Anisotropic Shear Behavior of Soil-Structure Interfaces: Bio-Inspiration from Snake Skin

Abstract

This paper presents the results of an experimental study on the shear behavior of soil-structure interfaces between snake skin-inspired surfaces and sand. Snakes were used as the model organism because the scales along their underbody (i.e., ventral scales) mobilize high frictional resistances when soil is sheared against them (i.e., cranial direction) to generate reaction for locomotion. On the other hand, these same ventral scales mobilize less frictional resistance when soil is sheared along them (i.e., caudal direction) in order to minimize friction during forward movement. The results presented consist of two-way cyclic interface shear tests between sand and bioinspired surfaces, and sand and a surface consisting of sand glued on steel. Two of the snake-inspired profiles are shown to mobilize significant frictional anisotropy, which is dependent on the shape of the asperities and the imposed testing sequence. The third snake-inspired surface, and the glued sand surface, mobilized negligible to moderate degrees of frictional anisotropies. This paper also provides a discussion of the practical implications for potential adoption of surfaces that mobilize frictional anisotropy in geotechnical design.