Abstract: As one of ‘the Belt and Road Initiative’ economic development program, the Cross-sea Bridge in Male-Airport island was constructed by China. The foundation of the bridge was located in coral reef which was similar to the geotechnical structure in South China Sea. Due to lack of design experience of rock-socketed pile in coral reef in China and overseas, it is necessary to obtain the load-bearing characteristics and relevant data of rock-socketed pile in coral reef by appropriate test method. Indoor experimental study was conducted on mechanical properties of reef limestone cores that came from pile foundation of the bridge in Male-Airport island. Basic physical and mechanical parameters such as density, relative density, saturate uniaxial compressive strength and triaxial shear strength of the reef limestone were tested. Combining the consequence with the results from model rock-socketed pile test on the reef limestone, the variation law of the bearing capacity with the pile tip displacement was obtained. The investigation suggested that the interface of the pile and rock experienced elastic shear, shear stress drop and fiction shear stage. In the elastic shear stage, the shear deformation was mainly elastic deformation, and the ultimate elastic displacement decreased with the increase of the elastic modulus. In the stage of shear stress drop, the stress rapidly softened, and transformed to the fiction shear stage. In the test, the shaft resistance of reef limestone was positively correlated with the saturate uniaxial compressive strength under low confining pressure. Meanwhile, shaft resistance was greatly influenced by the confining pressure when confining pressure rose.

Key words: reef limestone, rock-socketed pile, side resistance of pile, model test