Partially saturated soils are ubiquitous in natural environments but still pose significant challenges for constitutive modeling. In this paper, a simple hypoplastic constitutive model incorporating a structural factor to describe the wetting-induced collapse behavior of unsaturated soils is proposed. The model features a straightforward formulation with robust prediction capacity using 10 material parameters, most of which can be calibrated through conventional laboratory tests. Comparison between numerical simulations of element tests and experimental results demonstrates that the proposed model is able to replicate the salient features of unsaturated soils, including shear dilatation, strain softening, and wetting collapse.
