A multi-tiered dynamic resilience coastal defense system and design method

Abstract

The application discloses a multi-layer dynamic flexibility coastal defense system and a design method, and the system comprises, from the sea to the land, a front edge self-adapting buffer zone, which is arranged at a sea bed cliff of a front edge of a main sea dike, is composed of a granular material, and is arranged to dynamically adjust a shape to a stable profile under the action of water power; an off-shore submerged type siltation promoting wave breaking screen, which is arranged in parallel behind the front edge self-adapting buffer zone, has a top elevation near an average tide level, and is arranged to reduce wave energy and form a siltation promoting area between the screen and the main sea dike; an artificial bionic wave breaking beach reef system, which is formed in the siltation promoting area, has a width and an elevation simulating a natural reef flat, and is arranged to make waves break in advance to dissipate wave energy; and an ecological composite section main protection structure, which is used as ultimate protection and has a gentle slope or a composite section; and the application ensures safety, reliability and economy of the engineering scheme.

Description

Technical Field

[0001] This invention relates to the fields of coastal engineering, disaster prevention and mitigation, and ecological revetment technology, specifically to a multi-level dynamic resilient coastal protection system and its design method. Background Technology

[0002] During their long service life, sea dikes have been affected by climate change, with continuous sea level rise and uneven settlement occurring frequently in coastal silty soft soil foundation areas. Existing sea dikes are unable to meet the flood (tidal) control requirements under current water and sediment conditions, resulting in passive downgrading, which contradicts the needs of urban development and sea dike upgrading. Upgrading sea dikes through traditional methods of heightening and widening them increases engineering risks and costs, while simultaneously isolating biological migration and material exchange between the inside and outside of the sea dike, leading to a decline in the resilience and ecological benefits of the project. Therefore, existing technologies face the following bottlenecks: outdated protection concepts, reliance on a single rigid structure, and inability to adapt to dynamic water and sediment conditions; and outdated design specifications (such as the "Design Code for Sea Dike Engineering" GB / T 51015-2014), whose wave run-up calculation methods are not applicable to new composite and ecological sea dike cross sections, especially lacking quantitative consideration of the wave dissipation and siltation promotion effects of beach protection projects (along the dike), the complex morphology of composite cross sections, and the impact of dike-dike spacing, which seriously restricts the engineering application of advanced protection concepts. Summary of the Invention

[0003] Purpose of the invention: This invention provides a multi-level dynamic resilient coastal protection system and design method to solve the problems that relying on a single rigid structure cannot adapt to dynamic water and sand conditions; and that wave run-up calculation methods are not applicable to new composite and ecological seawall sections.

[0004] Technical Solution: The multi-level dynamic resilient coastal protection system of this invention comprises, from sea to land: an adaptive buffer zone at the leading edge of the main seawall, constructed of granular materials, designed to form a stable profile adapted to local wave and current conditions through particle movement under hydrodynamic action; an offshore submersible silt-dissipating barrier, positioned parallel to the adaptive buffer zone behind it, with its top elevation near the mean tide level, designed to reduce wave energy and form a silt-dissipating zone between it and the main seawall; an artificial biomimetic wave-dissipating reef system, formed within the silt-dissipating zone, having a width and elevation simulating a natural reef flat, designed to break waves prematurely to dissipate wave energy; and an ecological composite section main protection structure, serving as the ultimate protection, with a gentle slope or a composite section; the surface of the artificial biomimetic wave-dissipating reef system is formed by siltation by the offshore submersible silt-dissipating barrier, and elevation restoration is achieved through natural sediment replenishment or artificial sediment replenishment. Among them, the leading edge adaptive buffer zone, the shore-submersible siltation and wave-dissipating barrier, the artificial bionic wave-dissipating reef system, and the ecological composite section main protection structure together form an organic whole that dissipates energy step by step and achieves dynamic balance.

[0005] Furthermore, the leading edge adaptive buffer zone is a riprap dam, with 50-100kg of loose stone as the bulk material.

[0006] Furthermore, offshore submersible siltation and wave-dissipating barriers are constructed using either pipe pile dams or riprap dams.

[0007] Furthermore, the elevation of the embankment crest in the main protective structure of the ecological composite section is determined, including:

[0008] The design wave height H* on the main protective structure is determined by the following formula:

[0009] ;

[0010] in, The height of the transmitted wave after attenuation by the leading-edge adaptive buffer zone and the offshore submersible siltation and wave-dissipating barrier; To determine the water depth in front of the artificial biomimetic wave-dissipating reef system The wave height is calculated based on the wave breaking condition;

[0011] Based on the design wave height H*, the wave run-up at a cumulative frequency of 2% on the main protective structure is calculated. ;

[0012] Climbing according to the waves The design tide level and safety elevation are used to determine the top elevation of the main protective structure of the ecological composite section dike.

