Particle morphology characteristics of coral sand from the South China Sea and their effects on single-particle strength

In this study, single-particle crushing tests were conducted on coral sand particles with three sieve size fractions, and their particle morphology characteristics were obtained using X-ray micro-computed tomography (μCT). The distribution characteristics of particle size, shape, and intra-particle pore parameters of coral sand, as well as their correlations, were investigated. The influence trends and magnitudes of each particle characteristic on single-particle strength were then quantitatively analyzed through Spearman’s rank correlation coefficients. The results showed that there were significant positive correlations in coral sand between flatness FL and sphericity S , and between sphericity S and convexity C . Significant negative correlation was observed between total intra-particle porosity n and roundness R 3 , indicating that coral sand particles with smoother surfaces had fewer intra-particle pores. Furthermore, coral sand particles with larger particle sizes and higher shape irregularity exhibited lower single-particle strength. For intra-particle pore parameters, lower intra-particle porosity and higher anisotropy and non-uniformity of intra-particle pores in coral sand were associated with higher single-particle strength. Furthermore, an evolutionary polynomial regression (EPR) model was proposed to predict the single-particle crushing strength of coral sand relating to seven particle characteristics, which could approximately predict the single-particle strength of coral sand, with a coefficient of determination ( R 2 ) of 0.825.