Influence of the mechanical properties of consolidated clays on their water retention curve

Based on both new experimental data and data collected from the literature, the paper presents a framework representing the drying-wetting behaviour of either natural or reconstituted clays whose current state has resulted from a stress-strain history in saturated conditions. The data concern the suction, the degree of saturation and the porosity variations of clays subjected to drying-wetting paths. The general drying-wetting behavioural features of clayey soils are pointed out, in relation to their history and current mechanical properties. In particular, the influence on the water retention curve of the clay structure and loading history is discussed. A peculiar stage of drying is distinguished for the clays, that corresponds to a marked volume decrease at almost constant suction, defined as "drying collapse", which is found to correspond to the onset of major desaturation. In the behavioural framework considered, this major desaturation is distinguished as "gross air entry", since it represents the pace from quasi-saturated to unsaturated soil states. The hysteretic hydraulic behaviour of natural clays is also investigated. Based on the presented framework, the paper is concluded with the modelling of the water retention curve of clays consolidated under saturated conditions before drying