An erosion and bend protection system for a submarine cable

Abstract

This invention relates to the field of marine cable protection technology, specifically to an anti-scouring and anti-bending protection system for submarine cables. The system includes multiple bend limiter units connected in sequence; an anti-scouring module, disposed on the bend limiter units, comprising an anti-scouring ring and a fixing part, used to reduce the scouring effect of water flow on the submarine cable; and an anti-bending module, disposed between at least some adjacent anti-scouring modules and connected to the fixing part, used to improve the local bending resistance of the submarine cable. By incorporating the anti-scouring module, when seawater flows through the submarine cable, the anti-scouring module can guide and break up the water flow, suppressing vortex-induced vibration. Through the synergistic effect of the anti-bending module and the bend limiter units, the adaptability of the submarine cable in complex marine environments is further enhanced, effectively suppressing excessive bending.

Description

Technical Field

[0001] This invention relates to the field of marine cable protection technology, specifically to an anti-scouring and anti-bending protection system for submarine cables. Background Technology

[0002] Bending limiters, as key protective devices in marine cable systems, are widely used in suspended cable areas and stress concentration points. Their main function is to prevent damage or breakage of the cable due to excessive bending by effectively transferring bending moments. In the complex marine environment, submarine cables not only bear dynamic loads such as waves and currents, but are also exposed to long-term mechanical impacts from water erosion, eddy-induced vibration, and seabed topographic changes. This places extremely high demands on the structural strength, erosion resistance, and bending performance of bending limiters. However, existing bending limiters generally suffer from complex structures, difficult maintenance, and insufficient bending resistance. Especially under strong currents or storm conditions, traditional bending limiters struggle to effectively suppress local stress concentration, leading to fatigue damage or even breakage in the suspended cable sections. Industry statistics show that the failure rate of current bending limiters in actual service is as high as 50%, requiring numerous replacements and repairs annually in projects such as offshore wind farms, significantly increasing operation and maintenance costs and safety risks.

[0003] To address the aforementioned issues, some improvement solutions attempt to enhance protective performance by adding external structures. For example, Chinese patent CN118423553A proposes a bend limiter with irregularly shaped spiral plates, which suppresses vortex-induced vibration and reduces pipeline amplitude by setting spiral plates with arc-shaped cross-sections on the outer wall. While this design improves the impact of water flow disturbance on submarine cables to some extent, its overall structure remains complex, containing multiple precision-fitting components, which not only increases manufacturing costs but also complicates on-site installation and subsequent maintenance. More importantly, this solution does not enhance the bending stiffness of the bend limiter itself from a structural mechanism perspective, and it still cannot effectively prevent excessive bending of the submarine cable at critical locations under extreme marine loads. Furthermore, existing products generally lack intelligent response mechanisms and cannot dynamically adjust the protective strength according to the magnitude of external loads, potentially introducing unnecessary rigid constraints under normal operating conditions, while failing to provide sufficient bending support in a timely manner under high-risk conditions.

[0004] Therefore, there is an urgent need for a new type of submarine cable protection system that combines efficient scour resistance with adaptive bending resistance, which can actively cope with external forces of varying intensities in complex and ever-changing marine environments, while also possessing modular and easy-to-maintain structural features to significantly improve the reliability and service life of submarine cable systems. Summary of the Invention

[0005] This invention addresses the technical shortcomings of existing submarine cable bend limiters, such as complex structure, difficult maintenance, insufficient erosion resistance, and limited bending performance under high load conditions. It provides a erosion and bending protection system for submarine cables. Through the synergistic effect of a modular structural design, a spiral anti-erosion structure, and a dual-state switching bending resistance mechanism, this system achieves energy dissipation under normal water flow conditions while possessing a localized bending enhancement mechanism that automatically activates under strong currents or large waves. This effectively prevents damage or breakage of the submarine cable due to excessive bending or prolonged erosion.

[0006] An anti-erosion and anti-bending protection system for submarine cables, comprising: Multiple bend limiter units connected in sequence; An anti-scouring module is installed on the bend limiter unit. The anti-scouring module includes an anti-scouring ring and a fixing part, which is used to reduce the scouring effect of water flow on the submarine cable. An anti-bending module is disposed between at least partially adjacent anti-scouring modules and connected to the fixing part to improve the local anti-bending performance of the submarine cable.

