Effects of curvature-related DEM contact model on the macro- and micro-mechanical behaviours of granular soils

A comprehensive comparison between the Hertz-Mindlin model and the linear spring model in true triaxial shear simulations of granular soils was conducted using the discrete-element method (DEM). The no-slip Hertz-Mindlin model for general elastic non-spherical particles with smooth surfaces was revisited and implemented for superellipsoidal particles in an in-house DEM code. Three groups of specimens with a grain size distribution of Ottawa 20-30 sands, consisting of spheres, ellipsoids and superellipsoids, respectively, were subjected to triaxial shear DEM simulations with the Hertz-Mindlin model and the linear spring model. The corresponding mechanical behaviours were examined in terms of a series of macro- and micro-parameters. It was found that the linear spring model was able to resemble the Hertz-Mindlin model in aspects of both microscopic and macroscopic mechanical behaviours of granular media with spherical and/or non-spherical particles. This finding suggests that the linear spring model can be used to investigate micro-mechanical behaviours of granular soils, even with complex particle shapes.