Full-Scale Site Investigations on Soil-Plugging Inside Tubular Piles

Abstract

Soil-plugging inside open-ended piles is a well-known phenomenon which increases vertical bearing capacity on the one hand but also leads to increasing driving resistance. There are many different factors affecting the tendency of soil-plug formation like pile diameter, geometry of the pile, installation method, soil density and so on. In the present contribution, in-situ measurements regarding two tubular piles with a diameter of 71 cm are presented. The piles are first vibratory driven up to 6.5 m penetration and afterwards they are impact driven to their final penetration depth. During the installation internal and external stresses at the pile toe and accelerations and strains at the pile head are measured on both piles. Furthermore, one pile is equipped with a cone penetrometer inside the pile to monitor cone and shaft resistance during the installation. At the end of the installation the height of the internal soil column is measured. The results are discussed with focus on the installation method on soil plugging tendency. Concluding they are compared to classical analytical approaches.