Method for designing scour protection for marine pile foundations

Abstract

The application provides a design method of a marine pile foundation scour combined protection device, and belongs to the technical field of marine pile protection devices. The protection device comprises a seabed, a single pile and a foundation scour combined protection device. The foundation scour combined protection device is arranged around the single pile and above the seabed. The design method comprises the following steps: selecting several foundation scour protection devices with different combined forms; establishing a numerical model of the pile foundation, the foundation scour protection device and the seabed under actual sea conditions; analyzing the shear force distribution of the riprap edge and the riprap surface caused by waves and water flow under different combined actions; extracting the maximum shear force of the riprap edge seabed and the riprap surface caused by waves and water flow under different combined actions, respectively, and taking the average of the two maximum shear forces; and selecting the combined form with the minimum shear force average as the protection mode with the best protection effect under this working condition. The application aims to solve the problems of subsidence damage and edge damage that easily occur in the riprap protection process.

Description

Technical Field

[0001] This invention belongs to the technical field of marine pile protection devices, and more specifically, relates to the design method of a combined protection device for marine pile foundation scour. Background Technology

[0002] Against the backdrop of dual carbon emissions, offshore wind power has achieved rapid development, with coastal provinces across China constructing large-scale offshore wind farms. In these constructed offshore wind farms, monopile foundations account for over 75%. Monopile foundations are also frequently used in the supporting structures of cross-sea bridges and marine ranches.

[0003] my country's coastal areas are primarily composed of soft clay, which is prone to scour pits around monopile foundations due to ocean currents and waves. These scour pits can reach depths up to the pile foundation diameter (approximately 8 meters) and can extend to about five times the pile diameter. These large scour pits reduce the embedment depth of the monopile foundation, decrease its bearing capacity, and severely compromise the structural safety.

[0004] Currently, rockfill is commonly used in engineering projects for scour protection to reduce the scour effect around the foundation. However, rockfill is based on experience and lacks theoretical guidance, especially in practical engineering implementation where it lacks adaptability and specificity for different marine dynamic environmental parameters such as water depth, wave height, and current velocity. Moreover, rockfill is prone to subsidence and edge damage in the short term, leading to failure. Therefore, there is an urgent need to develop scour protection methods with long-lasting protective effects and specific applications in practical engineering projects. Summary of the Invention

[0005] In view of this, the design method of the marine pile foundation scour protection device proposed in this invention aims to solve the problems of subsidence and edge damage that are prone to occur during the rock dumping protection process, and can enhance the durability and effectiveness of rock dumping protection.

[0006] This invention is implemented as follows:

[0007] S1: Select several basic scour protection devices with different combinations;

[0008] This invention provides a combined protection device for marine pile foundation scour, comprising a seabed, a monopile, and the combined protection device for foundation scour. The combined protection device for foundation scour is disposed around the monopile and on the seabed to reduce the scour caused by seawater on the seabed around the monopile. The combined protection device for foundation scour is a combination of riprap and turbulence ring, a combination of riprap and sleeve, or a combination of riprap and biomimetic aquatic plants.

[0009] Based on the above technical solution, the marine pile foundation scour protection device of the present invention can be further improved as follows:

[0010] The combined protective device of boulders and turbulence rings includes: an attachment shell fixed to the side of the monopile, a turbulence ring fixed to the seabed by a support pile, and multiple boulders located on the seabed surface around the monopile; the attachment shell is a cylindrical shell formed by two symmetrical semi-cylindrical plates connected at both ends by hinges; the turbulence ring is a circular ring formed by two symmetrical semi-circular rings connected at both ends by hinges; the turbulence ring surrounds the monopile and is coaxially arranged with the monopile, and both the turbulence ring and the attachment shell are located above the boulders; a connecting rod is provided between the turbulence ring and the attachment shell, and the two ends of the connecting rod are hinged to the turbulence ring and the attachment shell.

