Abstract: The dynamic response of carbonate sand-steel interface is of great significance to the safety and stability of foundations in reef islands. Based on the interface ring shear apparatus, a series of cyclic shear tests on the interface between carbonate sand and steel was carried out. The effects of normal stress, cyclic amplitude and particle size on the interface shear stiffness and damping ratio were investigated, and compared with quartz sand. The results show that normal stress and cyclic amplitude have significant effects on the interface shear stiffness and damping ratio; the increase of normal stress level increases the shear stiffness and decreases the damping ratio; the increase of cyclic amplitude leads to an approximate inverse reduction of shear stiffness and an approximate logarithmic increase of damping ratio; for carbonate sand with a uniform particle size, a critical particle size exists that results in a significantly different interface shear behavior. When the particle size of quartz sands is large, the shear stiffness and damping ratio are different from those of carbonate sands. But, if the particle size is small, the shear stiffness and damping ratio of these two sands are almost the same.

Key words: carbonate sand, steel interface, cyclic shear, shear stiffness, damping ratio