[0013] Furthermore, the formula for transmitted wave height is as follows:

[0014] ,

[0015] in, Indicates the transmission coefficient of the leading edge adaptive buffer band; Represents the incident wave height in the open sea; Transmission coefficient of offshore submersible siltation and wave-damping barrier.

[0016] Furthermore, calculate wave rise. The formula is as follows:

[0017] Typical calculated value: Maximum constraint value:

[0018] ;

[0019] in, This represents a climb rate of 2% cumulative frequency, taking the smaller value between the general calculated value and the maximum constraint value. This represents the comprehensive roughness and permeability coefficient related to the main protective structure of the ecological composite section. A coefficient representing the relationship to wind speed; This represents the platform reduction factor; The coefficients representing the distance between the offshore submersible silt-dissipating and wave-damping barriers and the main protective structures of the ecological composite cross-section; Indicates the influence coefficient of oblique waves; This represents the wave breaking parameters.

[0020] Furthermore, Determined in the following ways:

[0021] when hour, ;

[0022] when hour, ;

[0023] in, L represents the horizontal spacing between the offshore submersible silt-dissipating and wave-dissipating barrier and the main protective structure of the ecological composite section; L* represents the wavelength between the artificial bionic wave-dissipating reef system and the main protective structure of the ecological composite section.

[0024] Beneficial Effects: Compared with existing technologies, this invention has the following significant advantages: The four-tiered defense system of this invention achieves the gradual dissipation of wave energy from the sea to the beach to the dike, mitigating the destructive force of waves within the system itself, resulting in overall resilience far exceeding that of a single seawall. By using width instead of height and promoting siltation and beach formation, the amount of building materials used in the main seawall and the dike crest elevation are significantly reduced, lowering project costs and total life-cycle costs. The wave run-up calculation method provided fills a gap in existing standards, solves a core bottleneck in composite system design, ensures the safety, reliability, and economy of the engineering solution, and avoids conservative or risky designs. Attached Figure Description

[0025] Figure 1 This is a system design diagram of the present invention;

[0026] Figure 2 This is a cross-sectional plan view of the main protective structure of the ecological composite section of the present invention;

[0027] Figure 3 This is a three-dimensional cross-sectional view of the main protective structure of the eco-friendly composite cross-section of the present invention;

[0028] Figure 4 This is a three-dimensional cross-sectional view of the artificial biomimetic wave-dissipating reef system of the present invention;

[0029] Figure 5 This is a cross-sectional plan view of the artificial biomimetic wave-dissipating reef system of the present invention;

[0030] Figure 6 This is a cross-sectional plan view of the offshore submersible siltation-promoting and wave-dissipating barrier of the present invention (taking a pipe pile dam as an example);

[0031] Figure 7 This is a three-dimensional cross-sectional view of the offshore submersible silt-promoting and wave-dissipating barrier of the present invention (taking a pipe pile dam as an example).

[0032] Figure 8 This is a plan view of the offshore submersible siltation-promoting and wave-dissipating barrier of the present invention (taking a pipe pile dam as an example);

[0033] Figure 9 This is a planar view of the leading edge adaptive buffer strip of the present invention;

[0034] Figure 10 This is a three-dimensional view of the leading edge adaptive buffer band of the present invention. Detailed Implementation

[0035] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0036] like Figure 1 As shown, this embodiment of the invention provides a multi-level dynamic resilient coastal protection system, which includes, from sea to land, a leading-edge adaptive buffer zone 1, located at the seabed sill at the leading edge of the main seawall, composed of granular material. The particles of this material roll, slide, and reorganize under hydrodynamic forces, ultimately forming an equilibrium profile adapted to local wave and current conditions. This profile can be protected by shields. Predictions are made using parameters or similar sediment transport theories; an offshore submersible silt-dissipating barrier 2, parallel to the adaptive buffer zone 1, with its top elevation near the mean tide level, is designed to reduce wave energy and create a silt-dissipating zone between it and the main seawall; an artificial biomimetic wave-dissipating reef system 3, formed within the silt-dissipating zone, has the width and elevation of a simulated natural reef flat, designed to break waves prematurely to dissipate wave energy; and an ecological composite section main protection structure 4, as the final protection, has a gentle slope or a complex section; the beach surface of the artificial biomimetic wave-dissipating reef system 3 is formed by siltation from the offshore submersible silt-dissipating barrier 2, and its original elevation is restored through natural sediment replenishment or artificial assisted sediment replenishment. Salt-tolerant plants can be planted to enhance beach surface stability. The adaptive buffer zone 1, the offshore submersible silt-dissipating barrier 2, the artificial biomimetic wave-dissipating reef system 3, and the ecological composite section main protection structure 4 together constitute a hierarchical energy dissipation and dynamically balanced organic whole. Among them, the leading edge adaptive buffer zone 1 is a riprap dam, with 50-100 kg of loose stones as the material. The offshore submersible siltation and wave-dissipating barrier 2 is a pipe pile dam or a riprap dam.

