Irreversible effects of drying-wetting cycles on shrinkage and water retention of compacted London clay

Abstract

Long-linear assets, such as roads and railways, supported by earthworks are susceptible to deterioration caused by weather cycles, that translate into changes in soil hydro-mechanical properties. Failures in these earthworks are expected to become more common due to climate change as periods of drought and extreme rainfall events become more frequent. In the present study, the effect of the suction range of the moisture cycle on the soil-water retention curve (SWRC) and soil shrink-swell curve (SSC) of active London clay is investigated. Soil samples compacted at Proctor optimum conditions were subjected to drying-wetting cycles within a variable suction interval. A change in the SSC was observed when the water content reduced below a threshold that approximates to the shrinkage limit. A reduction in the ability of the soil to hold suction was observed with SWRCs becoming less steep, as the Primary Drying Line was steeper than subsequent drying phases (Scanning Drying Lines). Once the Scanning Drying Line intersects the Primary Drying Line, a yielding point is identified, and the soil loses further ability to hold suction. Irreversible deformations were observed associated with changes in the SWRC from drying-wetting cycles.