Effect of Water on Subcritical Crack Growth Index and Long-term Strength for Rock

Abstract

Long-term stability is required for the structures in a rock mass. Especially, the estimation of long-term strength of rock is essential to consider the long-term stability. In this study, we investigated the time-dependent crack growth in rock. Specifically, subcritical crack growth in water and in air with different relative humidities was measured in order to investigate the effect of water on the value of subcritical crack growth index and the long-term strength for rock. It was shown that subcritical crack growth index in water was smaller than that in air. Additionally, subcritical crack growth index tended to be smaller when the relative humidity was higher. The long-term strength in water was smaller than that in air. In air, the long-term strength tended to be smaller when the relative humidity was higher. The long-term strength is larger when subcritical crack growth index is larger. For the long-term stability, it is thus important to achieve a condition where subcritical crack growth index becomes larger. It is concluded that retarding the migration of water into and through rock and keeping low humidity is important.