Re-recognizing the impact of particle shape on physical and mechanical properties of sandy soils: A numerical study

The particle shape created by geological processes is an essential characteristic that determines the physical and mechanical properties of sandy soils. However, the nature of the arbitrary shape and the individual volume of particles in natural sand have been given scant regard. In this study, we constructed a particle flow code (PFC) model using a number of clumps with random irregular shapes (called "Irreg-Sam"), and simulated direct shear tests on silica sand. Further, particle shapes were investigated via a series of numerical tests on Irreg-Sams and comparative models with rounded particles (called "Reg-Sam"). The results indicate that Irreg-Sam can form a lower minimum void ratio and interval of extreme void ratios than Reg-Sam. Conversely, Reg-Sam has a greater peak shear strength than Irreg-Sam when the normal stress is less than 200 kPa. However, there was no noticeable difference in the critical shear strengths of these two samples. Because of the higher dilatancy angle under relatively low stress levels, sand with irregularly shaped particles will exhibit a greater peak shear strength than sand with rounded particles. The nature of the arbitrary shape and the individual volume of particles in sandy soils were found to be two important factors that cannot be ignored when studying the effect of particle shape. This research will facilitate better understanding of the role of particle shapes in sandy soils.