[0011] To address the mechanism of subsidence and damage in riprap layers, a combination of riprap placement and turbulence rings is employed as a protective method. The turbulence rings attract and trap horseshoe vortices. Installing turbulence rings around the foundation ensures that the horseshoe vortices remain around them, thus distancing them from the bed surface. This reduces the gap velocity generated by the horseshoe vortices within the riprap gaps, decreasing the amount of sediment carried away from the riprap layer and achieving a better protective effect.

[0012] Furthermore, the combined protective device of boulders and sleeve includes: a sleeve buried around the monopile, and multiple boulders located on the seabed surface around the monopile; the sleeve is a cylindrical shell formed by splicing two semi-cylindrical plates at both ends inside the seabed, and the top of the sleeve is flush with the seabed surface.

[0013] Combining the rock-laying and sleeve protection methods, when the rock-laying layer sinks to a certain extent, the presence of the sleeve can fix the stones at the edge of the rock-laying layer, preventing them from shifting or falling, thus reducing edge damage to the rock-laying layer. Furthermore, the stones falling from the outside of the sleeve adhere closely to the sleeve wall, further reducing scouring around the sleeve. At the same time, the presence of rocks inside the sleeve may increase the upward component of the water flow when it exits the sleeve, further reducing the shedding of the wake vortex, thereby reducing downstream scouring.

[0014] Furthermore, the combined protective device of riprap and bionic aquatic plants includes: a bionic aquatic plant cover laid on the seabed surface around the monopile, and multiple riprap placed on top of the bionic aquatic plant cover; the bionic aquatic plant cover consists of bionic aquatic plants, a base mat, and a counterweight, with one end of the bionic aquatic plants fixedly connected to the upper surface of the base mat, and the counterweight fixedly connected to the lower part of the base mat.

[0015] To address the subsidence and shear damage of the riprap layer, a combination of riprap and biomimetic aquatic plants is employed. The biomimetic aquatic plants reduce the direct contact between the undercurrent in front of the pile and the surrounding bed surface. Furthermore, the grass fibers on the surface of the biomimetic aquatic plants and the riprap above them can suppress the generation of horseshoe vortices, thereby reducing the energy of the undercurrent and horseshoe vortices to a certain extent and alleviating the subsidence damage of the riprap layer. In addition, the biomimetic aquatic plants can also hinder the forward flow, reducing its approach velocity to a level insufficient to reach the critical shear velocity of the riprap, thus preventing shear damage. The riprap layer above the aquatic plants helps stabilize the biomimetic aquatic plant mat. When scouring occurs at its edges, the biomimetic aquatic plant mat can quickly bend to conform to the bed surface due to the gravity of the riprap, preventing secondary scouring.

[0016] This invention provides a design method for a combined protection device for scour of marine pile foundations, comprising:

[0017] S2: Establish numerical models of pile foundation-foundation scour protection device-seabed with different combination forms;

[0018] S3: Analyze the shear force distribution on the seabed at the edge of the riprap and on the upper surface of the riprap under the action of numerical models of pile foundation-foundation scour protection device-seabed with different combinations;

[0019] S4: Extract the maximum shear force on the seabed and the upper surface of the riprap edge caused by waves and water flow under the action of numerical models of pile foundation-foundation scour protection device-seabed with different combinations, and take the average of the two maximum shear forces.

[0020] S5: Select the combination with the smallest mean shear force as the protection method with the best protection effect under the corresponding sea state of the numerical model.

[0021] Based on the above technical solution, the design method of the marine pile foundation scour protection device of the present invention can be further improved as follows:

[0022] Furthermore, the specific operating steps for selecting several different combinations of basic scour protection devices are as follows:

[0023] The selection process involves using an arithmetic progression method to select components from the physical characteristics of each component in the foundation scour protection device. Components with different physical characteristics are then combined without repetition to form foundation scour protection devices with different combinations.

[0024] Based on the median block diameter and laying range of the riprap, the arrangement elevation, inner diameter, and outer diameter of the turbulence ring, several different combinations of riprap and turbulence ring combination protection devices were selected.

[0025] Alternatively, depending on the median diameter and laying range of the riprap, the diameter of the sleeve, and the distance from the seabed, several different combinations of riprap and sleeve combination protective devices can be selected.

