Horizontal vibration characteristics of offshore twin–pile foundations

Abstract

Accurately estimating the horizontal dynamic parameters of offshore pile groups plays a critical role in offshore foundation engineering. Most of the current research ignored the hydrodynamic force applied to the piles, making it difficult to accurately simulate the operational conditions of offshore pile groups. This study considered the dynamic soil resistance and hydrodynamic pressure induced by pile horizontal vibration, providing a more accurate and comprehensive dynamic analysis of offshore twin–pile foundations. By incorporating the determined pile–soil and pile–water interaction forces and solving the horizontal vibration equations of piles, the dynamic impedance and displacement amplitude of the offshore twin–pile system were derived. After validating the rationality of the proposed solutions, the effects of hydrodynamic force, pile arrangement, and pile geometrical dimensions were extensively discussed. The main conclusions are as: (1) The influence of hydrodynamic force on the dynamic stiffness of the twin-pile system becomes gradually significant as the load frequency increases; (2) Neglecting the effects of hydrodynamic force leads to an overestimation of the natural frequency of twin–pile foundations; (3) Compared to a single pile, the natural frequency of twin–pile foundations is less sensitive to the changes in geometrical dimensions.