AU2020202017A1 - Dredging apparatus - Google Patents

Abstract

A dredging apparatus for collecting or removing material from an underwater, underlying surface, the dredging apparatus comprises a vehicle and a dredging head. The vehicle is operable to move along an underlying surface. The dredging head is operably coupled to the vehicle. The dredging head comprises and/or is configurable to define a first opening and a hollow chamber substantially above the first opening. At least part of the dredging head is locatable on, or at least over, the underlying surface to substantially enclose material on the underlying surface inside the chamber. The dredging head comprises at least one outlet for discharge of enclosed material from the dredging head via the outlet. The dredging head is operable to decrease a volume of the chamber when the dredging head is on, or at least over, the underlying surface, substantially enclosing material on the underlying surface in the chamber. (Figure 1.) 1/18 N NN -1 AL Tr 00

Description

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DREDGING APPARATUS

[0001] This application claims the benefit of Australian Provisional Patent Application No. 2019900935 (AU 2019900935) that was filed on 20 March 2019. The entire contents of AU 2019900935, as originally filed, are incorporated herein by reference.

FIELD

[0002] The present invention relates to apparatus, a system and a method for performing dredging. More particularly, an embodiment of the present invention relates to apparatus for performing underwater dredging by collecting or removing material, such as mud or sludge, from an underwater, underlying surface, such as a canal or river bed.

BACKGROUND

[0003] Dredges are commonly used to collect and remove material from canals, rivers, lakes, dams, the sea and other waterways. For example, dredges may be used to collect and remove mud and sludge from a canal bed to deepen and/or widen the canal.

[0004] One example of a dredge for removing material from an underwater surface, such as a sea floor or bed, is a cutter suction dredge. A cutter suction dredge typically comprises a barge that is moored to the sea floor by a one or more "spuds" or "spud legs" that extend downwardly from the barge to the sea floor, a rotating cutter head at the end of a boom that extends downwardly from the barge to the sea floor and is configured for cutting and fragmenting soils on the sea floor, a high-volume pump on the barge, and a conduit that extends between the pump and the cutter head through which water and soil around the cutter head is sucked up from the sea floor. The spuds retain the barge in a work area by preventing the barge drifting away from the work area. During dredging, winches, cables and anchors are used to swing and pivot the barge sideways about the spuds. Soil, or sludge or mud, sucked up using a cutter suction dredge generally contains around 10% solids (by volume), and about % water. The sucked up sludge or mud may be liquefied and discharged through a floating pipeline to a deposit or bund area onshore. In time, the sludge or mud settles in the bund. Further mechanical handling of the mud may be used to dry the sludge further to, for example, about 20% water content (by volume) prior to removal to a landfill. Alternatively, the dried sludge may be discharged out to sea.

[0005] Another example of a previously proposed device for removing material is an excavator mounted on a barge or other platform. The excavator may be used to excavate mud and other material from an underwater, underlying surface by digging or scooping the mud from the surface. The excavator deposits or unloads the excavated mud to a deposit area, either on the main barge or on a hopper barge moored beside or near the main barge, for subsequent transfer of the excavated material to another remote location. The excavated mud or sludge is not typically liquefied because it is more cost effective to load the mud into a hopper for removal to sea. To get the mud to a landfill would require additional handling to offload the mud from the main or hopper barge onto trucks that would then need to transport the mud to a landfill for further drying.

[0006] Problems exist with previously proposed devices for dredging material underwater. The above-described devices, for example, are relatively slow and noisy, and can be a nuisance to residents and other users of a waterway being dredged. Cutter suction dredges used in marina canals, for example, may only have a sludge output of about 30 -40 meters 3/hour. Excavators are normally even slower, typically having a sludge output of about 12 meters 3/70 minute cycle. Excavators do not normally operate continuously. Further, the described devices are often unable to work around and access areas close to and under obstacles commonly present in or around waterways, including pontoons, boats, bridges and other structures, because the barges are unable to safely and/or efficiently move close to and/or around such obstacles. Further, the described devices are typically unable to accurately dredge to a predetermined alignment and grade.

[00071 In the instance of a cutter suction dredge, the cutter dredge operation has been found to damage clay lined canals. The teethed cutter head can also damage other structure located in the area being dredged. Further, the swing cables used to swing or pivot the dredge can obstruct a canal. Further, the rotating cutter head that is configured to fragment soils underwater disturbs and muddies the surrounding water, increasing the turbidity of the water, and increasing the water content and volume of the mud/soil sucked up by the pump. In consequence, cutter suction dredges that are arranged to substantially suck up everything around the cutter head are normally inefficient. As discussed above, the disturbed mixture of water and soil, or similar material, around the cutting head that is sucked up by the pump may comprise up to about 90% water (by volume) and as little as about 10% soil. Accordingly, cutter suction dredges typically require large areas to be set aside for sludge handling.

Further, when the sludge is discharged to large settling bunds or ponds, the bunds or ponds tend to give off an unpleasant odour that can be a nuisance, particularly if the ponds are located in or near a residential area.

[0008] In the instance of an excavator mounted on a barge, the excavated material normally needs to be handled at least twice: once when the excavator deposits or unloads the excavated material to a deposit area on the main barge or on adjacent hopper barge, and again when the excavated material is transferred to another remote location. Further, an excavator mounted on a barge can normally only work in relatively shallow bodies of water because the excavator needs to reach down from the barge to the underlying surface. Further, an excavator can stir up mud being removed and create turbidity. Further, in practice, an excavator can normally only reclaim about 80% of the mud or sludge on a canal floor. Excavations are generally followed by a levelling bar drag operation to level off high spots.

[0009] A preferred embodiment of the present invention seeks to overcome or at least mitigate one or more disadvantages associated with existing devices for performing underwater dredging.

[0010] Alternatively or additionally, an embodiment of the present invention seeks to at least provide the public with a useful choice.

SUMMARY

[0011] A first aspect the present invention provides dredging apparatus for collecting or removing material from an underwater, underlying surface, the dredging apparatus comprising: a vehicle operable to move along an underlying surface; and a dredging head operably coupled to the vehicle, the dredging head comprising or being configurable to define a first opening and a hollow chamber substantially above the first opening, at least part of the dredging head being locatable on, or at least over, the underlying surface to substantially enclose material on the underlying surface inside the chamber, the dredging head comprising at least one outlet for discharge of enclosed material from the dredging head via the outlet; wherein the dredging head is operable to decrease a volume of the chamber when the dredging head is on, or at least over, the underlying surface, substantially enclosing material on the underlying surface in the chamber.

[0012] Preferably, the dredging head comprises at least a first portion and a second portion that each at least partly defines the chamber, and the dredging head is operable to reduce the volume of the chamber by moving the first portion relatively towards the second portion.

[00131 Preferably, the vehicle is operable to move in at least a first direction along the underlying surface towards the second portion to thereby reduce the volume of the chamber by moving the first portion relatively towards the second portion.

[0014] Preferably, the dredging apparatus comprises at least one connecting member connecting the vehicle to the second portion, the connecting member being operable to elevate, or lift or raise, the second portion above the underlying surface, to move the elevated second portion in the first direction away from the first portion, and then lower the second portion down on, or at least over, the underlying surface to substantially enclose material on the underlying surface in the chamber. The connecting member may be operable to lower the second portion by, for example, dropping the second portion down on the underlying surface.

[0015] Preferably, the dredging head comprises a bucket member that comprises or defines the first portion, the bucket member having a mouth, and a recess arranged to receive enclosed material in the chamber passing into the recess through the mouth, wherein the bucket member comprises the at least one outlet.

[00161 Preferably, at least part of the bucket member is moveable upwardly relative to the vehicle, and the bucket member comprises an inclined lip member arranged to deflect the at least a part of the bucket member upwardly over an obstacle on an underlying surface.

[00171 Preferably, the dredging head comprises a screen arranged across the mouth for screening enclosed material in the chamber passing into the recess through the mouth.

[00181 Preferably, the dredging head comprises at least one screen wiper arranged to move within the chamber across or adjacent an upper face of the screen.

[0019] Preferably, the dredging head comprises at least one bucket stirrer for stirring material in the recess.

