Unified hardening (UH) model for unsaturated expansive clays

In this paper, by introducing a new yielding mechanism based on the widely acknowledged double-structure theory, the original UH model for unsaturated soils is extended to capture the behaviour of expansive clays. A novel expansion potential is further established to evaluate the effect of overconsolidation on the volume change of unsaturated expansive clays during wetting. With only one additional parameter, the proposed model can describe the behaviour of both wetting-collapse and wetting-induced swelling for unsaturated clays. Comparisons between model predictions and test results show a good agreement which verifies the capability of the proposed model in charactering the features of unsaturated expansive clays under various stress histories and stress paths.

Automated summary

In this paper, a new yielding mechanism is introduced based on double-structure theory to extend the original UH model for unsaturated soils and capture the behavior of expansive clays. A novel expansion potential is established to evaluate the effect of overconsolidation on volume change during wetting. With only one additional parameter, the proposed model can accurately describe the wetting-collapse and wetting-induced swelling behavior of unsaturated clays. Comparison with test results confirms the capability of the model to characterize unsaturated expansive clays under different stress conditions.