A method for installing submarine cables between land and sea

Abstract

This invention discloses a method for installing submarine cables between land and sea, belonging to the technical field of submarine cable installation and construction. It includes the submarine cable laying process at the starting land switch station, specifically including the following steps: Step 1, inspection of the landing site at sea; Step 2, positioning of the vessel; Step 3, sealing of the submarine cable head; Step 4, laying of traction steel wire; Step 5, landing construction of the submarine cable head: starting the traction winch and the electric submarine cable reel on the construction vessel, the submarine cable on the electric submarine cable reel is unwound while the traction winch pulls it. During the unwound and traction process of the submarine cable, a float is tied to the submarine cable every 1-3m, and rollers are set below the submarine cable every 3-4m; Step 6, moving the submarine cable head to the switch station tower; Step 7, moving the submarine cable head to the switch station tower and fixing the submarine cable. In the submarine cable laying process at the initial land-based switch station, this invention arranges buoys and rollers on the submarine cable to make the submarine cable section float on the sea surface to avoid contact with the seabed. When the submarine cable is moved to land, the rollers contact the land, which not only reduces slip resistance and lowers traction energy consumption, but also protects the submarine cable and prevents it from being scratched during the slip process.

Description

Technical Field

[0001] This invention relates to the field of submarine cable installation and construction technology, specifically a method for installing submarine cables between land and sea. Background Technology

[0002] Currently, the installation of submarine cables between offshore booster stations and onshore switch stations faces the following problems: First, during the process of pulling the cable head from the offshore construction vessel to the land, the cable is very heavy, weighing approximately 125.7 kg per meter. It slides along the seabed and land, resulting in high resistance, high energy consumption, and sometimes damage to the cable during this sliding process. In existing technology, after the cable head reaches the land, it is placed on a pulley. However, in the tidal flats, the cable has already touched the ground and slides along the bottom surface of the tidal flats, making the seabed in the tidal flats even more... Firstly, the submarine cable is easily scratched, and the onshore switch station is a long distance from the sea. If the section of submarine cable on land is not in contact with the ground, multiple pulleys must be installed on land. Since the submarine cable is very heavy, the manpower and labor required to arrange multiple pulleys on the submarine cable are very large. Secondly, the bottom side of the offshore substation is subject to the impact of seawater, and scour pits are easily formed near the pile foundation of the offshore substation. This often washes out the end of the J-shaped pipe, causing the submarine cable to be suspended in the air. Then, with the back and forth movement of the ocean current, the cable will sway, causing the submarine cable tension to increase and leading to damage to the submarine cable. Summary of the Invention

[0003] The purpose of this invention is to provide a method for installing submarine cables between land and sea. In the submarine cable laying process at the initial land-based switching station, this invention not only reduces slippage resistance and lowers traction energy consumption, but also protects the submarine cable, preventing damage during slippage.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0005] A method for installing submarine cables between land and sea includes a submarine cable laying process at the initial land-based switching station, specifically comprising the following steps:

[0006] Step 1: Inspection of the landing site at sea: Inspect the landing site at sea to ensure that there are no sharp protrusions on the seabed at the landing site, and to ensure the safety of the submarine cable construction vessel on the beach.

[0007] Step 2, Vessel Positioning: Drive the construction vessel carrying the submarine cable to the offshore landing point near the shore, with one side of the construction vessel facing the onshore switch station. With the assistance of the DGPS positioning system, accurately drop the positioning anchor to secure the construction vessel.

[0008] Step 3, Sealing the cable head: Seal the cable head with a heat-shrink cap and wrap it with waterproof tape;

[0009] Step 4: Laying the traction wire: Connect the traction wire to the traction net sleeve on the submarine cable head. At low tide, lay the other end of the traction wire from the ship's side to the landing point on the shore and connect it to the traction winch that has been set up on land in advance.

[0010] Step 5, Submarine Cable Head Landing Construction: Start the traction winch and the electric submarine cable reel on the construction vessel. While the submarine cable on the electric submarine cable reel is unwinding, the traction winch pulls it. During the unwinding and pulling process, a buoy is tied to the submarine cable every 1-3m, and rollers are set every 3-4m below the submarine cable. Under the action of the buoys, the submarine cable floats on the water surface. When the submarine cable lands, the rollers touch the ground.

