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.