanced functions， including seismic-wave loading and dynamic loading-seepage coupling. The test results indicate that the system can effectively account for dynamic loading parameters such as waveform， frequency， amplitude， and loading combinations， thereby enabling investigations into the evolution of morphology and physico-mechanical properties of rock joints with different sizes under the coupled actions of seismic loading， seepage， and anchorage. Its stable testing process and reliable data acquisition will provide robust experimental data support for related engineering applications.