Experimental Study of Interface Shearing between Calcareous Sand and Steel Plate Considering Surface Roughness and Particle Size

The shear behavior of sand-steel interface plays an important role in the performance of steel pipe piles that support marine structures. In this study, the effects of surface roughness (from rough surface to smooth surface) and mean particle size on mobilized sand-steel interface friction were investigated by direct shear tests. Three types of calcareous sand with different particle sizes and three steel plates with different surface roughness were employed in the experimental program. Results indicate that the surface roughness of steel plate has a significant effect on the shear behavior between calcareous sand and steel. The peak shear strength increases with the surface roughness, and the interface friction angle reaches 90% of the internal friction angle of calcareous sand with various particle size. Moreover, the interface friction angle of calcareous sand is higher than that of siliceous sand, which is due to the effect of soil densification and particle breakage during the specimen preparation of calcareous sand.