Effect of particle shape on cyclic liquefaction resistance of granular materials

This study adopts three-dimensional discrete element method to examine how particle shape affects the cyclic liquefaction resistance of granular materials. A family of superquadric particles is employed to model different particle shapes by varying two shape parameters: aspect ratio (AR) and blockiness (B). Five smooth and convex particle shapes are considered in this study, with AR ranging from 0.5 to 1.5, and B varying from 2 to 8. These particles are used to create isotropically compressed samples at an initial confinement of 100 kPa and two relative densities (D_r) of 20% and 50%, resulting in ten samples. These samples are then subjected to constant-volume cyclic simple shearing with various levels of cyclic stress ratios until initial liquefaction occurs in 41 simulations. The results of these simulations reveal that at D_r=20%, the spherical particles exhibit the highest liquefaction resistance compared to the non-spherical particles. However, this trend is reversed for the samples with D_r=50%. By employing the overall regularity (OR) as a synthetic descriptor of particle shape, it is observed that liquefaction strength generally increases with higher OR at D_r=20%, while it demonstrates an approximately decreasing trend at D_r=50%. Furthermore, the initial coordination number and two critical state parameters based on the void ratio and the coordination number at the pre-shearing state of the samples, demonstrate a strong correlation with the cyclic liquefaction resistance within the ranges of particle shape and D_r considered in this study.