Method for weakening damage of channel ship traveling waves to seawall

Abstract

A method for weakening damage of navigation channel ship traveling waves to a seawall belongs to the field of ocean engineering, and comprises the following steps: determining a structure: firstly, determining a water wave frequency of a sailing ship in a research target navigation channel, and designing a water wave crystal structure according to the water wave frequency, the water wave crystal structure has a band gap frequency range matched with the water wave frequency of a navigation channel sailing ship so as to limit water waves from spreading to a seawall; a water wave crystal structure is arranged on the seabed in front of the seawall, when a sailing ship passes and water waves are generated, the water waves are spread to the water wave crystal structure, the water wave crystal structure can effectively block the water wave frequency, spreading of water wave energy is weakened, and therefore damage of the water waves to the seawall is prevented. The method can obviously weaken the damage of water waves of navigation ships to the seawall, protect coast facilities and reduce the maintenance cost.

Description

Technical Field

[0001] The present invention relates to the field of ocean engineering, and particularly to a method for weakening the damage of ship traveling waves in a waterway to a seawall, aiming to weaken the damage of water waves generated by ships traveling in a fixed waterway to the seawall, thereby reducing the maintenance cost of the seawall. Background Art

[0002] With the continuous development of the shipping industry, ships frequently travel in waterways. In the global ship archives, the number of international navigation ships in global operation is relatively large. The greater the weight of a ship, the higher its displacement, and the deeper its draft, the stronger its ability to squeeze water when sailing, and the greater the energy of the ship traveling wave. The ship traveling wave repeatedly erodes the seawall, resulting in different forms of damage to the seawall. Therefore, the heavier the ship, the easier it is to damage the seawall. For example, due to the frequent passage of large container ships in the Yangtze Estuary waterway, the annual repair area of some seawalls reaches 800 ㎡ / km, and the average annual seawall maintenance cost is 2 - 4 million yuan / km.

[0003] Currently, there are already various methods (such as traditional breakwater structures and ecological slope protection) for weakening the damage of water waves to seawalls. The traditional breakwater structure can weaken the damage of water waves to a certain extent, however, this method has certain limitations. Due to the frequent maintenance of traditional breakwaters and the short service life of materials, the long-term cost is actually higher. Ecological slope protection uses the roots of plants to fix the soil, enhancing the shear strength and anti-sliding ability of the slope body, which can effectively prevent soil erosion and reduce the scouring damage of water flow to the seawall. The initial construction cost of ecological slope protection is relatively low. Except for the necessary slope protection materials, the main cost lies in vegetation planting and maintenance. However, if there is a large-scale death of vegetation or damage to the ecosystem, the restoration cost may be relatively high.

[0004] Therefore, how to reduce costs while improving the stability and safety of seawall protection urgently needs to be solved. Summary of the Invention

[0005] In order to overcome the deficiencies of the prior art, the present invention provides a method for weakening the damage of ship traveling waves in a waterway to a seawall, which can significantly weaken the damage of water waves of ships traveling in the waterway to the seawall, protect coastal facilities, and reduce maintenance costs.

[0006] A method for weakening the damage of ship traveling waves in a waterway to a seawall includes:

[0007] S1. Determine the structure: First, determine the water wave frequency of ships traveling in the target waterway under study, and design a water wave crystal structure according to the water wave frequency. The water wave crystal structure has a bandgap frequency range matching the water wave frequency of ships traveling in the waterway to limit the propagation of water waves to the seawall;

[0008] S2. Determine the placement location: Arrange the water wave crystal structure on the seabed in front of the seawall. When a ship passes by and generates water waves, the water waves propagate to the water wave crystal structure. The water wave crystal structure can effectively block the water wave frequency and weaken the propagation of the water wave energy, thereby preventing the water waves from damaging the seawall.

[0009] Further, the water wave crystal structure includes a plurality of columnar bodies arranged in a periodic array.

[0010] Further, the material of the columnar body is corrosion-resistant concrete.

[0011] Further, it also includes step S3 of verifying the water wave crystal structure;

[0012] The coastal area studied is a shallow water area, so the shallow water approximate water wave equation is obtained:

[0013]

[0014] The dispersion relation is:

[0015] w 2 = gh·k 2

[0016] In the formula, represents the Laplace operator, h is the water depth, p is the static water surface pressure, w is the angular frequency, k is the wave number. Based on COMSOL Multiphysics for verification, first establish a two-dimensional model of the columnar structure arranged periodically, apply Bloch's theorem to set the periodic boundary conditions for the structure, conduct eigenfrequency analysis, set parametric scanning, that is, scan the wave vector k, and finally form the band diagram of the periodic structure, that is, the relationship between the wave vector k and the frequency ω, so as to verify the existence of the water wave band gap.

