Effect of temperatures on the time-dependent behavior of granite

Abstract

Heat generated from the waste in the repository will result in an increase in rock temperature and substantially change the stress state of the host rock surrounding a nuclear waste repository. In this study, a series of uniaxial constant loading tests with acoustic emission monitoring has been conducted on wet granite in MTS 815 under different stress levels at room temperature, 50°C and 90°C. The results indicate that temperature under 50°C has no significant effect on the time dependent behavior. When the temperature is raised to 90°C, the crack damage stress, which is related to the long-term strength of granite, decreases to 90% of that at room temperature. The time to failure response decreases accordingly. Effect of temperature on the strain rate and acoustic emission rate under constant loading will also be discussed in the paper. Therefore, rock engineers need to consider the long-term in-situ strength of a rock at different temperatures in the design and construction of excavations in the rock for nuclear waste repositories.