Dynamic response of floating piles subjected to axial loads considering three-dimensional soil deformations

Abstract

This paper presents a systematic study on the effect of radial soil deformations on the dynamic response of floating piles subjected to axial loads. The study is facilitated by a novel mathematical model, that allows rigorously considering both vertical and radial soil displacements generated by axial pile vibration, under an extended Tajimi-type framework. Following the presentation of the mathematical model and the solution, we show that the model produces similar results compared to rigorous numerical boundary integral methods. Then we compare results of the proposed model against an earlier model that is formulated on the basis of confined elastodynamics i.e. on ignoring radial soil deformations. We demonstrate that the confined model overestimates stiffness and underestimates damping of the pile impedance in the low frequency range, regardless of the problem conditions, and we explain the mechanisms that lead to these discrepancies. Although the proposed model is based on the elastodynamic theory, findings of this study are not limited to small-strain problems, as the identified mechanisms are solely associated with the effect of radial soil deformations, and not with the constitutive behavior of soil.