Abstract : A coupled model for three-phase unsaturated porous media, with allowance for both the stress-strain relationships of the soil and the flow of water and air, is presented. It is aimed at improving the settlement predictions and stability analyses of geotechnical structures. A system of non linear equations, both for the stress-strain relationships and for the flow of fluids, is first derived, on the basis of the static equilibrium equations, of the continuity equations and of the constitutive relationships of each of the three phases. This system of equations is then solved using the finite element method and an implicit integration scheme for time dependency. This work resulted in the implementation in the finite element program CESAR-LCPC of a new family of elements, devoted to the two-dimensional consolidation analysis of unsaturated soils, and of an iterative algorithm, combining the method of variable stiffness for the flow nonlinearities and the initial stress method for the material nonlinearities. A new subroutine of CESAR-LCPC, termed CSNS (for Consolidation of Unsaturated Soils, in French), was created for performing this type of analysis. The subroutine CSNS takes into account the staged construction of the geotechnical structures and can accommodate any type of boundary conditions. It was checked against the observed behaviour of a test section of an existing motorway. The comparison of the observed and calculated displacements and water pressures in the embankment gave encouraging insight into the capabilities of the method.