[0020] Preferably, the dredging head comprises at least one bucket wiper for feeding or urging material in the recess towards a region in the recess that is associated with the at least one outlet to facilitate discharge of material via the at least one outlet.

[00211 Preferably, the dredging head comprises a screen for screening enclosed material in the chamber.

[0022] Preferably, the dredging head comprises an apron member that comprises or defines the second portion, the apron member being arranged to feed or urge enclosed material in the chamber relatively towards thefirst portion when the dredging head is operated to reduce the volume of the chamber by moving the first portion relatively towards the second portion.

[0023] Preferably, the apron member comprises an apron body that defines an end of the chamber, and two spaced-apart apron sides that each define a respective side of the chamber, the end wall comprising or defining the second portion, and each apron side extending from the apron body, generally in a direction towards the first portion, to or at least near a respective side of the first portion.

[0024] Preferably, the dredging apparatus comprises at least one sensor for sensing a pressure inside the chamber.

[0025] Preferably, the chamber has a second opening for water in the chamber to pass out of the chamber when the volume the chamber is being reduced. Preferably, the opening is an upper or top opening substantially arranged above the chamber.

[0026] Preferably, the dredging apparatus comprises at least one sensor and/or transmitter for determining a position of at least part of the dredging apparatus.

[00271 Preferably, the dredging apparatus comprises a pump for pumping or conveying material in the chamber to a remote location. Preferably, the pump is a submersible pump. Preferably, the pump is a positive displacement pump. By way of non-limiting example, the pump may be a piston pump, such as double barrel piston pump. Preferably, the pump has a working pressure ofup to at least 80 bar. Preferably, the pump is mounted or secured to the vehicle. Preferably, the pump is in communication with the dredging head via the at least one outlet.

[0028] Preferably, the dredging apparatus comprises at least one auger for feeding material from the dredging head to the pump via the outlet. The dredging apparatus may have, for example, two augers for feeding material from the dredging head to the pump via the outlet.

[0029] Preferably, the vehicle is a submersible vehicle. Preferably, the vehicle is a crawler vehicle. Preferably the vehicle is a submersible, crawler vehicle.

[00301 A further aspect of the present invention provides a system for collecting or removing material from an underwater, underlying surface, the system comprising: the dredging apparatus according to the first aspect; a surface member arranged for remotely controlling operation of the dredging apparatus from substantially above or near the water surface, and at least one umbilical extending or extendible between the dredging apparatus and the surface member for remotely controlling operation of dredging apparatus from or via the surface member when the dredging apparatus is underwater. Preferably, the surface member is a vessel, such as a boat or barge. Alternatively, the surface member may be a platform or other structure arranged for remotely controlling the operation of the dredge apparatus from above or near the surface. Preferably, the umbilical is configured to convey power and/or communications between the surface member and the dredging apparatus underwater.

[0031] Preferably, the system comprises a discharge conduit that is in fluid communication with an outlet of the pump for transferring, or conveying, material from the pump to a remote location.

[0032] A still further aspect of the present invention provides dredging apparatus for collecting a method of collecting or removing material from an underwater, underlying surface, the method comprising: providing dredging apparatus comprising a vehicle operable to move along the underlying surface, a dredging head that is operably coupled to the vehicle, and at least one outlet for discharge of enclosed material from the dredging head via the outlet, the dredging head comprising or being configurable to define a first opening and a hollow chamber substantially above the first opening; locating the vehicle on the underlying surface, locating at least part of the dredging head on, or at least over, the underlying surface to substantially enclose material on the underlying surface in the chamber; decreasing a volume of the chamber when the dredging head is on, or at least over, the underlying surface, substantially enclosing material on the underlying surface in the chamber.

[00331 Preferably, the method comprises: moving a first portion of the dredging head relatively towards a second portion of the dredging head to reduce the volume of the chamber, the first portion and the second portion each at least partly defining the chamber.

[0034] Preferably, the method comprises: moving the vehicle in a first direction along the underlying surface towards the second portion to thereby reduce the volume of the chamber by moving the first portion relatively towards the second portion.

[00351 Preferably, the dredging apparatus comprises at least one connecting member connecting the vehicle to the second portion, and the method comprises: operating the connecting member to: elevate the second portion above the underlying surface; move the elevated second portion in the first direction away from the first portion; and lower the elevated second portion down on, or at least over, the underlying surface to substantially enclose material on the underlying surface in the chamber.

[00361 Preferably, the method comprises: conveying material from the dredging head to another or remote location away from the dredging assembly, either above water or below water.

[00371 As used herein the term "underlying surface" is to be construed broadly as a bed, a floor, a bottom or other typically underwater, underlying surface of a canal, a river, a pond, a dam, a lake, an inlet, the sea or other similar body of water.

[00381 As used herein the term "material" is to be construed broadly as a substance situated underwater, which has typically settled on an underwater, underlying surface, or forming part of the underlying surface itself, including wet, soft earth or earthy matter or soil (herein "mud"), sludge, clay, sediment, and tailings and other waste. Material can include, for example, solid particles up to about 75 millimeters in diameter. Material such as, for example, mud and sludge, before being dredged, may contain up to about 50% water content (by volume).

BRIEF DESCRIPTION OF THE DRAWINGS

[00391 The present invention will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which:

[00401 Figure 1 is a schematic side view of an example of dredging apparatus, including a submersible vehicle and a dredging head that is operably supported by the submersible vehicle, showing the dredging apparatus out of water with an apron member of the dredging head resting on the ground;

[0041] Figure 2 is a schematic perspective view of the dredging apparatus of Figure 1, showing the dredging apparatus out of water with the apron member elevated above the ground;

[0042] Figure 3 is a schematic side view of an example of a pump suitable for use in the dredging apparatus of Figure 1;

[0043] Figure 4 is a schematic perspective front view of the submersible vehicle of the dredging apparatus of Figure 1, and the pump of Figure 3 mounted to or assembled with the submersible vehicle.

[0044] Figure 5 is another schematic perspective view of the submersible vehicle of the dredging apparatus Figure 1, and the pump of Figure 3 mounted to or assembled with the submersible vehicle.

[0045] Figure 6 is schematic cross-section view of the dredging apparatus of Figure 1;

[0046] Figure 7 is schematic cross-section view of a bucket member of the dredging head of the dredging apparatus of Figure 1, showing a screen, a screen wiper, a bucket stirrer, and a bucket wiper;

[00471 Figure 8(a) is a schematic front perspective view of the bucket member of Figure 7, showing the screen arranged across a mouth of the bucket member and screen wipers in a first position;

[0048] Figure 8(b) is schematic a side perspective view of the bucket member of Figure 7, showing the screen wipers in a second positon;

[0049] Figure 9 is a schematic top view of part of the inside of the bucket member of Figure 7, showing ends of augers for feeding material to the pump that extend into the bucket, the bucket stirrer and bucket wipers;

[0050] Figure 10(a) is a schematic view of an example of a boat suitable for use with the dredging apparatus of Figure 1, showing the boat out of water;

[0051] Figure 10(b) is a schematic perspective view of the boat of Figure10(b), showing the boat in a canal;

[0052] Figure 11 is a schematic perspective view of an example of a system for collecting or removing material for an underwater, underlying surface, including the dredging apparatus of Figure 1 and the boat of Figure 10;

[0053] Figure 12(a) is schematic cross-section view of the dredging apparatus of Figure 1, showing the dredging head in a first configuration with the dredging head on an underwater, underlying surface and substantially enclosing material on the underlying surface inside a chamber of the dredging head;

[0054] Figure 12(b) is schematic cross-section view of the dredging apparatus of Figure 1, showing the dredging head in a second configuration, during or after discharge of enclosed material from the dredging head;

[0055] Figure 13(a) is a schematic top view of the dredging head of the dredging apparatus of Figure 1, showing the dredging head in the first configuration shown in Figure 12(a);

[0056] Figure 13(b) is a schematic top view of the dredging head of the dredging apparatus of Figure 1, showing the dredging head in the second configuration shown in Figure 12(b);

[00571 Figure 13(c) is a schematic top view of the dredging head of the dredging apparatus of Figure 1, showing the dredging head in a third configuration with the apron member of the dredging head having been or being elevated, by arms connecting the dredging head to the submersible vehicle, above the underlying surface;

[0058] Figure 13(d) is a schematic top view of the dredging head of the dredging apparatus of Figure 1, showing the dredging head in a fourth configuration with arms of the dredging apparatus having been or being extended to move an end wall of the apron member away from the bucket member;

[0059] Figure 14(a) is a schematic front view of the dredging apparatus of Figure 1, showing the dredging head in substantially the first configuration shown in Figure 13(a);

[0060] Figure 14(b) is a schematic front view of the dredging head of the dredging apparatus of Figure 1, showing mud escaping from a bottom opening of the dredging head as the head moves from the first to the second configuration;

[0061] Figure 14(c) is a schematic front view of the dredging apparatus of Figure 1, showing the dredging head in substantially the second configuration shown in Figure 13(b);

[0062] Figure 14(d) is a schematic front view of the dredging apparatus of Figure 1, showing the dredging head in substantially the third configuration shown in Figure 13(c);

[0063] Figure 14(e) is a schematic front view of the dredging apparatus of Figure 1, showing the dredging head in substantially the fourth configuration shown infigure 13(d).

