ABSTRACT
ABSTRACT: A triaxial compressive testing machine, called the Absolute Triaxial Testing (ATT) machine, has been developed. The machine is equipped with coordinated loading in the three principal directions and can be controlled by three independent hydraulic systems. Thus, all the principal stresses can be controlled independently and simultaneously. Since the hydraulic systems are designed to maintain constant pressure for a long period of time, creep loading tests under constant pressure are also possible. Using this testing machine, rock salt can be tested under various compressive stress conditions. In static experiments, the mechanical characteristics of rock salt under various stress conditions were investigated. On the basis of the experimental results, a failure criterion for rock salt is proposed, where the minimum principal stress is a key parameter along with the octahedral shear stress and the mean stress. The effect of the intermediate principal stress is also discussed.
