A fully coupled hydro-mechanical-chemo model for saturated clayey soils with pore-chemistry-induced and time-dependent deformation

Hydro-mechanical-chemo (HMC) coupling in clayey soils governs the long-term performance of critical infrastructures exposed to chemical environments. Existing models predominantly emphasize the one-way effect of consolidation on solute transport, with the influence of pore-water chemistry on soil deformation remaining insufficiently addressed. This study develops a fully coupled HMC elastic–viscoplastic (EVP) numerical model. It integrates consolidation and solute transport processes by introducing a novel chemical-influenced, time-dependent constitutive relationship. This relationship is formulated as a chemically enhanced EVP (C-EVP) framework by introducing a generalized effective stress concept instead of classical Terzaghi effective stress. The governing equations, rigorously derived from the C-EVP framework, form the core of the proposed HMC model and are solved using an implicit finite-difference scheme. The present solution is further validated against analytical solutions of a simplified HMC model for elastic soil and oedometer tests under combined mechanical and chemical loadings. The model successfully reproduces chemically induced compression, volume rebound under salinity reduction, and salinity-dependent creep under constant load. These results demonstrate that the proposed HMC formulation, which explicitly incorporates the C-EVP framework, provides a rigorous and reliable tool for predicting long-term settlement and solute evolution in clayey soils exposed to chemical environment.