Multidimensional High-Cyclic Loading In Experiment And In Finite Element Model

Multidimensional high-cyclic loading in experiment and in finite element model The behaviour of granular soils under multidimensional cyclic loading is of great importance for many engineering applications or design issues. For example, wind and wave loads from different directions of incidence and with temporal offset can affect the behavior of geotechnical structures of offshore wind energy turbines (OWT), from which a multidimensional cyclic stress results. It is known that a multidimensional cyclic load leads to a greater accumulation of deformation in the soil than a one-dimensional load of the same amplitude. If the accumulated deformations become too large, this can leads to an unforeseen loss of serviceability. The numerical simulation of the multidimensional problem and the prediction of the expected deformations is therefore in such cases essential. Subject of this contribution is the investigation of the soil behaviour under multidimensional cyclic loading. Within the conduction of more than 120 cyclic triaxial and hollow cylinder tests, the soil behaviour under one to four dimensional loading is intensively investigated. For the first time, the mathematical formulation of the multidimensional strain amplitude in the high-cycle accumulation (HCA) model after Niemunis et al. with up to four dimensional loading can be proven experimentally. The HCA model with the validated definition of the strain amplitude is then used in exemplary numerical calculations of an OWT monopile foundation under multidimensional loading caused by simultaneous wind and wave action. This way, the applicability and the added value of the definition of the multidimensional strain amplitude in the HCA-model for engineering applications and design purposes.