[0026] Alternatively, depending on the median block diameter and laying range of the riprap, the laying range, inter-plant distance, and plant height of the bionic aquatic plants, several different combinations of riprap and bionic aquatic plant combination protection devices can be selected.

[0027] Furthermore, the specific operational steps for establishing numerical models of pile foundation-foundation scour protection devices-seabed with different combinations are as follows:

[0028] Numerical models are created using 3D modeling software;

[0029] Based on the geometric characteristics, dimensions, and locations of the selected combined rock-rock and turbulence ring protective devices with different combinations, numerical models of the pile foundation-rock-turbulence ring combined protective device-seabed with different combinations are established.

[0030] Alternatively, based on the geometric characteristics, dimensions, and locations of the selected combination of riprap and sleeve protective devices, numerical models of pile foundation-riprap and sleeve protective devices-seabed with different combination forms can be established.

[0031] Alternatively, based on the geometric characteristics, dimensions, and locations of the selected combination of riprap and biomimetic aquatic plant protective devices, numerical models of the pile foundation-riprap and biomimetic aquatic plant protective device-seabed with different combination forms can be established.

[0032] Furthermore, the specific operational steps for analyzing the shear force distribution on the edge and surface of the riprap caused by waves and currents under the numerical model of different combinations of pile foundation-foundation scour protection device-seabed are as follows:

[0033] Numerical models of pile foundation-foundation scour protection device-seabed with different combinations were imported into fluid analysis software. The actual physical parameters of each component were set, including density. Based on the actual sea conditions, water depth, and wave and current conditions, parameters such as wave generation, current generation boundary, water flow velocity, wave height, and wave period were set through the fluid analysis software to conduct real-world wave and current simulation. The shear stress distribution under the simulated wave and current environment was calculated and output through the fluid analysis software.

[0034] Based on the established numerical model of the interaction between the pile foundation-rock and turbulence ring combined protection device-seabed, shear stress analysis was performed using fluid analysis software to obtain the shear force distribution of the rock edge and rock surface caused by waves and water flow under the action of rock and turbulence ring combined protection devices with different combination forms.

[0035] Alternatively, based on the established numerical model of the interaction between the pile foundation, riprap and sleeve combined protective device and the seabed, shear stress analysis can be performed using fluid analysis software to obtain the shear force distribution of the riprap edge and riprap surface caused by waves and water flow under the action of several different combinations of riprap and sleeve combined protective devices.

[0036] Alternatively, based on the established numerical model of the interaction between the pile foundation, riprap, and biomimetic aquatic plant combination protection device and the seabed, shear stress analysis can be performed using fluid analysis software to obtain the shear force distribution on the edge and surface of the riprap caused by waves and water flow under the action of riprap and biomimetic aquatic plant combination protection devices with different combination forms.

[0037] Furthermore, the scope of consideration for selecting the physical characteristic parameters of each component in the basic scour protection device using arithmetic progressions is as follows:

[0038] The pile diameter is the actual measured diameter of the single pile requiring protective equipment.

[0039] The range of arithmetic progression selection for the physical characteristic parameters of boulders:

[0040] The median diameter of the riprap is between 0.1 and 0.2 times the pile diameter; the riprap laying range is between 2 and 5 times the pile diameter.

[0041] The range of arithmetic progression selection for the physical characteristic parameters of the spoiler ring:

[0042] The elevation of the disturbance ring is between 0 and 1 times the pile foundation diameter from the seabed surface; the outer diameter of the disturbance ring is between 1.8 and 2.4 times the pile foundation diameter; and the inner diameter of the disturbance ring is between 1.6 and 2.2 times the pile foundation diameter.

[0043] The range of arithmetic progression selection for the physical characteristic parameters of the sleeve:

[0044] The diameter of the sleeve is between 2 and 5 times the diameter of the pile foundation;

[0045] The distance between the sleeve and the seabed plane is between 0 and 1 times the pile diameter;

[0046] The range of arithmetic progression selection for the physical characteristic parameters of biomimetic aquatic plants:

[0047] The biomimetic aquatic plants are laid within a range of 2 to 5 times the diameter of the pile foundation; the spacing between each biomimetic aquatic plant is between 0.05 and 0.1 times the diameter of the pile foundation; and the average height of the biomimetic aquatic plants is between 0.1 and 0.3 times the diameter of the pile foundation.

