Kinematic pile-soil interaction using a rigorous two-parameter foundation model

Abstract

The response of a single pile to vertically incident shear waves embedded in a homogenous visco-elastic soil layer of finite thickness is considered. In order to study the influence of the soil shear, the pile-soil interaction is modelled using a rigorous analytical elastic continuum model recently proposed by the first author that translates into a two-parameter Pasternak-type mechanical model with a viscose component to account for energy dissipation. The viscose behavior is represented by a bed of dashpots each arranged in parallel with an elastic spring. The elastic part of the model has two distinct important features. Primarily, its second elastic parameter directly represents the soil shear, which is missing in the classical beam-on-dynamic-Winkler foundation model. Secondly, the model is provided with fully-established parameters that are known down to a single coefficient determined through a calibration process with the help of the finite element method. These unique model parameters adjusted for the static pile response are used in the dynamic analysis. The second model parameter is used to study the influence of the soil shear on the pile response in terms of the various kinematic factors. The parametric study shows in general that the soil shear influence increases with decreasing pile-soil stiffness ratio over a wide range of frequency and pile slenderness ratios. It has been particularly observed that neglecting the soil shear can excessively overestimate the pile response, especially of reinforced concrete piles in soils of wide ranging stiffness among other effects.