Role of Fines in the K ₀ -Value and Particle Breakage of Coral Sand under High-Pressure Conditions

Abstract

Coral sand, characterized by high compressibility and particle breakage under high-pressure conditions, often contains fines that significantly influence its mechanical behavior. This study investigates the role of fines in the coefficient of earth pressure at rest K 0 and particle breakage in binary coral sand under high-pressure one-dimensional compression. A specially designed high-pressure oedometer equipped with curved earth pressure sensors and friction-reduction techniques was employed. Tests were conducted on binary mixtures with a wide range of fines contents and different coarse-to-fine particle size ratios. Results reveal that both K 0 and particle breakage exhibit nonmonotonic variations with increasing fines content. They first decrease as fines fill voids and improve force chain uniformity and then increase as the soil fabric becomes fine-dominated. Accordingly, an overall increasing trend of K 0 with particle breakage was determined. The final compression states were shown to converge toward a unique curved surface in the void ratio–stress-breakage index space. Relationships between particle breakage and input work under different fines contents were established. Furthermore, particle breakage was found to correlate strongly with the volumetric strain regardless of the influence of fines content, particle size ratio, and vertical stress, following a logistic relationship. The findings of this study provide critical insights into the mechanical behavior of coral sand and have practical implications for the construction of marine infrastructure.