[0048] Furthermore, the 3D modeling software includes: SOLIDWORKS, CAD, and UG; the fluid analysis software includes: FLOW-3D, Fluent, and OpenFOAM.

[0049] Compared with the prior art, the beneficial effects of the design method of the marine pile foundation scour protection device provided by the present invention are: by analyzing different marine dynamic environment parameters such as different water depths, wave heights, and current velocities, and by adopting various combination methods and adjusting the design method, it can protect marine pile foundations from scour under different conditions, which has a certain degree of pertinence and practicality, and the protection effect is long-lasting. Attached Figure Description

[0050] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments of the present invention 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.

[0051] Figure 1 A schematic diagram of a combined rock-throwing and turbulence-disrupting ring protective device;

[0052] Figure 2 A three-dimensional schematic diagram of a combined rock-throwing and turbulence-disrupting ring protective device;

[0053] Figure 3 Schematic diagram of a combined rock-throwing and sleeve protection device;

[0054] Figure 4 A schematic diagram of a protective device combining boulders and biomimetic aquatic plants;

[0055] Figure 5 This is a schematic diagram of a biomimetic aquatic plant cover structure;

[0056] Figure 6 Flowchart of the design method for combined scour protection devices for marine pile foundations;

[0057] The attached diagram lists the components represented by each number as follows:

[0058] 1. Seabed; 2. Monopile; 3. Turbidity ring; 4. Rockfill; 5. Attached shell; 6. Support pile; 7. Sleeve; 8. Bionic aquatic plant cover; 81. Bionic aquatic plants; 82. Base mat; 83. Counterweight. Detailed Implementation

[0059] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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, 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.

[0060] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0061] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0062] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not 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.

[0063] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0064] S1: Select several basic scour protection devices with different combinations;

[0065] like Figure 1-5The image shows a combined protection device for marine pile foundation scour, provided by the present invention. It includes a seabed 1, a monopile 2, and a combined protection device for foundation scour. The combined protection device for foundation scour is installed around the monopile 2 and on the seabed 1 to reduce the scour caused by seawater on the seabed 1 around the monopile 2. The combined protection device for foundation scour is a combination of riprap and turbulence ring, a combination of riprap and sleeve, or a combination of riprap and biomimetic aquatic plants.

[0066] In the above technical solution, the combined protective device of boulders and turbulence rings includes: an attachment shell 5 fixed to the side of the monopile 2, a turbulence ring 3 fixed to the seabed 1 by a support pile 6, and multiple boulders 4 located on the surface of the seabed 1 around the monopile 2; the attachment shell 5 is a cylindrical shell formed by two symmetrical semi-cylindrical plates connected at both ends by hinges; the turbulence ring 3 is a circular ring formed by two symmetrical semi-circular rings connected at both ends by hinges; the turbulence ring 3 surrounds the monopile 2 and is coaxially arranged with the monopile 2, and both the turbulence ring 3 and the attachment shell 5 are located above the boulders 4, and a connecting rod is provided between the turbulence ring 3 and the attachment shell 5, with both ends of the connecting rod hinged to the turbulence ring 3 and the attachment shell 5.

[0067] The crane vessel lifts the two semi-cylindrical pieces of the attachment shell 5 to the sea level around the seabed 1, so that the two semi-cylindrical pieces of the attachment shell 5 are tightly attached to the side of the monopile 2; then the hinge between the two semi-cylindrical pieces of the attachment shell 5 is connected; then the crane vessel releases the turbulence ring 3, so that the support pile 6 at the bottom of the turbulence ring 3 is deeply buried and fixed to the seabed 1, and the turbulence ring 3 is installed in the designated position, completing the turbulence ring construction; finally, the rock-throwing vessel throws the rock 4 according to the designated rock-throwing range and thickness to complete the rock-throwing construction.

