Submarine pipeline scouring protection artificial fish reef structure

Abstract

The invention discloses a subsea pipeline scouring protection artificial fish reef structure, and relates to the technical field of ocean engineering. The structure comprises a fixing device covering the outer surface of the pipeline body, an artificial fish reef of a hollow cuboid structure and a telescopic rod assembly connecting the fixing device and the artificial fish reef. The shortest distance limiter, the longest distance limiter and the spring are arranged in the telescopic rod assembly, the distance between the artificial fish reef and the pipeline can be limited, the flow guide angle of the artificial fish reef is adjusted through elastic deformation of the spring under strong ocean current, water flow is guided upwards, and the pipeline is prevented from being directly scoured. The position and the shape of the artificial fish reef are optimized through numerical simulation, the scouring depth around the pipeline is remarkably reduced, the flow field condition is improved, fishes are attracted to gather, and synergistic interaction of subsea pipeline protection and marine ranch construction is achieved.

Description

Technical Field

[0001] This invention relates to the field of marine engineering technology, and in particular to an artificial reef structure for protecting against scour of submarine pipelines. Background Technology

[0002] Subsea pipelines are critical infrastructure for transporting marine oil, gas, and energy. However, they are constantly exposed to complex dynamic environments such as waves and currents, making them highly susceptible to localized scour damage. Scour can lead to the loss and suspension of soil beneath the pipeline, resulting in vortex-induced vibration and structural failure, seriously threatening energy transport safety and posing significant economic and environmental risks. In engineering protection practices, common measures mainly fall into two categories: one is to suppress scour by reducing the pressure difference and seepage at the bed surface, such as using riprap and subgrade; the other is to promote pipeline self-burial by altering the flow field structure, such as using baffles and flexible plates. However, the former is often costly, while the latter may exacerbate vibration risks.

[0003] Therefore, there is a need to provide a more efficient, economical, and safer method for preventing pipeline erosion. Summary of the Invention

[0004] The purpose of this invention is to provide an artificial reef structure for protecting against submarine pipeline erosion, in order to solve the problems existing in the prior art.

[0005] To achieve the above objectives, the present invention provides an artificial reef structure for protecting submarine pipelines from scour, including a fixing device that covers the outer surface of the pipeline. Artificial reefs are provided on both sides of the pipeline. The artificial reefs are hollow cuboid structures. A telescopic rod assembly is provided between the artificial reefs and the fixing device, and the artificial reefs and the fixing device are connected through the telescopic rod assembly.

[0006] Preferably, the thickness of the fixing device is 0.05 to 0.15 times the outer diameter of the pipe.

[0007] Preferably, the telescopic rod assembly includes an inclined support rod and a positive support rod. Both the inclined support rod and the positive support rod include an outer sleeve and an inner sleeve slidably disposed inside the outer sleeve. The outer sleeve is provided with a closest distance limiter and a farthest distance limiter. The inner sleeve is provided with a spring, and the two ends of the spring are respectively connected to the inner sleeve and the outer sleeve.

[0008] Preferably, the spring constant in the inclined support rod is greater than the spring constant in the upright support rod.

[0009] Preferably, the artificial reef includes a vertical plate and multiple horizontal plates fixedly disposed on the same side of the vertical plate. The vertical plate is provided with multiple inclined through holes, which are located between two adjacent horizontal plates. The distance between two adjacent horizontal plates is 50mm to 200mm. The length of the artificial reef is 1m to 3m, the width of the artificial reef is 0.5m to 1.5m, and the height of the artificial reef is 0.5m to 1.5m.

[0010] Preferably, the horizontal distance between the artificial reef and the pipeline is 0.5m to 2.0m.

[0011] Preferably, the fixing device is an annular sleeve structure, and the inner wall of the fixing device is provided with an anti-slip pad.

[0012] Preferably, the telescopic rod assembly consists of four rods, each connected to one of the four corners of the artificial reef.

[0013] Preferably, the fixing devices are arranged at intervals along the axial direction of the pipeline, and the distance between two adjacent fixing devices is 10m to 30m.

[0014] Preferably, the surface of the artificial reef is coated with an anti-corrosion and anti-fouling coating.

