Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Water-control structure and cladding element therefor
The invention relates to a water-control structure, comprising a control
structure
body which is exposed, at least on one side, to the effects of a body of
water, and
adjacent cladding elements which cover the control structure body and which
each
comprise a base, and adjacent bases of the cladding elements between
themselves
define passages for allowing water through.
Such a water-control structure is generally known. The cladding elements which
could be made, for example, from concrete, ensure that the control structure
body is
better protected against the effects of the water, in particular against the
effects of
waves. The control structure body may be made of, for example, sand, clay or
mixtures
thereof with hard core, and would run the danger of being swept away or eroded
if it
were directly exposed to water.
The base of the cladding elements is usually configured such that a certain
percentage of open spaces are left between adjacent bases, so that water which
has
entered the control structure body is able to escape without the cladding
being forced
upwards from below as a result of water pressure. These open spaces may
comprise a
filling of, for example, hard core or gravel. This hard core results in the
cladding
elements performing a clamping action on each other. As a result thereof, the
stability
of the layer of cladding elements is increased, while the water-permeability
is
maintained. The upper side of the cladding elements has a shape which is
adapted to
the circumstances determined by the body of water, and may, for example, in
particular
be suitable for dissipating wave energy.
Water-control structures may be configured in various ways. By way of
example, water-control structures whose free surface is formed by the top of
the
cladding elements are mentioned. Other water-control structures have a soil
layer
which determines the top surface. In the latter cases, it is very important
that this soil
layer is securely anchored with respect to the control structure body. It is
an object of
the invention to provide an improved stabilizing action for this latter type
of water-
control structures.
This object is achieved by the fact that the cladding elements are covered by
a
covering layer which is provided between and above the projections. With the
water-
control structure according to the invention, the covering layer, such as a
soil layer, is
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stabilized by the fact that it is anchored on the underside by means of the
projections of
the cladding elements which protrude therein. As a result thereof, the
covering layer is
securely fixed, even when it is subjected to the effects of water currents,
waves and the
like. It is not readily possible to make the complete covering layer slide
with the water,
not even as a result of the inclined position which the soil layer often has.
This
retaining effect is partly due to the projections each being embedded in the
covering
layer around the entire periphery thereof.
Preferably, the cladding elements are configured such that they have one and
only one projection which is upright with respect to the base. As a result
thereof, the
production is facilitated. The projections may be completely embedded in the
soil layer
on all sides, thus ensuring a good retaining action on the soil layer. In this
connection,
each projection is preferably at a distance from every other projection and
preferably
does not touch any other projection.
The cladding elements with covering layer may be situated on the side which
faces the body of water, and/or on the side which faces away from the body of
water. In
the latter case, the covering layer also offers protection against water which
swaps over
the water-control structure. Usually, this leads to the unprotected covering
layer, such
as a soil layer, being washed away, resulting in a weakening of the water-
control
structure from the rear and consequently giving way. However, due to the
stabilizing
action of the cladding elements according to the invention, crumbling can be
prevented.
Preferably, the cladding consisting of adjacent cladding elements and/or
adjacent damping elements extends across the crown of the control structure
body and
across at least one side in an uninterrupted manner. Preferably, the cladding
extends
across both sides and the crown in an uninterrupted manner. Such a continuous
cladding has various advantages. Firstly, such a cladding forms a skin which
stabilizes
the climate in the dike. As a result thereof, the control structure body is
prevented from
becoming too wet in the winter and too dry in the summer. This stabilizing
effect is
particularly important in the case of peat dikes, since the formation of
cracks due to the
control structure body drying out can thereby also be prevented. It is found
that, in
practice, problems occur mainly in the locations at the transitions in the
cladding. This
may affect transitions between surfaces which are arranged at different
angles, such as
from oblique to horizontal, with stepped transitions and the like. Due to the
locally
higher flow rates, these transitions may suffer from weakening phenomena. By
means
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of a continuous cladding consisting of closely adjoining cladding elements,
such
phenomena can be prevented. The cladding element may be configured in
different
ways. For example, the base may have an approximately substantially square
periphery.
Also, the sides of the base may be convexly curved and adjoin one another via
an
obtuse internal angle. In other words, the cladding element has a basic shape
which is
square, with the sides of the base being slightly convexly curved to the
outside. Due to
these slightly convexly shaped sides, adjacent cladding elements only contact
one
another to a limited degree and mutually enclose open spaces. As has already
been
mentioned, these open spaces may contain gravel or hard core which promotes
the
mutual retaining action of the cladding elements. Such a series of adjacent
cladding
elements has an acceptable percentage of open spaces, so that no great water
pressures
can occur underneath the cladding.
In a further advantageous embodiment, the sides of the base are directed
obliquely towards one another, in an upward direction. For example, the cross
section
of the base in the upward direction may decrease monotonously up to and
including the
attachment of the projection at the base. Hard core can be dumped in the gaps
which
are thus created between the bases of the cladding elements, and exert a
clamping
action and consequently a retaining action on the cladding elements.
The projection may have different shapes; thus, the cross section of the
projection may be circular. Alternatively, the cross section of the projection
may be
approximately square, but other shapes, such as triangular, are also possible.
