[0001] The present invention relates to a dredging device, comprising a dredging vessel
adapted for movement in a direction of movement, a dredge suction head connected to
the dredging vessel and having a dredge suction opening, a dredge pump placed on the
dredging vessel and having a suction connection, a suction conduit connecting the
dredge suction head to the suction connection of the dredge pump, and support means
placed between the dredging vessel and the dredge suction head for supporting the
dredge suction conduit, the support means being adapted to determine the depth of
the dredge suction head.
[0002] Such dredging devices are generally known.
GB 908529 discloses a dredger and a drag head connected to the dredger. The suction tube of
the drag head is provided with an echo sounder near the end for measuring the distance
between the drag head and the bottom.
DE 4405451 A1 discloses a drag head that is at a rear end thereof provided with water spray nozzles
at the height of a heel plate. A tubular structure provided at the rear end of the
drag head rests on the ground.
[0003] A known dredge suction head is provided here with teeth arranged around the dredge
suction opening for the purpose of dislodging from the bottom material to be brought
up by dredging. During use such a dredge suction head is dragged forward over or in
the bottom for dredging, wherein the teeth dislodge the soil. Such a dredge suction
head is therefore also referred to as a trailing dredge suction head. These are very
satisfactory for dredging bottoms of basins in which dredging is possible without
the danger of damaging structures present in the bottom for dredging. Dredging operations
must however be carried out at locations where there is danger of damaging structures
present in the bottom. Such structures are formed for instance by cables or conduits
present in the bottom. There is a danger here of the dredging head and/or the teeth
of the dredging head damaging these structures. Damage to these structures can result
in great problems since the thus resulting damage is usually difficult to repair and
so can only be repaired with great difficulty and only at high cost.
[0004] The present invention seeks to provide means for dredging with reduced danger of
damage to structures present in the bottom.
[0005] This object is achieved with a dredging device in accordance with claim 1. In the
dredging device of the above stated type, the dredge suction opening of the dredge
suction head is provided with smooth edges and the dredging device further comprises
a measuring device for measuring the distance between the dredge suction head and
the bottom.
[0006] As a result of the smooth edges the danger of damage to structures present in the
bottom is per se already greatly reduced. The measuring device moreover allows the
distance between the dredge suction head and the bottom to be visualized for the helmsman
of the dredging vessel.
[0007] The invention likewise relates to a method for dredging the bottom of a basin according
to claim 10. During dredging the dredge suction head is held at a distance from the
bottom of the basin for dredging. The danger of damage to structures present in the
bottom is reduced still further as a result of the distance relative to the bottom
and the smooth edges.
[0008] In the prior art dredge suction heads the teeth loosen the material present on the
bottom, whereby this material can be easily suctioned up. The dredging device according
to the invention is preferably not provided with teeth to obtain the smooth edges.
When use is made according to the invention of a suction opening with smooth edges
and no teeth, less material, or even no material, is expected to be loosened. It is
surprising that sufficient bottom material can nevertheless be dredged using the dredge
suction head.
[0009] In order to enable dredging with a sufficient flow rate of dredged material, it is
attractive for the surface area of the dredge suction opening of the dredge suction
head to be relatively small in relation to the periphery of the dredge suction opening.
A good dredging efficiency is achieved by making use of such an embodiment, among
other reasons because of the thus increased suction pressure. In most types of ground
sufficient material is hereby dislodged from the bottom. According to the invention
the ratio of the surface area of the dredge suction opening to the periphery thereof
lies between 0.03 m and 0.25 m and preferably between 0.05 m and 0.10 m. In an embodiment
in which the dredge suction opening takes an elongate form, it preferably has a width
of 0.5 m to 10 m, and a height of 0.05 m to 1 m. Other dimensions are however possible.
[0010] In order to enable effective use of the working width of the dredge suction head,
a further preferred embodiment proposes that the longitudinal direction of the dredge
suction opening extends substantially transversely of the direction of movement.