[0015] Compared with the prior art, the present invention has the following advantages and technical effects:

[0016] 1. The artificial reef structure for protecting submarine pipelines from scour provided by the present invention has a telescopic rod assembly equipped with a closest distance limiter, a farthest distance limiter and a spring, which can limit the distance between the artificial reef and the pipeline, and adjust the guiding angle of the artificial reef through the elastic deformation of the spring under strong ocean currents, so as to guide the water flow upward and avoid directly scouring the pipeline.

[0017] 2. This invention significantly reduces the scouring depth around the pipeline, improves flow field conditions, attracts fish to gather, and achieves synergistic effects between submarine pipeline protection and marine ranching construction; it is adaptable to complex marine environments and has broad application prospects. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the artificial reef structure for protecting submarine pipelines from scour, as described in this invention.

[0020] Figure 2This is a schematic diagram of the internal structure of the telescopic rod assembly of the present invention;

[0021] Figure 3 This is a schematic diagram of the artificial reef of the present invention;

[0022] Figure 4 Diagrams showing the erosion surface morphology of the pipeline in two scenarios: before and after the artificial reef.

[0023] Figure 5 The graph shows the variation of the maximum scour depth of the pipeline with artificial reefs over time.

[0024] Figure 6 A statistical chart for simulating the selection of artificial reefs based on different locations, heights, widths, and spacing between boards;

[0025] In the diagram: 1. Fixing device; 2. Telescopic rod assembly; 21. Closest distance limiter; 22. Farthest distance limiter; 23. Spring; 24. Diagonal support rod; 25. Positive support rod; 3. Artificial reef. Detailed Implementation

[0026] It should be noted that, unless otherwise specified, the embodiments and features described in this invention can be combined with each other. The described embodiments are merely some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this invention. The invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0027] like Figures 1 to 3 As shown, the present invention provides an artificial reef structure for protecting submarine pipelines from scour, including a fixing device 1, which is installed on the outer surface of the pipeline. Artificial reefs 3 are provided on both sides of the pipeline. The artificial reefs 3 are hollow cuboid structures. A telescopic rod assembly 2 is provided between the artificial reefs 3 and the fixing device 1. The artificial reefs 3 and the fixing device 1 are connected by the telescopic rod assembly 2.

[0028] Further optimization of the scheme: the thickness of the fixing device 1 is 0.05 to 0.15 times the outer diameter of the pipe.

[0029] Further optimization of the scheme: the telescopic rod assembly 2 includes an inclined support rod 24 and a positive support rod 25. Both the inclined support rod 24 and the positive support rod 25 include an outer sleeve and an inner sleeve that is slidably disposed inside the outer sleeve. The outer sleeve is provided with a closest distance limiter 21 and a farthest distance limiter 22. The inner sleeve is provided with a spring 23, and the two ends of the spring 23 are respectively connected to the inner sleeve and the outer sleeve.

[0030] Further optimization of the design resulted in the spring coefficient of spring 23 inside the inclined support rod 24 being greater than that of spring 23 inside the positive support rod 25.

[0031] Further optimization of the design: the artificial reef 3 includes a vertical plate and multiple horizontal plates fixed on the same side of the vertical plate. The vertical plate is provided with multiple inclined through holes, which are located between two adjacent horizontal plates. The spacing between two adjacent horizontal plates is 50mm to 200mm. The length of the artificial reef 3 is 1m to 3m, the width of the artificial reef 3 is 0.5m to 1.5m, and the height of the artificial reef 3 is 0.5m to 1.5m.

[0032] The plan was further optimized so that the horizontal distance between the artificial reef 3 and the pipeline is 0.5m to 2.0m.

[0033] Further optimization of the design: the fixing device 1 is a ring sleeve structure, and the inner wall of the fixing device 1 is provided with an anti-slip pad 11.

[0034] The design was further optimized so that the number of telescopic rod components 2 is four, which are connected to the four corners of the artificial reef 3 respectively.

[0035] Further optimization of the scheme: the fixing devices 1 are arranged at intervals along the axial direction of the pipeline, and the distance between two adjacent fixing devices 1 is 10m to 30m.

