Effects of particle sphericity and initial fabric on the shearing behavior of soil–rough structural interface

In this study, the effects of particle sphericity and initial fabric on the shearing behavior of soil-structural interface were analyzed by discrete element method (DEM). Three types of clustered particles were designed to represent irregular particles featuring various sphericities. The extreme porosities of granular materials composed of various clustered particles were affected by particle sphericity. Moreover, five specimens consisting of differently oriented particles were prepared to study the effect of initial fabric. A series of interface shear tests featuring varying interface roughnesses were carried out using three-dimensional (3D) DEM simulations. The macro-response showed that the shear strength of the interface increased as particle sphericity decreased, while stress softening and dilatancy were easily observed during the shearing. From the particle-scale analysis, it was found that the thickness of the localized band was affected by the interface roughness, the normal stress and the initial fabric while independent of the particle sphericity. The thickness generally ranged between 4 and 6 times that of the median particle equivalent diameter. A thicker localized band was formed in the case of rougher interface and in soil composed of inclined placed and randomly placed particles. The coordination number measured in the interface zone and upper zone suggested that the dilation mostly occurs inside the interface zone. Anisotropy was induced by the interface shearing of the initial isotropic specimens. The direction of shear-induced anisotropy correlates with the shearing direction. The evolutions of anisotropies for the anisotropic specimens depend on the initial fabric.