[0037] Among them, determining the top elevation of the embankment in the main protective structure 4 of the ecological composite section includes:

[0038] The design wave height H* on the main protective structure is determined by the following formula:

[0039] ;

[0040] in, Represents the transmitted wave height; Indicates the water depth of the artificial bionic wave-dissipating reef system associated wave height;

[0041] Based on the design wave height H*, the wave run-up at a cumulative frequency of 2% on the main protective structure is calculated. ;

[0042] Climbing according to the waves The design tide level and safety elevation are used to determine the top elevation of the main protective structure of the ecological composite section dike.

[0043] The formula for transmitted wave height is as follows:

[0044] ,

[0045] in, Indicates the transmission coefficient of the leading edge adaptive buffer band; Represents the incident wave height in the open sea; This represents the transmission coefficient of an offshore submersible silt-promoting and wave-dissipating barrier. Among them, and The transmission coefficient was determined as follows: when the offshore submersible silt-promoting wave-dissipating barrier 2 is a pipe pile longitudinal dam, the transmission coefficient is... The formula for (the degree of wave height attenuation after the waves pass through the pipe piles along the dam) is as follows:

[0046]

[0047]

[0048]

[0049] in, Indicates wave number; This indicates the permeability coefficient of the pipe pile along the dam; Indicates the distance between pile walls (m); Indicates the pile diameter (m); The coefficient represents a value determined based on whether the dam crest is submerged, and is used to adjust the permeability coefficient; when hour, =0.8; when hour, ; This indicates the height (m) of the dam crest above the still water level. Indicates a wave after one decay; For intermediate parameters, This indicates the vertical distance (m) from the still water level in front of the dam to the seabed.

[0050] The current edge adaptive buffer zone 1 or the offshore submersible silt-promoting and wave-dissipating barrier 2 is a rockfill dam. (The formula for the ratio of wave height after riprap placement to incident wave height is as follows:)

[0051]

[0052] in, Indicates the width of the dam crest (m); The slope is represented by g; g represents the acceleration due to gravity; L represents the incident wavelength at sea level. Indicates the wave cycle.

[0053] Calculate wave rise The formula is as follows:

[0054] Typical calculated value:

[0055] Maximum constraint value:

[0056]

[0057] in, This represents a climb rate of 2% cumulative frequency, taking the smaller value between the general calculated value and the maximum constraint value. The comprehensive roughness and permeability coefficient is related to the type of the revetment structure of the main protective structure of the ecological composite section. It is obtained by referring to the table based on the revetment type in the "Code for Design of Seawall Engineering". The coefficients related to wind speed are obtained from the appendix of the "Code for Design of Seawall Engineering" based on the design wind speed. This represents the platform reduction factor; The coefficients representing the distance between the offshore submersible silt-dissipating and wave-damping barriers and the main protective structures of the ecological composite cross-section; Indicates the influence coefficient of oblique waves; Represents the wave breaking parameters, from Calculate, where θ is the slope of the beach. This represents the wavelength corresponding to the wave height H*.

[0058] in, Determined in the following ways:

[0059] when hour,

[0060] when hour,

[0061] in, L represents the distance between the offshore submersible silt-dissipating and wave-dissipating barrier and the main protective structure of the ecological composite section; L* represents the wavelength between the artificial biomimetic wave-dissipating reef system and the main protective structure of the ecological composite section.

[0062] like Figures 2-3 As shown, 41 represents the top elevation of the main protective structure of the ecological composite section, taken as the static water level + +Safety height increase, the safety height increase is 0.6~1m; 42 indicates the uphill slope of the main protective structure of the ecological composite section, corresponding to the slope. and roughness coefficient It is recommended to design Take a value of 3 to 6, and select the roughness-permeability coefficient. Smaller protective structures, such as fence panels and triangular blocks; 43 indicates the wave-dissipating platform of the main protective structure of the ecological composite section, corresponding to the platform width. and the water depth on the platform It is recommended to design Take 3~8m, Take 0~2m; 44 represents the downslope of the main protective structure of the ecological composite section, corresponding to the slope. and roughness coefficient It is recommended to design The values ​​are 2 to 5. Since the downhill slope has a relatively small impact on wave run-up, no requirements are placed on the selection of the facing material; 8 represents the design wave height after three attenuations. (Design wave height on the main protective structure), take .

