Experimental Study on the Shear Behavior of Rock Due to Changes in Pore Pressure in Discontinuities

ABSTRACT: The thermo-hydro-mechanical (THM) environment in underground masses significantly affects the shear behavior of discontinuities. Understanding and evaluating this behavior is crucial for assessing the stability and integrity of rock structures. This study investigates the shear behavior of discontinuities under varying hydro-mechanical conditions. A custom-designed hydro-shear test apparatus was developed to control confining stress and pore pressure on the rock discontinuity surface. Shear stress and pore pressure were gradually increased under three different normal stress conditions, while the resulting shear behavior was monitored using acoustic emission (AE) analysis. The experimental results demonstrated that under low normal stress conditions, the discontinuity exhibited stable sliding, whereas stick slip became more prominent as normal stress increased. These findings were validated through stress, displacement, and AE data recorded during the experiments. This study provides experimental insights into the impact of hydro-mechanical conditions on the shear behavior of discontinuities. Future studies will expand the range of experimental conditions to further explore the representative characteristics of hydro-mechanical shear behavior in rock masses.