Numerical Modelling of consolidation-induced solute transport in unsaturated soil with dynamic hydraulic conductivity and degree of saturation

Abstract

The effects of the pore pressure related dynamic hydraulic conductivity and dynamic degree of saturation on the consolidation-induced solute transport in deformable unsaturated soils are investigated. The storage equation and solute transport equations are revised to account for the dependence of these two soil parameters on pore pressures. Three dynamic models were conducted for dynamic hydraulic conductivity, dynamic degree of saturation, and both. Compared with the conventional model, the simulation results showed that both hydraulic conductivity and degree of saturation increased near the soil surface where pore pressure exceeded air-entry value. Dynamic hydraulic conductivity results in a slightly slower solute transport while dynamic degree of saturation accelerates the migration of contaminants. Including both dynamic effects produced limited differences in solute concentration, while consolidation results were affected significantly. Although dynamic degree of saturation has some influences on consolidation-induced solute transport, the correlation of the dynamic path is less significant. The air-entry value is an important parameter to determine when soil parameters become dynamic, and it affects the soil consolidation process in certain extent. This study provides new methods to incorporate in-homogeneous soil parameters, which are not only spatiotemporal variables, but also dynamic variations with pore pressure.