Effect of particle crushing on the mechanical behavior of unreinforced and geogrid-reinforced marine coral sands

• A 3D DEM modelling considering particle crushing and reinforcement is developed. • The effect of particle crushing on the macroscopic mechanical response is analyzed. • Fine-scale crushing and spatial distribution are characterized. • Methods for calculating shear mechanical parameters are evaluated. • The effect of crushing on shear and deformation mechanisms is revealed. Strength deterioration induced by particle crushing is detrimental to the construction of marine geo-structures. As an efficient reinforcement method, the geogrid-reinforced coral sand (GRCS) technique also suffers from the adverse effects of particle crushing. In this study, the macro-micro mechanical behavior of unreinforced and geogrid-reinforced coral sands under triaxial loading was investigated using an experimentally validated three-dimensional discrete element method (DEM), focusing on the effect of particle crushing. The results reveal that crushability determines the stress-strain response, strength parameters, spatial distribution of crushing, and number of particle fragments differently. The analysis of microscopic contact forces indicates that the resistance pattern of GRCS under triaxial loading results in the gap in spatial distribution patterns and the number of fragments compared with the unreinforced condition. Further micro-scale analysis of the crushing behavior shows that the increased fragments induce a transition of the particle morphology from angular to round-like patterns, thus the low occlusion and increased plasticity of crushed coral sands contribute to the stress-strain softening and peak strength reduction. In conjunction with the effect of crushing on shear strength, the strength envelope characteristics and the evolution mechanism of shear mechanical parameters are revealed under the effects of reinforcement, low crushing, and high crushing.