QUADRIPHASIC MECHANICS OF SWELLING INCOMPRESSIBLE POROUS-MEDIA

A chemo-electro-mechanical formulation of quasi-static finite deformat ion of swelling incompressible porous media is derived from mixture th eory. The model consists of an electrically charged porous solid satur ated with a monovalent ionic solution. Incompressible and isothermal d eformation is assumed. Hydration forces are neglected. The mixture as a whole is assumed locally electroneutral. Four phases following diffe rent kinematic paths are defined: solid, fluid, anions and cations. Ba lance laws are derived for each phase and for the mixture asa whole. A Lagrangian form of the second law of thermodynamics is derived for in compressible porous media and is used to derive the constitutive relat ionships of the medium. It is shown that the theory is consistent with Blot's theory for the limiting case without ionic effects and with St averman's results for the limiting case without deformation. (C) 1997 Elsevier Science Ltd.