Modeling swelling–shrinkage behavior of compacted expansive soils during wetting–drying cycles

Abstract

This paper presents a straightforward approach for modelling volume change behavior of expansive soils during wetting–drying cycles. The swelling–shrinkage strain of expansive soils induced by cyclic wetting and drying was decomposed with distinctive physical background into a reversible component, which shows a synchronous change with the cyclic change of suction, and an irreversible component, which is generated mainly in the early stage of the wetting–drying process. The mechanisms of the two swelling–shrinkage strain components can be well explained through the double-level structure of expansive soils and its evolution with mechanical and hydraulic loading. The reversible component originates from the reversible deformation behavior of aggregates, and primarily depends on current suction or water content. The irreversible component is associated with the irreversible change of macrostructure, reflecting the difference in soil structures at current state and the equilibrium state. A practical constitutive model was proposed for compacted expansive clays from a global and phenomenological perspective. The model parameters can be calibrated with observed macroscopic deformation behavior without measuring microstructural parameters. The performance of the presented model was validated by simulating cyclic suction-controlled tests as well as an alternately soaked and dried test with irregular amplitudes of suctions.