Abstract: The South China Sea shows strategic significance for China's economic development, resource exploitation, and maintenance of national land integrity. At present, China has built a series of coral reef islands in the South China Sea by the means of reclamation. A number of structures, such as buildings, breakwaters and airports etc., have been built on these reclaimed coral reef islands. As the foundation materials, calcareous sand’s response to extreme ocean wave and strong seismic wave play an important role in evaluating the stability of these structures on these reclaimed islands. In this study, taking the coral reef island reclamation project in the South China Sea as the engineering background, a series of tri-axial cyclic tests is performed for the calcareous sands sampled from reclaimed islands, to investigate their dynamic mechanical properties. The experimental results show that the calcareous could become partially liquefied under cyclic loading in undrained condition. While they can’t become liquefied in drained condition. In undrained condition, the relationship between normalized residual pore pressure u/ and cycle times ratio N/Nf is found in accordance with the inverse sine development model proposed by Seed. Furthermore, the relationship curves between the dynamic deformation modulus of all calcareous sand samples and their corresponding normalized strain ?m /?r all overlap on one hyperbolic line, indicating that the relationship between the dynamic deformation modulus and normalized strain ?m /?r of calcareous sand is independent on dry density, particles size gradation.

Key words: coral calcareous sand, tri-axial cyclic test, liquefaction characteristics, coral reef island reclamation project in South China Sea