Title
Influence of the slope angle on wave overtopping at rubble mound breakwaters
Author
van Marrewijk, Jaap (TU Delft Civil Engineering & Geosciences; TU Delft Coastal Engineering; TU Delft Hydraulic Engineering)
Contributor
van Gent, M.R.A. (mentor)
Jumelet, D. (graduation committee)
Mares Nasarre, P. (graduation committee) 
Degree granting institution
Delft University of Technology
Programme
Civil Engineering | Hydraulic Engineering
Date
2024-01-24
Abstract
The objective of this research is to gather more information about a possible relation between the slope angle of a rubble mound breakwater and the wave overtopping at this breakwater. The following research question is covered in this thesis: What is the influence of the slope angle of rubble mound breakwaters on wave overtopping? To answer this research question, a literature study was done and physical model tests were performed at Deltares in Delft, the Netherlands. In total, tests to five different breakwater configurations were performed, with a slope of 1:1.5, 1:2, 1:4, 1:6 and 1:8. These breakwaters were exposed to varying significant wave heights and wave steepnesses. During these tests, the amount of water from waves overtopping the structure was collected in order to determine the average wave overtopping discharge for every performed test.
Results of this study show that the slope angle has a large influence on wave overtopping at rubble mound breakwaters. It follows that the steeper the slope, the larger the wave overtopping discharge for the same dimensionless crest freeboard. This trend was captured regardless the wave steepness. This relation can be seen V both for breaking and for non-breaking wave loading. However, the dependency between the slope angle and the wave overtopping discharge appears to be larger for breaking waves than for non-breaking waves.
Furthermore, it was found that the wave steepness has a large influence on wave overtopping at rubble mound breakwaters, both for non-breaking waves and for breaking waves. In general, it can be said that the lower the wave steepness, the larger the wave overtopping discharge for the same dimensionless crest freeboard. This relation was found regardless of the slope angle of the breakwater. However, it followed that the wave steepness has a larger influence on the wave overtopping discharge at gentle slopes, like 1:6 and 1:8. It should be noted that for non-breaking waves, the influence of the slope angle and wave steepness is not present in the existing manuals, while the effects are important.
The formulas in the current guidelines to calculate the wave overtopping discharge were compared to each other and the data. These formulas were further modified based on the data gathered during the physical model tests to obtain even more accurate predictions for overtopping discharges. This resulted in the proposal of two equations to calculate the average wave overtopping discharge at permeable rubble mound breakwaters for wave loading that can be characterized as breaking waves and non-breaking waves.
Subject
Wave overtopping
Rubble mound breakwaters
Physical model tests
To reference this document use:
http://resolver.tudelft.nl/uuid:6d1f6c28-f4c3-4822-affa-7a761856cd07
Embargo date
2025-01-24
Part of collection
Student theses
Document type
master thesis
Rights
© 2024 Jaap van Marrewijk