[0007] Furthermore, the anti-scouring ring is provided with anti-scouring plates arranged in a spiral shape.

[0008] Furthermore, the bend limiter unit includes pipe segments and connectors, and the pipe segments of adjacent bend limiter units are connected by the connectors, which allow relative rotation and bending deformation between adjacent pipe segments.

[0009] Furthermore, the connector includes a slot and a block that cooperate with each other.

[0010] Furthermore, the anti-bending module includes two slidingly fitted anti-bending cover plates and a damping component; The bending cover plate is provided with through holes; The damping element includes a shaft and blades disposed on the shaft, the shaft passing through the through hole and being able to slide axially therein and rotate about its own axis, and the blades being used to generate resistance when rotating in the water flow.

[0011] Furthermore, the through hole includes a first hole segment and a second hole segment with different shapes; When the shaft is located in the first hole section, its rotation is restricted; When the shaft is located in the second hole section, it can rotate freely.

[0012] Furthermore, the cross-sectional shape of the first hole segment matches the cross-sectional shape of the rotating shaft to restrict rotation, and the cross-section of the second hole segment is circular.

[0013] Furthermore, a transition slope is provided between the first hole segment and the second hole segment.

[0014] Furthermore, the damping component also includes a convex ring, which is disposed on the rotating shaft and has a diameter larger than that of the through hole, for axially limiting the rotating shaft.

[0015] Furthermore, the blade has a plate-like structure or a streamlined structure.

[0016] Furthermore, the damping element is made of corrosion-resistant metal material.

[0017] Furthermore, both the anti-erosion module and the anti-bending cover are made of polyurethane material.

[0018] Furthermore, the present invention also proposes a method for operating the aforementioned anti-erosion and anti-bending protection system, comprising the following steps: S1: Structural design and installation: S2: System operation under state one condition: When the external load on the submarine cable is lower than the preset threshold, the rotating shaft is located in the first hole section, its rotation is restricted, and the damping component does not function. S3: System operation when switching from state one to state two: When the external load on the submarine cable exceeds the preset threshold, the rotating shaft is moved to the second hole section and can rotate freely. The blade rotates with the rotating shaft and generates a damping torque in the water to improve the bending resistance. S4: Load reduction state reversal: When the external load weakens to below the preset threshold, the rotating shaft moves back to the first hole section, and the system returns to the state where the damping component does not function.

[0019] Compared with the prior art, the beneficial effects of the present invention are: (1) By setting up an anti-scouring module, when seawater flows through the submarine cable, under the action of the anti-scouring ring, especially under the action of the spirally set anti-scouring plate, the anti-scouring module can guide and break up the water flow, so that the water flow is dispersed and slowed down in the circumferential and axial directions, thereby reducing the scouring effect of waves and currents on the surface of the submarine cable and the bend limiter, suppressing vortex-induced vibration, and reducing the structural amplitude. At the same time, through the synergistic effect of the anti-bending module and the bend limiter unit, the adaptability of the submarine cable in complex marine environments is further improved. When the submarine cable is bent by external load, the anti-bending cover plate adjusts its position through sliding fit, and the blades rotate under the drive of the rotating shaft, using the seawater resistance to generate a damping torque, effectively suppressing excessive bending.

[0020] (2) Through structural design, the present invention realizes intelligent adaptive control of the bending behavior of submarine cable during state switching. No external energy intervention is required. The state switching is completed by the mechanical interaction between the structure and the environmental load. This ensures low resistance and low loss operation under normal working conditions, and can respond quickly in extreme marine environments, providing strong bending protection and significantly improving the reliability and durability of the submarine cable protection system.

