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.

砂钢界面的剪切特性在支撑海洋结构的钢管桩性能中起着重要作用。在这项研究中，通过直接剪切试验研究了表面粗糙度（从粗糙表面到光滑表面）和平均粒径对动员的砂钢界面摩擦的影响。在实验程序中使用了三种不同粒径的钙质砂和三种具有不同表面粗糙度的钢板。结果表明，钢板的表面粗糙度对钙质砂和钢之间的剪切行为有显着影响。峰值抗剪强度随表面粗糙度的增加而增加，界面摩擦角达到各种粒径钙质砂内摩擦角的90％。此外，