Behavior of a Sensitive Clay in Isotropically Consolidated K̇o-Drained Triaxial Tests

Abstract

Abstract This paper presented experimental results obtained in isotropically consolidated K̇o-drained triaxial tests on a lightly overconsolidated sensitive clay from Louiseville (Quebec). For the tests that start near the origin, the results showed that the response of the structured clay can be divided into three distinct phases of deformation. At low mean effective stress levels, the value of K̇o ranged between 0.2 and 0.3, and the shear stress varied linearly with strain. A critical shear stress was reached at the end of the first phase of deformation. At intermediate stress levels, the clay behaved like a plastic material, with K̇o = 0 and the shear stress remained approximately constant during deformation. At high stress levels, the clay becomes normally consolidated with K̇o = 1 − sin ϕ′, where ϕ′ is the friction angle of the destructured clay. However, the clay does not become normally consolidated for vertical effective stresses just in excess of the vertical preconsolidation pressure σ′vp. Rather, the effective vertical stress must exceed 1.36 σ′vp for the clay to reach a normally consolidated state. Comparisons were made with test results obtained on other sensitive clays of Eastern Canada, which showed a response similar to that of Louiseville clay.