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In this paper, an analytical methodology is proposed to study the vibration of an offshore friction pile embedded in multilayered saturated viscoelastic soils by combining Biot’s saturated wave propagation theory, Novak’s plane-strain model, and the fictitious saturated soil pile model. The corresponding semi-analytical solution for the dynamic response of the pile is developed considering the heterogeneity, porosity, and limited thickness of the soils. The approach and relevant solution presented are validated by comparisons with existing solutions. Furthermore, numerical instances are used to investigate the influences of the porosity and heterogeneity of the saturated soils around and beneath the pile on the vibration of the pile. The findings from this paper provide a theoretical reference for a comprehensive understanding of the wave propagation characteristics of a friction pile embedded in heterogeneous saturated soil with limited thickness.

The vertical vibration of a viscoelastic pile immersed in arbitrarily layered soil is investigated by taking the interaction among pile, pile surrounding soil (PSS) and pile end soil (PES) into account. Firstly, considering both the stratification and stress wave effect of soil, a mathematical model of the pile–soil system is established based on the fictitious soil pile (FSP) model. Then, utilizing the impedance function transfer method and Laplace transform technique, the analytical solutions of the vertical dynamic impedance of pile are derived in the frequency domain. The analytical solutions are validated by comparing them with other existing solutions. Finally, a parametric study is put forward to investigate the properties of PES on the vertical dynamic impedance of pile. The results reveal that the properties of PES have a significant effect on the vertical dynamic impedance of pile, but there is a critical influence thickness for this effect. For the cases of the PES thickness exceeding the critical influence thickness, further increase of PES thickness will not affect the dynamic behavior of the pile–soil system.