EurOCEAN 2000 - Vlaams Instituut voor de Zee

Both the Zeebrugge and the Petten sites are
accurately modelled and tested in 5 different
laboratories. Model tests are carried out in 2D
wave flumes (Flanders Hydraulics, Delft
Hydraulics and Universidad Politecnica de
Valencia) and in 3D wave tanks (Aalborg
University and University College Cork) to cover
a whole range of parametric tests and the
reproduction of measured storms. The scale of
the models varies between 1:30 and 1:40. In
order to model the flow in the core of the
breakwater properly a special scaling method has
been chosen for scaling the core material
(Burcharth et al. (1999)), resulting into coarser
Fig. 4: UG-step gauge
core material than the overall scale. The Zeebrugge model is also tested in a combined wave
flume and wind tunnel to study the influence of wind on run-up, overtopping and spray.
Failure of a seawall is often initiated by damage to the crest. When waves overtop the structure,
the downrushing water may damage the landward slope of a dike. This can lead to the total
failure of the structure.
Therefore the crest stability is studied in a wave flume. A series of model tests on wave
overtopping and wave run-up is carried out to investigate wave overtopping rates, overtopping
velocities and water layer thicknesses for different seaward (1:6, 1:4 and 1:3) and landward
slopes. Tests are performed for regular and irregular waves, for different freeboards and water
depths,… in order to test a wide range of parameters. The results of this investigation will help
in a better assessment of the crest stability of overtopped structures.
•
• DISCUSSION OF RESULTS
Analysis of the available Zeebrugge data
reveals many points of interest. The
Ru 2%
dimensionless run-up value seems
H mo
to be dependent on the water level:
Ru 2%
values increase when water depth
H mo
decreases. Ru is defined as the difference
between wave run-up level and mean water
level. The run-up which is exceeded by 2 %
of the run-up events is called Ru2%. Hmo is
the significant wave height, based on
spectral analysis. When time series of
492
Ru 2%/H mo [-]
3
2
1
0
-1
-2
0 1 2 3 4 5
Rd 2%/H mo [-]
ξ m [-]
Zeebrugge small scale results (Murphy et al. (1996))
Zeebrugge prototype results
Fig. 5: Comparison between prototype
and scale model wave run-up results