System for excavating a trench in submerged ground and associated excavation method

Abstract

The invention relates to a system (100) for excavating a trench in ground (S) submerged in water (E), the system comprising an excavation device (110) comprising: - moving means (112) capable of moving the excavation device (110) on the submerged ground (S), - excavation means capable of being supplied with pressurised water and excavating the submerged ground (S) using the pressurised water, the system further comprising control means (120) configured to control the moving means (112) and supply means (130) configured to supply pressurised water to the excavation means, characterised in that the supply means (130) comprise at least one water-jet turbine (140).

Description

Technical Field

[0001] The present invention relates to the general field of trenching, and concerns in particular a system for digging a trench in soil immersed in water, for example marine soil.

[0002] The invention applies in particular, but not exclusively, to digging a trench in soil submerged in shallow water, typically marine soil positioned less than fifty meters from the water surface (for example around a beach edge). Previous technique

[0003] As is known, the burial of an underwater pipeline is carried out using a system including a digging device capable of digging trenches in the seabed.

[0004] More specifically, such a digging device is capable of moving on the seabed, while digging the seabed using pressurized water, so as to dig a trench.

[0005] The digging device is supplied with pressurized water by a pump positioned on the deck of a boat, with a supply pipe connecting the digging device to the pump.

[0006] However, such a system is poorly suited to burying a pipeline in shallow water. Indeed, due to its size, the boat on which the pump is mounted cannot navigate in shallow waters and must therefore remain offshore. A long supply pipe must then be used, resulting in a loss of efficiency during excavation.

[0007] Therefore, there is a need for a solution that allows for the efficient digging of a trench in shallow marine soil.

[0008] Document CN 108 019 564 A is an example of prior art. Description of the invention

[0009] The present invention relates to a system for digging a trench in soil submerged in water, said system comprising a digging device including: means of transport capable of moving said digging device on the submerged ground, digging means capable of being supplied with pressurized water and of digging the submerged ground using pressurized water, said system further comprising control means configured to control the means of movement and supply means configured to supply pressurized water to the digging means, characterized in that the supply means comprise at least one hydrojet turbine, said at least one hydrojet turbine being positioned on flotation means adapted to position a water inlet of said at least one hydrojet turbine submerged in water.

[0010] The high power of the hydrojet turbine allows the digging device to efficiently excavate submerged soil. Furthermore, the dimensions of the hydrojet turbine allow it to be used in shallow water.

[0011] The hydrojet turbine can therefore be positioned close to the digging device, even in shallow waters, which allows for better recovery of the power of the hydrojet turbine.

[0012] In a particular embodiment, the digging system includes at least one personal watercraft comprising said at least one hydrojet-type turbine and flotation means.

[0013] The personal watercraft is a common piece of equipment, lightweight (approximately 300 kilograms), maneuverable, and easily transportable. Furthermore, the personal watercraft allows the hydrojet turbine to be positioned close to the dredging device, even in shallow water, thus maximizing its power output.

[0014] In a particular embodiment, the digging system further includes detection means, capable of detecting a pipe positioned on the submerged ground, and control means capable of controlling the movement means so as to dig the submerged ground below the pipe.

[0015] In one particular embodiment, the digging system further comprises: of the first means of obtaining the position of the digging device, of the second means of obtaining the depth of the water at said position of the digging device, by emission and reception of acoustic waves, the control means being capable of controlling the means of movement according to the position obtained and / or the depth obtained.

[0016] The measurement of depth using acoustic waves, made possible by the shallow water depth, allows the control means to efficiently control the means of movement of the digging device.

[0017] In a particular embodiment: The control means are positioned on a boat, the second means of obtaining the equipment are positioned at the water's surface at the position of the digging device. the second means of obtaining being capable of transmitting the depth obtained to the control means via radio waves.

[0018] In one particular embodiment, the digging device is a trenching robot.

[0019] In a particular embodiment, the digging system includes first connection means suitable for connecting the digging means to the hydrojet type turbine, taking the form of a pipeline whose length is less than thirty meters.

[0020] The short length of the pipeline helps to limit power losses between the turbine and the digging equipment.

[0021] The invention further relates to a method for digging a trench in soil submerged in water, comprising the following steps: control, by means of control, of means of movement of a digging device, so as to move said digging device on the submerged ground, supply of pressurized water, by means of supply, of means of digging said digging device, the submerged ground being excavated by the digging means using pressurized water, the supply means comprising at least one hydrojet type turbine, said at least one hydrojet type turbine being positioned on flotation means adapted to position a water inlet of said at least one hydrojet type turbine submerged in the water.

[0022] The advantages stated for the digging system as described above are directly applicable to the digging process.

[0023] In one particular embodiment, the process further comprises the following step: detection of a pipe positioned on the submerged ground, the means of movement being controlled so that the digging means dig the submerged ground below the pipeline.

