Macro-Micro Mechanics of Granular Soils Under Shear Considering Coupled Effects of Particle Size Distribution and Particle Morphology

This paper investigates the effects of particle morphology (PM) and particle size distribution (PSD) on the micro-macro mechanical behaviours of granular soils through a novel X-ray micro-computed tomography (μCT)-based discrete element method (DEM) technique. This technique contains the grain-scale property extraction by the X-ray μCT, DEM parameter calibration by the one-to-one mapping technique, and the massive derivative DEM simulations. In total, 25 DEM samples were generated with a consideration of six PSDs and four PMs. The effects of PSD and PM on the micro-macro mechanical behaviours were carefully investigated, and the coupled effects were highlighted. It is found that (a) PM plays a significant role in the micro-macro mechanical responses of granular soils under triaxial shear; (b) the PSD uniformity can enhance the particle morphology effect in dictating the peak deviatoric stress, maximum volumetric strain, contact-based coordination number, fabric evolution, and shear band formation, while showing limited influences in the maximum dilation angle and particle-based coordination number; (c) with the same PSD uniformity and PM degree, the mean particle volume shows minimal effects on the macro-micro mechanical behaviours of granular soils as well as the particle morphology effects.