[0021] (3) Both the anti-scouring module and the anti-bending module of the present invention adopt a modular structure design. When the device is partially damaged during service, the staff only needs to disassemble the corresponding pipe section or the anti-bending cover plate to complete the fixed-point replacement. There is no need to disassemble the entire bending limiter on a large scale, which simplifies the disassembly and assembly steps, reduces maintenance costs, and greatly improves the efficiency of later construction and maintenance. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the overall structure of the anti-erosion and anti-bending protection system for submarine cables according to Embodiment 1 of the present invention. Figure 2 This is a schematic cross-sectional view of the bending limiter unit in Embodiment 1 of the present invention; Figure 3 This is a schematic diagram of the anti-bending module in state one of Embodiment 1 of the present invention; Figure 4 This is a schematic diagram of the anti-bending module in Embodiment 1 of the present invention when it is in State 2; Figure 5 This is a schematic diagram of the anti-bending module in state one in Embodiment 2 of the present invention; Figure 6 This is a schematic diagram of the anti-bending module in state two of Embodiment 2 of the present invention; Figure 7 This is a flowchart illustrating the erosion and bending protection system in Embodiment 2 of the present invention.

[0023] In the picture: 1. Anti-erosion module; 11. Anti-erosion ring; 12. Fixing ring; 2. Anti-bending module; 21. Anti-bending cover plate; 211. Through hole; 2111. First hole section; 2112. Second hole section; 22. Damping component; 221. Rotating shaft; 222. Convex ring; 223. Blade; 3. Bending limiter unit; 31. Pipe section; 32. Connector; 321. Slot; 322. Block; 4. Mounting components; 5. Mounting holes; Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] This invention provides an anti-erosion and anti-bending protection system for submarine cables. A preferred embodiment of the invention will be described in detail below with reference to the accompanying drawings.

[0026] Example 1: like Figure 1 and Figure 2 As shown, the anti-scouring and anti-bending protection system for submarine cables of the present invention includes multiple bend limiter units, an anti-scouring module 1, and an anti-bending module 2. The multiple bend limiter units are connected sequentially, and each bend limiter unit is equipped with an anti-scouring module 1. The anti-scouring module 1 includes an anti-scouring ring 11 and two fixing parts 12. The anti-scouring ring 11 is disposed between the two fixing parts 12, so that the anti-scouring modules 1 are arranged sequentially along the axial direction of the submarine cable, forming a continuous sheath structure to protect the submarine cable from the effects of ocean current scouring and sediment erosion. Specifically, the anti-scouring ring 11 is provided with spirally arranged anti-scouring plates, that is, the anti-scouring plates are spirally arranged around the axial direction of the submarine cable and extend axially on the anti-scouring ring 11. This spiral arrangement structure can effectively guide the direction of water flow, slow down the flow velocity, and reduce the direct impact on the surface of the submarine cable, thereby significantly improving the anti-scouring effect.

[0027] By setting up the anti-scouring module 1, when seawater flows through the submarine cable, the anti-scouring ring 11, especially the spiral anti-scouring plate, can guide and break up the water flow, causing the water flow to be dispersed and slowed down in the circumferential and axial directions. This reduces the scouring effect of waves and currents on the surface of the submarine cable and the bend limiter, suppresses vortex-induced vibration, and reduces the structural amplitude.

[0028] In addition, some or all of the adjacent anti-scour modules 1 are provided with anti-bending modules 2. The anti-bending modules 2 are fixed to the fixing part 12 of the adjacent anti-scour modules 1 to improve the local bending resistance when the submarine cable is subjected to large bending forces. The partial or complete installation of the anti-bending modules 2 is determined based on the actual marine environmental conditions and the bending risk assessment results of the submarine cable laying path. According to the actual sea conditions and engineering requirements, key bending locations are identified, and anti-bending modules 2 are deployed in these locations to enhance structural stability. Specifically, based on conventional submarine cable bending structure analysis, anti-scour modules 1 can be placed near the starting point of the submarine cable span and the end joint, thereby significantly increasing the bending resistance of the submarine cable at that location.

[0029] like Figure 2 As shown, the bend limiter unit 3 includes a pipe section 31 and a connector 32. The pipe sections 31 of adjacent bend limiter units are connected by the connector 32. Preferably, the connector 32 includes a slot 321 and a block 322. With the setting of the slot 321 and the block 322, the two adjacent pipe sections 31 can be allowed to generate relative rotation and bending deformation within a limited range. At this time, when the marine cable bends under the action of external loads such as waves and ocean currents, the relative movement between the adjacent pipe sections at the connector 32 achieves the overall controlled bending, thereby transferring the bending moment of the marine cable, avoiding the bending concentration in local positions, and reducing the risk of breakage of the submarine cable in the suspension area and stress concentration area.

