Introduction and analysis of a strain-softening damage model for soil–structure interfaces considering shear thickness

A damage strain softening model for predicting the shear behavior of soil–structure interfaces is presented. The damage model, which contains only four parameters (i.e., undamaged shear modulus G′, damage evolution parameters n and m, and the residual shear stress τr), is developed based on Weibull distribution statistical damage theory. By fitting curves, the model parameters are obtained from director simple shear tests. As the shear thickness is usually considered an important factor on soil–structure interface constitutive relations, the shear thickness ratio (η) is introduced to the model to compensate for the influence of the shear thickness. The relationships between the model parameters and the shear thickness ratio η are also analyzed under different levels of normal stress based on data from both direct and simple shear tests. The results show that the undamaged shear modulus G′ increases with increasing normal stress and increasing shear thickness. The shear thickness has a significant effect on the damage evolution parameter n, but the normal stress does not. Neither normal stress nor shear thickness have significant effects on the damage evolution parameter m. The residual shear stress τr increases with increasing normal stress.