[0011] Step 6: Moving the submarine cable head towards the switch station tower: During the movement of the submarine cable head, remove the float on the submarine cable. When it reaches the switch station tower, remove the roller on the submarine cable.

[0012] Step 7: Move the submarine cable head onto the switch station tower and secure the submarine cable: After the submarine cable head passes through the protective sleeve, workers set up scaffolding around the tower. After the submarine cable head climbs up the switch station tower from the outer side, a clamp is installed to secure the submarine cable to the switch station tower. The protective sleeve is located at the bottom side of the switch station tower.

[0013] Furthermore, in step 2, the electric cable reel on the construction vessel has a diameter of 27 meters. The electric cable reel is driven by 6 variable frequency motors distributed around it. The electric cable reel can carry 6,000 tons of cable at a time, with a cable length of 30-40 km.

[0014] Furthermore, before the submarine cable laying process at the initial onshore switching station, a cable transfer and splicing process is also included. The steps of the cable transfer and splicing process are as follows: S1. Before the cable transfer and splicing, the performance of the submarine cable is tested at the submarine cable factory; S2. The construction vessel is moored at the submarine cable factory wharf, and its position is adjusted and fixed so that the center of the cable reel of the construction vessel is aligned with the center of the cable conveyor frame of the submarine cable manufacturer; S3. The submarine cable is transported to the construction vessel along the trestle, and the workers tie a steel rope net to the cable head. After the cable head passes through the cable conveyor frame on the construction vessel, it is pulled into the electric cable reel. Before coiling, a 5m length of the cable head is reserved in the electric cable reel to facilitate cable testing; S4. The electric turntable is started, and the cable is automatically rotated to retrieve the cable. The cable transfer and splicing speed is controlled within 600m / h; S5. After the cable transfer and splicing is completed, the performance of the submarine cable is tested again to confirm that all performance indicators meet the engineering design requirements.

[0015] Furthermore, after the submarine cable laying process at the initial onshore switching station is completed, the submarine cable laying process and the submarine cable laying process at the terminal offshore booster station are carried out in sequence.

[0016] Furthermore, the process of laying submarine cables includes the following steps: S100, deploying the laying machine; S200, submarine cable laying construction: the anchor boat, based on the pre-determined laying route of the submarine cable using DGPS positioning, sets a traction anchor on the seabed in front of the construction vessel. The construction vessel is equipped with a drive winch, one end of the traction steel cable on the drive winch is tied to the traction anchor in the sea. The drive winch is started, the traction steel cable drives the construction vessel to move, the construction vessel drives the laying machine to move, and the high-pressure water pump on the laying machine is started. The high-pressure water pump draws in seawater, and the water supply hose supplies water to the hydraulic plow of the laying machine. The hydraulic plow cuts trenches in the seabed soil along the cable laying path using water jets, and places the cable into the trenches. The sled at the rear of the laying machine smooths the trenches to lay the cable. S300 Real-time detection of the laying route trajectory: During the cable laying process, the construction vessel command team monitors the real-time coordinates of the cable laying, the underwater attitude of the laying machine, and the burial depth of the cable through the cable laying navigation and positioning system and the burial depth monitoring system. The burial depth from the outer edge of the cable armor to the seabed mud surface in this section is not less than 3 meters. S400 After the submarine cable laying process is completed, the laying machine is retrieved.

[0017] Further, in step S100, the process of deploying the burial machine is as follows: first, the submarine cable is passed through the cable guide cage and placed into the cavity of the burial machine. The burial machine is then lifted by a crane and suspended above the water surface. The high-pressure water pump is connected to the water supply hose of the burial machine. Then, the burial machine, together with the submarine cable, is gently lowered into the water, keeping the burial machine horizontal during the process.

[0018] Furthermore, in step S300, the tilt sensor, attitude sensor, ground contact sensor, and water depth sensor of the burial monitoring system are used to detect the current attitude of the burial machine on the seabed and the current water depth; the electronic compass and DGPS positioning system of the burial monitoring system are used to detect the current position of the ship and the position of the submarine cable on the seabed; after the receiver receives the information sent by the transmitter, the computer system processes it to determine the relative position of the burial machine and the construction vessel, and displays the actual burial route trajectory of the submarine cable on the screen.

[0019] Furthermore, in step S400, when the construction vessel is laid near the location of the booster station platform, the construction speed is slowed down, the remaining length of the submarine cable in the electric turntable is constantly monitored, and preparations are made for the laying of the submarine cable. The DP positioning is changed to anchor positioning, and the anchor boat is used in conjunction with the construction vessel to anchor and fix the vessel position, and the operation of recovering the laying machine begins.

