Elastic coefficients for liquid- and gas-saturated porous media (Q1315706)

The paper is an investigation of the isothermal elastic behavior of porous media saturated by both gas and liquid phases. It is a continuation of a previous work of the same author [Int. J. Eng. Sci. 30, No. 5, 571-577 (1992; Zbl 0759.73008)]. In the present formulation thermal and reactive effects are neglected, which enables a clearer presentation of the results. Only hydraulic transport, deformation of the solid skeleton, compressibility of the constituents and capillary phenomenon are taken into account in the study. The solid, liquid and gas are considered as individual continuous phases and the equations are established theoretically within the framework of the theory of mixtures. It is demonstrated that there exist two independent stress state variables, whereas for the single fluid-saturated porous media only one is needed. The linear poroelastic media model is detailled. It is shown that the mechanical response of the media depends on the conventionally defined elastic properties like Biot's constants and two other parameters that describe the capillary effect and the deformation of the media. A special case of this linear model: the compressible gas model, in which both liquid and solid are considered as incompressible, is studied in the last section in order to emphasize the effect of the capillary pressure on the elastic coefficients of the three-phase media.