Piled rafts under cyclic horizontal loading

• Applicant: Professor Dr.-Ing. Oliver Reul
• Subject Area: Geotechnics, Hydraulic Engineering
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 522823945

In Germany, the design, dimensioning, assessment and construction of piled rafts is based on the KPP-Richtlinie (DGGT 2001). However, the bearing behaviour of piled rafts under cyclic loading is not addressed in the KPP-Richtlinie. Overall, according to EA-Pfähle (DGGT 2012) there is only lim-ited knowledge available on the bearing behaviour of piles subjected to cyclic loading. Based on the DFG-funded research project "Pile groups under cyclic horizontal loading", the next step will therefore be to investigate the load-bearing behaviour of piled rafts under cyclic horizontal loading, such as those resulting from cyclic, temperature-related constraints in integral and semi-integral bridge structures. Within the scope of the project, small-scale model tests on foundations are to be carried out in order to identify the decisive parameters influencing the load-bearing behaviour of piled rafts under cyclic horizontal loading. The following investigations with a numerical model based on the finite element method (FEM) and verified by the back-analysis of selected model tests will be used to quantify these influencing parameters and to develop approaches for estimating the loadbearing behaviour of cyclically loaded piled rafts. In detail, the following aspects are to be addressed: How does the vertical load affect the distribution of the horizontal pile resistances within the foundation? How do the number of load cycles, the type of load, i.e. one-way- od two-way-cyclic loading, and the magnitude of the load amplitude affect - the distribution of vertical and horizontal pile resistances within the foundation, - the contribution of the piles in the vertical and horizontal load transfer, and - the accumulation of vertical and horizontal displacements? The ultimate goal is then to develop approaches that allow the estimation of the above-mentioned parameters from the corresponding value under monotonic loading, the number of load cycles and the load amplitude.

• DFG Programme: Research Grants