STUDIES ON THE STATIONARY DYNAMIC RESPONSE OF A FOUNDATION SUPPORTED BY FLEXIBLE PILE AND SOIL TO A VERTICAL INCIDENT WAVE FIELD OR EXTERNAL FORCE

Resumo

This paper investigates the vertical response of rigid circular foundation resting on the surface
of a three-dimensional, transversely isotropic soil. In a previous study, the dynamic response of a surface
foundation laying on a homogeneous transversely isotropic half-space was compared to the response of
the same foundation supported by a pile embedded in the soil profile. External forces and vertical
incident waves were considered as exciting energy sources in those studies. But the modelling presented
in the previous analysis was subjected to many simplifying assumptions. The incident vertical wave
field was assumed to impinge solely at the head of the pile. The response of the pile to an incident wave
field impinging the whole length of the embedded pile was not considered. The present article intends
to show a numerical methodology and results to overcome these mentioned simplifying assumptions. In
the present case the surface foundation is rigid and the incident vertical wave field will be interacting
with the pile throughout its entire length. The soil response was previously obtained through the
synthesis of a series of Green’s functions. The pile was modelled as a one dimensional, elastic finite
element body. This pile-soil coupling was obtained by establishing direct kinematic compatibility and
equilibrium at discrete points of the pile-soil contact. The numerical studies reported in this article
investigate the role of the pile inertia ratio as well as the relative stiffness of the soil and the pile. The
results show the influence of the pile presence on the vibration amplitude on the foundation.