During the period 1975-1979, 45 of these
centrifugal tests were undertaken for
Rijkswaterstaat, most of which were for the
parametric studies for the piers of the
Oosterschelde barrier. Predictions were also
made regarding the outcome of physical tests
on a scale of 1:10 at Kats.
One of the other forms of research is the
physical model-test. By this means, the shear
stress on the horizontal displacement of the
piers was investigated in a physical model at
Schelphoek. The friction co-efficient proved to
be 0.67, whereas 0.3 would have been sufficient.
Waves at the mouth of the Oosterschelde
The waves along the Dutch coast are mostly
caused by winds on the North Sea or on the
Norwegian Sea. The height of the waves is
strongly influenced by the direction of the
wind: coming from the North the wind-shear
can affect the waves over a distance of 2,500
km. The higher the water-levels, the higher the
waves that are generated. The coastal area,
however, acts as a filter, limiting the
wave-heights and causing small changes in the
wave-direction. On the other hand, the local
wind will add energy to the wave-pattern.
The factors concerned and the relations
between them are being studied in the
mathematical FILTER model.
The prediction of the waves forms an essential
part of the boundary conditions set for the
Oosterschelde barrier.
Drainage of the construction-pit for the
'Krammer' locks
When a structure is built in a construction-pit,
which is itself surrounded by water, it has to be
pumped dry and kept dry. To this end a
pumping-station must be installed and kept
working during the entire operation. In addition,
other drainage equipment must be available
when, in the initial stages, the construction-pit
is still completely full of water. In advance,
instructions for the pumping procedures and
an estimate of the costs will be prepared.
The construction-pit for the push-tow locks in
the Philips Dam has been equipped with more
than the normal number of level gauges and
discharge meters in order to study in general
the peculiarities of a pumping operation. The
location on the Plaat van de Vliet displays a
peculiar soil mechanical phenomenon: there
are two layers of water-bearing soil sandwiching
an almost impermeable layer. Sand piles had
to be driven through the intermediate layer
because only the lowest layer was drained. 40
percent of the water that was drained was
done by filter-pumping and the remaining 60
percent by the normal de-watering process.
Improvement of the Kanaal door Zuid-Beveland
The Canal through South-Beveland will be
improved, in conjunction with the other
hydraulic engineering works in the
Oosterschelde. The sluice on the northern side
near Wemeldinge will no longer be used, thus
enabling the reduced tidal action to penetrate
the Canal. The shipping route will be made
suitable for a train of four push-tow barges. As
a consequence and also because of the tidal
action, the Canal will have to be widened and
deepened. The dikes along the Canal will be
raised. The southern sluice, near Hansweert,
will be rebuilt completely at a different location
and be of the same dimensions as the sluices
in the Krammer and the Philips dam; the
height of the dam walls will be in accordance
with the stipulations laid down in the Delta
Law.
A scouring test near the discharge-sluice in the
Brouwers-dam
Up till now, for the solution of problems
regarding scourings near structures, one has
depended entirely on hydraulic model tests.
Not only the fact that the translation of a test
into the actual situation offers some
uncertainty, also the fact that the data used in
model tests are only abstracted from the actual
situation causes uncertainty about the question
of the intrinsic value of the test.
Recently a physical scouring test has been
performed on the inside of the discharge-sluice
in the Brouwersdam, i.e. a test on the scale of
1:1, which was later repeated in the model. In
fact, the physical test was divided into two
parts i.e. a test with the natural bed-soil,
followed by a test performed with artificial
homogenous sediment. Only the results of the
first test and of the model are discussed here.
The outcome is not unfavourable for the
model.
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