The installation effects of screwed displacement piles

Abstract

During construction in urban areas often noise and vibrations are not tolerated. For the installation of the foundation piles in these cases there is often chosen for screwed displacement piles. These piles can be installed without nuisance for the vicinity, but do induce large soil displacements during installation. The soil displacements can cause increased soil pressure on adjacent structures. Because urban areas are getting more densely built, these problems will occur more often in the future. The effects can be minimilized when they are known in advanced. This research looks into the possibility of predicting the installation effects of screwed displacements piles on adjacent structures. This is divided in the prediction of the soil displacement in a finite element analysis and in the effect of the soil displacement on adjacent piles. This is done with two case studies. First data from tests in Shanghai is used to create a finite element model. After this measurements are done in Rotterdam to verify this model for Dutch cases.
Combining all the analysis of the measured and modelled displacements showed that the displacement is depended on the stiffness of the soil layers, the initial displacement at the edge of the pile and the distance from the pile. The soil parameters influence the initial displacements in each soil layers. When the initial displacements are correctly determined with tests, it is possible to predict the soil displacement due to the installation of a screw pile with a finite element model. No conclusion could be made on the effect of the soil displacements on adjacent structures.