[0036] The design was further optimized by coating the surface of artificial reef 3 with an anti-corrosion and anti-fouling coating.

[0037] The artificial reef structure for protecting subsea pipelines from scour provided by this invention determines the magnitude of the ocean current force on the artificial reef 3 based on the watershed flow velocity. Under normal use, the ocean current force is relatively small, and the artificial reef 3 guides the flow parallel to the pipeline direction, mitigating scour while also attracting fish. When the seabed current velocity increases to a certain speed, the current force compresses the inclined support rod 24 and the main support rod 25. The spring 23 of the inclined support rod 24 has a larger elastic coefficient than the spring 23 of the main support rod 25, resulting in less compression of the inclined support rod 24 than the main support rod 25. This causes the artificial reef 3 to form a certain angle, guiding the rapid water flow upwards and preventing direct scour of the pipeline. Similarly, the artificial reef 3 downstream of the pipeline also propels the water upwards.

[0038] The artificial reef structure for protecting submarine pipelines from erosion provided by this invention is used as follows:

[0039] First, the artificial reef type 3 was selected using numerical simulation. The SedFoam two-phase flow solver based on the OpenFOAM platform was used to solve the mass and momentum conservation equations for both the fluid and particle phases. Based on the sea state and sand quality of the deployment area, the flow field characteristics were determined for both extreme and normal operating conditions. A three-dimensional numerical flume model was constructed, including the artificial reef 3, pipelines, flow field, and sediment. A target inflow field was generated at the inflow boundary, and inlet and outlet boundary conditions were set at the outflow boundary. The numerical model was used to simulate the scour depth around the pipeline without a pre-designed artificial reef. Orthogonal experimental designs were conducted for key differences (different locations, heights, lengths, widths, and plate spacing).

[0040] 1. First, fix other parameters and optimize the spacing ratio: length L of artificial reef 3 / outer diameter D of pipe;

[0041] 2. Based on the optimal L / D ratio, optimize the width ratio: width W of artificial reef 3 / outer diameter D of pipe;

[0042] 3. Optimize the height ratio in sequence: the height H of the artificial reef 3 / the outer diameter D of the pipe, and the plate spacing ratio: the spacing K between two adjacent horizontal plates / the outer diameter D of the pipe;

[0043] 4. Verify the protective effect of the final parameter combination by comparing changes in indicators such as maximum scour depth, scour stabilization time, scour pit morphology, and flow field vortex structure development. Assign scores to different indicators according to pipeline operation requirements and select the optimal parameter with the highest comprehensive score as the optimal type.

[0044] Figure 4 Diagrams showing the erosion surface morphology of the pipeline in two scenarios: before and after the artificial reef. Figure 5 The graph shows the maximum scour depth of a pipeline with artificial reefs changing over time. Considering both the pipeline before and after the artificial reef 3, the change in the scour surface morphology can be observed, indicating that the artificial reef 3 promotes sediment deposition, alters the scour surface morphology, and even accelerates self-burial. The maximum scour depth with artificial reefs is significantly reduced compared to the case without artificial reefs, and the scour can quickly reach equilibrium. Both phenomena indicate that this type of artificial reef 3 can be used as an effective pipeline anti-scour measure.

[0045] Figure 6 This is a statistical chart used to simulate the selection of artificial reefs at different locations, heights, widths, and spacing between boards; the summarized data is shown in Table 1.

[0046] Table 1

[0047]

[0048] By simulating and selecting artificial reefs with different locations, heights, widths, and spacing, the optimal solution for scour prevention can be effectively chosen. Taking the sea condition with an average flow velocity of 1.5 m / s as an example, the optimal selection can reduce the maximum scour depth by 49.76%.

[0049] Next, the device is installed. During this process, the fixing devices 1 are placed at certain intervals on the pipeline and fixed. Then, the telescopic rod assembly 2 is connected to the fixing device 1 through the reserved rod. The artificial reef 3 is then hoisted to the other end of the telescopic rod assembly 2 and connected to the four corners of the artificial reef 3. Multiple artificial reef structures provided by this invention can be installed on a single pipeline.