DETAILED DESCRIPTION

[0064] An example of a system 10 for collecting or removing material 12, such as mud or sludge, from an underwater, underlying surface 14, such as a canal or river bed, is schematically shown in Figure 11.

Dredging apparatus

[0065] In this example, the system 10 comprises dredging apparatus 16 schematically shown in Figures 1-9 and 11-13 for collecting or removing material 12 from the underlying surface 14, a surface or support member 18 in the form of a support vessel 20 schematically shown in Figures 10(a), 10(b) and 11 for remotely controlling operation of the dredging apparatus 16 from substantially above or near the water surface 22, at least one umbilical (not shown) that extends between the dredging apparatus 16 and the support vessel 20 for remotely controlling operation of the dredging apparatus 16 from or via the vessel 20 when the dredging apparatus 16 is underwater, and a discharge conduit 26 for transferring or conveying material 12 from the dredging apparatus 16 to another location.

[0066] The preferred embodiment dredging apparatus or assembly 16 comprises a dredging vehicle in the form of a submersible or amphibious vehicle 28 operable to move, under water, along a horizontally-extending underlying surface 14, and a dredging head 30 that is operably supported by, or connected or coupled to, the submersible vehicle 28. The moving components of the example apparatus 16 are all hydraulically or pneumatically controlled and actuated. The apparatus 16 is remotely operable or controllable from the surface 22 when the vehicle 28 is under water, such from or via the support vessel 20. In one example, the apparatus 16 may be automatically operated from the surface 22.

Dredging vehicle

[00671 With reference to Figures 1, 2, 4 and 5, the example submersible vehicle 28 is a hydraulically powered crawler vehicle having spaced-part, substantially continuous tracks 32, such as caterpillar tracks, for propelling or driving, and steering, the vehicle 28 forward and in reverse along the underlying surface 14. The vehicle 28 may also be configured to move sideways. Alternatively or additionally, the vehicle 28 may comprise one or more other means of propulsion, including wheels (not associated with a continuous track) and thruster(s). By way of non-limiting example, the example vehicle 28 is about 3.4 meters wide and has a ground clearance of about 0.3 metres.

[0068] An example prototype submersible vehicle 28 shown in the Figures was built using a Morooka@ carrier (model MST2200). The vehicle 28 as shown in Figures 1, 2 and 5 includes the operator cabin and engine/power pack of the carrier, both generally indicated by the reference number 34. However, during the construction of the vehicle 28 according to one embodiment, both the operator cabin and engine/power pack 34 were subsequently removed from the carrier leaving the carrier body or undercarriage 36, the tracks 32 of the carrier and the hydraulic motors for the drive tracks 32 (see the submersible vehicle 28 as shown in Figures 4 and 11 without the cabin and engine/power pack 34). The carrier was also widened to accommodate a pump 38 (discussed below) between the tracks 32.

[0069] The system 10 is configured to track the position or location of the dredging apparatus 16 underwater. The apparatus 16 may comprise at least one sensor and/or transmitter for determining a position or location of at least part of the dredging apparatus 16, such as the vehicle 28. The example dredging apparatus 16 comprises two spaced-apart sensors (not shown) in the form of two spaced-apart Global Positioning System (GPS) sensors. The dredging apparatus 16 is configured to transmit information, from or derived from the GPS sensors, that is indicative of a position of the dredging apparatus 16 to a controller and/or control system located on the support vessel 20 or another location typically above the surface. The dredging apparatus 16 may be configured to transmit the information via, for example, the umbilical and/or wirelessly.

[00701 In the example dredging apparatus 16, the GPS sensors are mounted or secured to the submersible vehicle 28. With reference to Figure 11, the sensors are mounted to two spaced-apart elongate, upstanding supports or towers 40 that are fixed to the body 36 of the vehicle 28 and extend upwardly from the vehicle 28. The supports 40 may be posts or poles. The sensors are each located at or near a top of a respective one of the supports. Alternatively, the sensors may be mounted spaced-apart on a single support. The supports 40 advantageously keep the sensors above the water surface 22 when the vehicle 28 is moving along an underwater, underlying surface 14. The supports 40 may be arranged to support the GPS sensors at least about five metres, preferably at least about six metres, preferably at least about seven metres, preferably at least about eight meters, preferably at least about nine meters, preferably at least about ten meters, above the underlying surface 14. By way of non limiting example only, the supports of the example dredging apparatus 16 are arranged to support the GPS sensors about eight metres above the underlying surface 14 so that submersible vehicle 28 can travel up to about seven metres underneath the water surface 22 with the sensors about one meter above the water surface 22. The height(s) of the supports/sensors may be varied for different bodies of water, depending on depth(s) of the underlying surface 14. One or more of the supports 40 may be connected to the support vessel via one or more cables, ropes and/or chains (not shown) that extend between the supports and the vessel 20 such that the support(s) 40 act like sliding anchor(s). As the vehicle 28 moves forward on its tracks 32, the vehicle 28/supports 40 can pull the vessel 20 along with the dredging apparatus 16.

[00711 The system 10 comprises the pump 38 arranged to pump material 12 from the dredging head 30 to the support vessel 20 or to a separate hopper barge. Alternatively, the pump 38 may be arranged to transfer or convey material 12 form the dredging head 30 to any other remote and/or desired location that is either under water or above water.

[0072] In the example system 10, the dredging apparatus 16 comprises the pump 38. The pump 38 is a submersible pump that is mounted to the body 36 of the vehicle 28, generally between the tracks 32. With reference to Figure 6, a rearward end of the pump 38 is pivotally mounted to the body 36 of the vehicle 28 at pivot 42, such as towards a rearward end of the body 36, so that a forward end of the pump 38 can pivotally move upwardly and then back down relative to the body 36.

[00731 The example pump 38 is a hydraulically powered pump suitable for pumping mud, concrete and similar substances. The pump 38 is a piston pump. The example pump 38 shown in the Figures is a Mecbo@ double piston mud pump 38. The pump 38 has a maximum pump pressure ofup to around 80 bar, and a pump delivery of typically about 25m3 to 90m3 per hour. The pump 38 may be able to convey material 12, such as mud, through a hose or pipeline to another location up to about 700 metres away, depending on the consistency and/or viscosity of the mud.

[0074] However, other types of pumps may be used to transfer or convey material 12 from the dredging head 30 to another location. Further, alternatively, the pump may be located above the surface, on the support vessel 20 or at another location, and coupled to the dredging head 30 via a conduit associated with an inlet of the pump 38 that extends between the pump 38 and the dredging apparatus 16.

[00751 The pump 38 comprises at least one inlet 44 for receiving, or drawing or sucking, material 12 from the dredging head 30, and at least one outlet 46. The pump 38 has two inlets 44 and one outlet 46. The inlets 44 and the outlet 46 are arranged at or near a forward end of the pump 38. Each inlet 44 is for or associated with a respective pump piston and is in fluid communication with at least one outlet 54 of the dredging head 30. The pump outlet 46 is located between the inlets 44, and is in fluid communication with, or connected to, the discharge conduit 26. The discharge conduit 26 may comprise a high-pressure hose, pipes and/ or pipeline, such as a floating pipeline.

