Abstract: To investigate the dynamic mechanical properties and damage characteristics of two types of coral reef limestones under impact loading, split Hopkinson pressure bar (SHPB) test apparatus was used to conduct impact compression tests on coral lattice limestone and coral clastic limestone in the strain rate range of 10~190 s^-1. The stress-strain curves of reef limestone under different strain rates were analyzed to obtain the strain rate effect and energy dissipation of dynamic peak stress and elastic modulus. In addition, the damage and failure characteristics of samples were revealed using high-resolution CT scanning and image processing technology. Results show that the dynamic stress-strain curves of lattice limestone exhibit an obvious elastic deformation stage, while the compaction stage of clastic limestone is more apparent. Furthermore, the dynamic peak stress increases as a power function with the increase of strain rate, and the strain rate effect of lattice limestone is stronger. The relationship between dynamic elastic modulus and strain rate is negatively exponential. Moreover, the energy absorption capacity of lattice limestone is stronger than that of clastic limestone. The damage cracks of reef limestone are mostly found along sites with poor cementation of biological components or many penetrative pores. Under medium and high strain rates, the damage cracks of lattice limestone mainly undergo matrix propagation and transfixion, presenting brittle fracture failure, and clastic limestone perforation propagation, presenting crushing failure mode. The research findings are of guiding significance for preventing dynamic disasters in island and reef engineering construction.

Key words: dynamic peak stress, damage characteristics, coral reef limestone, strain rate effect, energy dissipation, dynamic disaster prevention