[0011] Although the danger of damage to structures present in the bottom, such as cables
and conduits, is already greatly reduced by the absence of teeth and other protruding
parts and by moving the dredge suction head at a distance from the bottom during use,
there is still the danger of the edges of the suction opening causing damage when
they make incidental contact with the bottom. In order to also reduce this danger,
the invention yielding smooth edges proposes that a structure with a rounded cross-section
is arranged extending at least partially around the suction opening. The rounded cross-section
is after all less likely to catch on a cable or conduit.
[0012] In the known method the known dredge suction head is dragged through the bottom,
wherein the material on the bottom is dislodged by the teeth of the dredge suction
head. In the invention these teeth are no longer present, so that it is the expectation
that less material is removed from the bottom. In order to avoid this possible drawback,
a further preferred embodiment proposes that the dredging head is provided with water
jet nozzles for generating water jets directed substantially transversely of the plane
of the dredge suction opening. The water jet nozzles serve here to dislodge the material
from the bottom. The danger of damaging the structures present in the bottom is negligible
here because the water jet nozzles are situated at a distance from the bottom during
use and because of the relatively limited operational range of the water jet nozzles.
[0013] In order to optimize the effectiveness of the water jet nozzles it is attractive
for the water jet nozzles to comprise a directional component directed toward the
dredge suction opening. Material is thus dislodged here at the location where it is
suctioned away.
[0014] The water jet nozzles are preferably placed on a tube extending in the longitudinal
direction of the suction opening.
[0015] Although the problem of damage to structures present in the bottom of the basin for
dredging is avoided, there is the danger of the suction opening incidentally resting
directly on the bottom and suctioning itself too deeply into the bottom. Structures
situated deeper in the bottom can hereby be damaged. This is also highly undesirable.
[0016] The dredge suction head suctioning itself fixedly to the bottom may be an incidental
occurrence. In order to avoid this a further embodiment proposes that in at least
one of the walls of the dredge suction head an opening is arranged in which is placed
a water valve controllable by a valve control device, and that the valve control device
is adapted to keep the valve closed and to open the valve when a determined difference
between the surrounding water pressure and the pressure prevailing inside the dredge
suction head is exceeded. This embodiment makes use of the fact that the dredge suction
head being suctioned too deeply into the ground can be detected by the increase in
the difference between the surrounding pressure and the pressure inside the dredge
suction head. This embodiment also proposes a method wherein the pressure prevailing
in the dredge suction head is determined during dredging and, in the case of deviations
from an adjustable pressure range, a valve arranged in one of the walls of the dredge
suction head is opened, preferably manually. This avoids damage being caused, for
instance to the dredge pump, by the increased underpressure in the dredge suction
head and suction conduit.
[0017] A particularly effective dredging device according to an embodiment of the invention
is characterized in that the valve control device comprises a spring which is adapted
to keep the valve closed and which, when a determined difference between the surrounding
water pressure and the pressure prevailing inside the dredge suction head is exceeded,
deforms such that the valve opens.
[0018] According to a structurally attractive embodiment, the valve with a spring as valve
control device is adapted to rest in closed position against the inner side of a valve
seat enclosing the opening. This measure has the result that the difference in pressure
between the surrounding area and the interior of the dredge suction head keeps the
valve closed due to the reaction of the spring, and no special means need be provided
in addition to the spring for the purpose of opening the valve. Should the pressure
difference become too great, the spring will then extend, causing the valve to displace
inward.
[0019] In order to further avoid these drawbacks, according to the invention the dredging
device comprises a control device adapted to control the support means for the purpose
of holding the dredge suction head at an, if desired predetermined, distance from
the bottom of the basin for dredging. This measure makes it possible to hold the dredge
suction head, and thereby the suction opening arranged therein, at a distance from
the bottom for dredging. This not only prevents the suction opening suctioning itself
fixedly to the bottom, the dredging process is moreover kept more constant because
a water flow can be maintained at all times through the dredging device. The same
embodiment results in a method of the above stated type, wherein during dredging the
dredge suction head is held as much as possible at a distance from the bottom of the
basin for dredging.
