Analysis and characteristics of dynamic response of large pile groups

Abstract

Dynamic response of pile foundations has been studied for many years with different models ranging from distributed Winkler springs to advanced analytical solutions. The special features in the dynamic impedances of pile foundations, which are mostly related to the group effect or pile-soil-pile interaction, have inspired researchers to develop dedicated computational tools for capturing them. In parallel, several research studies have been carried out to investigate whether these features are realistic, rather than being the result of the idealized models used for the piles and the soil domain. For example, one issue is to what extent the number of piles and the pile configuration affect the large peaks in the impedance functions. Another question is if these impedance characteristics change by the soil heterogeneity in the vertical and horizontal directions.\n This paper attempts to answer some of these questions in the range of nearly elastic soil response for a large group consisting of 225 piles. Two profiles with shear moduli representing typical sand (parabolic with depth) and typical clay (linear with depth) are considered together with a homogenous soil profile for reference and for comparison of the results. The presented results include the foundation impedances of the pile foundations as functions of frequency in the horizontal and vertical directions together with their kinematic earthquake response. In addition, a limited number of analyses are performed to assess the effect of soil nonlinearity on the pile-soil-pile interaction.