A Macro-Microscopic Coupled Mixed Finite Element Model for Landslide Prediction in Saturated Porous Media with Compressible Constituents

The purpose of this study is to develop a numerical model for landslide prediction in saturated poro-elasto-plastic media, which explicitly incorporates the compressibility of both solid and fluid constituents, alongside the porosity-dependent evolution of compressibility and permeability. While previous models have yielded valuable insights into the behavior of saturated porous media—typically relying on simplified assumptions that link effective stress to material properties—this work introduces a more comprehensive framework that integrates macroscopic deformation and microscopic volumetric responses in a unified manner.​ Specifically, the proposed model achieves full coupling of three primary field variables: the displacement of the solid skeleton, the intrinsic volumetric strain of the solid constituent, and the pore fluid pressure. This macro–microscopic coupling ensures a representation of porosity evolution and its feedback effects on the hydraulic and mechanical behavior of the medium.​ In this work, the numerical implementation of the macro–microscopic coupled mixed finite element formulation is first presented. Then, the model is extended to incorporate porosity-dependent compressibility and permeability. Finally, based on the proposed framework, the influence of solid and fluid constituent compressibility on slope deformation and collapse is systematically investigated and discussed.