Three-dimensional elasto-plastic damage model for gravelly soil-structure interface considering the shear coupling effect

The gravelly soil-structure interface was observed to exhibit a significant coupling effect among the orthogonal shear directions due to the three-dimensional shear application in different experimental investigations, which governs major three-dimensional features of the interface. In this paper, initially, a three-dimensional modeling framework is established based on the analyses of interface behavior under different shear coupling conditions. A series of concepts and assumptions are derived in this framework, banking on which a three-dimensional model scheme is proposed by reasonably modeling the shear coupling effect. Afterward, a three-dimensional elasto-plastic damage interface model is developed based on the proposed model scheme and modified formulations of a previous two-dimensional EPDI model. Only a single new parameter is introduced in the three-dimensional shear stress-strain relationship modeling scheme to quantify the three-dimensional shear response of the interface besides already known parameters of the EPDI model. The model can simulate the monotonic and cyclic response of interface along two and three-dimensional shear paths in a unified manner. The performance of the model is validated based on test data from the literature. The model can capture different essential features of the gravelly soil-structure interface behavior under three-dimensional conditions, e.g., coupling effect, volumetric change behavior and aeolotropy.