ABSTRACT
A continuum model is adopted for describing a porous skeleton whose pore space is assumed to be partly saturated by a wetting fluid (w) and a gaseous mixture of vapor and dry air (a). The wetting fluid is required to be incompressible and the effect of the partial saturation is described by introducing the degree of saturation Sr. The poromechanical constitutive model, capable for describing the behavior of partially saturated soils will be deduced extending classical thermodynamical arguments. Following Houlsby (1997) and Coussy (2010), the dissipation and consequently the Clausius-Duhem inequality is:
− − −
+
11 ρ φ, ρ φ,⎜
σ
p b
M p−a b
M
d dt
p d dt
d dt
ε φ φa+ + − ≥ ,Ψ 0 (1)
1 INTRODUCTION
The behavior of two partially saturated geomaterials is compared and analyzed in terms of the stress paths induced by rainfall infiltration. We distinguish between a coarse and a fine-grained material, specifying on one hand different physical and mechanical properties, on the other different hydraulic characteristics. Within this context partial saturation is expected to strongly affect the constitutive law of the overall porous medium, in terms of its elasto-plastic behavior, retention properties and the permeability of the skeleton.
