Abstract: The aim of this article is to validate the predictive effectiveness of Sun's proposed coupled hydraulic-mechanical intrinsic model for unsaturated soils with respect to the density state. The loess in the eastern suburbs of Xi’an City, Shaanxi Province was selected as the research object. The isotropic compression test, triaxial compression test and triaxial tensile test were carried out on unsaturated loess samples. The model prediction results were compared with the experimental results, which confirmed the validity of the model proposed by Sun to predict the stress-strain and water-holding behavior of unsaturated loess. The experimental results show that the loading-collapsing (LC) yield curves obtained by Sun model and BBM model were compared, and it was found that the prediction results of Sun model were closer to the experimental data points. The loess samples with different initial void ratios were subjected to isotropic compression tests and humidified, and Sun model could better predict the collapsible deformation trend of loess. Comparing the prediction results of the model with the results of triaxial compression test and triaxial compression test of unsaturated loess, it was confirmed that the model could better predict the stress-strain behavior of unsaturated loess, and depict the change of saturation degree.

Key words: loess, unsaturated soil, elastic-plastic, hydraulic coupling