[0068] Furthermore, in the above technical solution, the combined protective device of boulders and sleeves includes: sleeves 7 buried around the monopile 2, and multiple boulders 4 located on the surface of the seabed 1 around the monopile 2; the sleeve 7 is a cylindrical shell formed by splicing two semi-cylindrical plates at both ends inside the seabed 1, and the top of the sleeve 7 is flush with the surface of the seabed 1.

[0069] The crane vessel lifts the two semi-cylindrical pieces of the sleeve 7 from both sides of the single pile 2, and places the two semi-cylindrical pieces of the sleeve 7 at the designated positions on the seabed surface. After splicing the two semi-cylindrical pieces of the sleeve 7 to form a cylindrical shell, the sleeve 7 is buried into the seabed using equipment such as a hydraulic pile hammer, and the top of the sleeve is made flush with the seabed. Finally, the stone-throwing construction is completed by throwing the stones 4 according to the designated throwing range and thickness using a stone-throwing vessel.

[0070] Furthermore, in the above technical solution, the combined protective device of riprap and bionic aquatic plants includes: a bionic aquatic plant cover 8 laid on the surface of the seabed 1 around the monopile 2, and multiple riprap 4 placed on top of the bionic aquatic plant cover 8; the bionic aquatic plant cover 8 is composed of bionic aquatic plants 81, a base pad 82, and a counterweight 83, with one end of the bionic aquatic plants 81 fixedly connected to the upper surface of the base pad 82, and the counterweight 83 fixedly connected to the lower part of the base pad 82.

[0071] The crane vessel lifts several biomimetic aquatic plant blankets 8 in sequence and releases them onto the designated seabed surface; then the stone-throwing vessel throws the stones 4 according to the designated throwing range and thickness to complete the stone-throwing construction.

[0072] like Figure 6 The diagram shows a flowchart of the design method for the combined scour protection device for marine pile foundations provided by this invention, including:

[0073] S2: Establish numerical models of pile foundation-foundation scour protection device-seabed with different combination forms;

[0074] S3: Analyze the shear force distribution on the seabed at the edge of the riprap and on the upper surface of the riprap under the action of numerical models of pile foundation-foundation scour protection device-seabed with different combinations;

[0075] S4: Extract the maximum shear force on the seabed and the upper surface of the riprap edge caused by waves and water flow under the action of numerical models of pile foundation-foundation scour protection device-seabed with different combinations, and take the average of the two maximum shear forces.

[0076] S5: Select the combination with the smallest mean shear force as the protection method with the best protection effect under the corresponding sea state of the numerical model.

[0077] Furthermore, in the above technical solutions, the specific operating steps for several different combinations of foundation scour protection devices are as follows:

[0078] The selection process involves using an arithmetic progression method to select components from the physical characteristics of each component in the foundation scour protection device. Components with different physical characteristics are then combined without repetition to form foundation scour protection devices with different combinations.

[0079] Based on the median block diameter and laying range of the riprap, the arrangement elevation, inner diameter, and outer diameter of the turbulence ring, several different combinations of riprap and turbulence ring combination protection devices were selected.

[0080] Alternatively, depending on the median diameter and laying range of the riprap, the diameter of the sleeve, and the distance from the seabed, several different combinations of riprap and sleeve combination protective devices can be selected.

[0081] Alternatively, depending on the median block diameter and laying range of the riprap, the laying range, inter-plant distance, and plant height of the bionic aquatic plants, several different combinations of riprap and bionic aquatic plant combination protection devices can be selected.

[0082] Furthermore, in the above technical solution, the specific operational steps for establishing numerical models of pile foundation-foundation scour protection device-seabed with different combination forms are as follows:

[0083] Numerical models are created using 3D modeling software;

[0084] Based on the geometric characteristics, dimensions, and locations of the selected combined rock-rock and turbulence ring protective devices with different combinations, numerical models of the pile foundation-rock-turbulence ring combined protective device-seabed with different combinations are established.

