Cyclic behavior of interface shear between carbonate sand and steel

The shear properties of carbonate sand and structure interface are of significance for the engineering construction. The parallel paper (Rui et al. in Acta Geotech, 2020) focuses on the monotonic behavior of the interface between carbonate sand and steel. In this paper, by a series of shear tests on the interface between carbonate sand and steel, the evolutions of interface strength during cyclic interface shear were investigated. Further, the influences of cyclic amplitude, particle size, surface roughness and normal stress on the sand–steel interface shear behavior were discussed. Using a kind of transparent ring, the particle movements near the interface were observed to explain the mechanism during cyclic interface shear. The experimental results show that the shear zone appears near the interface, and is mainly composed of crushed fine particles and original particles. With lower steel roughness condition, the volume contraction is dominant in cyclic interface shear, while the dilation and contraction occur alternatively for higher roughness, which leads to higher interface shear strength. Compared with monotonic shear, the thickness of shear zone after cyclic shear is relatively small. Cyclic interface shear can lead to more fine particles, but less is embedded into the interface. It is found that under cyclic shearing, the interaction between particles and steel is enhanced, which is the main factor for promoting the interface strength, so interface strength in cyclic shear is higher than that in monotonic shear.