Semi-analytical solutions for soil consolidation induced by drying

Drying induced consolidation is ubiquitous in nature, yet no theoretical model is available to delineate this phenomenon. Fundamentally, this phenomenon is a multi-physical process involving that the soil-water interaction energy lowers (becomes more negative), thereby soil's suction stress, elastic modulus, and hydraulic conductivity change. Therefore, the drying induced consolidation is a phenomenon reflecting soil's mechanical, hydraulic, and hydro-mechanical properties altered by soil-water interaction. Here, a theoretical framework is developed for drying induced consolidation. Richards equation is selected to describe moisture flow subject to drying. The impact of soil-water interaction on soil mechanical properties is quantified via an elastic modulus characteristic curve equation and a unified effective stress equation, respectively. Gardner's model is selected for representing soil water retention and hydraulic properties, facilitating the semi-analytical solutions for drying induced consolidation. The accuracy of solutions is verified by comparing with numerical solutions of moisture flow and soil shrinkage curve data. It reveals that the adsorption induced effective stress can reach up to hundreds of kPa and contributes 96.7% of the total consolidation settlement for clayey soils. In addition, the elastic modulus variation is commonly overlooked in existing consolidation models, but this overlook can lead to either underestimation up to 0.66 times or overestimation up to 6.86 times of consolidation settlement.