This paper presents a model for the evaluation of the void ratio dependency of water retention curve (WRC) in deformable porous media. Models currently available in the literature for this purpose are primarily empirical in nature and rely on extensive laboratory testing for parameter identification. The approach proposed requires no additional parameters and enables quantification of the dependency of WRC on void ratio solely based on the form of WRC at the reference void ratio. Particular attention is given to the effect of hydraulic hysteresis on the evolution process, an aspect rarely addressed in the literature. Incremental expressions are presented for the evolution of main drying, main wetting, and scanning curves due to loading and change in the hydraulic path from scanning to main wetting/drying and vice versa. Validity of the model is demonstrated using experimental data for a range of compacted and reconstituted soils subjected to various hydro-mechanical paths. Good agreement is obtained between model predictions and experimental data in all the cases considered.

Numerical analyses have been widely used to investigate the stability of deep excavations. The results of this type of analyses rely on the constitutive model that is adopted for the analyses. Although many advanced constitutive models have been developed for the simulation of soil behavior, they are often complex, expensive to use, and not well understood by practicing engineers. Hence, simple constitutive models, such as the Mohr–Coulomb model, are widely used in geotechnical engineering practice. However, these simple models, fail to represent some key features of soil behavior. Of particular importance in granular soils is the effect of changes in soil density on the soil behavior, an aspect that is often overlooked when simple constitutive models are used. In this study, a series of triaxial tests will be conducted on reconstructed gravelly sand to investigate the effect of the relative density and confining pressure on strength and stiffness characteristics of the soil. According to the test results, variations of the soil stiffness and peak deviatoric stress with relative density and confining pressure will be established. A novel disturbance function will then be proposed based on the disturbance state concept to capture the effect of soil density on its behavior. Subsequently, a constitutive model that is based on the original Duncan and Chang model will be developed that considers the effects of the confining pressure and relative density of the soil using the proposed disturbance function. The model is implemented in ABAQUS software and is verified by comparing the numerical results with experimental data. The application of the model is presented through the simulation of a deep supported excavation. The numerical results show that the model successfully simulates horizontal displacements of the support piles, with errors of <5% for the monitoring points. In particular, it is highlighted that the model is superior to the widely used Mohr–Coulomb model in the simulation of excavation problems, and yielded a safer design than that obtained using the Mohr–Coulomb model.