Dynamic analysis of wave propagation due to pile installation using numerical simulations

This paper discusses the results of a preliminary study of numerical simulations investigating wave propagation during the installation of in-situ driven concrete piles (type Franki pile). Franki piles are cast-in-situ piles that are installed by driving a steel casing into the ground using heavy ramming of a cylindrical hammer. It is a dynamic pile installation process where the hammer directly transfers the dynamic forces to the soil within the installation tube causing high wave propagation through the soil. When installed in groups, the vibrations caused by the driving process of one pile may result in damages to the early-age concrete of adjacent piles. The dynamic response of a pile during driving is very complex, involving the interactions of hammer, pile, and soil during the impact. Such complex soil-structure interaction problems can be represented numerically by modeling the pile installation process using realistic parameters (ground conditions, ramming energy etc.). As a preliminary study, a single pile installation is simulated using the FEM software Abaqus. The simulation is based on a Coupled Eulerian-Lagrangian (CEL) approach where the soil is modeled using the hypoplastic constitutive model. The aim is to investigate parts of the installation process regarding the effect of discrete hammer drops. Within the CEL method, the pile hammer is modeled as a Lagrangian part, while the soil is treated as a Eulerian part. As a result of the simulations, a realistic amplitude pattern can be observed. This study serves as the basis for the subsequent phase, wherein a newly installed neighboring pile is introduced alongside the pre-existing pile. In this context, the influence of the adjacent pile on the wave propagation due to the neighboring pile is evaluated.