Effect mechanism of particle size and interface geometry characteristics on shear mechanical behavior of sand-concrete interface

The effects of sand grain size and interface groove spacing on the shear behavior of the sand-concrete interface were investigated under consistent roughness conditions through a series of interface shear tests. Tests utilized different grain sizes of sand and concrete slabs with varying surface textures, based on the sand pouring method. The results were compared with those of pure sand shear tests to evaluate variation characteristics in parameters such as shear stress and friction angle in the interface shear tests. Additionally, the particle flow model was employed to comprehensively analyze rotation characteristics of sand particles and the development trend of shear band width. The findings indicate that: (1) interface shear strength is closely linked to grain size distribution range and groove spacing; (2) thickness of the shear band is positively correlated with particle size, while its correlation with groove spacing is weaker.