南沙群岛珊瑚礁灰岩的动态力学性能试验

Tests on dynamic properties of coral-reef limestone in South China Sea

Biogenic coral-reef limestone is distinct from the traditional geological rock. In this study, Hopkinson pressure bar tests on coral-reef limestone are conducted to investigate the dynamic fracture morphology and dynamic properties of coral-reef limestones of the South China Sea. Research results show that the high-strength and dense coral-reef limestone with vertical sedimentary evolution has high elastic wave velocity and uniaxial compressive strength; the tensile failure of coral-reef limestone mainly occurs along axis under uniaxial impact loading, and mainly in the weak parts such as the cementation surfaces between the bio-component, coral gravel and coral algae; the dynamic stress-strain model of reef limestone has obvious compaction stage, which is different from normal rock; the dynamic compressive strength of coral-reef limestone is more sensitive to the strain rate than that of normal rock；the energy density of the coral-reef limestone is linearly related to the incident energy and the dynamic compressive strength, and it shows a power function relationship with the strain rate. The dynamic mechanical properties of coral-reef limestone has an important guiding significance for the reef engineering practices such as blasting excavation, impact crushing, earthquake proof and antiknock design.