Modelling erosion progression for steady overflow and wave overtopping conditions
(2023) , 78 pages
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Overflow_and_Overtopping_Erosion_ModellingFinalReport.pdf
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- Abstract
- This report aims to outline a practical approach to evaluating the erosion rate of clay covers on levees due to wave overtopping and overflow. The erosive behaviour of clay is dependent on soil parameters. This dependency is still a topic of academic research. As this differs per levee, it would be impossible to translate the outcomes of large-scale erosion experiments on one levee in the Living Lab Hedwige Prosperpolder to other levees. Only the general erosion behaviour may be transmittable. In line with the objective to be able to apply user-friendly models for predicting the rate of erosion and breach formation, here small-scale erosion tests are evaluated, based on their ability to accurately assess the erosion characteristics of soil. Large-scale erosion tests have been performed to learn more about the erosive behaviour of clays subjected to realistic wave overtopping and overflow loads. The erosive behaviour observed has been simplified and entered into a user-friendly breach model. Also, the erosion characteristics of the clay have been derived based on the large-scale tests. Besides these large-scale erosion tests, small scale erosion tests have also been performed on the clays to determine the erosion characteristics. The small-scale tests have been evaluated based on the correlation that could be found with the erosion parameters of the clay found with the large-scale test. The existence of such a correlation would allow levee managers to quickly evaluate the erosion characteristics of their levees. The locally found erosion characteristics could then be entered into the erosion model to evaluate the erosion resistance of the levee overall. Thus, we define three research questions: 1. What is the large-scale erosion process in the clay layer of a levee with a sand core and a clay cover layer? 2. What are the erosion parameters for clay based on the outcome of large-scale overflow tests, and how do these vary in space? 3. Is it possible to correlate the predictions of the erosion coefficients based on small scale tests to those performed on large scale? Chapter 2 gives an overview of the large-scale erosion experiments that were performed. Chapter 3 gives an overview of the small-scale erosion experiment that were done on the levee clay cover. Chapter 4 gives an overview of different methods to determine erosion rates. In chapter 5 the largescale, small-scale and hydrodynamic model results are given and compared to find correlations. Chapter 6 provides a discussion of the experiments and results. Conclusions and recommendations are given in chapter 7.
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Citations
Myron van Damme, Cédrine Alleon, Antoine Neuts, André Koelewijn, Abdelkrim Bennabi, Ebrahimi, M., Soares Frazao, S., Philippe Sergent, & Hassan Samoui. (2023). Modelling erosion progression for steady overflow and wave overtopping conditions.