One-dimensional consolidation theory: unsaturated soils

Abstract

A one-dimensional consolidation theory is presented for unsaturated soils. The assumptions made are in keeping with those used in the conventional theory of consolidation for saturated soils, with the additional assumption that the air phase is continuous. Two partial differential equations are derived to describe the transient processes taking place as a result of the application of a total load to an unsaturated soil.After a load has been applied to the soil, air and water flow simultaneously from the soil until equilibrium conditions are achieved. The simultaneous solution of the two partial differential equations gives the pore-air and pore-water pressures at any time and any depth throughout the soil. Two families of dimensionless curves are generated to show the pore-air and pore-water dissipation curves for various soil properties.For the case of an applied total load, two equations are also derived to predict the initial pore-air and pore-water pressure boundary conditions. An example problem demonstrates the nature of the results.