Dredging head

[0076] The pump 38 comprises at least one auger 48, or screw, configured to rotate and feed or draw enclosed material 12 from the dredging head 30 into the pump 38. The example pump 38 comprises two augers 48. With reference to Figures 5, 7 and 9 each auger 48 extends out of a respective one of the pump inlets 44 and into the dredging head 30.

[00771 The dredging head or attachment 30 comprises or is configurable to define a first, lower or bottom, opening 50, and a hollow chamber 52, or recess or cavity, located substantially above the first opening 50. The dredging head 30 further comprises at least one discharge outlet 54 for discharge of enclosed material 12 from the dredging head 30 via the outlet. The example dredging head 30 comprises two outlets 54 that are each in fluid communication with a respective pump inlet 44.

[00781 With reference to Figure 12(a), the dredging apparatus 16 is operable to locate or positon at least part of the dredging head 30 on, or at least over, an underlying surface 14 to substantially enclose, or surround or isolate or encapsulate, material 12 on the underlying surface 14 inside the chamber 52. As the at least a part of the dredging head 30 is lowered, for example dropped, onto or over the underlying surface 14, the opening 50 that is associated with and in communication with the chamber 52 descends on material 12 on the underlying surface 14, and a bottom 56 of the dredging head 30 generally forms a seal with the underlying surface 14. Material 12 that is resting on the surface 14 passes relatively through the descending opening 50, and is substantially enclosed and isolated within the chamber 52.

[00791 The dredging head 30 is operable to decrease, or shrink or reduce, a volume or size of the chamber 52 when the dredging head 30 is on or at least over, the underlying surface 14, substantially enclosing material 12 on the underlying surface 14 in the chamber 52. Withreferenceto Figure 6, the example dredginghead30 comprises at least afirst portion or element 58 and a second portion or element 60 that each at least partly define the chamber 52. The dredging head 30 is operable to reduce the volume of the chamber 52 by moving the first portion 58 relatively towards the second portion 60.

[0080] In the example dredging apparatus 16, the second portion 60, with respect to a first forward direction of the submersible vehicle 28 that is generally indicated by the arrow 62 in Figure 6, is generally located upstream or forwardly relative to the first portion 58. Moving the submersible vehicle 28 in the forward direction 62 towards the second portion 60, when the second portion is stationary, causes the first portion 58 that may be substantially fixed relative to the vehicle 28 to correspondingly move in the direction 62 towards the second portion 60 with the vehicle 28.

[0081] The dredging apparatus 16 further comprises at least one connecting member in the form of an arm or boom 66 connecting the submersible vehicle 28 to the second portion , and arranged to move the second portion 60 relative to the vehicle 28. The apparatus 16 comprises two spaced-apart, hydraulically actuatable, generally parallel arms 66 that extend forwardly of at least part of the submersible vehicle 28. One end of each arm 66 is pivotally connected to the submersible vehicle 28 at pivot 68 at or towards a first end of the arm 66 so that the arms 66 can lift the second portion 60 up from an underlying surface 14 and lower, for example drop, the second portion 60 onto or over the underlying surface 14 as indicated by the arrow 70 in Figure 6. The arms 66 are also arranged to extend and retract, as indicated by the arrow 72 in Figure 6, so as to move the second portion 60 forwardly away from the first portion 58 and move or allow the second portion 60 to move relatively towards the first portion 58. The example arms 66 are telescoping arms, as shown extended and retracted in Figures 12(a) and 12(b) respectively. Alternatively, the connecting member(s) may have any suitable configuration. For example, the at least one connecting member may comprise an articulated arm or boom having multiple, pivotally connected sections, such as an excavator boom and stick.

[0082] The hydraulically actuatable arms 66 are remotely operable, such as from the support vessel 20, to pivotally elevate, or lift or raise, the second portion 60 relative to the underlying surface 14 and/or the vehicle 28, to extend to move the elevated second portion 60 in the forward direction 62 away from the first portion 58, and to pivotally lower the second portion 60 back down on top of, or at least over, the underlying surface 14.

[0083] The example dredging head 30 shown schematically in Figures 1, 2 and 5 generally has a box-shape. However, it will be understood that the dredging head 30 and/or the internal chamber 52 may have other shapes. The dredging head 30 comprises a receptacle in the form of a bucket member 74 that comprises, or at least partly defines or is, the first portion 58. In the example dredging head 30, the bucket member 74 substantially is the first portion58. The bucket member 74 has a mouth 76 and a recess 78 arranged below the mouth to receive material 12 from the chamber 52. In use, material 12 is passed, for example spills and/or is urged, into the recess 78 via the mouth 76 when the internal volume of the chamber 52 is reduced. The bucket member 74 also comprises the outlets 54 for discharge of enclosed material 12 from the dredging head 30 via the outlets 54 that are each in fluid communication with a respective one of the pump inlets 44. In Figures 5, 7 and 9, the augers 48 of the pump 38 can be seen extending through a rear wall 80, or blade or similar part, of the bucket member 74 and the outlets 54 into the recess 78 of the bucket member 74 (only the rear wall of the dredging head 30/bucket member 74 is shown in Figure 5). The bucket member 74 is slightly wider than the vehicle 28. By way of non-limiting example, the bucket member 74 may be about 3.5 metres wide.

[0084] At least part of the bucket member 74 is movable upwardly and then back downwardly relative to the submersible vehicle 28. In the example dredging head 30, the bucket member 74 is secured to the forward end of the pump 38 so that the bucket member substantially hangs from the end of pump 38 at the forward end of the vehicle 28 and can move up and down with the front end of the pivotally-mounted pump 38. The pump 38 may be hydraulically mounted to the vehicle 28 so that the pump 38 can hydraulically pivot to raise or lower the bucket member 74 relative to the underlying surface 14. The bucket member 74 comprises a leading, forwardly inclined lip member 82, or lip or guard, in the form of a front wall of the bucket member 74. The lip member 82 extends upwardly from a bottom of the bucket member 74 and across the width of the bucket member. When the submersible vehicle 28 is arranged on a, for example, substantially horizontal underlying surface 14 with a bottom of the bucket member 74 being maintained generally at a same level as orjust above a level of a bottom of the tracks 32 so as not to bite into the surface 14, the lip member 82 may form an angle, for example, of between about 20 to 50 degrees, preferably about 30 to 40 degrees with the underlying surface 14. For example, the underlying surface 14 may be a liner, such as a clay liner or similar liner. The lip member 82 may extend vertically upwardly, that is have a height of, between about 200 to 800 millimetres, preferably between about 300 to 700 millimetres, preferably between about 400 to 600 millimetres. When the dredging apparatus 19 is operating in a dredge mode, the bucket member that is secured to the forward end of the hydraulically pivotable pump 38 is advantageously in a hydraulic floating mode. Accordingly, when the vehicle 28 is substantially moving in the forward direction 62 and the leading lip member 82 of the bucket member 74 collides with an obstacle, the lip member 82 can deflect the bucket member upwardly so that the bucket member can ride up and over, or "float" over, the obstacle (in upwardly direction 70 in Figure 6). Typical obstacles on a canal floor may include, for example, tyres filled with concrete or other solid structures. The trailing vehicle 28 can often then drive over the obstacle. It will be understood the vehicle 28, and the dredging apparatus 16 generally, may be used to dredge on sloped surfaces.

[00851 With reference to Figures 7, 8(a) and 8(b), the dredging head 30 comprises a screen 84 for screening enclosed material 12 in the chamber 52, prior to the enclosed material 12 exiting the chamber 52 via the outlets 54. In the example dredging head 30, the screen 84 is arranged or extends across the mouth 76 of the bucket member 74 for screening enclosed material 12 inside the chamber 52 passing into the recess 78 through or via the mouth 76. The screen 84 is generally arranged above an upper edge 87 of the lip member 82, and is inclined backwardly from the upper edge 87 with reference to the forward direction 62 of the submersible vehicle 28. When the submersible vehicle 28 is arranged on a, for example, substantially horizontal underlying surface 14 with the bucket member 74 resting on the surface 14, the screen 84 may form an angle of between about 20 to 70 degrees, preferably about 30 to 60 degrees, preferably about 40 to 50 degrees with the underlying surface 14. Alternatively, the screen 84 may extend substantially horizontally, or may be declined backwardly from the upper edge 87.