[0020] A preferred embodiment of the dredging device according to the invention has the
feature that the control device comprises a swell compensating device adapted to hold
the support means at a predetermined tension. The support means preferably comprise
one or more cables from which the suction conduit (and therefore also the dredge suction
head) is suspended. The swell compensating device measures the tension in the cable(s)
and then adjusts the length of the cable(s) such that the tension remains substantially
constant or varies within determined limits. According to the present embodiment of
the invention, the constant (desired) tension in the cable(s) is set such that it
equals the underwater weight of the dredge suction head and attachments. Should the
dredging head make incidental contact with the bottom, the tension in the cable(s)
will then decrease quickly. The swell compensating device reacts to this decrease
by tightening the cable(s), whereby the suction conduit (and the dredge suction head)
is moved in the direction of the water surface and the dredge suction head, and in
particular the dredge suction opening, still hardly rests on the bottom and pressure
on the bottom is minimal.
[0021] A further possibility for maintaining this distance is that the control device is
coupled to a measuring device for measuring the distance between the dredge suction
head and the bottom, and the control device is adapted to control the suction head
support means subject to the distance between the dredge suction head and the bottom.
This is a relatively simple embodiment, the advantages of which are likewise gained
when the distance between the dredge suction opening and the basin bottom is determined
during dredging and, in the case of deviations from an adjustable value of this distance,
the distance is adjusted. It is likewise possible to make use of a camera or ultrasonic
multibeam or the like mounted on the dredging head and pointed in the direction of
movement, the information from which is viewed in the form of images or measurement
values by a person on the dredging vessel, and the person adjusts the height of the
dredging head. It is also possible to fulfil this function electronically when means
are used for processing images.
[0022] A further option for maintaining this distance comprises the measure that the control
device is coupled to a pressure measuring device for measuring the pressure prevailing
in the dredge suction head, and that the control device is adapted to control suction
head support means subject to the pressure prevailing in the dredge suction head.
A smaller distance between the suction opening and the bottom will after all result
in a lower flow rate, and thereby in a greater pressure difference between the surrounding
pressure and the pressure prevailing inside the dredge suction head. This option can
be used instead of the above-mentioned measure of measuring the distance, but also
as addition to this measure. These advantages are likewise achieved by a method wherein
during dredging the pressure prevailing in the dredge suction head is determined and,
in the case of deviations from an adjustable pressure range, the distance between
the dredge suction opening and the basin bottom is adjusted.
[0023] Another option for maintaining this distance comprises the measure that the dredge
suction head is provided with one or more spacers. Such spacers comprise for instance
wide wheels arranged on both sides of the dredge suction head. The underside of the
wheels (or the spacer in general) is situated a certain distance, for instance 10
cm, below the underside of the dredge suction head. In the case that during dredging
the dredge suction head threatens to sink undesirably deeper than the certain distance,
the wheels make contact with the bottom without the dredge suction head coming into
contact with the bottom. Owing to the form of the wheels (a relatively large contact
surface with the bottom), and the spacer(s) in general, they will not sink into the
bottom, or do so only slightly. Another possibility comprises a carriage and/or round
tube mounted on the dredge suction head. It will be apparent that other embodiments
of spacers can be applied within the scope of the present invention.
[0024] According to the invention the dredge suction head is held a determined distance
from the bottom during dredging. A preferred distance here is less than 1 m, more
preferably less than 0.6 m, still more preferably less than 0.45 m and most preferably
less than 0.25 m.
[0025] In some dredging operations a material is brought up by dredging which oxidizes in
the air and thereby acquires environmentally undesirable properties. In order to prevent
the dredged material being exposed to the air, a preferred embodiment provides the
measure that the outlet connection of the dredge pump is connected to a pressure conduit,
the end of which debouches under the water surface. This embodiment also provides
a method wherein the material brought up by dredging is discharged under the water
surface.
[0026] The present invention will now be elucidated in more detail with reference to the
accompanying figures, in which:
- Figure 1
- is a schematic cross-sectional view of a dredging device according to the invention;
- Figure 2
- is a detail view of the dredge suction head shown in figure 1;
- Figure 3
- is a top view of the dredge suction head according to a preferred embodiment;
- Figure 4
- is a side view of the dredge suction head shown in figure 3; and
- Figure 5
- is a front view of the dredge suction head shown in figures 3 and 4.
