Implementation of porous media formulation for geomaterials

The mechanical behavior of saturated geomaterials is largely governed by th e interaction of the solid skeleton with the fluids present in the pore str ucture. Traditional geotechnical analyses, commonly based on simplified eff ective stress theories, fail to fully describe the behavior of saturated po rous materials. Hence, it has become necessary to use more robust and compl ete formulations. In this context, the use of multiphase theories appears t o be an alternative and more appropriate approach. In this work, the govern ing equations of a porous media interacting with immiscible porous fluids a re presented in the light of the theory of mixtures. A generalized Galekin procedure is devised to establish the coupled mixed finite-element equation set with u-p-U form, An unconditionally stable implicit solution procedure is used for the time domain numerical solution. Finally, a recently develo ped constitutive model based on the fuzzy set plasticity concept is describ ed and implemented in the finite-element tool. A companion paper focuses on applications of this theory, and case studies are used to evaluate the pro posed formulation.