For the long-term maintenance and stability assessment of underground structures, it is essential to understand the time-dependent behavior of rock, including loading-rate dependence, creep, and relaxation. This article introduces the test methods developed previously by the authors to investigate the time-dependent behavior of rock using a small number of specimens in a short period of time and presents further modified metho...

Creep tests under constant stress are among the most important tests for investigating the time-dependent behavior of rock. In previous studies, creep tests were conducted under various loading and environmental conditions; however, it was very difficult to demonstrate accelerating creep at failure at stresses less than 50% of strength in conventional creep tests. In this study, a new test method is proposed that combines an a...