[0085] Alternatively, based on the geometric characteristics, dimensions, and locations of the selected combination of riprap and sleeve protective devices, numerical models of pile foundation-riprap and sleeve protective devices-seabed with different combination forms can be established.

[0086] Alternatively, based on the geometric characteristics, dimensions, and locations of the selected combination of riprap and biomimetic aquatic plant protective devices, numerical models of the pile foundation-riprap and biomimetic aquatic plant protective device-seabed with different combination forms can be established.

[0087] Furthermore, in the above technical solution, the specific operational steps for analyzing the shear force distribution on the edge and surface of the riprap caused by waves and currents under the numerical model of different combinations of pile foundation-foundation scour protection device-seabed are as follows:

[0088] Numerical models of pile foundation-foundation scour protection device-seabed with different combinations were imported into fluid analysis software. The actual physical parameters of each component were set, including density. Based on the actual sea conditions, water depth, and wave and current conditions, parameters such as wave generation, current generation boundary, water flow velocity, wave height, and wave period were set through the fluid analysis software to conduct real-world wave and current simulation. The shear stress distribution under the simulated wave and current environment was calculated and output through the fluid analysis software.

[0089] Based on the established numerical model of the interaction between the pile foundation-rock and turbulence ring combined protection device-seabed, shear stress analysis was performed using fluid analysis software to obtain the shear force distribution of the rock edge and rock surface caused by waves and water flow under the action of rock and turbulence ring combined protection devices with different combination forms.

[0090] Alternatively, based on the established numerical model of the interaction between the pile foundation, riprap and sleeve combined protective device and the seabed, shear stress analysis can be performed using fluid analysis software to obtain the shear force distribution of the riprap edge and riprap surface caused by waves and water flow under the action of several different combinations of riprap and sleeve combined protective devices.

[0091] Alternatively, based on the established numerical model of the interaction between the pile foundation, riprap, and biomimetic aquatic plant combination protection device and the seabed, shear stress analysis can be performed using fluid analysis software to obtain the shear force distribution on the edge and surface of the riprap caused by waves and water flow under the action of riprap and biomimetic aquatic plant combination protection devices with different combination forms.

[0092] Furthermore, in the above technical solution, the scope of consideration for selecting the physical characteristic parameters of each component in the basic scour protection device using arithmetic progression is as follows:

[0093] The pile diameter is the actual measured diameter of the single pile requiring protective equipment.

[0094] The range of arithmetic progression selection for the physical characteristic parameters of boulders:

[0095] The median diameter of the riprap is between 0.1 and 0.2 times the pile diameter; the riprap laying range is between 2 and 5 times the pile diameter.

[0096] The range of arithmetic progression selection for the physical characteristic parameters of the spoiler ring:

[0097] The elevation of the disturbance ring is between 0 and 1 times the pile foundation diameter from the seabed surface; the outer diameter of the disturbance ring is between 1.8 and 2.4 times the pile foundation diameter; and the inner diameter of the disturbance ring is between 1.6 and 2.2 times the pile foundation diameter.

[0098] The range of arithmetic progression selection for the physical characteristic parameters of the sleeve:

[0099] The diameter of the sleeve is between 2 and 5 times the diameter of the pile foundation;

[0100] The distance between the sleeve and the seabed plane is between 0 and 1 times the pile diameter;

[0101] The range of arithmetic progression selection for the physical characteristic parameters of biomimetic aquatic plants:

[0102] The biomimetic aquatic plants are laid within a range of 2 to 5 times the diameter of the pile foundation; the spacing between each biomimetic aquatic plant is between 0.05 and 0.1 times the diameter of the pile foundation; and the average height of the biomimetic aquatic plants is between 0.1 and 0.3 times the diameter of the pile foundation.

[0103] Furthermore, in the above technical solutions, the 3D modeling software includes: SOLIDWORKS, CAD, and UG; the fluid analysis software includes: FLOW-3D, Fluent, and OpenFOAM.

[0104] Among them, FLOW-3D is preferred.