Furthermore, the surface of the cross section of the projection may decrease
in the
upward direction. As a result thereof, the soil layer can penetrate well up to
and around
the cladding elements. In this connection, the surface of the top of the
projection may
be smaller than any cross section of the projection; optionally, the cross
section of the
projection in the upward direction may decrease monotonously up to and
including the
top.
The above-described water-control structure offers a multiple, fail-safe
protection. This is the result of the construction which consists of,
successively, the
cladding elements, the soil layer dumped on top thereof and the grass layer,
which
together form a continuous top layer. This top layer provides the desired
water-control
properties. However, if the grass layer were to be washed away for some
reason,
followed by the soil layer, the layer of cladding elements still offers stable
protection.
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As a result thereof, the control structure body remains protected against
attacks by
water sweeping over the dike.
Finally, the invention relates to a cladding element for a water-control
structure
as described above, comprising a base and one and only one projection which is
upright
with respect to the base, wherein the surface of the cross section of the
projection
decreases in the upward direction up to the top of the projection. Such a
cladding
element is preferably made of concrete. The shape of the cladding element is
preferably
detachable, that is to say that the cladding element which is produced in a
mould can be
removed from said mould in one piece. This can be achieved if the cross
section of the
projection decreases monotonously from the base in the upward direction up to
the top
of the projection. The base itself may likewise have such a detachable shape.
The invention will now be explained in more detail by means of exemplary
embodiments which are illustrated in the figures, in which:
Fig. 1 shows a longitudinal section through a dike.
Fig. 2 shows an enlarged view of the longitudinal section from Fig. 1.
Fig. 3 shows a perspective view of a section of the dike with the soil layer
partly
removed.
Fig. 4 shows a first variant of the cladding elements in perspective.
Fig. 5 shows a second variant of the cladding elements in perspective.
Fig. 6 shows a second embodiment of a dike.
Fig. 7 shows a third embodiment of a dike.
The water-control structure illustrated in Figs. 1 and 2 consists of the
control
structure body 1, made of for example sand, clay and the like, and the
cladding 2. This
cladding 2 in turn consists of the cladding elements 3, as illustrated on a
larger scale in
Fig. 2, with the soil layer 4 on top. This soil layer may be covered with
grass 5. The
water-control structure has a side 10 which faces a body of water 12 and a
side 11
which faces away from the latter.
The cladding elements 3 each consist of a base 6 and a projection 7 which is
vertical with respect to the base, as is also shown in perspective in Figs. 3
and 4. The
projection 7 has smaller cross sections than the base 6; as a result of which
there is a
leap in the cross sections of the cladding element 3 at the transition between
the
projection and the base. In the embodiment of these Figs. 3 and 4, the
projection 7 has
circular cross sections whose radius becomes increasingly smaller from the
base 6. As a
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result thereof, the soil layer 4 can readily penetrate as far as between the
projections 7.
The roots 19 of the grass 5 could also penetrate between the projections 7 and
also
between the bases 6 of the cladding elements 3 as far as into the control
structure body
1, which is advantageous for the stability of the cladding 2. In the variant
from Fig. 4,
5 the projections 7 have circular cross sections. The gaps between the
cladding elements
taper upwardly, although this cannot be seen in Figs. 3-5.
The base 6 of the cladding elements 3 may have sides 8 which are curved
slightly convexly, so that gaps 9 between adjacent sides 8 of neighbouring
cladding
elements 3 are prevented. Furthermore, the sides may recede slightly in the
upward
direction, so that the gaps between the sides 8 of neighbouring cladding
elements 3
taper downwardly in the shape of a wedge. By introducing hard core 13 in the
form of
fine granular material into these gaps, the stability of the cladding layer is
greatly
improved due to mutual clamping of the cladding elements. In addition, the
water-
permeability is maintained due to the gaps, so that a build-up of pressure
from water
behind the cladding elements is prevented or limited. This also has an
advantageous
effect on the stability of the layer of cladding elements 3.
Fig. 6 shows a further possible embodiment of a dike, in which cladding 2
comprising cladding elements 3 with a soil layer 4 on top is only present on
the side
facing the body of water 12. This cladding 2 is only provided in the area
which is
influenced by the body of water 12. The other parts of the dike are
constructed in a
traditional style.
Fig. 7 shows a dike which is provided with the cladding elements 6 according
to
the invention on the side 11 facing away from the body of water. These
cladding
elements retain the soil layer 4, even if water were to pour over the dike. On
the side 10
facing the body of water damping elements 15 are provided, each consisting of
a base
6, a neck 16 and a head 17. These damping elements 15 are suitable for damping
the
waves to which the dike is exposed. The water which strikes the side 10 of the
dike is
tempered in the damping spaces 14 which are situated between the heads 17 and
necks
16 of the damping elements 15.
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List of reference numerals
1. Control structure body
2. Cladding .
3. Cladding element
4. Soil layer
5. Grass layer
6. Base
7. Projection
8. Side
9. Gap
10. Side
11. Side
12. Body of water
13. Hard core
14. Damping space
15. Damping element
16. Neck
17. Head
18. Crown
19. Root
