Stress strain behavior of a saturated loessian lightly cemented soil under triaxial compression test

Abstract

The upper most modern loess deposits of the central area of Argentina are characterized by an open structure made of fine sand and volcanic silt particles weakly bonded and usually in unsaturated conditions. Heterogeneity in loess is usually present and arises mainly from the non-homogeneous cementation of the soil mass. As saturation increases, the structure of loess collapses even under geostatic pressures. In this work, some results of triaxial compression test performed in loess are presented. Specimens were tested in saturated condition. Testing results allows analyzing the stress-strain behavior of loess in a wide range of strain levels, taking into consideration the influence of structure and confining pressure. Below the yielding stress (collapse), the soil behaves almost as linear elastic and stiffness is governed by degree of cementation. At higher stresses, the collapse potential of the soil skeleton is governed by a complex interplay between applied external pressure and internal forces due to cementation, and probably others attraction-repulsion forces developed at particles of colloidal size. Cementation causes an increase in stiffness, yielding stress and shear strength.