A constitutive model for structured soils under saturated and unsaturated conditions

Abstract

AbstractMany constitutive models for unsaturated soils have been reported in the literature, but only a few of them attempted to incorporate the influence of soil structure, which is a combination of fabric and bonding. Some important aspects of unsaturated soil behaviour, such as the effects of soil structure on the loading collapse (LC) curve, cannot be well captured by the existing models. This study developed a new elastoplastic model for isotropic structured soils under saturated and unsaturated conditions. In particular, several new equations were proposed to model (i) the influence of soil structure on the LC curve; (ii) the evolution of the LC curve during structure degradation. Therefore, the initial soil structure and its evolution under hydro‐mechanical loads can be properly simulated. To validate this new model, it was applied to simulate the behaviour of structured and unsaturated soils along different suction and stress paths, including constant‐stress wetting, constant‐suction isotropic compression, one‐dimensional (1D) compression and triaxial shearing. The measured and computed results are well matched, demonstrating the good capability of the proposed model.