[0027] Figure 1 shows a dredging vessel 1 which is provided with a motor, not shown in the
drawing, for driving a propeller 2 via a propeller shaft for the purpose of propelling
dredging vessel 1. Also present are devices, not shown in the drawings, for steering
dredging vessel 1, such as a rudder and transversely placed propellers for facilitating
manoeuvring.
[0028] A dredge pump, not shown in the drawings, is arranged in dredging vessel 1. Arranged
against a side wall of the dredging vessel is a dredge suction conduit 3, one end
of which is connected to the suction connection of the dredge pump. In the present
embodiment the dredge suction conduit 3 comprises two members 3a and 3b which are
connected to each other by means of a coupling allowing some relative angular displacement.
The connection between upper member 3a of dredge suction conduit 3 and the vessel
also allows angular displacement in the vertical plane and about the axis. For support
of the movable end of upper member 3a of dredge suction conduit 3 this member is connected
to a cable 4a, the other end of which is connected to a winch 5a. For support of the
movable end of lower member 3b of dredge suction conduit 3 this member is likewise
connected to a cable 4b, the other end of which is connected to a winch 5b. It is
thus possible using winches 5a, 5b to vary the height of dredge suction conduit 3.
It will be apparent that, also subject to the depth of the basin for dredging, the
number of members of dredge suction conduit 3 can be increased or decreased, with
a corresponding adjustment of the number of cables 4 and winches 5.
As shown in the detail view of figure 2, a dredge suction head 6 is arranged on the
free end of the second member 3b of dredge suction conduit 3. Figure 2 shows a bracket
plate which is attached to the second member 3b of the dredge suction conduit and
to which cable 4b is attached. This figure also shows a curved piece of pipe 8 placed
between the second member 3b of the dredge suction conduit 3 and dredge suction head
6 for the purpose of determining the angular position of dredge suction head 6. It
will be apparent that the curvature of pipe piece 8 can be adjusted subject to the
dimensioning of dredge suction conduit 3 and the depth of the bottom for dredging.
[0029] The construction of dredge suction head 6 will now be discussed with reference to
figures 3, 4 and 5. In the shown embodiment the dredge suction head 6 comprises a
round flange 10 adapted for connection to the curved pipe piece 8 or to the terminal
member 3b of suction conduit 3. Connected by welding to flange 10 are plates 11, at
least a part of which is connected to an upper plate 12, to a lower plate 13 and to
two side plates 14, 15 respectively. The upper, lower and side plates 12, 13, 14 and
15 are positioned and connected to each other in a trapezium-shaped structure. Plates
11 serve for the purpose of forming a smooth transition between flange 10 and the
rectangular structure of the dredging head. A round tube 16 is arranged around suction
opening 17 (formed by the outer ends of plates 12, 13, 14 and 15), wherein tubes 16
together form a rectangular structure enclosing an opening forming the dredge suction
opening 17. The round shape of tubes 16 prevents catching on cables or conduits present
in the bottom. A number of strengthening rib plates 18 and 19 (running respectively
in the transverse and longitudinal direction) are also arranged on the outer side
of plates 12-15. The form of plates 12-15 is chosen for the purpose of obtaining an
elongate dredge suction opening 17.
[0030] Arranged as shown in figures 3-5 in one of the tubes 16 is a series of nozzles 20
which are adapted to generate water jets directed toward the bottom. These water jets
serve to dislodge material to be dredged from the bottom. For the purpose of generating
the water jets the interiors of each of the tubes 16 are connected to each other.
A water jet tube 21 extending with its axis substantially parallel to the axis of
dredge suction head 6 is connected to tubes 16, wherein the interior of water jet
tube 21 connects to the interior of tubes 16. Arranged on the free end of the water
jet tube is a pump 22 for generating a flow in the water jet tube, and thereby water
jets flowing from nozzles 20. Arranged in upper plate 12 of dredge suction head 6
is a round opening 25 in which a water valve 26 is placed. Valve 26 normally rests
against a valve seat, not shown in the drawing, arranged in opening 25, so that the
opening is normally closed. Valve 25 is arranged on the outer side of the valve seat
so that in normal operating conditions, wherein the pressure prevailing inside dredge
suction head 6 is lower than the pressure in the surrounding area, the pressure difference
presses valve 25 onto the valve seat. For the purpose of opening the valve a mechanism,
not shown in the drawings, is arranged for causing valve 25 to open when the pressure
difference exceeds predetermine values or when there are other reasons for opening
valve 25.
