Multistage creep tests with two types of sedimentary rock and estimation of long-term creep behavior

It is important for long-term stability of underground cavern to estimate the time dependent behavior of surrounding rock mass. In this study, multistage creep tests were conducted with two types of sedimentary rock. Creep behavior under low stress level was compared to high stress level with the aid of experimental data. It was probable that creep behavior under both low and high stress level was well explained with the parameter n obtained from the loading-rate dependency of strength. Then, strength and creep life time under various creep stress level were estimated from the results of multistage creep tests. Estimated strength well coincided with the results of uniaxial compression tests. (author)