[0086] The screen 84 comprises a plurality of openings 86 for material 12 inside the chamber 52 to pass through the screen 84 into the recess 78 through or via the mouth 76. The screen 84 is arranged so that material 12 passes through the screen 84 in manageable chunks or portions that the pump 38 can digest. Alternatively or additionally, the screen 84 prevents or at least inhibits solid and/or unwanted objects that are larger than the openings 86 from passing into the receptacle and the pump 38. By way of non-limiting example only, the openings 86 may be generally square, rectangular and/or triangular openings. By way ofnon limiting example only, each opening 86 may be about in the screen may about 50 by 50 millimetres. The openings 86 may be other suitable shapes and/or sizes, and may have different shapes and/or sizes to one another.

[00871 The example screen 84 is made from sections or elongate members 89 each having a triangular cross-section. The sections 89 are generally arranged in spaced-apart rows and columns, the rows being substantially perpendicular to the columns. One side of each section 86 forms part of an upwardly facing surface or face 88 of the screen 84, and the other two sides extend downwardly from the upwardly facing surface 88. Inuse,theshape(s)ofthe sections 86 advantageously inhibit material 12 passing through the screen 84 from being retarded by, and/or adhering or sticking to, the two downwardly extending sides as the material 12 passes through the screen 84.

[0088] The dredging head 30 comprises at least one screen wiper or cutter member 90 arranged to move through material 12 in the chamber 52 outside the recess 78. In the example dredging head 30, the screen wiper member 90 is arranged to move across or adjacent the screen 84 to prevent the material 12 clogging the screen 84 by wiping material 12 clear of the openings 86, and/or to form or cut material 12 passing through the screen 84 into manageable chunks. The wiper member 90 is arranged to reciprocally move in directions 92 that are substantially perpendicular relative to the forward direction 62 of the vehicle 28. The wiper member 90 is secured to a hydraulic cylinder 94 that is arranged to move the wiper member moves in a reciprocating motion as schematically indicated by the arrow in Figure 8(a). The directions 92 correspond and are parallel to the axis of the cylinder 94. The cylinder 94 is located below the screen 84 in the recess 78, and extends in a direction parallel to the edge 87. The wiper member 90 can be seen in a first position relative to the screen 84 in Figure 8(a) and in a different second position relative to the screen 84 in Figure 8(b). The example screen wiper member 90 has a rigid, generally rectangular frame 96 that comprises one or more wipers or cutters 98 that extend in a substantially perpendicular direction, to the directions of movement of the wiper member. The wiper member 90 comprises four spaced-apart wipers 98.

[0089] With reference to Figures 7 and 9, the dredging head 30 further comprises at least one bucket stirrer 100, or agitator or similar element, arranged to stir or similarly agitate material 12 in the recess 78. The stirrer 100 is generally arranged above and/or between the outlets 54 and the augers 48. The stirrer 100 is also secured to the hydraulic cylinder 94, and moves reciprocally in the directions 92 with the screen 84 wipers that are located on the other side of the screen 84. The stirrer 100 advantageously keeps material 12 in the recess 78 moving to prevent the material 12 in the recess 78 becoming static and inhibiting the feed action of the augers 48.

[0090] With reference to Figures 7 and 9, the dredging head 30 further comprises at least one bucket wiper 102, or blade or paddle, for generally feeding, or wiping or urging or pushing, material 12 in the recess 78 towards a region in the recess 78 that is associated with the outlets 54 to facilitate discharge of material 12 via the outlets. The example dredging head 30 comprises two bucket wipers 102, one arranged on the outside of each of the augers 48, arranged to feed or urge material 12 in the recess 78 towards the augers 48. The bucket wipers 102 are generally arranged below and on either side of the stirrer 100. Alternatively, the bucket wipers 102 may vertically overlap with the bucket stirrer 100. Advantageously the hydraulically actuatable bucket wipers 102 are also secured to the same single hydraulic cylinder 94 also arranged to reciprocally move the screen 84 wipers and bucket stirrer 100. Advantageously, the bucket wipers 102 are relatively thin, substantially planar, members configured to extend in a substantially vertical plane (shown in Figures 7 and 9) when feeding or pushing material 12 towards the augers 48, and then rotate/collapse substantially degrees to extend in a substantially horizontal plane (not shown) when moving away from the augers 48 so that relatively thin edges of the bucket wipers 102 substantially cut through material 12 in the recess 78 with limited resistance and without substantially feeding or pushing material 12 towards the sides of the bucket member 74 away from the augers 48.

[0091] The example dredging head 30 further comprises an apron member 104 that comprises or defines the second portion 60. In use, the apron member 104 feeds, or urges or pushes or compresses, enclosed material 12 in the chamber 52 relatively towards the first portion 58 when the dredging head 30 is operated to reduce the volume of the chamber 52 by moving the second portion 60 relatively towards the first portion 58.

[0092] The apron member 104 comprises an apron body or end part or portion 106 in the form of a wall or blade that defines one end of the chamber 52, and two spaced-apart, substantially parallel apron sides 108 in the form of side walls or blades that each defines a respective side of the chamber 52. The apron body 106 extends in a direction that is transverse, preferably substantially perpendicular, to the forward direction 62 of the vehicle 28, and comprises or at least partly defines the second portion 60. In the example dredging head 30, the apron body 106 is substantially the second portion 60. Each apron side 108 extends from a respective edge of the apron end part 106, substantially in a direction parallel to the forward direction 62 of the vehicle 28 back towards the bucket member 74, substantially to or past a respective side 110 of the bucket member 74. The apron body 106 and sides 108 are each a substantially planar member that substantially extends in a vertical plane when the apron member 104 is resting on a substantially horizontal underlying surface 14 (figures 12(a) and 12(b)). Alternatively, the apron body 106 and the apron side parts 108 may have other suitable shapes and orientations. For example, one or more of the apron body 106 and the sides 108 may be have a curved profile. Alternatively, one or more of the apron body 106 and the sides 108 may extend upwardly or downwardly in a substantially non vertical plane. For example, the body 106 may extend in a forwardly or rearwardly inclined. Or the sides 108 may extend upwardly in planes that converge towards or diverge away from or one another. By way of non-limiting example only, the body 106 may have a height of about 1.2 meters and the sides 108 may each have a height of about 1 metre.

[00931 The apron body 106 and side walls 108 and the bucket member 74 substantially define the hollow chamber 52. In use, when the submersible vehicle 28 is propelled or driven toward the apron body 106, the bucket member 74 that is substantially fixed to the front of the vehicle 28 moves towards the apron body 106, reducing the internal volume of the chamber 52. The bucket member 74, and eventually a front part of the vehicle 28, moves forwardly through and between the stationary apron sides 108. The gap between each of the bucket sides 110 and the respective apron side 108 is preferably minimised to prevent or at least inhibit material 12 in the chamber 52 exiting the chamber 52 via the gap. The gap is preferably less than about 5 millimetres. In practice, only a very small amount of material 12, such as mud, has been found to escape between the apron sides 108 and the bucket sides 110 during operation of the dredging head 30, which will be discussed below.

[0094] The dredging apparatus 16 may further comprise at least one sensor (not shown) for detecting or sensing a pressure in the chamber 52. The sensor may be used to temporarily adjust or stop, for example automatically control to adjust or stop, the operation of the dredging apparatus 16 to prevent or inhibit the pressure in the chamber 52 exceeding a pre determined pressure and to prevent damage to the dredging head 30 and/or pump 38. For example, if possible, the speed of the pump 38 discharges material via the conduit 26 may be increased. Alternatively or additionally, the movement of the submersible vehicle 28, and therefore the first portion 58/bucket member 74 towards the second portion 60 in the form of the apron body 106, may be slowed or stopped. The temporary operation of the dredging apparatus 16 may continue, for example, until the pressure in the chamber 52 has fallen below the predefined pressure indicating a manageable level.

