Influence of Particle Shape on the Density and Compressive Performance of Calcareous Sand

Particle shape influence the bearing capacity of calcareous sand foundations in island reef engineering. An improved Computer Image Analysis method that combined with mathematical statistics was proposed to categorize and sort different shapes of calcareous sand particles within the size range of 5-10 mm. Three single-shape calcareous sand specimens (granular shape, dendritic shape, long strip shape) were obtained. A new self-developed vibration device was used measuring the maximum density of calcareous, the shape and content as the variables in the orthogonal test. On this basis, the lateral compression tests were carried out to assess the influence of particle shape on the density, compressive performance of calcareous sand. Test results showed that better discriminability was achieved by taking mean flatness (E-L/B) as the quantification parameter of the particle shapes. The average flatness E-L/B of specimens is approximately normally distributed in the statistical results. The shape and content of sand particles had an obvious influence on the density of calcareous sand. The compressive properties of calcareous sands with different particle shapes have obvious differences. After loaded, the particle size distribution of specimen improved, the average flatness E-L/B of the granular-shaped specimens increased, while that of the dendritic-shaped and the long-strip-shaped specimens decreased, the average flatness E-L/B of the specimens tended to be uniform. The relative fracture rate B-r and the load value P-max satisfied the exponential function fitting relationship. Therefore, it can be argued that particle shape should be taken into consideration when optimizing the foundation design in island reef engineering to achieve better compressive performance of the foundation.