[0031] It is possible and advantageous to provide dredge suction head 6 with a camera (not
shown) pointed in the direction of movement, the images from which are viewed on the
dredging vessel by a person, for instance by visualizing the images or measurement
values on a computer screen. It is also possible to fulfil this function electronically
when means are used to process images.
[0032] The above described embodiment of a dredging device according to the invention operates
as follows. During dredging of basins where there is a danger of damaging structures
present on and/or in the bottom such as cables or conduits, dredge suction head 6
is held during sailing at a distance from the bottom of the basin for dredging. Use
is made in the present embodiment of the camera images which record the distance between
the bottom and the underside of dredge suction head 6. In the case the distance exceeds
or falls below predetermined values, the height position of dredge suction head 6
is changed by means of winches 5a and 5b. Winches 5a and 5b are for instance operated
by a crew member or can be controlled in other manner. It will be apparent that other
methods of controlling the height are not precluded and that the above elucidated
controls can be combined with each other.
[0033] The water jets flowing out of nozzles 20 also ensure that material is dislodged from
the bottom irrespective of the distance between the bottom and the underside of dredge
suction head 6.
[0034] Despite the height of dredge suction head 6 being adjusted relative to the bottom
during dredging, it may occur incidentally, for instance in the case of unevenness
in the surface of the bottom, that dredge suction head 6 'suctions itself fast' into
the bottom and/or penetrates increasingly deeper therein and so threatens to damage
structures located deeper in the ground. In order to move clear of such an undesirable
situation without stopping the dredge suction pump, use is preferably made of valve
26. The mechanism, not shown in the drawings, for opening the valve is adapted to
open valve 25 in the case of an excessive pressure difference between the surrounding
pressure and the pressure prevailing inside dredge suction head 6, whereby the pressure
difference is equalized and dredge suction head 6 can be moved away from the bottom.
A possible mechanism comprises a spring.
[0035] Instead of the usual method of discharging the dredged material, such as in a bin,
a transport vessel or on land, the dredged material is preferably discharged under
the water surface in order to prevent oxidation.
1. Dredging device (1, 2, 3) comprising:
- a dredging vessel (1) adapted for movement in a direction of movement;
- a dredge suction head (6) connected to the dredging vessel (1) and having a dredge
suction opening; (17)
- a dredge pump placed on the dredging vessel (1) and having a suction connection;
- a suction conduit (3) connecting the dredge suction head (6) to the suction connection
of the dredge pump;
- support means (4, 5) placed between the dredging vessel (1) and the dredge suction
head (6) for supporting the dredge suction conduit (3), the support means (4, 5) being
adapted to determine the depth of the dredge suction head (6),
- wherein the dredging vessel (1) comprises a measuring device for measuring the distance
between the dredge suction head (6) and the bottom, characterised by a control device adapted to control the support means (4, 5) for the purpose of holding
the dredge suction head (6) at a distance from the bottom of the basin for dredging,
- wherein edges (16) of the dredge suction opening (17) of the dredge suction head
(6) that can come into contact with the bottom are provided as smooth edges (16) with
a rounded cross-section, and
- wherein the ratio of the surface area of the dredge suction opening (17) to the
periphery thereof lies between 0.03 m and 0.25 m.
2. Dredging device as claimed in any of the claims 1, characterized in that the longitudinal direction of the dredge suction opening extends substantially transversely
of the direction of movement.
3. Dredging device as claimed in any of the claims 1-2, characterized in that a structure with a rounded cross-section is arranged extending at least partially
around the dredge suction opening.
