Study on the mechanical properties of coral sands with different particle gradations

Abstract

The properties of coral sands are significantly affected by the gradation changes caused by the particle breakage. In this paper, a series of triaxial consolidated drained (CD) shear tests were carried out to investigate the influence of gradation on the particle breakage and mechanical properties of coral sands. The results showed that the softening and dilatancy during shearing are more significant for coral sands with smaller average particle sizes under low confining pressure. The peak friction angle decreases with the confining pressure and can be fitted by a power function for different gradations. The particle size distribution of the “hyperbolic” or “straight” curve has a trend to transform into a “sigmoidal” type after shearing; and the variation is affected by the confining pressure and the initial gradation. The critical state lines of the coral sands with different gradations are parallel straight lines on the $e-{(p\prime /p_a)}^{\xi }$ plane. In addition, the relative breakage of coral sand particles increases with the confining pressure and the mean particle size. Based on the triaxial compression test results, the expressions relating relative breakages to the confining pressure and the gradation parameters were proposed.

Keywords:

• Coral sands
• triaxial test
• particle size distribution
• critical state
• particle breakage

Acknowledgements

This research was supported by the National Natural Science Foundation of China (N0. 51909171) and the Central Public-Interest Scientific Institution Basal Research Fund (N0. Y321005; N0. Y321008).

Disclosure statement

No potential conflict of interest was reported by the authors.