Abstract: In deep rock engineering, rocks are often in high water-pressure and high-stress environments. Under dynamic load disturbances such as blasting excavation, water pressure and in-situ stress influence the extent of rock damage, thereby affecting the propagation characteristics of stress waves. Using a self-developed testing system for stress wave propagation in rock under high water pressure and high axial static stress, the propagation characteristics of stress waves in red sandstone under hydro-mechanical coupling were investigated. Six water pressure levels and five axial static stress levels were designed to simulate the in-situ environment of engineering rock masses. Stress wave propagation tests were carried out on saturated red sandstone specimens to obtain stress wave waveforms under different working conditions. From the time-domain perspective of stress waves, the evolution laws of the transmission coefficient and propagation velocity with axial static stress and water pressure were analyzed, and corresponding empirical models were established. The results show that: at a given water pressure, both the propagation velocity and transmission coefficient of stress waves exhibit a Gaussian relationship with axial static stress; at a given axial static stress, both the transmission coefficient and propagation velocity first increase and then decrease with increasing water pressure, also following a Gaussian relationship. The transmission coefficient and propagation velocity show similar sensitivity to changes in axial static stress, whereas the transmission coefficient is more sensitive to water pressure than the propagation velocity.

Key words: rock dynamic mechanics, high water pressure, high geostress, stress wave propagation velocity, stress wave transmission coefficient