[0024] In one particular embodiment, the process further comprises the following steps: obtaining the position of the digging device, obtaining the water depth at said position of the digging device, by emission and reception of acoustic waves, the control of the means of movement being carried out according to the position obtained and / or the depth obtained.

[0025] In one particular embodiment, The control means are positioned on a boat; depth determination is achieved by means of obtaining the depth, referred to as secondary means of obtaining the depth, positioned at the water's surface at the position of the digging device. the process further includes a transmission of the depth measured by the second means of obtaining the depth to the control means via radio waves. Brief description of the drawings

[0026] Other features and advantages of the present invention will become apparent from the description below, with reference to the accompanying drawings, which illustrate an example of an embodiment without being limiting in any way. In the figures: [ Fig. 1 ] There figure 1 represents, schematically, a digging system according to an example of an embodiment of the invention; [ Fig. 2 ] There figure 2 represents, schematically, a hydrojet-type turbine of a digging system according to an example of an embodiment of the invention; [ Fig. 3 ] There figure 3 represents, in the form of a flowchart, the main stages of a digging process according to an example of an embodiment of the invention; [ Fig. 4 ] There figure 4 represents, schematically, a digging system according to another embodiment of the invention; [ Fig. 5 ] There figure 5 represents, schematically, the digging system of the figure 4 ; Fig. 6 ] There figure 6 represents, schematically, a digging device of a digging system according to an example of an embodiment of the invention. Description of the implementation methods

[0027] The invention relates to a system for digging a trench in soil immersed in water, for example marine soil.

[0028] The invention applies in particular, but not exclusively, to digging a trench in soil submerged in shallow water, typically marine soil positioned less than fifty meters from the water surface (for example around a beach edge).

[0029] There figure 1 represents, schematically, an example of an embodiment of a digging system 100 according to the invention.

[0030] The digging system 100 includes a digging device 110. This digging device 110 is adapted to be immersed in water E and to be positioned against the submerged ground S.

[0031] An example of a digging device 110 is shown schematically in figure 6 .

[0032] The digging device 110 includes means of movement 112 capable of moving said digging device 110 on the submerged ground S.

[0033] Means of locomotion 112 include, for example, one or more wheels, one or more tracks, and / or one or more skids.

[0034] In addition, the digging device 110 includes digging means 116 capable of being supplied with pressurized water and of digging the submerged soil S using this pressurized water.

[0035] The digging means 116 typically include one or more nozzles, each nozzle being adapted to concentrate a jet of pressurized water, the water jet enabling the digging of the submerged soil S.

[0036] The digging device 110 may also include detection means 114 configured to detect a pipe C (for example, a cable) positioned on the submerged soil S. For example, the detection means 114 include a TSS sensor (an acronym for "Turbidity, Suspended Solids" in Anglo-Saxon terminology).

[0037] The digging device 110 is typically a trenching robot (“trencher”, in Anglo-Saxon terminology), or a sledge-type robot (“sledge”, in Anglo-Saxon terminology).

[0038] The digging system 100 further includes control means 120 configured to control the movement means 112 of the digging device 110.

[0039] The control means 120 may include a control station 122, which can be positioned on a boat B. Boat B is positioned in deep water, that is typically at a distance greater than 50 meters or 100 meters from the shore R.

[0040] In addition, the control means 120 typically include a motor 124, the motor being able to be positioned on the shore R (see figures 4 And 5 ) typically when the digging device 110 is a sled-type robot, on boat B or on the digging device 110 (typically when the digging device 110 is a trenching robot).

[0041] According to other embodiments, the control means 120 can be placed in a control station positioned on land, for example on a beach.

[0042] In addition, the digging system 100 includes supply means 130 configured to supply the digging means 116 with pressurized water.

[0043] The power supply means 130 include at least one hydrojet turbine 140. In the remainder of this description, it will be assumed that the power supply means 130 include one hydrojet turbine 140. However, the power supply means 130 may include one or more additional hydrojet turbines 140, the hydrojet turbines 140 of the power supply means 130 being connected by conduit connection means.

[0044] As shown by figure 2 , The hydrojet turbine 140 typically comprises a conduit 141 in which is positioned a propeller 142 connected to a motor 143 by a transmission shaft 144. The conduit 141 includes a water inlet 145 and opens into a nozzle 146. The nozzle 146 includes a water outlet 147, the diameter of the water outlet 147 being smaller than the diameter of the part of the nozzle 146 connected to the conduit 141.

[0045] Furthermore, the power supply means 130 include flotation means 132, on which the hydrojet-type turbine 140 is positioned. The flotation means 132 are adapted to position and maintain the water inlet 145 of the turbine 140 submerged in the water. When the turbine is operating, the water inlet 145 is typically positioned at a distance of at least approximately 20 cm from the water surface. This makes it possible to position the turbine 140 close to the digging device, even in shallow water, as the minimum water depth required for the turbine to operate is approximately 20 cm. Of course, depending on the turbine used, the minimum water depth may vary.

