Coupled Poromechanics and Adsorption in Multiple-Porosity Solids

This paper presents a general constitutive model to describe the coupling among bulk solid stress, pore fluid pressure, and adsorption in a fluid-saturated multiple-porosity elastic solid. The general case of N coexisting porosities is considered. Each porosity system may contain fluid in the free or adsorbed phase, as well as in both phases. Thus, the utility of the developed constitutive relations extends to materials with complex pore structures, which may involve several scales of pore size. These relations are obtained from the thermodynamic free energy density function for deformation of the porous solid frame while incorporating the surface energy stored at the interface between the pore fluid and solid phase. A number of previously published models for coupled adsorption and poroelasticity in microporous and mesoporous materials are examined as special cases. Possible means of estimating the constitutive model parameters are discussed.