Healing and Shear Stress Reduction of Rock Salt Single Fracture Under Slide-Hold-Slide Direct Shear Experiments

The evolution of the long-term mechanical, hydraulic, and transport characteristics of rock fractures must be predicted in advance by considering the issue of the underground deposits of the energy by products of high-level radioactive waste. This paper presents slide-hold-slide direct shear experiments conducted for rock salt (halite) specimens with single fractures so as to investigate the effects of load holding on the mechanical properties of rock joints. From the experimental results, it is confirmed that the shear stress reduction can be observed during load holding. It is also confirmed that the shear strength recovery can be observed after load holding and it is found to increase with the increment of load holding period. This is because the dominant factor in the shear strength recovery during holding may be attributed to a purely mechanical process, like creep deformation at the contacting asperities.