Abstract
In the following paper, we have taken constant strain rate drained triaxial tests and drained creep tests for porous tuff; Tomuro rock-one of Oya rock. Applying Vaid's concept on equation of state in stress-strain-strain rate to drained condition, and, moreover, by using Akai's concept on the essential relationship in stress-strain-time for saturated clay, essentially we try to explain time dependent behavior of soft rock that shows strain-softening.
