Large Strain Consolidation of Unsaturated Soil: Model Formulation and Numerical Analysis

A nonlinear large strain consolidation model for unsaturated soils is presented in this paper. The model uses the Lagrangian-convective coordinate to track the flow of air and water through a deformed layer and the state surface approach to approximate the hydromechanical behavior of unsaturated soils. The model comprises a set of governing equations to integrate the water flow, airflow, and layer consolidation where large strain deformation of the layer occurs. The governing equations were discretized and solved using the finite-difference method, with the solutions verified against the analytical answers. The model was implemented to surcharge preloading studies with a focus on the effects of the initial wet degree of layers on consolidation. The results suggest that the initial wet degree affects the consolidation curves. Higher consolidation settlement occurs in the wet soil layers than in the less-wet layers. In the same layer, the pore air pressure dissipation is completed earlier than the pore-water pressure.