[0020] Furthermore, the submarine cable laying process for the offshore substation includes the following steps: The cable laying machine on the construction vessel pulls the submarine cable using a torsion bar, and places the unwound cable from the electric cable reel in a figure-eight shape on the deck of the construction vessel; when the unwound cable reaches the final laying length, it is cut on the construction vessel; the cut cable end is sealed with a heat-shrink cap and wrapped with waterproof tape, and a center clamp and bending limiter are installed at the predetermined position on the cable; a diver inspects the J-pipe inlet of the offshore substation underwater; if the J-pipe inlet has been silted up, an air suction device is used to flush out sufficient space at the J-pipe inlet; the diver uses the traction winch on the construction vessel... One end of the steel wire passes through the lower opening of the J-shaped tube, and the traction steel wire passes through the upper opening of the J-shaped tube and passes over the guide pulley on the gantry before connecting to the submarine cable head on the construction vessel. The traction winch is started, and the traction speed is adjusted according to the site conditions until the submarine cable head passes through the J-shaped tube and moves upward to the offshore substation, leaving sufficient design slack for the submarine cable. At this time, the guide cone on one side of the center clamp is inserted and locked in the lower opening of the J-shaped tube. The lower section of the bending limiter is located on the seabed, and the bending limiter is in a static free bending state, which can effectively protect the submarine cable and ensure its bending radius, avoiding damage to the submarine cable due to excessive bending. Finally, the submarine cable is fixed on the support of the offshore substation, completing the laying of the submarine cable terminal on the offshore substation side.

[0021] Furthermore, in the submarine cable laying process of the terminal offshore substation, the installation method of the center clamp and bending limiter is as follows:

[0022] 1) Determine the installation position of the center clamp on the submarine cable based on the location of the J-tube on the booster station side and the required submarine cable allowance, and mark it on the submarine cable.

[0023] 2) Install the intermediate clamp at the marked position. The intermediate clamp is a Haver-type structure. After aligning the two halves of the intermediate clamp with the submarine cable, tighten the bolts. The torque range of the bolts is 70-80 N·m.

[0024] 3) Install conical rings on both sides of the intermediate clamp, ensuring the correct angle of the conical rings;

[0025] 4) Install a guide cone on the side of the intermediate clamp that is close to the cable head on the submarine cable, and tighten the bolts. The torque range of tightening the bolts is 70-80 N·m. Connect the guide cone and the intermediate clamp with screws.

[0026] 5) Install a connecting shaft on the other side of the intermediate clamp to hold the submarine cable and tighten the bolts; sacrificial anode cathodic protection blocks are provided on both sides of the intermediate clamp, which are used to ensure that the central clamp is not corroded for 25 years;

[0027] 6) Install a bend limiter on the submarine cable. The bend limiter is a Haver-type structure. After aligning the two halves of the bend limiter around the submarine cable, tighten the bolts. The tightening torque of the bolts is 150-200 N·m. Then connect the bend limiter to the connecting shaft.

[0028] The beneficial effects of this invention are as follows:

[0029] In the process of laying submarine cables at the initial land-based switching station, this invention arranges floats and rollers on the submarine cable during the process of pulling the cable head onto land. This allows the submarine cable section at sea to float on the sea surface to avoid contact with the seabed. When the submarine cable is moved onto land, the rollers contact the land. This not only reduces slip resistance and lowers traction energy consumption, but also protects the submarine cable and prevents it from being scratched during the slippage process.

[0030] In particular, this invention incorporates roller installation on the ship. During the unwinding and traction of the submarine cable, the cable is at a certain height above the ship's deck. The cable is moved while the roller is installed, which not only improves installation efficiency but also eliminates the need for workers to lift the cable, greatly reducing labor. Furthermore, the cable begins to slide along the seabed in the shallow waters before it even reaches land, providing excellent protection for the cable.

[0031] This invention relates to a method for installing a central clamp and a bending limiter on the submarine cable at the J-shaped pipe inlet during the submarine cable laying process at an offshore substation. This prevents excessive bending of the cable and effectively avoids damage. The bending limiter is made of polyurethane and other materials with high hardness, high strength, and seawater corrosion resistance. The material has a low density, ensuring no additional weight is added to the submarine cable underwater, and its tensile strength is not less than 40 MPa. The bending limiter can withstand 8 tons of lateral pressure, and its service life is not less than 30 years. Attached Figure Description

[0032] Figure 1 This is a flowchart of the submarine cable laying process at the onshore switching station at the beginning of this invention.