[0105] The above description is merely a specific embodiment 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 technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A design method for a combined scour protection device for marine pile foundations, characterized in that, include: S1: Select several basic scour protection devices with different combinations; Among them, the marine pile foundation scour protection device includes a seabed (1), a single pile (2), and a foundation scour protection device. The foundation scour protection device is installed around the single pile (2) and on the seabed (1) to reduce the scour caused by seawater on the seabed (1) around the single pile (2). The foundation scour protection device is a combination protection device of riprap and turbulence ring, or a combination protection device of riprap and sleeve, or a combination protection device of riprap and bionic aquatic plants. The combined protective device of boulders and turbulence rings includes: an attachment shell (5) fixed to the side of the monopile (2), a turbulence ring (3) fixed on the seabed (1) by a support pile (6), and multiple boulders (4) on the surface of the seabed (1) around the monopile (2); the attachment shell (5) is a cylindrical shell formed by two symmetrical semi-cylindrical plates connected at both ends by hinges; the turbulence ring (3) is a circular ring formed by two symmetrical semi-circular rings connected at both ends by hinges; the turbulence ring (3) surrounds the monopile (2) and is coaxially arranged with the monopile (2); both the turbulence ring (3) and the attachment shell (5) are located above the boulders (4); a connecting rod is provided between the turbulence ring (3) and the attachment shell (5); the two ends of the connecting rod are hinged to the turbulence ring (3) and the attachment shell (5); The combined protective device of boulders and sleeves includes: sleeves (7) buried around the monopile (2), and multiple boulders (4) located on the surface of the seabed (1) around the monopile (2); the sleeve (7) is a cylindrical shell formed by splicing two semi-cylindrical plates at both ends inside the seabed (1), and the top of the sleeve (7) is flush with the surface of the seabed (1); The combined protective device of boulders and bionic aquatic plants includes: a bionic aquatic plant cover (8) laid on the surface of the seabed (1) around the monopile (2), and multiple boulders (4) pressing on the bionic aquatic plant cover (8); the bionic aquatic plant cover (8) is composed of bionic aquatic plants (81), a base mat (82), and a counterweight (83), one end of the bionic aquatic plants (81) is fixedly connected to the upper surface of the base mat (82), and the counterweight (83) is fixedly connected to the lower part of the base mat (82); S2: Establish numerical models of pile foundation-foundation scour protection device-seabed with different combination forms; S3: Analyze the shear force distribution on the seabed at the edge of the riprap and on the upper surface of the riprap under the action of numerical models of pile foundation-foundation scour protection device-seabed with different combinations; S4: Extract the maximum shear force on the seabed and the upper surface of the riprap edge caused by waves and water flow under the action of numerical models of pile foundation-foundation scour protection device-seabed with different combinations, and take the average of the two maximum shear forces. S5: Select the combination with the smallest mean shear force as the protection method with the best protection effect under the corresponding sea state of the numerical model.

2. The design method of the combined protection device for scour of marine pile foundations according to claim 1, characterized in that, The specific operating steps for selecting several basic scour protection devices with different combinations are as follows: The selection process involves using an arithmetic progression method to select components from the physical characteristics of each component in the foundation scour protection device. Components with different physical characteristics are then combined without repetition to form foundation scour protection devices with different combinations. Based on the median block diameter and laying range of the riprap, the arrangement elevation, inner diameter, and outer diameter of the turbulence ring, several different combinations of riprap and turbulence ring combination protection devices were selected. Alternatively, depending on the median diameter and laying range of the riprap, the diameter of the sleeve, and the distance from the seabed, several different combinations of riprap and sleeve combination protective devices can be selected. Alternatively, depending on the median block diameter and laying range of the riprap, the laying range, inter-plant distance, and plant height of the bionic aquatic plants, several different combinations of riprap and bionic aquatic plant combination protection devices can be selected.

