No abstract

The destructive effect of expansive soils on infrastructure is one of the classical issues associated with unsaturated soils. Given the continuing challenges associated with swelling soils there is still a need for a practical analysis method. The swelling equilibrium limit (SEL) provides a concept for modeling expansive soil behaviour. The SEL is an upper bound swelling limit, which depends on the soil’s initial state and the boundary conditions upon wetting. The SEL is obtained experimentally from swelling tests performed by applying a range of swelling scenarios from rigid boundary condition to free swelling without confinement. In this paper, improvements to the triaxial swelling apparatus are reported, SELs for two new swelling soils are characterized, and a framework for SEL prediction is developed. The SEL framework is developed to relate SEL parameters to index properties as well as the soil’s initial volume. SEL parameters are correlated to liquid limit, plasticity index, free swell potential, and specific volume. The relationships are used to estimate the SEL for Regina clay, which is shown to agree with experimental data.

No abstract

A new laboratory test apparatus and methodology have been developed for characterizing the swelling potential of expansive soil under free stress conditions. Soil specimens are given access to water under true free swell conditions, and the maximum swelling potential is determined experimentally. Real-time deformation measurements and interpretation are obtained through digital image correlation using GeoPIV. The capabilities of the new test are illustrated using a remolded natural swelling soil. Both primary and secondary swelling behavior were observed during testing. The effect of the aspect ratio was assessed, and it was found that smaller specimens achieved equivalent swelling strains with significantly shorter test durations. The non-contact deformation results agree with the end-of-test hand measurements. The non-contact method also provides additional valuable information regarding the time-dependent swell behavior and evaluation of the end-of-test criterion. The results are interpreted using the Swell Equilibrium Limit, which is a unifying framework for the analysis and prediction of swelling soil deformations under defined initial and boundary conditions.