[0033] Figure 2 This is a state diagram of the submarine cable laying and installation of the offshore substation terminal of the present invention.

[0034] Figure 3 This is a diagram showing the state after the installation of the central clamp and bending limiter of the present invention is completed;

[0035] Figure 4 This is a schematic diagram of the structure of the roller, support frame and clamp of the present invention. Detailed Implementation

[0036] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of this application can be combined with each other.

[0037] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper surface," "lower surface," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "forward," "reverse," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0038] like Figure 1 As shown, a method for installing submarine cables between land and sea includes the cable laying process at the starting land-based switch station, specifically including the following steps:

[0039] Step 1: Inspection of the landing site at sea: Inspect the landing site at sea to ensure that there are no sharp protrusions on the seabed at the landing site, so as to ensure the safety of the submarine cable construction vessel on the beach.

[0040] Step 2, Vessel Positioning: Drive the construction vessel carrying the submarine cable to the offshore landing point near the shore, ensuring one side of the vessel faces the onshore switch station. With the assistance of the DGPS positioning system, accurately deploy the positioning anchor to secure the construction vessel. The electric submarine cable reel on the construction vessel has a diameter of 27 meters and is driven by 6 variable frequency motors distributed around it. The electric submarine cable reel can carry 6,000 tons of submarine cable at a time, with a cable length of 30-40 km.

[0041] Step 3, Sealing the cable head: Seal the cable head with a heat shrink cap and wrap it with waterproof tape.

[0042] Step 4: Laying the traction wire: Connect the traction wire to the traction net sleeve on the submarine cable head. At low tide, lay the other end of the traction wire from the ship's side to the landing point on the shore and connect it to the traction winch that has been set up on land.

[0043] Step 5, Submarine Cable Head Landing Construction: Start the traction winch and the electric submarine cable reel on the construction vessel. While the submarine cable on the electric submarine cable reel is unwinding, the traction winch pulls it. During the unwinding and pulling process, a buoy is tied to the submarine cable every 1-3m, and rollers are set every 3-4m below the submarine cable. Under the action of the buoys, the submarine cable floats on the water surface. When the submarine cable lands, the rollers touch the ground.

[0044] like Figure 4 As shown, specifically, roller 14 is a universal roller, and there are two of them. The two universal rollers are installed at the bottom of the support frame 15. A clamp 16 is fixed at the top of the support frame 15. The clamp 16 is clamped and fixed to the submarine cable by screws 17. An elastic pad is provided between the clamp 16 and the submarine cable. The elastic pad helps the clamp 16 to clamp the submarine cable tightly.

[0045] A translational conveyor belt is installed on the deck of the construction vessel along the direction of the cable unwinding movement. The conveyor belt moves at the same speed as the cable. Workers stand on the conveyor belt to install the omnidirectional rollers and buoys. Multiple workers take turns installing the rollers at various installation positions on the cable. This invention implements roller installation on the ship. During the cable unwinding and traction process, the cable is at a certain height above the ship's deck. The cable moves while the rollers are being installed, which not only improves installation efficiency but also eliminates the need for workers to lift the cable, greatly reducing labor. Furthermore, the cable begins to slide along the seabed in the shallow waters before landing, providing excellent protection for the cable.

[0046] Step 6: Moving the submarine cable head towards the switch station tower: During the movement of the submarine cable head, remove the float on the submarine cable. When it reaches the switch station tower, remove the roller on the submarine cable.

[0047] Step 7: Move the submarine cable head onto the switch station tower and secure the submarine cable: After the submarine cable head passes through the protective sleeve, workers set up scaffolding around the tower. After the submarine cable head climbs up the switch station tower from the outer side, a clamp is installed to secure the submarine cable to the switch station tower. The protective sleeve is located at the bottom side of the switch station tower.

[0048] In the process of laying submarine cables at the initial land-based switching station, this invention arranges floats and rollers on the submarine cable during the process of pulling the cable head onto land. This allows the submarine cable section at sea to float on the sea surface to avoid contact with the seabed. When the submarine cable is moved onto land, the rollers contact the land. This not only reduces slip resistance and lowers traction energy consumption, but also protects the submarine cable and prevents it from being scratched during the slippage process.

