Recent studies on time-dependent behavior of rock and the effects of confining pressure

Hashiba, Kimihiro

To estimate the long-term stability of deep underground structures, it is important to investigate the time-dependent behavior of rock. Loading rate dependency, creep and so on has been well examined under uniaxial stress state. However, a little knowledge has been stored up under confining pressure. In this study, recent experimental and theoretical studies on the time-dependency of rock were reviewed especially focusing on the effects of the confining pressure. Firstly, the time-dependent behavior under confining pressure was compared with that under uniaxial stress state. The loading rate dependency, creep and the relation between them were examined with the aid of the recent theoretical studies. The close relations among the time-dependency, probability distribution of rock properties and scale effect were explained theoretically. Then, the equipment and the practical testing methods to investigate the time-dependent behavior under confining pressure were reviewed.