Stress Changes due to Shape Effects in the Construction Process of Pile Walls

Abstract

The shaft friction of displacement piles in sand depends on the change in the horizontal stresses on the pile shaft during installation. Recent research has revealed that the sectional shape of a pile has a strong influence on the horizontal stresses, leading to great difference of the pile shaft friction. Based on these findings, an optimization idea has been proposed, referred to as the “switched-on mechanism”. The main emphasis in this paper is given to understanding the changes in horizontal stresses measured during “switching-on” from open-section (installation individually) to closed (load testing for whole pile walls) in cross section. In order to model the construction and load test process for pile walls, a dual installation system was installed into the beam centrifuge. This paper discusses the stress changes through the whole construction process and the efficiency of the switched-on mechanism, and highlights how physical modelling has allowed this highly complex problem to be quantified.