[0049] A method for installing submarine cables between land and sea includes a cable transfer and splicing process before the cable laying process at the initial land-based switching station. The steps of the cable transfer and splicing process are as follows: S1. Before the cable transfer and splicing, the performance of the submarine cable is tested at the submarine cable factory; S2. The construction vessel is moored at the submarine cable factory wharf, and its position is adjusted and fixed so that the center of the cable reel on the construction vessel is aligned with the center of the cable conveyor frame of the submarine cable manufacturer; S3. The submarine cable is transported to the construction vessel along the trestle, and workers tie a steel rope net to the cable head. After the cable head passes through the cable conveyor frame on the construction vessel, it is pulled into the electric cable reel. Before coiling, a 5m length of the cable head is left in the electric cable reel to facilitate cable testing; S4. The electric turntable is started, and the cable is automatically rotated to retrieve the cable. The cable transfer and splicing speed is controlled within 600m / h; S5. After the cable transfer and splicing is completed, the performance of the submarine cable is tested again to confirm that all performance indicators meet the engineering design requirements.

[0050] After the submarine cable laying process at the initial onshore switching station is completed, the submarine cable laying process and the submarine cable laying process at the terminal offshore booster station are carried out in sequence.

[0051] The process of laying submarine cables includes the following steps:

[0052] S100, Deploying the burying machine: The process of deploying the burying machine is as follows: First, the submarine cable is passed through the cable guide cage and placed into the cavity of the burying machine. The burying machine is then lifted by a crane and suspended above the water surface. The high-pressure water pump is connected to the water supply hose of the burying machine. Then, the burying machine, together with the submarine cable, is slowly lowered into the water, keeping the burying machine horizontal during the process.

[0053] S200 Submarine Cable Laying Construction: The anchor boat, based on the pre-determined DGPS positioning of the submarine cable laying route, sets the traction anchor on the seabed in front of the construction vessel. The construction vessel is equipped with a drive winch, one end of which is attached to the traction anchor in the sea. The drive winch is started, and the traction cable drives the construction vessel to move. The construction vessel moves the laying machine and starts the high-pressure water pump on the laying machine. The high-pressure water pump draws in seawater, and the water supply hose supplies water to the hydraulic rake of the laying machine. The hydraulic rake cuts the seabed soil into trenches along the submarine cable laying path using water jets and places the submarine cable into the trenches. The sled at the rear of the laying machine smooths the trenches to lay the submarine cable.

[0054] The transmitter of the burial monitoring system is installed at the tail of the burial machine, and the receiver is installed on the construction vessel. Four ground contact sensors are installed at the four ends of the burial machine's sled, and three pressure sensors are installed at the submarine cable exit of the burial machine. The information central processing box is installed on the upper part of the sled to prevent damage. The burial monitoring system uses tilt sensors, attitude sensors, ground contact sensors, and depth sensors to detect the current attitude of the burial machine on the seabed and the current water depth. The electronic compass and DGPS positioning system of the burial monitoring system are used to detect the current position of the vessel and the position of the submarine cable on the seabed. After receiving the information from the transmitter, the receiver processes it through the computer system to determine the relative position of the burial machine and the construction vessel, and displays the actual burial route of the submarine cable on the screen. At the same time, the traction direction, burial depth, and traction speed are determined based on the force of the three pressure sensors.

[0055] S300 Real-time detection of laying route trajectory: During the laying of submarine cables, the construction vessel command team monitors the real-time coordinates of the submarine cable laying, the underwater attitude of the laying machine and the burial depth of the submarine cable through the submarine cable laying navigation and positioning system and the burial depth monitoring system. The burial depth from the outer edge of the submarine cable armor to the seabed mud surface in this section is not less than 3 meters.

[0056] After the S400 submarine cable laying process is completed, the laying machine is retrieved. Specifically, when the construction vessel reaches the vicinity of the substation platform, the construction speed is slowed down, the remaining length of the submarine cable in the electric turntable is constantly monitored, and preparations are made for the cable sinking. The DP positioning is changed to anchor positioning, and the anchor boat is used to help the construction vessel to anchor and fix the vessel position before starting the retrieval of the laying machine.

