Long-term settlements of a ship lock: Measurements vs. FE-prediction using a high cycle accumulation model

During their lifetime many geotechnical structures are subject to a high number of repetitive loading cycles with small strain amplitudes, a so-called high-cyclic loading. Well-known examples are foundations for offshore wind turbines exposed to a cyclic loading caused by wind and water waves. In the case of ship locks, being the subject of the present paper, the high-cyclic loading results from the repeated filling and emptying of the lock chamber which leads to a cyclic change of the water pressures acting on the walls and the bottom of the chamber. Generally, a high-cyclic loading may lead to progressive settlements and a tilting of foundations. Up to now, the availability of validated and standardized analysis procedures for the proof of the serviceability limit state for foundations subject to high-cyclic loading is still limited. One procedure which proved good results for that purpose in recent years is a numerical approach based on finite element (FE) calculations using a high-cycle accumulation (HCA) model to predict the long-term behavior of the subsoil. Subject of this contribution is the application of the HCA model in FE simulations of the ship lock Uelzen I, aiming on a further validation of the proposed procedure. This ship is a well documented structure with long-term monitoring, significantly differing from foundations for offshore wind turbines, which were studied for the validation of the HCA-model so far. Simplifications of the subsoil and the determination of the input parameters for the FE simulations are presented. The long-term settlements predicted by the HCA model are compared to field measurements over two decades. Furthermore, a sensitivity study regarding the influence of various parameters on the predicted settlements is shown.