[0050] After installation, under normal circumstances, the springs 23 inside the telescopic rod assembly 2 are all compressed and tend to extend outwards. The artificial reef 3 is located at the farthest distance limiter 22 of the telescopic rod assembly 2, parallel to the pipe. When the ocean current flows through the holes of the artificial reef 3, a low-velocity vortex is formed behind the artificial reef 3, which can attract fish to gather and reduce scouring and vortex-induced vibration. Under strong ocean currents, the artificial reef 3 moves towards the pipe side due to the current, further compressing the spring 23 inside the telescopic rod assembly 2. Since the elastic coefficient of the inclined support rod 24 is greater than that of the positive support rod 25, the positive support rod 25 is compressed more than the inclined support rod 24. The opening of the artificial reef 3 is angled upward, propelling the incoming flow towards the pipe, thus avoiding direct scouring of the sediment around the pipe. During this process, the artificial reef 3 is located at the closest distance limiter 21 of the telescopic rod assembly 2. The reef behind the pipe moves away from the pipe due to the current, stretching the spring 23 inside the telescopic rod assembly 2. Since the elastic coefficient of the inclined support rod 24 is greater than that of the positive support rod 25, the positive support rod 25 is stretched more than the inclined support rod 24. The opening of the artificial reef 3 is angled upward, propelling the incoming flow from the pipe side upward, reducing the flow velocity behind the pipe, and promoting sediment settling.

[0051] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A scour protection artificial reef structure for a subsea pipeline, the structure comprising: The utility model provides a kind of artificial reef fixing device, including fixing device (1), the fixing device (1) is overlaid on the outer surface of pipeline, both sides of the pipeline are provided with artificial reef (3), the artificial reef (3) is hollow cuboid structure, and telescopic rod assembly (2) is arranged between the artificial reef (3) and the fixing device (1), and the artificial reef (3) is connected with the fixing device (1) by the telescopic rod assembly (2).

2. The seabed pipeline scour protection artificial reef structure of claim 1, wherein, The thickness of the fixing device (1) is 0.05-0.15 times the outer diameter of the pipeline.

3. The seabed pipeline scour protection artificial reef structure of claim 1, wherein, The telescopic rod assembly (2) includes an inclined support rod (24) and a vertical support rod (25), both of which include an outer sleeve and an inner sleeve slidingly arranged inside the outer sleeve. The outer sleeve is provided with a nearest distance limiter (21) and a farthest distance limiter (22); the inner sleeve is provided with a spring (23), and the two ends of the spring (23) are connected with the inner sleeve and the outer sleeve respectively.

4. The seabed pipeline scour protection artificial reef structure of claim 3, wherein, The spring (23) in the inclined support rod (24) has a greater elastic coefficient than the spring (23) in the vertical support rod (25).

5. The seabed pipeline scour protection artificial reef structure of claim 1, wherein, The artificial reef (3) includes a vertical plate and multiple horizontal plates fixed on the same side of the vertical plate. The vertical plate is provided with multiple inclined through holes between adjacent horizontal plates. The distance between adjacent horizontal plates is 50-200 mm, the length of the artificial reef (3) is 1-3 m, the width of the artificial reef (3) is 0.5-1.5 m, and the height of the artificial reef (3) is 0.5-1.5 m.

6. The seabed pipeline scour protection artificial reef structure of claim 1, wherein, The horizontal distance between the artificial reef (3) and the pipeline is 0.5-2.0 m.

7. The seabed pipeline scour protection artificial reef structure of claim 1, wherein, The fixing device (1) is a ring sleeve structure, and the inner wall of the fixing device (1) is provided with an anti-skid pad.

8. The seabed pipeline scour protection artificial reef structure of claim 1, wherein, The number of telescopic rod assemblies (2) is four, and each is connected to a corner of the artificial reef (3).

9. The seabed pipeline scour protection artificial reef structure of claim 1, wherein, The fixing devices (1) are arranged along the axial direction of the pipeline at intervals, and the distance between adjacent fixing devices (1) is 10-30 m.

10. The seabed pipeline scour protection artificial reef structure of claim 1, wherein, The surface of the artificial reef (3) is coated with an anticorrosive and antifouling coating.

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