3. The design method of the combined protection device for scour of marine pile foundations according to claim 2, characterized in that, The specific operational steps for establishing numerical models of pile foundation-foundation scour protection devices-seabed with different combinations are as follows: Numerical models are created using 3D modeling software; Based on the geometric characteristics, dimensions, and locations of the selected combined rock-rock and turbulence ring protective devices with different combinations, numerical models of the pile foundation-rock-turbulence ring combined protective device-seabed with different combinations are established. Alternatively, based on the geometric characteristics, dimensions, and locations of the selected combination of riprap and sleeve protective devices, numerical models of pile foundation-riprap and sleeve protective devices-seabed with different combination forms can be established. Alternatively, based on the geometric characteristics, dimensions, and locations of the selected combination of riprap and biomimetic aquatic plant protective devices, numerical models of the pile foundation-riprap and biomimetic aquatic plant protective device-seabed with different combination forms can be established.

4. The design method of the combined protection device for scour of marine pile foundations according to claim 3, characterized in that, The specific operational steps for analyzing the shear force distribution on the edge and surface of the riprap caused by waves and currents under the numerical model of different combinations of pile foundation-foundation scour protection devices-seabed are as follows: Numerical models of pile foundation-foundation scour protection device-seabed with different combinations were imported into fluid analysis software. The actual physical parameters of each component were set, including density. Based on the actual sea conditions, water depth, and wave and current conditions, parameters such as wave generation, current generation boundary, water flow velocity, wave height, and wave period were set through the fluid analysis software to conduct real-world wave and current simulation. The shear stress distribution under the simulated wave and current environment was calculated and output through the fluid analysis software. Based on the established numerical model of the interaction between the pile foundation-rock and turbulence ring combined protection device-seabed, shear stress analysis was performed using fluid analysis software to obtain the shear force distribution of the rock edge and rock surface caused by waves and water flow under the action of rock and turbulence ring combined protection devices with different combination forms. Alternatively, based on the established numerical model of the interaction between the pile foundation, riprap and sleeve combined protective device and the seabed, shear stress analysis can be performed using fluid analysis software to obtain the shear force distribution of the riprap edge and riprap surface caused by waves and water flow under the action of several different combinations of riprap and sleeve combined protective devices. Alternatively, based on the established numerical model of the interaction between the pile foundation, riprap, and biomimetic aquatic plant combination protection device and the seabed, shear stress analysis can be performed using fluid analysis software to obtain the shear force distribution on the edge and surface of the riprap caused by waves and water flow under the action of riprap and biomimetic aquatic plant combination protection devices with different combination forms.

5. The design method of the combined protection device for scour of marine pile foundations according to claim 4, characterized in that, in, The scope of consideration for selecting the physical characteristic parameters of each component in the basic scour protection device using arithmetic progression is as follows: The pile diameter is the actual measured diameter of the single pile requiring protective equipment. The range of arithmetic progression selection for the physical characteristic parameters of boulders: The median diameter of the riprap is between 0.1 and 0.2 times the pile diameter; the riprap laying range is between 2 and 5 times the pile diameter. The range of arithmetic progression selection for the physical characteristic parameters of the spoiler ring: The elevation of the disturbance ring is between 0 and 1 times the pile foundation diameter from the seabed surface; the outer diameter of the disturbance ring is between 1.8 and 2.4 times the pile foundation diameter; and the inner diameter of the disturbance ring is between 1.6 and 2.2 times the pile foundation diameter. The range of arithmetic progression selection for the physical characteristic parameters of the sleeve: The diameter of the sleeve is between 2 and 5 times the diameter of the pile foundation; The distance between the sleeve and the seabed plane is between 0 and 1 times the pile diameter; The range of arithmetic progression selection for the physical characteristic parameters of biomimetic aquatic plants: The biomimetic aquatic plants are laid within a range of 2 to 5 times the diameter of the pile foundation; the spacing between each biomimetic aquatic plant is between 0.05 and 0.1 times the diameter of the pile foundation; and the average height of the biomimetic aquatic plants is between 0.1 and 0.3 times the diameter of the pile foundation.

6. The design method of the combined protection device for scour of marine pile foundations according to claim 5, characterized in that, in, The 3D modeling software includes: SOLIDWORKS, CAD, and UG; the fluid analysis software includes: FLOW-3D, Fluent, and OpenFOAM.

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