Saturated compressible and incompressible porous solids: Macro- and micromechanical approaches

In this paper two complementary approaches are used to describe the mechani cal behavior of saturated compressible and incompressible porous solids. Th e macroscopic investigation is based on the mixture theory, restricted by t he volume fraction concept. In the micromechanical approach, a hierarchy of conditionally ensemble averaged fluid and solid phase momentum balance equ ations are derived for a simple model of quasi-static liquid saturated poro us media. The ensemble averaged equations for both the phases agree remarka bly well with the macroscopic results. A micromechanical basis for Terzhagi 's effective stress concept is presented. In addition, an expression for ad ditional partial solid stress modifying the effective stress principle, to account for deformability of solid materials, is also derived.