[0057] In a method for installing submarine cables between land and sea, the submarine cable laying process for the terminal offshore substation includes the following steps:

[0058] like Figure 2As shown, the cable laying machine on construction vessel 1 pulls the submarine cable through the unwinding frame and places the unwound submarine cable from the electric cable reel in a figure-eight shape on the deck of the construction vessel; when the unwound submarine cable reaches the laying length of the submarine cable terminal, the submarine cable is cut on the construction vessel; the cut submarine cable end is sealed with a heat shrink cap and wrapped with waterproof tape, and a center clamp and bending limiter are installed at the predetermined position of the submarine cable; a diver inspects the inlet of the J-shaped pipe 3 on the offshore booster station 2 underwater. If the inlet of the J-shaped pipe 3 has been silted up, an air suction device is used to flush out enough space at the inlet of the J-shaped pipe; the diver inserts one end of the traction wire 7 on the traction winch 6 on the construction vessel through the lower opening of the J-shaped pipe, and pulls... The steel wire passes through the upper opening of the J-shaped tube and around the guide pulley 5 on the gantry 4 before connecting to the submarine cable head on the construction vessel 1. The traction winch 6 is started, and the traction speed is adjusted according to the site conditions until the submarine cable head passes through the J-shaped tube and moves upward to the offshore substation 2, leaving sufficient design slack for the submarine cable. At this time, the guide cone 9 on one side of the central clamp 8 is inserted and locked into the lower opening of the J-shaped tube 3. The lower section of the bending limiter 10 is located on the seabed surface, and the bending limiter 10 is in a static free bending state, which can effectively protect the submarine cable and ensure its bending radius, avoiding damage to the submarine cable caused by excessive bending. Finally, the submarine cable is fixed on the support of the offshore substation, completing the laying of the submarine cable terminal on the offshore substation side.

[0059] like Figure 3 As shown, the installation method of the center clamp and bending limiter in the submarine cable laying process of the terminal offshore substation is as follows:

[0060] 1) Determine the installation position of the center clamp on the submarine cable based on the location of the J-tube on the booster station side and the required submarine cable allowance, and mark it on the submarine cable.

[0061] 2) Install the intermediate clamp 8 at the marked position. The intermediate clamp 8 is a Haver-type structure. After the two halves of the intermediate clamp are wrapped around the submarine cable and aligned, tighten the bolts. The torque range of the bolts is 70-80 N·m.

[0062] 3) Install conical rings 11 on both sides of the intermediate clamp 8, and make sure that the angle of the conical rings is correct;

[0063] 4) Install the guide cone 9 on one side of the intermediate clamp 8, which is close to the cable head on the submarine cable, and tighten the bolts. The torque range of tightening the bolts is 70-80 N·m. Connect the guide cone and the intermediate clamp with screws.

[0064] 5) Install the connecting shaft 12 on the other side of the intermediate clamp 8 to hold the submarine cable and tighten the bolts; sacrificial anode cathodic protection blocks are provided on both sides of the intermediate clamp, and the sacrificial anode cathodic protection blocks are used to ensure that the central clamp is not corroded for 25 years;

[0065] 6) Install a bend limiter 10 on the submarine cable. The bend limiter has a Haver-type structure. After aligning the two halves of the bend limiter around the submarine cable 13, tighten the bolts to a torque of 150-200 N·m, and then connect the bend limiter 10 to the connecting shaft 12. This invention, in the submarine cable laying process of an offshore substation, installs a central clamp and a bend limiter on the submarine cable at the J-shaped pipe inlet to prevent excessive bending of the submarine cable and effectively avoid damage. The bend limiter is made of polyurethane and other materials with high hardness, high strength, and seawater corrosion resistance. The material has a low density, ensuring no additional weight on the submarine cable underwater, and a tensile strength of not less than 40 MPa. The bend limiter can withstand 8 tons of lateral pressure, and the product has a service life of not less than 30 years.

