Monotonic and Cyclic Frictional Resistance Directionality in Snakeskin-Inspired Surfaces and Piles

Abstract

Interface friction is a governing parameter in the performance of piled foundations and other applications. Piles and other foundation elements typically mobilize a similar interface friction angle during loading in tension and compression. However, some applications may benefit from surfaces that mobilize higher shear resistance in one direction of loading relative to another. Such behavior can be achieved through inspiration from the underbelly scales of snakes, which produce frictional directionality or anisotropy. This paper presents the results of an experimental investigation on the monotonic and cyclic interface shear behavior of snakeskin-inspired surfaces and piles with sand. Laboratory test results provide evidence that snakeskin-inspired surfaces mobilize shear resistance, volumetric behavior, and strength degradation that depend on the shearing direction. Boundary conditions, sand relative density, and cyclic displacement amplitude are also indicated to influence the interface shear response. Centrifuge pile load tests are used to evaluate the installation forces, pullout capacity, and cyclic loading response mobilized by snakeskin-inspired piles. These results suggest that snakeskin-inspired surfaces can readily mobilize skin friction that depends on the direction of the displacement in piling applications.