Crack generation and propagation during stress relaxation of crystalline rock under water-saturated uniaxial condition

Microcrack generation and propagation play an essential role to predict the long-term behavior of crystalline rock. We developed a new relaxation testing equipment that enables us to observe a granite specimen under the state of relaxation. Series of relaxation tests have been performed under constant temperature. In this paper, we show a few patterns of microcrack propagation and the relationship between pre-existed crack and crack development under the state of relaxation.