[0063] like Figures 4-5 As shown, 31 represents the water depth above the artificial bionic wave-dissipating reef system, corresponding to... It is recommended to design Take 2~4m; 7 indicates the wave after secondary attenuation. (transmitted wave height), take .

[0064] like Figures 6-8 As shown, 21 represents the height of the dam crest above the still water level for both pipe pile and rockfill dams. It is recommended to design Take -2 to 0m; 22 represents the diameter of the pipe pile along the dam, corresponding to It is recommended to design Take 0.5~1m; 32 represents the spacing between the offshore submersible silt-promoting and wave-dissipating barrier and the main protective structure of the ecological composite section, corresponding to It is recommended to design Take 50~120m; 6 indicates the wave after one attenuation. ,Pick ;23 indicates the spacing between pipe piles along the dam wall, corresponding to It is recommended to design Take a depth of 0.3~0.8m;

[0065] like Figures 9-10As shown, 21 represents the height of the dam crest above the still water level for both pipe pile and rockfill dams. 24 indicates the width of the riprap dam crest, corresponding to It is recommended to design Take 2~3m; 25 represents the slope of the riprap dam, corresponding to It is recommended to design Take 1~2; 5 represents the incident wave in the open sea, take .

Claims

1. A multi-tiered dynamic resilience coastal defense system, characterized in that, From sea to land, it comprises in turn: a front edge adaptive buffer zone (1) arranged at the sea bed scarp in front of the main sea embankment, composed of granular material, arranged to form a stable profile adapted to local wave conditions by particle movement under the action of water power; an offshore submerged siltation-promoting wave-dissipating barrier (2) arranged in parallel behind the front edge adaptive buffer zone (1), with the top elevation near the mean sea level, arranged to reduce wave energy and form a siltation-promoting area between it and the main sea embankment; an artificial bionic wave-dissipating beach reef system (3) formed in the siltation-promoting area, with a width and elevation simulating a natural reef flat, arranged to make the wave break ahead to dissipate wave energy; an ecological composite section main protection structure (4) as the ultimate protection, with a gentle slope or a complex section; wherein the beach surface of the artificial bionic wave-dissipating beach reef system (3) is formed by siltation of the offshore submerged siltation-promoting wave-dissipating barrier (2), and the elevation is restored by natural sediment supply or artificial sand replenishment; wherein the determination of the top elevation of the ecological composite section main protection structure (4) comprises: Determine the design wave height H* on the main protection structure, as follows: ； wherein, is the transmitted wave height after attenuation by the pre-crest adaptive buffer zone and the offshore submerged silt-promoting dissipative breakwater; is the water depth in front of the artificial bio-mimicking dissipative reef system is the wave height based on wave breaking conditions at the location; Based on the design wave height H*, the wave run-up at 2% exceedance on the main protection structure is calculated ; According to wave run-up , design the tidal level and the safe heightening value, and determine the top elevation of the main protection structure of the ecological compound section. The transmission wave height is as follows: ， wherein, represents the front edge adaptive buffer zone transmission coefficient; represents the offshore incident wave height; offshore submerged siltation promoting dissipating breakwater transmission coefficient; wave run-up is calculated The formula is as follows: Typical calculated values: Maximum constraint value: ； wherein, represents the height of the 2% cumulative frequency, the minimum value between the general calculation and the maximum constraint being taken; represents the overall roughness coefficient related to the ecological composite section main protection structure; represents the coefficient related to the wind speed; represents the platform reduction coefficient; represents the coefficient related to the distance between the offshore submerged type siltation promoting and dissipating breakwater and the ecological composite section main protection structure; represents the oblique wave influence coefficient; represents the breaking wave parameter; is determined by the following way: When Time, ; When time, ; wherein, represents the horizontal spacing of the offshore submerged siltation-promoting and wave-dissipating breakwater and the ecological composite cross-section main body protection structure; L* is the wavelength between the artificial bionic wave-dissipating beach reef system and the ecological composite cross-section main body protection structure.

2. A multi-tiered dynamic resilience coastal defense system according to claim 1, characterized in that, The front edge adaptive buffer zone (1) is a riprap dam, and the granular material is 50-100 kg block stone.

3. A multi-tiered dynamic resilience coastal defense system according to claim 1, characterized in that, The offshore submerged siltation-promoting wave-dissipating barrier (2) is a pipe pile dam or a riprap dam.

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