Mechanism Analysis of Strengthening the Coral Reef Sand Foundation by Dynamic Compaction Method Based on Discrete Element Theory

The dynamic compaction method for reinforcing foundation has the advantages of significant effectiveness, saving in materials and short construction period, which is suitable for reinforcing coral reef sand foundation. To conduct the mechanism of strengthening coral reef sand foundation by dynamic compaction method, a numerical model was established based on discrete element method which could simulate both the shape of coral reef sand and the characteristics of soil porosity changes during the dynamic compaction process. The numerical model reliability was verified by field test results, and finally the coral reef sand particle crushing process, force chain development and foundation settlement under different tamping energy were analyzed, so as to clarify the internal mechanism of foundation reinforcement. The research results showed that the foundation settlement of adopted discrete numerical model showed a good alignment with that of field results, proving that the model had low error and high reliability; under the action of dynamic compaction method, the pores of coral reef particles decreased, the particle fragmentation zone gradually developed to both ends of the ramming pit, and the force chain was concentrated and radially distributed towards the center of the ramming pit; the greater the tamping energy, the greater the surface and foundation settlement within a certain depth range, and the particle fragmentation zone and force chain developed in both depth and breadth.