<p>The macro- and micromechanical behaviour of pile penetrating coral sand is crucial for understanding the bearing characteristics of piles in coral sand foundations. In this study, large-scale physical model tests were conducted based on quasi-distributed fiber optic sensors to investigate pile penetration behaviour in coral sand. Subsequently, a corresponding two-dimensional discrete element method (DEM) model was established to discuss the effects of particle corner breakage, pile end type, and particle strength on pile penetration performance. The results revealed that the skin friction resistance underwent a three-stage evolution during pile penetrating into coral sands, which was related to the micromechanical behaviour of coral sand grains around the pile, including shear-induced dilation and breakage-induced contraction. Furthermore, the formation of the particle breakage zone around the pile tip was found to be related to the penetration depth. At smaller depths, the most severe breakage occurred in the shear zone located a certain distance below the tip. As pile penetration depth increased, the stresses at the pile bottom intensified, compacting the particles in the compression zone until they were eventually crushed. Finally, a two-phase schematic diagram of the breakage zone was proposed to describe the relationship between the breakage zone around pile tip and pile penetration depth, which can explain the inconsistent breakage zone results reported in previous studies.</p>