4. Dredging device as claimed in any of the foregoing claims, characterized in that the dredge suction head is provided with water jet nozzles for generating water jets
directed substantially transversely of the plane of the dredge suction opening.
5. Dredging device as claimed in any one of the preceding claims, characterized in that the control device is coupled to the measuring device for measuring the distance
between the dredge suction head and the bottom, and that the control device is adapted
to control the support means subject to the distance between the dredge suction head
and the bottom.
6. Dredging device as claimed in any one of the preceding claims, characterized in that the control device is coupled to a pressure measuring device for measuring the pressure
prevailing in the dredge suction head, and that the control device is adapted to control
the support means subject to the pressure prevailing in the dredge suction head.
7. Dredging device as claimed in any of the foregoing claims, characterized in that in at least one of the walls of the dredge suction head an opening is arranged in
which is placed a water valve controllable by a valve control device, and that the
valve control device is adapted to keep the valve closed and to open the valve when
a determined difference between the surrounding water pressure and the pressure prevailing
inside the dredge suction head is exceeded.
8. Dredging device as claimed in claim 7, characterized in that the valve control device comprises a spring which is adapted to keep the valve closed
and which, when a determined difference between the surrounding water pressure and
the pressure prevailing inside the dredge suction head is exceeded, deforms such that
the valve opens.
9. Dredging device as claimed in any of the foregoing claims, characterized in that the dredge suction head is provided with one or more spacers for adjusting the distance
between the dredge suction opening and the basin bottom.
10. Method for dredging the bottom of a basin with a dredge suction head, wherein use
is made of a dredging device according to any one of claims 1-9, wherein during dredging
the dredge suction head, or at least the suction opening thereof, is held at a distance
from the bottom of the basin for dredging, and wherein the distance between the dredge
suction opening and the basin bottom is determined during dredging and the distance
adjusted in the case of deviations from an adjustable value of this distance.
11. Method as claimed in claim 10, characterized in that the material brought up by dredging is discharged under the water surface.
1. Baggervorrichtung (1, 2, 3), die aufweist:
- ein Baggerwasserfahrzeug (1), das für die Bewegung in einer Bewegungsrichtung geeignet
ist;
- einen Baggersaugkopf (6), der mit dem Baggerwasserfahrzeug (1) verbunden ist und
eine Baggersaugöffnung (17) hat;
- eine Baggerpumpe, die auf dem Baggerwasserfahrzeug (1) angeordnet ist und eine Saugverbindung
hat;
- einen Saugkanal (3), der den Baggersaugkopf (6) mit dem Sauganschluss der Saugpumpe
verbindet;
- Halteeinrichtungen (4, 5), die zwischen dem Baggerwasserfahrzeug (1) und dem Baggersaugkopf
(6) angeordnet sind, um den Baggersaugkanal (3) zu halten, wobei die Halteeinrichtungen
geeignet sind, die Tiefe des Baggersaugkopfs (6) zu bestimmen,
- wobei das Baggerwasserfahrzeug (1) eine Messvorrichtung zum Messen des Abstands
zwischen dem Baggersaugkopf (6) und dem Boden aufweist, gekennzeichnet durch eine Steuervorrichtung, die geeignet ist, die Halteeinrichtungen (4, 5) zu dem Zweck
zu steuern, den Baggersaugkopf (6) in einem Abstand von dem Boden des Beckens zum
Baggern zu halten,
- wobei Ränder (16) der Baggersaugöffnung (17) des Baggersaugkopfs (6), die in Kontakt
mit dem Boden kommen können, als weiche Ränder (16) mit einem abgerundeten Querschnitt
bereitgestellt sind, und
- wobei das Verhältnis der Oberfläche der Baggersaugöffnung (17) zu ihrem Umfang zwischen
0,03 m und 0,25 m liegt.
2. Baggervorrichtung nach Anspruch 1, dadurch gekennzeichnet, dass die Längsrichtung der Baggersaugöffnung sich im Wesentlichen quer zu der Bewegungsrichtung
erstreckt.
3. Baggervorrichtung nach einem der Ansprüche 1 ― 2, dadurch gekennzeichnet, dass eine Struktur mit einem abgerundeten Querschnitt sich wenigstens teilweise um die
Baggersaugöffnung erstreckend eingerichtet ist.