[0046] In one embodiment, the digging system 100 comprises a personal watercraft 150, also called a jet ski or known as a "Jet Ski" (registered trademark). The personal watercraft 150 then comprises the power supply means 130, and therefore the hydrojet-type turbine 140, and the flotation means 132, the hull of the personal watercraft 150 forming the flotation means 132.

[0047] The digging system 100 may further include first connection means 160 suitable for connecting the digging means 116 of the digging device 110 to the hydrojet type turbine 140.

[0048] The first connection means 160 can take the form of a pipe, which is for example a flexible hose. One end of the pipe 160 is connected to the water outlet 147 of the turbine 140 and a second end is connected to a water inlet of the digging means 116.

[0049] The pipeline length is typically less than thirty meters, for example 20 meters. This short pipeline length helps to limit power losses between the turbine 140 and the digging equipment 116.

[0050] The digging system 110 may also include second connection means 170 suitable for electrically connecting the control means 120 to the digging device 110. The second connection means 170 typically take the form of a cable comprising one or more electrical wires and / or optical fibers, called an "umbilical cord".

[0051] The digging system may include first means of obtaining 180, suitable for obtaining the position of the digging device 110 and / or second means of obtaining 190 suitable for obtaining the depth of the water at the position of the digging device 110.

[0052] The first means of obtaining 180 are typically attached to the digging device 110 and are for example a camera.

[0053] The second means of obtaining 190 are for example an acoustic wave transmitter-receiver, adapted to be positioned on the surface of the water above the digging device 110.

[0054] The first acquisition means 180 and / or the second acquisition means 190 are configured to transmit the obtained position and / or depth, respectively, to the control means 120. The control means 120 are then able to determine the progress of the digging device 110. The control means 120 are configured to control the movement means 112 of the digging device 110 based on the obtained position and / or depth, as well as the position of the detected pipeline. The commands transmitted to the movement means 112 are determined based on this information, particularly because the response of the digging device 110 to the commands differs when it is fully submerged and when it begins to emerge from the water and move towards the shore.

[0055] The first obtaining means 180 are typically configured to transmit the obtained position to the control means 120 via a wired connection, for example via an optical fiber from the second connection means 170.

[0056] The second means of obtaining 190 are typically configured to transmit the depth obtained to the control means 120 by radio waves.

[0057] There figure 3 represents a method for digging a trench in a soil S submerged in water, such as a marine soil. This method is implemented by a digging system conforming to an exemplary embodiment of the invention, such as the digging system 100 of the figure 1 .

[0058] The digging process is typically implemented after the implementation of a process for laying a pipe C on the submerged soil S, the pipe C being adapted to be buried in the soil S (“embedded”).

[0059] In a step E300, the digging device 110 is immersed in water E in order to be positioned against the submerged soil S.

[0060] In a step E310, the detection means 114 of the digging device 110 detect the pipe C which has previously been laid on the ground S. The detection means 114 can then transmit one or more positioning data of the pipe C to the control means 120, typically via the second connection means 170.

[0061] Furthermore, in a step E320, the first obtaining means 180 obtain the PO position of the digging device 110. The obtained PO position is then typically transmitted to the control means 120 via the second connecting means 170, for example via an optical fiber from the second connecting means 170.

[0062] In a step E330, the second obtaining means 190 obtain the depth PR of the water E at the position PO of the digging device 110, typically the position PO obtained in step E320.

[0063] The depth PR is obtained for example by an acoustic wave transmitter-receiver 190, positioned on the surface of the water E above the digging device 110. The transmitter-receiver 190 emits an acoustic wave and then receives the acoustic wave reflected by the ground S, the time elapsed between the emission of the acoustic wave and the reception of the reflected acoustic wave allowing the depth PR of the water E to be calculated.

[0064] The depth PR obtained is then transmitted to the control means 120, typically via radio waves.

[0065] In a step E340, the control means 120 control the displacement means 112 of the digging device 110, so as to move the digging device 110 on the ground S, typically as a function of the positioning data of the cable or pipeline transmitted in step E310, the position of the digging device 110 transmitted in step E320 and / or the depth of the water transmitted in step E330.

[0066] The means of movement 112 then move the digging device 110, typically along the detected pipe.

[0067] In a step E350, implemented concomitantly with step E340, the supply means 130 supply pressurized water to the digging means 116 of the digging device 110. The soil S is then excavated by the digging means 116 using the pressurized water.

