Distributions of strength and creep failure time of Inada granite under confining pressure

In this paper we present the experimental results of standard triaxial compression tests and multi-step creep tests performed on Inada granite, at confining pressure varying from 0 to 40 MPa. The results were analyzed introducing the concepts of standardized strength and normalized failure time. By using the Janach's failure criterion we related the standardized strength with the confining pressure. Similarly. we defined a formulation to pass from the normalized failure time to creep failure time. Adopting such concepts we could predict the dispersion of both the time of creep failure and the rock strength at any confining pressure, regardless to loading rate or the stress path followed during the experimental characterization.