[0095] The dredging head 30 further comprises or is configurable to define a second, upper or top, opening 112 that is associated with and in communication with and generally arranged above the chamber 52, when the apron 104 is lowered on or over an underlying surface. In use, water and/or excess enclosed material 12 in the chamber 52 can pass or spill out of the chamber 52 via the second opening 112 as the volume of the chamber 52 is reduced.

[0096] In the example dredging head 30, the first lower opening 50 is substantially located between the bucket member 74 and the apron body 106, and between the apron side walls, at or near the bottom 56 of the dredging head 30. Similarly, the second upper opening 112 is substantially located between the bucket member 74 and the apron end wall, and between the apron side walls, at or near an upper region a top of the dredging head 30.

[00971 The dredging apparatus 16 may further comprise at least one sensor (not shown) for detecting the presence of material 12 in the chamber 52. The sensor may be located within the chamber 52, for example at or near an upper or top region of the chamber 52, such as at or near the second opening 112, so as to detect when material 12 in the chamber 52 is at or near the upper region of the chamber 52. The sensor may again be used to temporarily adjust or stop, for example automatically control to adjust or stop, the operation of the dredging apparatus 16 if the material 12 in chamber 52 exceeds a predetermined level to prevent damage to the dredging head 30 and/or the pump 38. For example, the speed of the pump 38 may be increased and/or the submersible vehicle 28, if moving towards the second portion 60 in the form of the apron body 106, may be slowed or stopped.

[0098] Where practical, parts of the dredging head 30, and similarly other components of dredging apparatus 16, such as the body 36 of the vehicle 28 and the connecting arms 66, are preferably manufactured from stainless steel and/or are galvanized to facilitate operation of the dredging apparatus 16 in marine (salt water) environments.

Surface member

[0099] In the example system 10, the surface or support member 18 is in the form of a support vessel 20. The operation of the dredging apparatus 16 may be remotely controlled from or via the vessel 20. The umbilical comprises a conduit, such as flexible conduit in the form of a hose or a pipe, that extends between vessel 20 and the dredging apparatus 16, and facilitates the remote control of the dredging apparatus 16 by conveying power and/or communications, such as from one or more sensors, between the vessel 20 and typically underwater dredging apparatus 16. The umbilical extends between the vessel 20 and the vehicle 28. More than one umbilical may extend between the vessel 20 and the dredging apparatus 16. The vessel 20 comprises at least one power source, or power pack, for providing hydraulic power/high pressure fluid via the umbilical to hydraulic motors and/or pumps on the vehicle 28 and to the pump 38 to operate the hydraulically actuated components of the dredging apparatus 16, including the propulsion system of the vehicle 28 (tracks 32), the pump 38, the connecting arms 66 and the cylinder 94 when dredging. The vessel 20 may comprise, for example, one power generator or power pack for the dredging apparatus 16, and another power generator or power pack for operating the vessel 20. Alternatively or additionally, the umbilical may be configured to provide electrical power to one or more electrically driven hydraulic pumps located on the dredging apparatus, such as on the vehicle 28, and configured to provide hydraulic power to the hydraulic motors and hydraulic pumps on or associated with the vehicle 28.

[00100] The example support vessel 20 is a boat in the form of a barge. The vessel 20 is advantageously arranged to support the dredging apparatus 16, such as for maintenance, repairs or relocation of the apparatus 16, and to lift the dredging apparatus 16 out of water, such as for maintenance, repairs or relocation of the apparatus 16, and to lower the dredging apparatus 16 into water via a recess 114 that extends through the hull and deck 116 of the vessel 20. The vessel 20 may be configured to lower and lift the apparatus 16, for example, via cables extending between one or more lifting devices (not shown) on the vessel20 and the submersible dredging vehicle 28. For example, the lifting devices may be cranes suspended from gantries 118 on the vessel 20. In Figure 10(b), apparatus 16/vehicle 28 (not seen) is hanging from the gantries 118, substantially below the vessel 20 and under the surface of the water.

[00101] The vessel 20 is preferably to arranged to track, or follow or move with, the dredge apparatus 16/vehicle 28 via the two supports or towers 40. As discussed above, advantageously the supports 40 are connected to the vessel 20 by one or more cables, ropes and/or chains. Alternatively, the supports 40 may each slidably extend through a respective spacer or collar (not shown) arranged on the vessel 20. As the vehicle 28 moves along an underlying surface 14, such as a canal bed, the two supports 40 may slide through the respective spacers on the vessel and drag the vessel 20 with the vehicle 28. Alternatively, if the dredge apparatus 16 is suspended from the vessel 20 (that is, the vehicle 28 is held suspended from the vessel 20, above the underlying surface 14, such that the vehicle is not substantially supported on the surface 14), the vessel 20 may be used to push or move the dredging apparatus 16, which is suspended under the vessel 20, via the supports 40.

[00102] The vessel 20 may also have one or more spuds (not shown), for example two spaced-apart spuds, that are arranged to extend downwardly from the barge to the underlying surface 14, and to prevent the vessel 20 moving or drifting away from the work area. For example, the spud(s) may be lowered to anchor and support the vessel 20 when lifting the dredge apparatus 16 out of or lowering the dredge apparatus 16 into the water.

[00103] Alternatively, the surface member 18 may be another vessel, or platform or other structure arranged for remotely controlling the operation of the dredge apparatus from above the surface 22.

Method

[00104] An example of a method of collecting or removing material 12, in the form of mud, from an underwater, underlying surface 14, in the form of a canal floor, using the system will now be described. The canal floor may be in the form a clay liner in a canal. The height of a mud layer on the clay liner may typically be about 0.3 metres to about 1.2 metres, but could be more or less.

[00105] The example method may also be applied to collect or remove other material 12, including but not limited to sludge, clay, and tailings and other waste. The example method may also be applied to collect or remove material 12 from other underlying surfaces/bodies of water, including but not limited to a bed, a floor, a bottom or other typically underwater, underlying surface of a river, a pond, a dam, a lake, an inlet, the sea or other similar body of water.

[00106] The method comprises locating or positioning the submersible vehicle 28 on the canal floor 14. For example, with reference to Figure 11, the vehicle 28 may be driven or crawled into the canal. Alternatively, the support vessel 20 may be used to first transport the vehicle 28 to a work area in the canal and the vehicle 28 then lowered from the vessel 20 to the canal floor. The vehicle 28 may be suspended from the vessel 20 during dredging. The umbilical extends between the vehicle 28 and the vessel 20 for remotely controlling operation of the vehicle 28 from or via the vessel 20 when the vehicle 28 is underwater. The umbilical is arranged to convey power and/or communications between the vehicle 28 and the vessel 20.

[00107] With reference to Figures 12(a) and (b), Figures 13(a)-(d) and Figures 14(a)-(e) an example cycle of the operation of the dredging apparatus 16 for dredging, by collecting or removing, mud from the canal floor will now be described.

[00108] Step 1. With the hydraulic arms 66 connecting the apron member 104 to the vehicle 28 extended, and the bucket member 74 substantially stationary resting on or above the canal floor, the apron member 104 is lowered, or at least over, the canal floor 14. The dredging head 30 comprises or defines the chamber 52, and the lower and upper openings 50, 112, that are associated with and in communication with the chamber 52, when the apron 104 is lowered on or over the canal floor. The apron member 104 may be substantially dropped onto the canal floor. The dredging head 30 may substantially have a first configuration as schematically shown in Figures 12(a), 13(a) and 14(a). The bottom 56 of the dredging head around the opening 50 and the canal floor advantageously substantially form a preferably tight seal. Mud is substantially enclosed, or encapsulated or isolated, in the chamber 52 arranged above the opening 50 as the opening is lowered onto the canal floor. The apron member 104 and the bucket member 74, when the apron member 104 is resting on the canal floor, form a generally box-shaped chamber 52 that is, for example, about 3.4 meters wide by 1.6 meters long (in the forward direction 62) x 1.2 meters high. Depending on the height of the mud on the canal floor 14, the encapsulated mud may only fill a lower portion of the chamber 52, with water filling the rest of the chamber 52 above the mud.

