Investigations on the drift of piles subjected to cyclic lateral loading with a changing loading direction and on the reduction of the drift

• Applicant: Professor Dr.-Ing. Jürgen Grabe
• Subject Area: Geotechnics, Hydraulic Engineering
• Term: from 2010 to 2017
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 163167571

Cyclic lateral loading of a pile will result in an accumulation of displacement and rotation of the pile. The accumulation can accelerate, if the load is changing its direction during the cyclic loading. Such a loading situation will occur i.e. from wind and wave loading on an offshore monopile. Preliminary studies and the results from the first project stage have shown an increased accumulation. Here, mainly 1g and ng model tests were performed. The second project stage is going to use a different approach on the drift phenomenon. Numerical studies using the finite element method (FEM) and element tests (simple shear tests with changing shearing direction) will be performed. They will complement the previous testing programme and will allow a wider interpretation of the results. The simple shear testing will link the pile results more closely to the question of the memory of the soil. The numerical simulation of these laboratory tests will prove the capability of the FEM and the constitutive model with respect to complex loading histories and loading paths. Furthermore, a prototype will be simulated with the FEM to evaluate the methods capabilities. The spatial variability of the void ratio will be considered to model realistic conditions. This soil inherent anisotropy might help to produce pile displacements that are non-parallel to the loading direction and thus reproduce the results from the model tests.

• DFG Programme: Research Grants