[0030] Furthermore, the present invention specifically proposes a novel anti-bending module 2, specifically, as follows: Figure 3 and Figure 4 As shown, the anti-bending module 2 includes two slidingly fitted anti-bending cover plates 21 and a damping element 22. The anti-bending cover plates 21 have through holes 211. The damping element 22 includes a rotating shaft 221, a convex ring 222, and a blade 223. Specifically, the rotating shaft 221 passes through the through hole 211 and extends into the inner side of the anti-bending cover plate 21. A convex ring 10 is installed at one end of the rotating shaft located inside the anti-bending cover plate 21. The rotating shaft 221 can slide axially within the through hole 211 and rotate around its own axis. The diameter of the convex ring 10 is larger than the diameter of the through hole 211, and it is used to dampen the rotating shaft. 221 provides axial limiting and fixes the position of the rotating shaft 221 to prevent the rotating shaft 221 from moving axially during operation. Several blades 223 are fixed circumferentially on the rotating shaft 221. The blades 223 extend radially outward along the rotating shaft 221. Preferably, the blades 223 are plate-shaped or streamlined, so that when the rotating shaft 221 drives the blades 223 to rotate in seawater, the blades 223 can generate resistance with the seawater, thereby forming a damping torque on the rotation of the rotating shaft 221 and improving the bending resistance of the bending limiter.

[0031] Through the synergistic effect of the anti-bending module 2 and the bending limiter unit 3, the adaptability of the submarine cable in complex marine environments is further enhanced. When the submarine cable is bent by external load, the anti-bending cover plate 21 adjusts its position through sliding fit, and the blade 223 rotates under the drive of the rotating shaft 221, using the resistance of seawater to generate a damping torque, effectively suppressing excessive bending.

[0032] Preferably, the damping element 22 is made of a corrosion-resistant metal material, such as stainless steel or titanium alloy, to ensure structural strength and durability and guarantee long-term performance in marine environments.

[0033] Preferably, both the anti-erosion module 1 and the anti-bending cover plate 21 are made of polyurethane material. Polyurethane material has excellent wear resistance, hydrolysis resistance and impact resistance, which can effectively resist the erosion of seabed sediments and external mechanical damage. At the same time, its high elastic modulus helps to improve the flexibility and fatigue life of the overall structure.

[0034] Furthermore, the fixing part 12 is provided with mounting holes 5. The anti-bending module 2 is detachably connected to the fixing part 12 through the mounting part 4, so as to realize the dynamic adjustment of the installation part. This makes it easy to flexibly configure the anti-bending strength and coverage according to the actual laying status and working conditions of the submarine cable, thereby improving the adaptability and maintenance efficiency of the system.

[0035] Preferably, mounting component 4 is a bolt, but it can also be a pin, clip, quick-release connector, or other equivalent structure to meet the convenience and reliability requirements of different installation scenarios.

[0036] Example 2: In order to achieve adaptive adjustment of the bending resistance performance of the bending resistance module 2, based on the first embodiment, this embodiment also proposes a switchable dual-state structural design, which automatically switches between the two working states of "free rotation" and "locked limit" by triggering the damping component by external load.

[0037] Specifically, such as Figure 5 and Figure 6 As shown, one of the two slidingly fitted bending cover plates 21 has a through hole 211 comprising a first hole segment 2111 and a second hole segment 2112 with different shapes. When the rotating shaft 221 is located in the first hole segment 2111, its rotation is restricted; when the rotating shaft 221 is located in the second hole segment 2112, it can rotate freely. Preferably, the cross-sectional shape of the first hole segment 2111 is rectangular, and the cross-sectional shape of the second hole segment 2112 is circular. In this case, the cross-sectional width of the first hole segment 2111 is basically the same as the diameter of the rotating shaft 221, meaning the gap between them is small, which can relatively restrict the rotation of the rotating shaft 221. The cross-sectional shape of the second hole segment 2112 is circular, and the cross-sectional shape of the first hole segment 2111 matches the cross-sectional shape of the rotating shaft 221, allowing the rotating shaft 221 to rotate freely in the second hole segment 2112.

