Study on cyclic shearing characteristics of calcareous sand-snake skin-inspired interfaces

In marine geotechnical engineering, the dynamic response of the calcareous sand-structure interfaces is critical to the overall stability of structures. The snake skin-inspired interface is a new type of interface developed based on the geometric asymmetry of the ventral scales of snakes, which has attracted the attention of researchers due to the frictional anisotropy during shear. Based on the interface direct shear apparatus, a series of cyclic shear tests were carried out on the interfaces between calcareous sand and snake skin-inspired steel surfaces. The effects of normal stress, cyclic amplitude and apparent interface shape on the shear stiffness and damping ratio were investigated. The test results show that increasing in normal stress increases the interface shear stiffness and decreases the damping ratio; increasing the cyclic amplitude leads to a decrease in the shear stiffness and an increase in the damping ratio; the shear stiffness decreases with the increase in the scale geometric ratio, while the damping ratio shows the opposite trend. In addition, for the same scale geometric ratio, the shear stiffness increases with the increase in scale height, while the damping ratio decreases. The data fitting results show that the shear stiffness and damping ratio have a linear and logarithmic relationship with the normal stress, respectively; the shear stiffness and damping ratio have an inverse reduction and logarithmic relationship with the shear displacement amplitude, respectively; and the power function can represent the relationship between the shear stiffness and scale geometric ratio, as well as the relationship between the damping ratio and scale geometric ratio.