[0066] Furthermore, those skilled in the art can combine and integrate the different embodiments or examples described herein, as well as the features of those embodiments or examples, without contradiction. Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for installing submarine cables between land and sea, comprising a submarine cable laying process at a starting land-based switching station, characterized in that, Specifically, the following steps are included: Step 1: Inspection of the landing site at sea: Inspect the landing site at sea to ensure that there are no sharp protrusions on the seabed at the landing site, and to ensure the safety of the submarine cable construction vessel on the beach. Step 2, Vessel Positioning: Position the construction vessel carrying the submarine cable to the landing point near the shore, ensuring one side of the vessel faces the onshore switch station. With the assistance of a DGPS positioning system, accurately deploy a positioning anchor to secure the vessel. The cable transfer and splicing process for the construction vessel carrying the submarine cable is as follows: S1. Before the transfer and splicing, test the performance of the submarine cable at the cable factory; S2. Moor the construction vessel at the cable factory dock, adjust and fix its position, aligning the center of the cable reel on the construction vessel with the center of the cable conveyor frame from the cable manufacturer; S3. Transport the submarine cable along the pier to the construction vessel. Workers attach a steel rope net to the cable head, pass the cable head through the cable conveyor frame on the construction vessel, and pull it into the electric cable reel. Before coiling, leave a 5m length of the cable head inside the electric cable reel for testing purposes; S4. Start the electric turntable, rotating to retrieve the cable, controlling the transfer and splicing speed at 600m / h. Within; S5, after the cable transfer is completed, the performance of the submarine cable is retested to confirm that all performance indicators meet the engineering design requirements; Step 3, Sealing the cable head: Seal the cable head with a heat-shrink cap and wrap it with waterproof tape; Step 4: Laying the traction wire: Connect the traction wire to the traction net sleeve on the submarine cable head. At low tide, lay the other end of the traction wire from the ship's side to the landing point on the shore and connect it to the traction winch that has been set up on land in advance. Step 5, Submarine Cable Head Landing Construction: Start the traction winch and the electric submarine cable reel on the construction vessel. While the submarine cable on the electric submarine cable reel is unwinding, the traction winch pulls it. During the unwinding and pulling process, a buoy is tied to the submarine cable every 1-3m, and rollers are set every 3-4m below the submarine cable. Under the action of the buoys, the submarine cable floats on the water surface. When the submarine cable lands, the rollers touch the ground. Step 6: Moving the submarine cable head towards the switch station tower: During the movement of the submarine cable head, remove the float on the submarine cable. When it reaches the switch station tower, remove the roller on the submarine cable. Step 7: Move the submarine cable head onto the switch station tower and secure the submarine cable: After the submarine cable head passes through the protective sleeve, workers set up scaffolding around the tower. After the submarine cable head climbs up the switch station tower from the outer side, a clamp is installed to secure the submarine cable to the switch station tower. The protective sleeve is located at the bottom side of the switch station tower.

2. The method for installing submarine cables between land and sea according to claim 1, characterized in that: In step 2, the electric cable reel on the construction vessel has a diameter of 27 meters. The electric cable reel is driven by 6 variable frequency motors distributed around it. The electric cable reel can carry 6,000 tons of cable at a time, with a cable length of 30-40 km.

3. The method for installing submarine cables between land and sea according to claim 2, characterized in that: After the submarine cable laying process at the initial onshore switching station is completed, the submarine cable laying process and the submarine cable laying process at the terminal offshore booster station are carried out in sequence.

4. The method for installing submarine cables between land and sea according to claim 3, characterized in that: In the process of laying submarine cables, The process includes the following steps: S100, deploying the cable laying machine; S200, submarine cable laying construction: The anchor boat, based on the pre-determined DGPS positioning of the submarine cable laying route, sets a traction anchor on the seabed in front of the construction vessel. The construction vessel is equipped with a drive winch, one end of which is attached to the traction anchor in the sea. The drive winch is started, and the traction cable drives the construction vessel to move. The construction vessel then moves the cable laying machine, and the high-pressure water pump on the cable laying machine is activated. The high-pressure water pump draws in seawater, and the water supply hose supplies water to the hydraulic plow of the cable laying machine. The hydraulic plow moves along the seabed... The cable laying path involves cutting trenches in the seabed soil using water jetting, placing the submarine cable into the trenches, and then smoothing the trenches with a sled at the rear of the laying machine to lay the cable. S300 Real-time monitoring of the laying route: During the cable laying process, the construction vessel command team monitors the real-time coordinates of the cable laying, the underwater attitude of the laying machine, and the cable burial depth using the cable laying navigation and positioning system and the burial depth monitoring system. The burial depth from the outer edge of the submarine cable armor to the seabed mud surface in this section is not less than 3 meters. S400 After the submarine cable laying process is completed, the laying machine is retrieved.

