Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Method for the automatic adjustment of ground profiles in waters
The invention relates to a method for the automatic adjustment of ground
profiles in
waters, in particular in a gravel pit to be sunk, by means of floating
conveying devices
DE-A 199 42 472 discloses a method for the cartographically controlled sinking
of
waters by means of floating conveying devices. Herein, at least one base map
on the
base of a screen or vector map is produced from an existing water area map, in
that the
water is scanned by means of suitable devices for producing a three-
dimensional depth
profile. The position and orientation of the floating conveying device,
typically a floating
dredger, is determined and marked in the base map. The so formed base map is
stored
in the computer of the system. The water ground and, if necessary, the water
bank are
scanned in short intervals in the near environment of the conveying device.
The data
which have been obtained thereby form a depth profile. On the base of the
depth profile,
an updated base map will be made. Such map elements, for which the depth lines
have
changed due to the sinking of the water ground, will be adapted, wherein the
depth
profile is preferably produced as colour running profile.
Floating conveying devices, in particular floating dredgers, can have
different extraction
means. These ones are preferably clams, cutting wheels, bucket chains or
suction
pipes, wherein the material layers present on the water ground, such as for
example
slush or gravel, are received by the respective extraction means and brought
to their
further destination.
For operating a floating conveying device, in particular for changing the
position, service
staff is required. The staff changes the length of the traction ropes, such
that the floating
conveying device is brought from a first extraction position into another
extraction
position.
The personnel costs of the service staff are naturally a substantial part of
the operating
costs. But over all, a plurality of parameters (water depth on the extraction
site, density
and Braining of the material to be extracted, water temperature, pressure in
the suction
pipe for suction dredgers, etc.) have to be considered and taken as base for
decisions
for the control of the device in order to obtain a continuous and optimum
operation of
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the conveying device. The simultaneous consideration of all the influencing
variables
which are essential herein and the transformation into optimizing control
commands
overtaxes the capacity of the service staff and can only be realized by modern
control
and computer technique.
It is the aim of the invention to put this understanding into practice in
order to provide an
automatic, almost staff-less and over all continuous operation with an
improved
extraction performance, higher extraction precision and reduced operational
costs.
This aim is achieved by a method for the automatic adjustment of ground
profiles in
waters, in particular in a gravel pit to be sunk, by means of floating
conveying devices,
in that at least one base map is produced from an existing water area map, the
water is
scanned by means of suitable devices for obtaining a depth profile, the
position as well
as the orientation of the conveying device is determined, a cyclic updating of
the actual
water depth and a comparison with a desired depth profile are realized,
wherein pre-
determinable parameters of the extraction means of the conveying device are
measured
in the course of a layer-wise sinking operation and supplied to a control
unit, and that in
case of divergences from the parameters, the position of the conveying device
will be
changed.
Advantageous embodiments of the method according to the invention are
disclosed in
the sub-claims.
Depending on the material to be extracted and the extraction depth,
parameters, such
as the negative pressure, which is for example comprised between 0.5 and 0.8
bar, can
be a corresponding threshold value. If the values remain under this threshold
value, for
example because no mixture, but only water is still extracted, this is a
possible criterion
for the fact that the position of the conveying device has to be changed. The
extraction
means has then namely either reached a depth, on which it must not further be
lowered
because of respecting a pre-determined desired depth, or it is on a
mechanically
maximum lowering depth thereof. Another parameter could be for example the
performance characteristics of the used pump, in particular a vacuum pump,
with
respect to the rotational speed, performance and efficiency thereof. If, for
example, the
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receiving area of the extraction means is clogged, this can lead to the
cavitation of the
pump as well as to the breakdown thereof.
Another parameter is also the flow rate of the water-solid-mixture after
passage through
the pump, i.e. in the subsequent pipeline.
Depending on the fact whether the decisive parameters exceed or remain beneath
pre-
determined limits, the control unit decides that the extraction at the given
position has to
be terminated. The position of the conveying device is modified automatically
by the
control unit which acts upon the mooring winches.
With the change of position the control unit brings the floating conveying
device into a
new extraction position, where material which is worth to be extracted is
present
according to the base map.
By means of adjustment of a certain maximum extraction depth, an economic and
reasonable layer-wise extraction of the material to be extracted becomes
possible.
Besides, the system detects extraction obstacles, which are marked on the base
map,
such as for example loam banks. Such obstacles are circumvented. Finally it is
also
possible to intervene in the automatics of the position change by means of
specified
desired parameters.
In contrast to the common methods, the subject of the invention furthermore
allows to
produce complex harmonious ground profiles depending on the requirements of
the
authorizing agencies and the operators. This ability is of a special
importance, since at
least in the filed of wet extraction of gravel and sand, more and more
ecologic
requirements with respect to flat water zones as spawning or brooding zones
and the
like have to be met.
