Innovative finite element based design methodology of structurally reinforced dikes in the Netherlands

In the Netherlands, where 9 million inhabitants live below sea level, the protection of land against flooding is of the utmost importance. In particular, the macro-stability of dikes under uplift conditions of the underlying aquifer connected to a tidal river is a major issue and has gained much attention. The traditional solution in this case consists of soil blankets. However, due to lack of space innovative techniques using structural reinforcement are needed in constructed areas. For this purpose, the water board WSRL and the Dutch research institute Deltares have provided an innovative design methodology for the Finite Element based design of structurally reinforced dikes. The methodology has been applied and further developed in the KIS project in the Netherlands, where a 17.5 km long part of a dike is reinforced to prevent failure caused by uplift, of which a significant part using anchored bored piles and diaphragm walls. A number of refinements have been identified and already been applied to optimize the design within the project. The experience gained in the KIS project has led to some important improvements of the design methodology. Further research is ongoing to investigate the safety level and the role of the residual geometrical profile after hypothetical failure. The experience gained at KIS will lead in the nearby future to a general, normative design guideline for structurally reinforced dikes.