5. The method for installing submarine cables between land and sea according to claim 4, characterized in that: In step S100, the process of deploying the burial machine is as follows: First, the submarine cable is passed through the cable guide cage and placed into the cavity of the burial machine. The burial machine is then lifted by a crane and suspended above the water surface. The high-pressure water pump is connected to the water supply hose of the burial machine. Then, the burial machine and the submarine cable are gently lowered into the water, keeping the burial machine horizontal during the process.

6. The method for installing submarine cables between land and sea according to claim 5, characterized in that: In step S300, the tilt sensor, attitude sensor, ground contact sensor, and water depth sensor of the burial monitoring system are used to detect the current attitude of the burial machine on the seabed and the current water depth. The electronic compass and DGPS positioning system of the burial monitoring system are used to detect the current position of the ship and the position of the submarine cable on the seabed. After receiving the information sent by the transmitter, the receiver processes it through the computer system to determine the relative position of the burial machine and the construction vessel, and displays the actual burial route of the submarine cable on the screen.

7. The method for installing submarine cables between land and sea according to claim 6, characterized in that: In step S400, when the construction vessel is laid near the location of the booster station platform, the construction speed is slowed down, the remaining length of the submarine cable in the electric turntable is constantly monitored, and preparations are made for the laying of the submarine cable. The DP positioning is changed to anchor positioning, and the anchor boat is used to anchor the construction vessel to fix the position. The operation of recovering the laying machine begins.

8. The method for installing submarine cables between land and sea according to claim 3, characterized in that: The submarine cable laying process for the offshore substation includes the following steps: The cable laying machine on the construction vessel pulls the submarine cable using a torsion bar, and the cable unwound from the electric cable reel is placed in a figure-eight shape on the deck of the construction vessel; when the unwound cable reaches the final laying length, it is cut on the construction vessel; the cut cable end is sealed with a heat-shrink cap and wrapped with waterproof tape, and a center clamp and bending limiter are installed at the predetermined position on the cable; divers inspect the J-pipe inlet of the offshore substation underwater; if the J-pipe inlet has been silted up, an air suction device is used to flush out sufficient space at the J-pipe inlet; the divers then use the traction winch on the construction vessel to pull the traction wire... One end of the cable passes through the lower opening of the J-shaped tube, and the traction wire passes through the upper opening of the J-shaped tube and passes over the guide pulley on the gantry before connecting to the submarine cable head on the construction vessel. The traction winch is started, and the traction speed is adjusted according to the site conditions until the submarine cable head passes through the J-shaped tube and moves upward to the offshore substation, leaving sufficient design slack for the submarine cable. At this time, the guide cone on one side of the center clamp is inserted and locked in the lower opening of the J-shaped tube. The lower section of the bending limiter is located on the seabed, and the bending limiter is in a static free bending state, which can effectively protect the submarine cable and ensure its bending radius, avoiding damage to the submarine cable caused by excessive bending. Finally, the submarine cable is fixed on the support of the offshore substation, completing the laying of the submarine cable terminal on the offshore substation side.

9. The method for installing submarine cables between land and sea according to claim 8, characterized in that: The installation method of the center clamp and bending limiter in the submarine cable laying process of the terminal offshore substation is as follows: 1) Determine the installation position of the center clamp on the submarine cable based on the location of the J-tube on the booster station side and the required submarine cable allowance, and mark it on the submarine cable. 2) Install the intermediate clamp at the marked position. The intermediate clamp is a Haver-type structure. After aligning the two halves of the intermediate clamp with the submarine cable, tighten the bolts. The torque range of the bolts is 70-80 N·m. 3) Install conical rings on both sides of the intermediate clamp, ensuring the correct angle of the conical rings; 4) Install a guide cone on the side of the intermediate clamp that is close to the cable head on the submarine cable, and tighten the bolts. The torque range of tightening the bolts is 70-80 N·m. Connect the guide cone and the intermediate clamp with screws. 5) Install a connecting shaft on the other side of the intermediate clamp to hold the submarine cable and tighten the bolts; sacrificial anode cathodic protection blocks are provided on both sides of the intermediate clamp, which are used to ensure that the central clamp is not corroded for 25 years; 6) Install a bend limiter on the submarine cable. The bend limiter is a Haver-type structure. After aligning the two halves of the bend limiter around the submarine cable, tighten the bolts. The tightening torque of the bolts is 150-200 N·m. Then connect the bend limiter to the connecting shaft.

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