Experimental study of particle crushing on the small-strain dynamic properties of pre-crushed marine calcareous sands

Calcareous sand, a marine sediment widely used as foundation material for island reclamation in the South China Sea, is prone to damage under monotonic and cyclic loading. Particle crushing can compromise the load-bearing capacity of reclamation foundations by reducing their dynamic resistance during earthquakes. Small-strain dynamic properties are essential for seismic response analysis and underground excavation of foundations constructed on degraded, hydraulically filled calcareous sand. However, a comprehensive understanding of the effect of particle crushing on the small-strain dynamic behavior of calcareous sand is still lacking. In this study, resonant column tests were performed on both original and pre-crushed calcareous sand samples to investigate the influence of particle crushing Br on the dynamic properties under varying confining pressures σc′ and void ratios e. The results indicate that crushing significantly modifies the microstructure and contact forces, reducing particle interlocking and shear strength, resulting in significant decreases in the maximum shear modulus Gmax and dynamic stiffness. A new empirical model incorporating a particle crushing index was developed, and the proposed model could accurately predict Gmax for varying densities and confining pressures. The study findings provide valuable insights into the dynamic behavior of calcareous sands and more resilient island reclamation foundations.