Modelling the soil-structure interaction of 60 m long piles under gradual loading during construction of a high-rise building in Rotterdam

Abstract

This thesis examines the load distribution on 60 m long piles under gradual static loading, considering the POST Rotterdam high-rise building as the study project. The research employs fibre optic (FO) instrumentation on site to monitor strain changes in the piles over time and assess load transfer mechanisms. This data is integrated into a Plaxis 3D model of the building's foundation to validate existing approaches on soil structure interaction (SSI), optimize SSI modelling, and assess the high-rise building's impact on nearby structures. Results show that at early stages, the resistance contribution comes from the shaft in contact with the Pleistocene sand layer. However, as loading progresses and the Kedichem clay layer consolidates, most of the resistance shifts to the tip and the shaft located in the deeper sands. The FO strain measurements follow a similar trend to the site stratigraphy, but there is high uncertainty about the results at early load stages. The latter requires further investigation to corroborate once the building is finalised. The piles were incorporated into the Plaxis 3D model by means of EBR with a layer-dependent force distribution. The resulting spring stiffness of various pile groups reveals the significance of the group effect. Regarding the impacts of POST loads on the adjacent Old Post Office building, an angular distortion of 1/555 in 50 years was obtained, which indicates a conservative result of slight damage in the structure. For the Timmerhuis building, a resulting angular distortion of 1/1428 indicates no damage. This study addresses gaps in understanding load distribution in 60 m long piles, offering a practical modelling approach and recommendations for future research. It contributes to optimizing design and safety protocols as the use of such piles becomes more common in Rotterdam. By utilizing advanced sensing techniques like FO, this research may lead to more accurate pile design and criteria, potentially reducing construction costs and enhancing safety for high-rise buildings and their surroundings.