[0017] The beneficial effects of the present invention compared with the prior art are:

[0018] 1. By arranging columnar bodies in a periodic array on the seabed in front of the seawall, the present invention can prevent the propagation of the water wave frequency generated by ships in the waterway, which is more harmful to the seawall, thereby reducing the damage of the water waves to the seawall, improving the stability and safety of the seawall, and reducing the maintenance cost of the seawall and the potential risks brought by the damage of the seawall.

[0019] 2. By precisely designing the size, spacing and arrangement of the structural units, the present invention can adjust the structure of the water wave crystal according to the water wave frequency, so that the band gap frequency range matches the water wave frequency of the ships in the waterway. This design method based on frequency matching not only improves the blocking of the water waves in a specific frequency range from propagating to the seawall, but also enhances its ability to control the water wave energy and enhances the protection of the seawall.

[0020] 3. The structure designed in the present invention selects corrosion-resistant concrete as the column material, ensuring that the columnar structural unit can work stably for a long time in the seabed environment, resisting adverse factors such as seawater corrosion and water flow impact, guaranteeing the durability and reliability of the entire structure, and reducing the possibility of the structure being damaged due to material problems.

[0021] The technical solutions of the present invention will be further described below with reference to the drawings and embodiments: BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a simplified diagram of a ship navigating in a waterway;

[0023] Figure 2 It is a structural diagram of periodically arranged columns;

[0024] Figure 3 It is an energy band structure diagram obtained from the periodic structure;

[0025] Main reference numerals in the drawings are explained as follows:

[0026] 1. Spheroid, 2. Base, 3. Seawall, 4. Water wave crystal structure, 5. Ship. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] The embodiments of the technical solutions of the present invention will be described in detail below with reference to the drawings. Unless otherwise specified, the technical terms or scientific terms used in this application have the ordinary meanings understood by those skilled in the art to which the present invention belongs.

[0028] Refer to Figures 1 - 3 , Step 1, Determine the structure: First, determine the water wave frequency of the ship navigating in the target waterway. Since it is necessary to limit the propagation of the water wave frequency, the water wave frequency should be within the forbidden band as much as possible. Design the structural parameters of the water wave crystal structure 4 according to the water wave frequency. The water wave crystal structure includes a plurality of columns arranged in a periodic array. By precisely designing the height, radius, and spacing of the cylinders; the radius of the cylinder is r mm, and the center distance between adjacent cylinders is a mm, where 2r = (0.5 - 0.7)a. Finally, a stepped array structure of cylinders 1 arranged on the periodically arranged base 2 is obtained, as Figure 2 shown.

[0029] Adjust the water wave crystal structure to generate a forbidden band that matches the water wave frequency range generated by the ship navigating in the target waterway. When the water wave propagates, due to the existence of the forbidden band, the frequency within the forbidden band is restricted from propagating. Specifically, this design can obtain the bandgap frequency range of the water wave crystal structure that matches the water wave frequency of the ship navigating in the waterway, thereby blocking the water wave from propagating towards the seawall 3 and significantly reducing the damage of the water wave to the seawall, achieving the purpose of protecting the seawall.

[0030] Optionally, preferably, through simulation, it is obtained that the radius of the cylinder is 0.875 mm and the center distance is 2.5 mm, which can block most of the water wave frequencies and has a good propagation effect.

[0031] Step 2: Determine the placement position: The placement of the water wave crystal structure 4 is as Figure 1 shown. Arrange the water wave crystal structure on the seabed in front of the seawall. Build columns with a periodic array arrangement on the seabed in front of the seawall 3. The material of the cylinder 1 is selected as corrosion-resistant concrete. This periodic array can, through the interaction between water waves and the water wave crystal structure 4, inhibit the propagation of water waves generated by ships in the channel within the frequency range that is more harmful to the seawall, thereby achieving the protection of the seawall. When a ship 5 passes by and generates water waves, the water waves propagate to the water wave crystal structure 4. Since this structure can effectively block most of the water wave frequencies, the propagation of the water wave energy is weakened, thus preventing the water waves from damaging the seawall.

[0032] Step 3: Verify the function of the structure:

[0033] The research on water wave control is extended based on the electromagnetic wave manipulation method of photonic crystals and metamaterials. Water wave crystals and water wave metamaterials are used to regulate water waves, thereby playing a role in protecting the seawall. Photonic crystals are a type of artificially designed and manufactured crystals with a periodic dielectric structure on the optical scale. Similar to the regulation of the electron wave function by the semiconductor lattice, the periodic structure of photonic crystals causes Bragg scattering of light waves, and light within a specific frequency range cannot propagate, forming an "optical forbidden zone". Photonic bandgap materials can regulate electromagnetic waves with corresponding wavelengths. When electromagnetic waves propagate in photonic bandgap materials, they are regulated due to the existence of Bragg scattering, and the electromagnetic wave energy forms an energy band structure as Figure 3 shown. There is a bandgap between energy bands, that is, the photonic bandgap. Photons with energies within the photonic bandgap cannot enter the crystal, so electromagnetic waves within a certain frequency range are restricted from propagating in this periodic structure.