[0068] More specifically, the engine 143 of the hydrojet turbine 140 is started and then drives the propeller 142 in rotation via the transmission shaft 144. The rotation of the propeller allows water E to be drawn in via the water inlet 145 and propelled towards the nozzle 146. The configuration of the nozzle 146 (i.e. the diameter of the water outlet 147 smaller than the diameter of the part of the nozzle 146 connected to the pipe 141) allows the speed of the water E flowing in the nozzle 146 to be accelerated (application of Bernoulli's theorem).

[0069] The water E then exits through the water outlet 147 and flows through the first connecting means 160 to reach the water inlet of the digging means 116, the digging means using this water E to dig the soil S.

[0070] The power of the 140 turbine is typically 310 hp (horsepower) or about 228 kW, a power of 620 hp (and therefore about 456 kW) can be obtained if two 140 turbines are coupled. The digging depth is typically two meters from the ground surface S.

[0071] The movement of the digging device 110 concomitant with the digging of the soil S allows the digging of a trench, typically along the detected pipe C and below the detected pipe C, the soil S can also be dug around the pipe C so that the pipe C can descend into the trench without friction on the sides of the trench.

Claims

1. Excavation system (100) for excavating a trench in ground (S) submerged in water (E), said system comprising an excavation device (110) comprising: - movement means (112) able to move said excavation device (110) over the submerged ground (S), - excavation means (116) able to be supplied with pressurized water and to excavate the submerged ground (S) using the pressurized water, said system further comprising control means (120) configured to control the movement means (112) and supply means (130) configured to supply pressurized water to the excavation means (116), characterized in that the supply means (130) comprise at least one hydrojet-type turbine (140), said at least one hydrojet-type turbine (140) being positioned on flotation means (132) suitable for positioning a water inlet (145) of said at least one hydrojet-type turbine (140) so that it is submerged in the water.

2. Excavation system according to Claim 1, comprising at least one watercraft (150) comprising said at least one hydrojet-type turbine (140) and the flotation means (132).

3. Excavation system according to either one of Claims 1 or 2, further comprising detection means (114) able to detect a pipeline (C) positioned on the submerged ground (S), the control means (120) being able to control the movement means (112) so as to excavate the submerged ground (S) underneath the pipeline (C).

4. Excavation system according to any one of Claims 1 to 3, further comprising: - first obtaining means (180) able to obtain the position (PO) of the excavation device (110), - second obtaining means (190) able to obtain the depth (PR) of the water (E) at said position (PO) of the excavation device (110) by emitting and receiving acoustic waves, the control means (120) being able to control the movement means (112) as a function of the obtained position (PO) and / or of the obtained depth (PR).

5. Excavation system according to Claim 4, wherein: - the control means (120) are positioned on a boat (B), - the second obtaining means (190) are positioned at the surface of the water (E) at the position (PO) of the excavation device (110), the second obtaining means (190) being able to transmit the obtained depth (PR) to the control means (120) via radio waves.

6. Excavation system according to any one of Claims 1 to 5, wherein the excavation device (110) is a trencher.

7. Excavation system according to any one of Claims 1 to 6, comprising first connection means (160) able to connect the excavation means (116) to the hydrojet-type turbine (140), these means assuming the form of a pipeline of a length of less than thirty metres.

8. Excavation method for excavating a trench in ground submerged in water, comprising the following steps: - controlling (E112), through use of the control means (120), movement means (112) of an excavation device (110) in such a way as to move said excavation device (110) over the submerged ground (S), - supplying (E350), through use of supply means (130), pressurized water to excavation means (116) of said excavation device (110), the submerged ground (S) being excavated by the excavation means (116) using the pressurized water, the supply means (130) comprising at least one hydrojet-type turbine (140), said at least one hydrojet-type turbine (140) being positioned on flotation means (132) suitable for positioning a water inlet (145) of said at least one hydrojet-type turbine (140) so that it is submerged in the water.

9. Excavation method according to Claim 8, further comprising the following step: - detecting (E310) a pipeline (C) positioned on the submerged ground (S), the movement means (112) being controlled in such a way that the excavation means (116) excavate the submerged ground (S) underneath the pipeline (C).

10. Excavation method according to Claim 8 or 9, further comprising the following steps: - obtaining (E320) the position (PO) of the excavation device (110), - obtaining (E330) the depth (PR) of the water (E) at said position (PO) of the excavation device (110) by emitting and receiving acoustic waves, the controlling (E340) of the movement means (112) being performed as a function of the obtained position (PO) and / or of the obtained depth (PR).

11. Excavation method according to any one of Claims 8 to 10, wherein: - the control means (120) are positioned on a boat (B), - the obtaining (E330) of the depth (PR) is performed by obtaining means (190) referred to as second obtaining means (190), positioned at the surface of the water (E) at the position (PO) of the excavation device (110), the method further comprising transmitting the depth measured by the second obtaining means (190) to the control means (120) via radio waves.

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