Influence of particle gradation and morphology on the deformation and crushing properties of coarse-grained soils under impact loading

Changes in mechanical behaviors of coarse-grained soils can affect the safety and stability of geotechnical infrastructures over their full life cycles. This occurs because particle gradation and morphology significantly influence the mechanical behaviors of coarse-grained soils. Exploring the influence of particle gradation and morphology on deformation and crushing properties is thus of vital importance for investigating the macromechanical responses of coarse-grained soils. In this study, the evolution of volumetric deformation and particle crushing are investigated through impact loading tests of coarse-grained soils with different input work conditions, taking into account the influences of particle gradation and morphology. The results show that the volumetric strain increases with an increase in the input work for a given initial coefficient of uniformity, whereas the volumetric strain decreases with an increase in the initial coefficient of uniformity for a given input work. The correlations among volumetric strain (or void ratio), initial coefficient of uniformity, and input work are established. As the input work increases, the grading curves of coarse-grained soils shift leftward, and the relative crushing increases. Among the three representative particle morphological parameters (i.e., aspect ratio, convexity and sphericity), the particle sphericity most significantly influences the deformation and crushing properties of coarse-grained soils. The relative crushing index decreases with an increase in the overall regularity of coarse-grained soils for a given input work. A three-dimensional surface describing the correlation among particle crushing, particle morphology and input work is established and verified for coarse-grained soils.