[00109] Step 2. With the apron member 104 substantially stationary on or closely above the canal floor, the vehicle 28 with the bucket member 74 attached to the front of the vehicle 28 is gradually moved, or driven, in the forward direction 62 towards the apron body 106. A front portion of the vehicle 28 crawls into the apron member 104. The movement of the bucket member 74 into the apron member 104 reduces the internal volume of the chamber 52, and correspondingly the size of the first bottom opening 50 and the top opening 112. In Figure 14(b), some mud (generally indicted by the reference number 120) can be seen escaping from the bottom opening 50 of the dredging head 30 during this compression or reduction stage. The volume of the chamber 52 may be reduced or decreased by at least 50%, preferably at least 60%, preferably at least 70%, preferably at least 80%, preferably at least % of its original volume corresponding to the configuration shown in Figures 12(a) and 13(a). By way of non-limiting example only, the bucket member 74 may be moved about 1.1 meters into the apron member 104 to reduce the volume of the chamber 52 by about 90%. The upper edge 87 of the lip of the bucket member 74 is preferably moved to or at least close to the end wall. After the bucket has been driven into the apron member 104 the dredging head 30 may substantially have a second configuration schematically shown in Figures 12(b), 13(b) and 14(c).

[00110] Shrinking the chamber 52 substantially compresses the mud inside the chamber 52. As the volume of the chamber 52 decreases, the enclosed mud in the chamber 52 passes, or is urged or spills, through the screen 84 via the mouth 76 of the bucket member 74 into the recess 78. The augers 48 that extend into the recess 78 feed the mud in the recess 78 to the pump 38 via the outlets 54. The pump 38 is configured to convey the collected mud to another location via the discharge conduit 26. By shrinking the size of the chamber 52 in an amoebia-like action, the substantially compressed mud advantageously holds or exerts a positive pressure on the augers 48.

[00111] As the volume of the chamber 52 is decreased, water enclosed in the chamber 52 that substantially rests on top of the mud is able to pass, or spill or be squeezed, out of the chamber 52 via the top opening 112. Excess mud enclosed in the chamber 52 is similarly able to, if necessary, pass or spill out of the top of the chamber 52 if there is too much mud in the chamber 52. Any foreign objects in the mud that are unable to pass through the screen 84 may be wiped clear of the screen 84 by the screen 84 wipers and can also pass out the top opening 112.

[00112] As discussed above, the dredging apparatus 16 advantageously has sensors so that the assembly can be, preferably automatically controlled/operated to prevent the pressure inside the chamber 52 exceeding a predetermined pressure and/or mud overflowing outside of the top opening 112 if the chamber 52 is full of mud. The dredging apparatus 16 may comprise a sensor for sensing a pressure inside the chamber 52. Additionally or alternatively, the dredging apparatus 16 may comprise a sensor for determining if mud is at or near the top opening 112 of the dredging apparatus 16. To prevent excessive pressure building up inside the chamber 52 and/or mud spilling or being squeezed out of the top opening 112 of the chamber 52 as the volume of the chamber 52 is reduced, the speed of the vehicle 28 may be temporarily reduced and/or stopped, and/or the speed of the pump 38 associated with discharge of mud from the chamber 52 via the outlets 54 may be temporarily increased as discussed above.

[00113] Step 3. The arms 66 are then used to elevate the apron member 104 above the canal floor. The example arms 66 pivotally lift the apron member 104 above the canal floor. The forward motion of the dredging vehicle 28 and the bucket member 74 may be temporarily stopped so the bucket is substantially stationary when raising the apron member 104. By way of non-limiting example only, the apron body 106 may be lifted about 0.4 meters to 0.6 meters off the canal floor. After the apron member 104 has been raised, the dredging head 30 substantially has a third configuration schematically shown in Figure 13(c) and 14(d).

[00114] Step 4. The arms 66 are then used to move the elevated apron member 104 in the forward direction 62 back away from the substantially stationary bucket member 74. The arms 66 are telescopically extended to move the apron member 104 in the forward direction 62. The apron member 104 is generally located over a new section of mud on the canal floor. The dredging head 30 may substantially have a fourth configuration as schematically shown in Figure 13(d) and 14(e).

[00115] With the arms 66 at the extended position schematically shown in Figure 13(d), the apron member 104 may be about 0.7 meters to 1.2 metres off the canal floor. Typically after the arms 66 reach a furthest extension position, the apron member 104 is dropped or lowered down to the canal floor. The cycle may then be repeated by returning to Step 1 to continue collecting or removing mud from the canal floor. The vehicle 28 and dredging head may be controlled, preferably automatically controlled, from or via the support vessel 20 to remove mud from the canal floor to a predetermined alignment and grade.

[00116] Advantageously, the GPS sensors that are supported above the water surface 22 can be used to accurately determine and record the exact position of the submersible vehicle 28. From the position of the submersible vehicle 28, it is possible to determine and record the position and orientation of the dredging head 30. The dredging system 10 is therefore able to accurately determine and record the level and surfaces dredged, including alignment and gradient, and to record completed work. Further, when restarting work, it is possible to move the dredge to and recommence dredging in the exact location where work stopped.

[00117] An example system 10 and method have several advantages over previously proposed dredges. The submersible vehicle 28 is able to work accurately on canal floors and slopes. Further size of the apparatus 16 can be up-scaled or down-scaled. For example, smaller apparatus 16 may be used and/or when working under and/or around pontoons, bridges and similar structures. Further, when collecting or removing material 12, the material 12 is substantially contained within a confined space within the chamber 52 before being discharged from the chamber 52 via the pump 38, avoiding disturbing and increasing the turbidity of the surrounding water and environment. The operation of the dredging apparatus 16 advantageously is also quieter than existing dredgers. Power sources for the dredging apparatus 16 may be located at a remote location, for example, on the support vessel 20 or at another location coupled to the vessel 20, such as via a conduit arranged to convey power to the boat.

[00118] The dredging apparatus 16 is also efficient, because the apparatus 16 creates relatively little turbidity in the water. The compressed material 12 discharged from the chamber 52 via the pump 38 may comprise relatively little water. In the instance of mud, for example, the removed material 12 may comprise as little as 5-10% added water content, preferably with very little water introduced into the mud during the dredging process. The collected or removed material 12 can then be used as engineered fill. For example, the collected or removed material 12 may modified or mixed with about 3% to 6% (by volume) general purpose cement, or similar binder, and used as engineered fill.

[00119] Further, the dredged apparatus 16 may be used in varying depths of water, and as discussed above, the dredging apparatus 16 may be used to excavate to a predetermined grade and alignment.

[00120] A system 10, apparatus 16 and method have been described by way of example only and modifications may be made thereto without departing from the scope of the invention.

[00121] For example, the apron member 104 may be secured to the front of the vehicle 28, the bucket member 74 may be located downstream (in the direction 62) of the apron member 104, and the arms 66 may connect the bucket member 74 to raise and drop the bucket member 74 to the vehicle 28. A conduit may extend between a discharge outlet in the bucket member 74 to the pump 38, or the pump 38 may be mounted to the bucket member 74. The volume of the chamber 52 may be decreased by moving the vehicle 28 and the apron member 104 at the front of the vehicle 28 towards the bucket member 74.

[00122] Alternatively, instead of the apron member 104 comprising side walls, the bucket member 74 may comprise side walls that extend away from the bucket member 74. Instead of an apron member, the apparatus may comprise a blade that is located downstream of the bucket member 74. When the volume of the chamber 52 is reduced by driving the bucket member towards the blade, the sides of the bucket member may move or slide past sides of the blade.

[00123] Further, the first portion 58 has been described above as being in the form of the bucket member 74 having a recess 78 and a mouth 76 generally arranged above the recess 78 for mud to pass into the recess 78. Alternatively, the first portion 58 may be in the form of an end wall or blade (for example, in the form of the rear wall 78 of the bucket member 74 shown in Figure 5), similar to the end wall of the feed apron, with a discharge outlet in communication with the pump 38 via an outlet in the end wall.

