Summaries
The 'Energo' project
A project has been set up to study the generation
and storage of energy in a basin in the mouth
of the Oosterschelde; for instance, at the site of
the construction docks in the Geul dam-section.
The night current of the electrical network, but
also the wind and tidal energy could be stored
by creating a difference in water levels between
this basin and the adjacent Oosterschelde; one
could conceive of a possibility that the water
level in the basin would either be considerably
raised or lowered. By means of hydraulic
turbines, the difference in water levels could be
adjusted to a certain degree at any desired
moment, to translate the energy of the water
into electricity.
The first question of this study, namely the
question of organisation, 'how will the basin be
used?', which question supersedes all technical
problems, must still be solved.
A preliminary design has been made based on
the information collected during the first
reconnaissance. For the time being, the plan is
considered a 'study project'.
Compaction of the subsoil near the piers
From October, 1979, until March, 1980, the
compaction vessel 'Mytilus', made several
trial runs during which the compacting
processes were optimalized as much as
possible. The effect of variations in horizontal
and vertical distance variations, the duration of
the vibration and the speed with which the
vibrator tubes are retracted, was determined by
tests. In addition, the standards required for
compaction were described in detail for each
layer of soil, depending on the thickness and
the depth of that layer. At the same time, a
method was developed to check the results of
the compaction.
Quarry stones for the Oosterschelde barrier
Quarry stones of varying kinds and sizes will
be used for the construction of the sill, the
abutments and the transitional structure
towards the aprons of the Oosterschelde
barrier. As the traditional visual control used
up till now did not satisfy the present
requirements, a new set of objective standards
was worked out by which the supplied quarry
stones could be tested.
After years of searching in quarries in many
European countries, the contract for supply of
the stones was awarded to one German and
two Finnish firms.
Not all the material supplies can be used
immediately. As a rule, a three month supply
will be stock-piled.
In the meantime, the required equipment for
unloading and transshipping this stone, has
been installed in the working-harbours near the
Oosterschelde barrier.
Change of the current during the construction
of the Oosterschelde barrier
It is very important to know how the current
will be affected in the mouth of the
Oosterschelde during the construction activities
as based on these data, the working conditions
can be predicted for the vessels which will
have to operate in the narrowed closure-gaps.
Therefore, these changes have been intensively
studied in various hydraulic models and in a
flume; to avoid unnecessary complication, the
data of an average tide have constantly been
assumed. For this study, both mathematical
models and field measurements were used.
The discharge will sharply decrease when the
sill-beams are placed; the distribution of the
water discharge over all the closure gaps will be
changed and, consequently, in each gap there
will be differing variations.
By extrapolating the established values, the
values for spring and neap-tides could also be
determined.
Study performed in the Delta flume regarding
the cyclic energy gradients occurring under the
piers
Mathematical models were used to investigate
the cyclic energy gradients occurring in the sill
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