Full-Scale Flume Experiments to Analyze the Surface Erosion Resistance of Dike Embankments Made of Dredged Materials

摘要

Dike embankments are usually protected using a revetment structure or a grass cover. On German sea dikes, marsh clay (North Sea) and glacial marl or bolder clay (Baltic Sea) are used mainly as erosion-resistant cover materials. The marl is usually covered with a thin soil layer if grass needs to be established. In recent years, more and more institutions have shown an interest in the use of fine-grained dredged materials, sometimes rich in organic matter, as a replacement for the standard materials. In Europe, dredged materials are legally considered as waste once they are taken out of the water body, although only a small proportion is contaminated. The embankments of dikes and levees are subject to heavy attack by water forces; thus, replacement materials need to be able to withstand these forces. Therefore, overflowing tests with turbulent, supercritical flow conditions were performed to analyze the erosion resistance of dredged materials on a full-scale dike embankment. The tests, which were based on a recent standard, show promising results, supporting different studies that state a grass cover is much more stable than usually assumed in embankment design and that the used dredged materials allow a particularly erosion-resistant grass cover to grow. The test method, however, also shows its limitations in investigating slope failure other than surface soil detachment.