Simplified three-dimensional analysis of horizontally vibrating floating and fixed-end pile groups

This note presents an approximate analytical solution for estimating the time-harmonic impedance of pile groups subjected to horizontal dynamic loads, for different boundary conditions at pile tip (free and fixed). The derived solution considers waves due to pile vibrations propagating in both horizontal and vertical directions, unlike earlier solutions based on the plane-strain model, which ignores vertically propagating waves. This allows accounting for pile boundary conditions on the soil attenuation function, as well as modeling the response of the pipe group-soil system near the first natural frequency of the soil layer, where solutions based on the plane-strain model fail to account for resonance phenomena.