4. Baggervorrichtung nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass der Baggersaugkopf mit Wasserstrahldüsen zum Erzeugen von Wasserstrahlen versehen
ist, die quer zu der Ebene der Baggersaugöffnung gerichtet sind.
5. Baggervorrichtung nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass die Steuervorrichtung mit der Messvorrichtung zum Messen des Abstands zwischen dem
Baggersaugkopf und dem Boden gekoppelt ist, und dass die Steuervorrichtung geeignet
ist, die Halteeinrichtungen, die dem Abstand zwischen dem Baggersaugkopf und dem Boden
unterliegen, zu steuern.
6. Baggervorrichtung nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass die Steuervorrichtung mit einer Druckmessvorrichtung zum Messen des in dem Baggersagkopf
vorherrschenden Drucks gekoppelt ist, und dass die Steuervorrichtung geeignet ist,
die Halteeinrichtung, die dem Abstand zwischen dem Baggersaugkopf und dem Boden unterliegt,
zu steuern.
7. Baggervorrichtung nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass in wenigstens einer der Wände des Baggersaugkopfs eine Öffnung eingerichtet ist,
in der ein von einer Ventilsteuervorrichtung steuerbares Wasserventil angeordnet ist,
und dass die Ventilsteuervorrichtung geeignet ist, das Ventil geschlossen zu halten
und das Ventil zu öffnen, wenn eine bestimmte Differenz zwischen dem umgebenden Wasserdruck
und dem im Inneren des Baggersaugkopfs vorherrschenden Drucks überschritten wird.
8. Baggervorrichtung nach Anspruch 7, dadurch gekennzeichnet, dass die Ventilsteuervorrichtung eine Feder aufweist, die geeignet ist, das Ventil geschlossen
zu halten, und die, wenn eine bestimmte Differenz zwischen dem umgebenden Wasserdruck
und dem Druck, der im Inneren des Baggersaugkopfs vorherrscht, überschritten wird,
sich derart verformt, dass sich das Ventil öffnet.
9. Baggervorrichtung nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass der Baggersaugkopf mit einem oder mehreren Abstandshaltern versehen ist, um den Abstand
zwischen der Baggersaugöffnung und dem Beckenboden einzustellen.
10. Verfahren zum Baggern des Bodens eines Beckens mit einem Baggersaugkopf, wobei eine
Baggervorrichtung nach einem der Ansprüche 1 - 9 genutzt wird, wobei während des Baggerns
der Baggersaugkopf oder wenigstens seine Saugöffnung in einem Abstand von dem Boden
des Beckens zum Baggern gehalten wird, und wobei der Abstand zwischen der Baggersaugöffnung
und dem Beckenboden während des Baggerns bestimmt wird und der Abstand in dem Fall
von Abweichungen von einem einstellbaren Wert dieses Abstands eingestellt wird.
11. Verfahren nach Anspruch 10, dadurch gekennzeichnet, dass das durch Baggern aufgebrachte Material unter der Wasseroberfläche abgeführt wird.
1. Dispositif de dragage (1, 2, 3) comprenant :
un cuve de dragage (1) adaptée de manière à se déplacer dans une direction de déplacement
;
une tête d'aspiration de drague (6) raccordée à la cuve de dragage (1) et comportant
une ouverture d'aspiration de drague (17) ;
une pompe de drague placée sur la cuve de dragage (1) et comportant un raccord d'aspiration
;
un conduit d'aspiration (3) raccordant la tête d'aspiration de drague (6) au raccord
d'aspiration de la pompe de drague ;
un moyen de support (4, 5) placé entre la cuve de dragage (1) et la tête d'aspiration
de drague (6) afin de supporter le conduit d'aspiration de drague (3), le moyen de
support (4, 5) étant adapté afin de déterminer la profondeur de la tête d'aspiration
de drague (6),
dans lequel la cuve de dragage (1) comprend un dispositif de mesure afin de mesurer
la distance entre la tête d'aspiration de drague (6) et le fond,
caractérisé par un dispositif de commande adapté afin de commander le moyen de support (4, 5) dans
le but de maintenir la tête d'aspiration de drague (6) à une certaine distance du
fond du bassin à draguer,
dans lequel des bords (16) de l'ouverture d'aspiration de drague (17) de la tête d'aspiration
de drague (6) qui peuvent entrer en contact avec le fond comportent des bords lisses
(16) présentant une section transversale arrondie, et
dans lequel le rapport de la surface efficace de l'ouverture d'aspiration de drague
(17) sur la circonférence de celle-ci est compris entre 0,03 m et 0,25 m.
