Characterization of pore structures in coral reef limestones and DEM simulations of compressive failure

The pore structure of coral reef limestones significantly impacts the stability of reef island engineering foundations. This study analyzed the pore-throat parameters of limestones with varying pore structures using computed tomography scanning. Quasi-static compression tests were conducted to investigate the influence of these structures on macroscopic failure and deformation. Furthermore, a skeleton-pore two-dimensional microscopic model was established using MatDem software to elucidate failure behaviors from the perspectives of deformation, microscopic force chains, and energy conversion. Results indicate distinct failure mechanisms for different pore types: (1) Coral reef limestone with native pores (N-CRL) exhibits shear-tensile failure with load-bearing force-chain pathways bypassing pore spaces. Normal and shear breakage occur simultaneously, dissipating kinetic energy after compaction. (2) Limestone with combined pores (D&N-CRL) shows shear failure along weak planes. Strong force chains concentrate at dissolved pore tips, with over 90% of particle connections undergoing normal breakage. Kinetic energy fluctuates significantly around peak stress. (3) Limestone with dissolved pores (D-CRL) experiences local shear failure. Dense force chains at pore tips induce crack initiation and coalescence, with energy dissipation patterns similar to those of combined pore structures. These findings provide theoretical insights for marine engineering stability.