A Novel Numerical Model for Coupled Large-Strain Consolidation and Solute Transport in Clayey Soils Considering Chemico-Osmotic and Creep Deformation

Abstract

Contaminated geomaterials in CDFs (confined disposal facilities) and CCLs (compacted clay layers) typically undergo a long-term process involving coupled finite strain consolidation and solute transport, posing challenges for fully coupled modeling. To fill this research gap, a novel finite strain consolidation-solute transport model incorporating chemico-osmotic and creep effects is developed. The predictive accuracy of the model is verified through comparisons with existing analytical and numerical solute transport models with consolidation effect, a finite-strain consolidation model, and a small-strain HMC (hydro-mechanical-chemo) model. The model effectively replicates oedometer tests with one-step and three-step salinization, revealing significant volume changes (15.6% and 5.74% for two tests) due to chemical loading, even larger than those (5.31% and 5.13%) due to mechanical loading. Finally, parametric studies highlight the influence of creep, compressibility, boundary conditions, initial concentration distribution, and adsorption, demonstrating that chemico-osmotic effects can generate large negative pore pressures (50% of initial pore pressure) and average consolidation degree (about 140%). Compared with consolidation-related parameters, the adsorption coefficient has a more noticeable effect on solute transport, leading to bottom concentration values ranging from 54% to 25% of the boundary concentration value as the adsorption coefficient increases from 0 to 1.5 mL/g. Overall, consolidation exhibits greater sensitivity to parameter variations than solute transport in these cases.