2. Dispositif de dragage selon la revendication 1, caractérisé en ce que la direction longitudinale de l'ouverture d'aspiration de drague s'étend sensiblement
transversalement par rapport à la direction de déplacement.
3. Dispositif de dragage selon l'une quelconque des revendications 1 et 2, caractérisé en ce qu'une structure avec une section transversale arrondie est agencée de manière à s'étendre
au moins partiellement autour de l'ouverture d'aspiration de drague.
4. Dispositif de dragage selon l'une quelconque des revendications précédentes, caractérisé en ce que la tête d'aspiration de drague comporte des orifices d'injection de jet d'eau destinés
à produire des jets d'eau dirigés sensiblement transversalement par rapport au plan
de l'ouverture d'aspiration de drague.
5. Dispositif de dragage selon l'une quelconque des revendications précédentes, caractérisé en ce que le dispositif de commande est couplé au dispositif de mesure afin de mesurer la distance
entre la tête d'aspiration de drague et le fond, et en ce que le dispositif de commande est adapté afin de commander le moyen de support en fonction
de la distance entre la tête d'aspiration de drague et le fond.
6. Dispositif de dragage selon l'une quelconque des revendications précédentes, caractérisé en ce que le dispositif de commande est couplé à un dispositif de mesure de pression afin de
mesurer la pression régnant dans la tête d'aspiration de drague, et en ce que le dispositif de commande est adapté afin de commander le moyen de support en fonction
de la pression régnant dans la tête d'aspiration de drague.
7. Dispositif de dragage selon l'une quelconque des revendications précédentes, caractérisé en ce que, sur au moins l'une des parois de la tête d'aspiration de drague, il est agencé une
ouverture sur laquelle est placée une vanne d'eau pouvant être commandée par un dispositif
de commande de vanne, et en ce que le dispositif de commande de vanne est adapté afin de maintenir la vanne fermée et
d'ouvrir la vanne lorsqu'une différence déterminée entre la pression environnante
de l'eau et la pression régnant à l'intérieur de la tête d'aspiration de drague est
dépassée.
8. Dispositif de dragage selon la revendication 7, caractérisé en ce que le dispositif de commande de vanne comprend un ressort qui est adapté afin de maintenir
la vanne fermée et qui, lorsqu'une différence déterminée entre la pression environnante
de l'eau et la pression régnant à l'intérieur de la tête d'aspiration de drague est
dépassée, se déforme de telle sorte que la vanne s'ouvre.
9. Dispositif de dragage selon l'une quelconque des revendications précédentes, caractérisé en ce que la tête d'aspiration de drague comporte une ou plusieurs entretoises afin de régler
la distance entre l'ouverture d'aspiration de drague et le fond de bassin.
10. Procédé de dragage du fond d'un bassin avec une tête d'aspiration de drague, dans
lequel il est utilisé un dispositif de dragage selon l'une quelconque des revendications
1 à 9, dans lequel au cours de l'opération de dragage, la tête d'aspiration de drague,
ou au moins l'ouverture d'aspiration de celle-ci, est maintenue à une certaine distance
du fond du bassin à draguer, et dans lequel la distance entre l'ouverture d'aspiration
de drague et le fond de bassin est déterminée au cours de l'opération de dragage et
la distance est réglée en cas d'écarts par rapport à une valeur réglable de cette
distance.
11. Procédé selon la revendication 10, caractérisé en ce que les matériau remontés par dragage sont déchargés au-dessous de la surface de l'eau.