Consolidation-Induced Contaminant Transport in Multi-Layer Soils

This paper presents a numerical investigation of the effects of large strain consolidation on contaminant transport in multi-layer soils. Numerical simulations were conducted using the CST3 model, which accounts for one-dimensional coupled large strain consolidation and contaminant transport in saturated multi-layer porous media. The consolidation algorithm accounts for vertical strain, soil self-weight, general constitutive relationships, relative velocity of fluid and solid phases, changing compressibility and hydraulic conductivity during consolidation, unload/reload, time-dependent loading, time-dependent boundary conditions, external hydraulic gradient, variable preconsolidation stress profiles, and multiple soil layers with different material properties. The contaminant transport algorithm accounts for advection, diffusion, mechanical dispersion, linear and nonlinear sorption, equilibrium and nonequilibrium sorption, porosity-dependent effective diffusion coefficient, and first-order decay reactions. Simulation results indicate that layered soil heterogeneity can have significant effects on both consolidation behavior and contaminant transport behavior. Characterization of a multi-layer soil stratum as a homogeneous single layer with average properties may result in significant errors in the analysis of consolidation-induced contaminant transport in multi-layer soils.