[0038] When the submarine cable is subjected to a small scouring effect and / or the bending limiter is subjected to a small tensile force, the rotating shaft 221 remains within the first hole section 2111. At this time, due to the restriction of the rotation of the rotating shaft 221 by the first hole section 2111, the rotating shaft 221 basically does not rotate relative to the first hole section 11 and is in a locked state. The damping element 22 does not play a significant role in this state. The protection system achieves basic bending and scouring functions by the anti-scouring module 1 and the bending limiter unit, ensuring the safe operation of the submarine cable under normal sea conditions.

[0039] When the submarine cable is subjected to significant scouring and / or the bending limiter is subjected to significant tension, the rotating shaft 221 will disengage from the restriction area of ​​the first section 2111 and enter the second section 2112. At this time, the rotating shaft 221 can rotate freely within the second section 2112, and the damping element plays a damping role. The damping torque is generated through the relative motion between the blade 223 and the seawater, thereby significantly improving the bending limiter's bending resistance under high load conditions.

[0040] Furthermore, a transition slope is provided between the first hole section 2111 and the second hole section 2112 to guide the rotating shaft 221 smoothly from the first hole section 2111 into the second hole section 2112 when the force increases, avoiding jamming; and can also guide the rotating shaft 221 smoothly back from the second hole section 2112 to the first hole section 2111 after the load decreases, realizing automatic state reset.

[0041] By improving the structure of through hole 211, adaptive adjustment of bending performance is achieved: maintaining structural stability and reducing unnecessary energy dissipation under low loads; and automatically activating the damping mechanism to enhance local stiffness response under high loads.

[0042] Accordingly, in this context, the present invention also proposes a method for operating a scour and bending protection system for submarine cables, specifically including the following steps: S1: Structural design and installation: Based on sea condition monitoring data, calculate and select the key bending points of the bending limiter, and calculate the preset threshold for state switching under environmental load, as well as the corresponding through hole size; install the anti-bending module 2 at the key bending points; S2: System operation under state one condition: When the external load on the submarine cable is lower than a preset threshold, the rotating shaft is located in the first hole section, its rotation is restricted, and the damping component does not function; specifically, as follows... Figure 4 As shown, in state one, the rotating shaft 221 of the anti-bending module 2 is in the first hole section 2111. By designing the working conditions, the length of the first hole section 2111 can be calculated in advance at the preset threshold of low environmental load (i.e., the threshold of low scouring and low bending tensile force under the design working conditions). This ensures that the rotating shaft 221 is kept constrained within the first hole section 2111 under this working condition. That is, the rotating shaft 221 moves only within the first hole section 2111 under the relative displacement of the two anti-bending cover plates 21. At this time, due to the restriction of the rotation of the rotating shaft 221 by the first hole section 2111, the rotating shaft 221 basically does not rotate relative to the first hole section 2111. The damping element 22 does not play a significant role in this state. The protection system achieves basic bending and anti-scouring functions by the anti-scouring module 1 and the bending limiter unit.

[0043] S3: System operation when switching from State 1 to State 2: When the external load on the submarine cable exceeds the preset threshold, the rotating shaft moves to the second hole section and can rotate freely. The blade rotates with the rotating shaft and generates a damping torque in the water to improve bending resistance. Specifically, as shown... Figure 5 As shown, state two is the state in which the rotating shaft 221 of the anti-bending module 2 is located in the second hole section 2112. At this time, the rotating shaft 221 can rotate freely in the second hole section 2112, and the damping element 22 is activated accordingly. Its blades 223 rotate with the rotating shaft 221 and generate relative motion with the surrounding seawater, thereby forming a fluid damping torque, which significantly improves the bending resistance of the bending limiter under high load conditions. This damping torque is positively correlated with the rotation speed and has adaptive response characteristics, effectively suppressing excessive bending of the submarine cable.

[0044] The switching process between state one and state two does not require external control intervention and is achieved solely through the mechanical response of the structure itself, ensuring the real-time performance and reliability of the system. The resistance between the damping element 22 and the seawater effectively improves the bending resistance of the bending limiter, preventing the submarine cable from bending excessively when subjected to large waves and strong currents.