[0034] A water wave crystal is an artificial material with a periodic structure. By introducing a periodic structure into the water wave system, the water waves interact with the structure to achieve the regulation of water waves. Since the water wave crystal is developed from the photonic crystal, the function of the water wave crystal can be obtained from the function of the photonic crystal. The periodic structure of the photonic crystal can also cause Bragg scattering of water waves, making water waves within a specific range unable to propagate, forming a "water wave forbidden zone", thereby achieving the function of protecting the seawall. The water wave crystal draws on the periodic structure principle of the photonic crystal and regulates water waves through Bragg scattering to form a water wave bandgap and prevent the propagation of water waves with specific frequencies.

[0035] Given the wave equation of water waves, since the coastal area under study is a shallow water area, the shallow water approximation of the water wave equation can be obtained

[0036]

[0037] The dispersion relation is:

[0038] w 2 = gh·k 2

[0039] In the formula, represents the Laplace operator, h is the water depth, p is the static water surface pressure, w is the angular frequency, k is the wave number, and g is the acceleration due to gravity.

[0040] Based on COMSOL Multiphysics for verification, first establish a two-dimensional model of a periodically arranged columnar structure, apply Bloch's theorem to set the periodic boundary conditions for the structure, conduct a characteristic frequency analysis, set a parametric sweep, that is, sweep the wave vector k, and finally form the band diagram of the periodic structure, that is, the relationship between the wave vector k and the frequency ω, so as to verify the existence of the water wave band gap. The simulation confirms the existence of the forbidden band, and the forbidden band can suppress the propagation of waves with specific frequencies through this periodic structure.

[0041] The present invention has been disclosed above with preferred embodiments. However, it is not intended to limit the present invention. Any person skilled in the art, without departing from the scope of the technical solution of the present invention, can make some changes or modifications to the above-disclosed structure and technical content as equivalent embodiments of equivalent changes, and all still fall within the scope of the technical solution of the present invention.

Claims

1. A method for reducing the damage of ship traveling waves in a waterway to a seawall, characterized in that: The method includes: S1. Determine the structure: First, determine the water wave frequency of the ship traveling in the target waterway to be studied, and design a water wave crystal structure according to the water wave frequency. The water wave crystal structure has a bandgap frequency range that matches the water wave frequency of the ship traveling in the waterway to limit the propagation of water waves towards the seawall. S2. Determine the placement position: Arrange the water wave crystal structure on the seabed in front of the seawall. When a ship passes by and generates water waves, the water waves propagate to the water wave crystal structure, and the water wave crystal structure can effectively block the water wave frequency, weaken the propagation of the water wave energy, and thus prevent the water waves from damaging the seawall.

2. The method for reducing the damage of navigation waves in a waterway to a seawall according to claim 1, characterized in that: The water wave crystal structure includes a plurality of columnar bodies arranged in a periodic array.

3. The method for reducing the damage of navigation waves in a waterway to a seawall according to claim 2, characterized in that: The columnar body is a cylinder.

4. The method for reducing the damage of navigation waves in the waterway to the seawall according to claim 2, characterized in that: The material of the columnar body is corrosion-resistant concrete.

5. The method for reducing the damage of navigation waves in the waterway to the seawall according to claim 1, characterized in that: It also includes step S3 of verifying the water wave crystal structure; The coastal area studied is a shallow water area, so the water wave equation of the shallow water approximation is obtained: The dispersion relation is: w 2 = gh·k 2 In the formula, represents the Laplace operator, h is the water depth, p is the hydrostatic pressure on the water surface, w is the angular frequency, k is the wave number. For verification based on COMSOL Multiphysics, first establish a two-dimensional model of a periodically arranged columnar structure, apply Bloch's theorem to set periodic boundary conditions for the structure, conduct eigenfrequency analysis, set parametric scanning, that is, scan the wave vector k, and finally form the band diagram of the periodic structure, that is, the relationship between the wave vector k and the frequency ω, so as to verify the existence of the water wave band gap.

6. The method for reducing the damage of navigation waves in a waterway to a seawall according to claim 3, characterized in that: The radius of the cylinder is r mm, and the center distance between adjacent cylinders is a mm, where: 2r = (0.5 - 0.7)a.

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