DEM investigation into the coupling effects of particle asphericity and interface roughness on shear behaviour of soil-structure interface

Soil-structure interfaces (SSI) are common in geotechnical structures, and understanding their shear behavior is essential for effective design. However, the coupling effects of particle shape and interface roughness on SSI remain understudied. This study addresses this gap by employing five types of super-ellipsoid particles with varying asphericity (η) values to model non-spherical particles. Interface shear tests with different roughness levels (R_n) were conducted using Discrete Element Method (DEM) simulations. The results show that both η and R_n significantly influence shear strength, localized shear band thickness, and soil fabric, with two types of coupling effects: single-factor dominance and double-factor interaction. The influence on coordination number (C_n) and probability distribution of normalized contact force is more straightforward. Specifically, non-spherical particles exhibit a higher initial C_n due to enhanced interlocking, while R_n has a lesser impact. The normalized contact force at the interface follows an exponential distribution, similar to pure soil, and is largely independent of η and R_n. Notably, the shear zone is divided into three equal parts for soil fabric analysis. These findings offer new insights into SSI, contributing to more effective and safer geotechnical designs.