[0045] S4: Load Reduction and State Reversal: When the external load weakens to below the preset threshold, the shaft moves back to the first bore section, and the system returns to the state where the damping element is not functioning. Specifically, when the external load weakens and falls below the preset threshold, the shaft 221 re-enters the first bore section 2111 under the relative displacement of the two bending cover plates 21, and the system returns to state one. At this time, the damping element 22 stops working, and the system re-enters a low-energy-consumption stable state.

[0046] Through the above structural design, the present invention achieves intelligent adaptive control of the bending behavior of submarine cables during state switching. It does not require external energy intervention and relies solely on the mechanical interaction between the structure and environmental loads to complete the state switching. This ensures low resistance and low loss operation under normal working conditions, while also enabling rapid response in extreme marine environments, providing strong bending protection, and significantly improving the reliability and durability of the submarine cable protection system.

[0047] Furthermore, both the anti-scouring module 1 and the anti-bending module 2 of this invention adopt a modular structure design. When the device is partially damaged during service, the staff only needs to disassemble the corresponding pipe section or the anti-bending cover plate to complete the fixed-point replacement. There is no need to disassemble the entire bending limiter on a large scale, which simplifies the disassembly and assembly steps, reduces maintenance costs, and greatly improves the efficiency of later construction and maintenance.

Claims

1. A system for protecting submarine cables from erosion and bending, characterized in that, include: Multiple bend limiter units connected in sequence; An anti-scouring module is installed on the bend limiter unit. The anti-scouring module includes an anti-scouring ring and a fixing part, which is used to reduce the scouring effect of water flow on the submarine cable. An anti-bending module is disposed between at least partially adjacent anti-scouring modules and connected to the fixing part to improve the local anti-bending performance of the submarine cable.

2. The anti-erosion and anti-bending protection system according to claim 1, characterized in that, The anti-scouring ring is provided with anti-scouring plates arranged in a spiral shape.

3. The anti-erosion and anti-bending protection system according to claim 1, characterized in that, The bend limiter unit includes pipe segments and connectors. The pipe segments of adjacent bend limiter units are connected by the connectors, which allow relative rotation and bending deformation between adjacent pipe segments.

4. The anti-erosion and anti-bending protection system according to any one of claims 1-3, characterized in that, The anti-bending module includes two slidingly fitted anti-bending cover plates and a damping component; The bending cover plate is provided with through holes; The damping element includes a shaft and blades disposed on the shaft, the shaft passing through the through hole and being able to slide axially therein and rotate about its own axis, and the blades being used to generate resistance when rotating in the water flow.

5. The anti-erosion and anti-bending protection system according to claim 4, characterized in that, The through hole includes a first hole segment and a second hole segment with different shapes; When the shaft is located in the first hole section, its rotation is restricted; When the shaft is located in the second hole section, it can rotate freely.

6. The anti-erosion and anti-bending protection system according to claim 5, characterized in that, The cross-sectional shape of the first hole section matches the cross-sectional shape of the rotating shaft to restrict rotation, and the cross-section of the second hole section is circular.

7. The anti-erosion and anti-bending protection system according to claim 5 or 6, characterized in that, A transition slope is provided between the first hole section and the second hole section.

8. The anti-erosion and anti-bending protection system according to claim 5, characterized in that, The damping component also includes a convex ring, which is disposed on the rotating shaft and has a diameter larger than that of the through hole, for axially limiting the rotating shaft.

9. The anti-erosion and anti-bending protection system according to claim 5, characterized in that, The damping component is made of corrosion-resistant metal material, and / or the anti-erosion module and the anti-bending cover are both made of polyurethane material.

10. A method of operation for the anti-erosion and anti-bending protection system according to any one of claims 5-9, characterized in that, Includes the following steps: S1: Structural design and installation: S2: System operation under state one condition: When the external load on the submarine cable is lower than the preset threshold, the rotating shaft is located in the first hole section, its rotation is restricted, and the damping component does not function. S3: System operation when switching from state one to state two: When the external load on the submarine cable exceeds the preset threshold, the rotating shaft is moved to the second hole section and can rotate freely. The blade rotates with the rotating shaft and generates a damping torque in the water to improve the bending resistance. S4: Load reduction state reversal: When the external load weakens to below the preset threshold, the rotating shaft moves back to the first hole section, and the system returns to the state where the damping component does not function.

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