Abstract: This project planed to investigate the law of shear action in pile-rock interface of bored rock-socketed pile in reef limestone stratum. For this purpose, the shear test, physical and mechanic property test were performed on the four structure types of reef limestone core samples including framestone, bindstone, rudstone and bioclastic limestone which were sampled from a certain core reef in South China sea. In this way, the variation law of shear stress-shear displacement curve of pile-rock interface was explored. Meanwhile, shear test on the interface between red sandstone and concrete was also carried out to reveal the basic reason for the difference of shear strength between two different sedimentary types of rock and concrete bond surfaces. Based upon these, the investigation suggested that shear strength of reef limestone-concrete interface was affected by the structure type of reef limestone and the strength ratio of pile-rock interface. As a result of the diffusive filling effect of cement slurry in reef limestone, the cohesive force and internal friction angle of the interface between reef limestone and concrete were both larger than those of sandstone-concrete interface. The shear strength response of the strength ratio of pile-rock interface was influenced by the type of reef limestone structure. Cohesive force of the limestone-concrete interface of framestone and bindstone were both larger at a small strength ratio of pile-rock interface than that at a large strength ratio. Internal friction angle of the interface between framestone and concrete was bigger at a large strength ratio of pile-rock interface than that at a small strength ratio while this index changed little in the bindstone -concrete interface.

Key words: coral reef limestone, rock-socketed piles, interface shear test, structural types, strength ratio