Efficient numerical model for the computation of impedance functions of inclined pile groups in layered soils

Abstract

This paper introduces a numerical model to obtain the time-harmonic dynamic response of pile foundations in non-homogeneous soils. The model is based on the integral formulation of the elastic problem and the use of Green's functions for the layered halfspace, and considers the soil as a group of zoned homogeneous, linear, isotropic, viscoelastic layers. The piles, on the other hand, are treated by finite elements as Timoshenko beams. Both formulations are coupled through the required compatibility and equilibrium equations along each pile. After being validated against previous results from the literature, the model is used to study the effects of soil non-homogeneity on the impedance functions of inclined piles and pile groups by considering different soil profiles whose properties vary with depth following a generalized power law. The impedance functions for three representative non-homogeneous soils are presented and compared with the ones of related homogeneous soils. Significant differences appear between the two situations for all studied rake angles. The magnitude of these differences strongly depends on the frequency range considered, specially for the case of pile groups, which shows the necessity of analyzing the problem using soil profiles as close as possible to the actual depth-varying ones.