Compressibility and crushing of coral sands under one-dimensional dynamic compaction

A series of one-dimensional dynamic compaction tests were conducted on coral sands with different impact energies. Effects of impact energy on the compressibility and crushing of coral sands were assessed in terms of the evolutions of axial deformation, particle size distribution, void ratio, relative breakage index and fractal dimension. The test results indicate that the axial deformation of coral sand specimen and the duration time of impact loading increase nonlinearly with an increase in impact energy, while decrease remarkably with an increase in the number of repeated loading. The void ratio of coral sands under dynamic compaction reduces from 1.56 to 0.86 as the singe impact energy increases from 10 to 160 J, demonstrating that dynamic compaction could effectively consolidate the coral sand specimen. The particle size distribution of coral sands under dynamic compaction tends to a well-grated distribution with the coral particles in the diameter size range of 2.36–4.75 mm primarily fragmentizing into smaller ones with size ranges of 1.18–2.36 mm and 0.6–1.18 mm. The relative breakage index of coral sands under dynamic loading grows approximately linearly with an increase in the input impact energy. The fractal dimension of coral sands under dynamic compaction increases monotonously and the corresponding slope decreases as the impact energy increases.