Field axial cyclic loading experiments on piles driven in sand

Abstract

Multiple axial cyclic and static loading tests have been performed on industrial steel pipe-piles driven at Dunkerque, northern France. This paper describes the site's geotechnical characteristics and experimental arrangements before defining and describing the stable, unstable or meta-stable responses observed under various combinations of cyclic loading. The interpretation draws on numerical analyses and a parallel model study by Tsuha et al. (2012), relating the field response to the probable shaft shear stress distributions and local effective stress conditions. It is argued that cyclic degradation is controlled by: (i) contraction in the highly constrained interface shear zone and (ii) kinematic yielding within the surrounding soil mass. Finally, interaction diagrams linking shaft response to cyclic loading parameters are proposed based on the field test data and a simplified cyclic capacity predictive approach.