[00124] Further, although the vehicle 28 according to one embodiment of the present invention is in the form of a submersible or amphibious vehicle, in an alternative embodiment of the present invention the vehicle may not be designed or configured to be fully submersible or amphibious. For example, the dredging apparatus may be configured so that only part of the dredging vehicle is designed to be located, travel and/or operate under the water surface. With reference to Figures 1, 2, 5 and Figure 14(a)-(e), for example, the engine/power pack 34 may be mounted or fixed to, or form part of, the vehicle, and be generally located above the carrier body or undercarriage 36. The engine/power pack 34 may not be configured to be located, travel and/or operate under the water surface. A vehicle having a power source 34 for providing hydraulic power/high pressure fluid to the motors and/or pumps on the vehicle 28 that is fixed to the dredging vehicle may be suitable for dredging in canals, or ponds or the like, that are up to, for example, about 1,400 millimetres deep so that the power source 34 is substantially kept above the water surface of the canal or pond. A stand-alone vehicle, which has or is associated with its own power pack or power source, may obviate the need for an umbilical that extends between the dredging apparatus and a support member (such as vessel ).

[00125] While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not by way of limitation. It will be apparent to a person skilled in the relevant art that various changes in form and detail can be made therein without departing from the spirit and scope of the invention. Thus, the present invention should not be limited by any of the above described exemplary embodiments.

[00126] The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that that prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavor to which this specification relates.

[00127] Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

[00128] As used herein the term "(s)" following a noun means the plural and/or singular form of that noun.

[00129] As used herein the term "and/or" means "and" or "or", or where the context allows both.

Claims (28)

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

1. Dredging apparatus for collecting or removing material from an underwater, underlying surface, the dredging apparatus comprising: a vehicle operable to move along an underlying surface; and a dredging head operably coupled to the vehicle, the dredging head comprising or being configurable to define a first opening and a hollow chamber substantially above the first opening, at least part of the dredging head being locatable on, or at least over, the underlying surface to substantially enclose material on the underlying surface inside the chamber, the dredging head comprising at least one outlet for discharge of enclosed material from the dredging head via the outlet; wherein the dredging head is operable to decrease a volume of the chamber when the dredging head is on, or at least over, the underlying surface, substantially enclosing material on the underlying surface in the chamber.

2. The dredging apparatus as claimed in claim 1, wherein the dredging head comprises at least a first portion and a second portion that each at least partly define the chamber, and the dredging head is operable to reduce the volume of the chamber by moving the first portion relatively towards the second portion.

3. The dredging apparatus as claimed in claim 2, wherein the vehicle is operable to move in at least a first direction along the underlying surface towards the second portion to thereby reduce the volume of the chamber by moving the first portion relatively towards the second portion.

4. The dredging apparatus as claimed in claim 3, comprising at least one connecting member connecting the vehicle to the second portion, the connecting member being operable to elevate the second portion above the underlying surface, to move the elevated second portion in the first direction away from the first portion, and then lower the second portion down on, or at least over, the underlying surface to substantially enclose material on the underlying surface in the chamber.

5. The dredging apparatus as claimed in any one of claims 2 to 4, wherein the dredging head comprises a bucket member that comprises or defines the first portion, the bucket member having a mouth, and a recess arranged to receive enclosed material in the chamber passing into the recess through the mouth, wherein the bucket member comprises the at least one outlet.

6. The dredging apparatus as claimed in claim 5, wherein at least part of the bucket member is moveable upwardly relative to the vehicle, and the bucket member comprises an inclined lip member arranged to deflect the at least a part of the bucket member upwardly over an obstacle on an underlying surface.

7. The dredging apparatus as claimed in claim 5 or claim 6, wherein the dredging head comprises a screen arranged across the mouth for screening enclosed material in the chamber passing into the recess through the mouth.

8. The dredging apparatus as claimed in claim 7, wherein the dredging head comprises at least one screen wiper arranged to move within the chamber across or adjacent an upper face of the screen.

9. The dredging apparatus as claimed in any one of claims 5 to 8, wherein the dredging head comprises at least one bucket stirrer for stirring material in the recess.

10. The dredging apparatus as claimed in any one of claims 5 to 9, wherein the dredging head comprises at least one bucket wiper for feeding or urging material in the recess towards a region in the recess that is associated with the at least one outlet to facilitate discharge of material via the at least one outlet.

11. The dredging apparatus as claimed in any one of claims 1 to 5, wherein the dredging head comprises a screen for screening enclosed material in the chamber.

12. The dredging apparatus as claimed in any one of claims 2 to 11, wherein the dredging head comprises an apron member that comprises or at least partly defines the second portion, the apron member being arranged to feed or urge enclosed material in the chamber relatively towards the first portion when the dredging head is operated to reduce the volume of the chamber by moving the first portion relatively towards the second portion.

13. The dredging apparatus as claimed in claim 12, wherein the apron member comprises an apron body that defines an end of the chamber, and two spaced-apart apron sides that each define a respective side of the chamber, the apron body comprising or at least partly defining the second portion, and each apron side extending from the apron body, generally in a direction towards the first portion, to or at least near a respective side of the first portion.

14. The dredging apparatus as claimed in any one of claims 1 to 13, comprising at least one sensor for sensing a pressure inside the chamber.

15. The dredging apparatus as claimed in any one of claims I to 14, wherein the chamber has a second opening for water in the chamber to pass out of the chamber when the volume the chamber is being reduced.

16. The dredging apparatus as claimed in any one of claims 1 to 16, comprising at least one sensor and/or transmitter for determining a position of at least part of the dredging apparatus.

17. The dredging apparatus as claimed in any one of claims I to 16, comprising a pump for conveying material in the chamber to a remote location.

18. The dredging apparatus as claimed in claim 17, comprising at least one auger for feeding material from the dredging head to the pump via the outlet.

19. The dredging apparatus as claimed in any one of claims 1 to 18, wherein the vehicle is a submersible vehicle.

20. The dredging apparatus as claimed in any one of claims I to 19, wherein the vehicle is a crawler vehicle.

21. A system for collecting or removing material from an underwater, underlying surface, the system comprising: the dredging apparatus as claimed in any one of claims 1 to 20; a surface member arranged for remotely controlling operation of the dredging apparatus from substantially above or near the water surface, and at least one umbilical extending or extendible between the dredging apparatus and the surface member for remotely controlling operation of dredging apparatus from or via the surface member when the dredging apparatus is underwater.

22. The system as claimed in claim 21, when dependent on claim 16, comprising: a discharge conduit that is in fluid communication with an outlet of the pump for transferring, or conveying, material from the pump to a remote location.

23. A method of collecting or removing material from an underwater, underlying surface, the method comprising: providing dredging apparatus comprising a vehicle operable to move along the underlying surface, a dredging head that is operably coupled to the vehicle, and at least one outlet for discharge of enclosed material from the dredging head via the outlet, the dredging head comprising or being configurable to define a first opening and a hollow chamber substantially above the first opening; locating the vehicle on the underlying surface, locating at least part of the dredging head on, or at least over, the underlying surface to substantially enclose material on the underlying surface in the chamber; and decreasing a volume of the chamber when the dredging head is on, or at least over, the underlying surface, substantially enclosing material on the underlying surface in the chamber.

24. The method as claimed in claim 23, comprising: moving a first portion of the dredging head relatively towards a second portion of the dredging head to reduce the volume of the chamber, the first portion and the second portion each at least partly defining the chamber.

25. The method as claimed in claim 24, comprising: moving the vehicle in a first direction along the underlying surface towards the second portion to thereby reduce the volume of the chamber by moving the first portion relatively towards the second portion.

26. The method as claimed in claim 25, wherein the dredging apparatus comprises at least one connecting member connecting the vehicle to the second portion, and the method comprises: operating the connecting member to: elevate the second portion above the underlying surface; move the elevated second portion in the first direction away from the first portion; and lower the elevated second portion down on, or at least over, the underlying surface to substantially enclose material on the underlying surface in the chamber.

27. The method as claimed in any one of claims 23 to 26, comprising: conveying material from the dredging head to a remote location.

28. The dredging apparatus as claimed in any one of claims 23 to 27, wherein the vehicle is operable to move along the underlying surface is a submersible vehicle operable to move along the underlying surface.

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106 112 30 52 108 68 104 38 Figure 1

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106 Figure 2