A continuum-based model on axial pile-head dynamic impedance in inhomogeneous soil

This paper presents a closed-form solution on the steady dynamic response of circular piles embedded in inhomogeneous soil. The soil is modeled as a viscoelastic continuum, and the pile is modeled as a one-dimensional elastic shaft. Fictitious soil pile model and Hamilton's energy principle are introduced to deduce the equations governing the layered pile-soil system. Impedance transfer method and iterative algorithm are deduced to decouple the pile-soil dynamic interaction. The results show that the modulus and thickness of inhomogeneous soil profile play a more significant role in the dynamic stiffness than the damping effects. The variation pattern of the dynamic impedance against the modulus of layered soil is dominated by the cut-off frequency. Particularly, in Gibson soil, the stiffer surface soil yields the greater pile-head stiffness. The dynamic stiffness of piles in Gibson soil could be approximated by two or more soil layers with equivalent Young's modulus.

Automated summary

This paper presents a closed-form solution for the steady dynamic response of circular piles embedded in inhomogeneous soil. The study models the soil as a viscoelastic continuum and the pile as a one-dimensional elastic shaft. The results show that the modulus and thickness of inhomogeneous soil profile have a significant impact on dynamic stiffness, with the variation pattern of dynamic impedance dominated by the cut-off frequency.