Effect of intermediate principal stress on the deformation response of sand

An experimental investigation of the relevance of the intermediate principal stress (σ 2 ) on the deformation response of a sand is presented. The effects of σ 2 are conveniently studied through the nondimensional stress parameter b = (σ 2 – σ 3 )/(σ 1 – σ 3 ). A series of stress path tests was performed on Ottawa sand specimens in a hollow cylinder torsional shear device. The experimental program includes shear loading at different values of b, and special b tests, in which b was continuously varied at different stress directions. It is shown that the b value may have a significant influence on the stress–strain response of sand, depending on the loading conditions.