Flexible membrane type submerged dike with cultivation function and design method of flexible membrane type submerged dike

Abstract

The invention discloses a flexible membrane type submerged dike with a breeding function and a design method thereof, and relates to the technical field of breakwaters, the flexible membrane type submerged dike comprises a breeding net and two flexible membrane type submerged dike bodies which are connected with the breeding net and arranged at the bottom of the breeding net side by side, and a plurality of weights connected with the breeding net are arranged in the non-flexible membrane type submerged dike body area at the bottom of the breeding net. A plurality of floating balls are arranged at the top of the culture net, the floating balls pull the top of the culture net under the action of buoyancy, so that a semi-closed net cage structure with an opening facing the sea surface direction is formed between the culture net and the flexible membrane type submerged dike body, and the interior of the net cage structure is a culture area; and flexible membrane type submerged dike design parameters suitable for the actual sea area are obtained through calculation. On the basis, coupling with a culture net is carried out, the wave dissipation effect is enhanced by utilizing the wave Bragg resonance principle, meanwhile, the culture function is achieved, the utilization rate of coastal water resources is effectively increased, and the development effect of the aquaculture industry is promoted.

Description

Technical Field

[0001] The present invention relates to the technical field of breakwaters, and in particular to a flexible membrane submerged breakwater with aquaculture function and a design method thereof. Background Art

[0002] Breakwater is a common port and coastal engineering structure, mainly used to defend against waves from the open sea, provide a stable environment for ship loading and unloading operations, and protect other port engineering structures. Breakwaters are usually divided into two categories: rigid structures and flexible structures. Among them, flexible membrane breakwaters made of high-strength fiber materials have attracted more and more attention and research due to their low cost, simple construction, easy maintenance and recycling, minimal impact on the marine environment, high toughness, and excellent impact resistance. Studies have found that the superposition of radiation waves and scattered waves generated by membrane movement will cause wave attenuation. The width, position and tension of the membrane are important factors affecting wave attenuation. Compared with rigid breakwater structures, flexible breakwaters have better wave dissipation characteristics than rigid submerged breakwaters under certain conditions. However, the wave dissipation effect of a single flexible submerged breakwater is still limited, and its wave dissipation effect on long waves in the ocean is weak. Considering the further improvement of its wave dissipation characteristics, the wave Bragg resonance principle is adopted to establish multiple rows of submerged breakwaters to achieve the above purpose.

[0003] In addition, the net cage is a porous structure that can also attenuate waves to a certain extent. By converting wave energy into structural kinetic energy and reducing the wave height behind the breakwater under the synergistic effects of wave reflection, friction, energy conversion and fragmentation, the shielding effect of the water area behind the breakwater is achieved. Some researchers have found that open-pored structures (nets) also have superior wave attenuation effects. By adjusting factors such as the length, permeability, number of layers and tension of the net and the type of mooring, the breakwater can achieve a good wave-dissipating effect. Summary of the invention

[0004] The embodiment of the present invention provides a flexible membrane submerged dike with aquaculture function and a design method thereof, and obtains the design parameters of the flexible membrane submerged dike suitable for the actual sea area through calculation. On this basis, it is coupled with the aquaculture net, and the wave Bragg resonance principle is used to achieve the enhanced wave dissipation effect while also having the aquaculture function, effectively improving the utilization rate of nearshore water resources and promoting the development of aquaculture.

[0005] A flexible membrane submerged dike with aquaculture function, comprising:

[0006] A breeding net, and two flexible membrane submerged dike bodies connected to the breeding net and arranged side by side at the bottom of the breeding net;

[0007] A plurality of weights connected to the non-flexible membrane-type submerged dike body at the bottom of the aquaculture net are provided;

[0008] A semi-enclosed cage structure with an opening facing the sea surface is formed between the aquaculture net and the flexible membrane submerged dike body, and the interior of the cage structure is a breeding area;

[0009] The top of the aquaculture net is equipped with a number of floats that float on the sea surface;

[0010] The flexible membrane submerged dike is composed of several sections, each of which is filled with pure water or water-sand mixture. The structural density of the pure water is close to that of seawater, and the relative density of the water-sand mixture is controlled at 1600-2000 kg / m 3 .

[0011] Furthermore, the flexible membrane submerged dike is elastic and can change its shape according to the state of the waves.

[0012] Furthermore, liquid is injected into the flexible membrane submerged dike body so that relative pressure is present inside the body.

[0013] Furthermore, the relative pressure p inside the flexible membrane submerged dike body i0 The range of / ρgh is: 0.05-0.1;

[0014] Among them, p i0 represents the actual pressure inside the flexible membrane submerged dike body; ρgh represents the water pressure, where ρ is the seawater density, g is the gravitational acceleration, and h is the water depth.

[0015] Furthermore, the height of the aquaculture net is greater than the extreme high water level plus twice the effective wave height, so as to keep the buoy always floating on the sea surface.

[0016] The embodiment of the present invention provides a method for designing a flexible membrane submerged dike with aquaculture function, comprising the following steps:

[0017] Conduct theoretical modeling and calculate the breakwater evaluation factors to obtain the design parameters of the flexible membrane submerged breakwater suitable for the actual sea area;

[0018] After the corresponding flexible membrane submerged dike body is manufactured using the above parameters, it is coupled with the aquaculture net to form a flexible membrane submerged dike with aquaculture function.

[0019] The beneficial effects of the above technical solution provided by the embodiment of the present invention include at least:

[0020] 1. Through theoretical modeling and the calculation of breakwater evaluation factors, the design parameters of flexible membrane submerged breakwater suitable for the actual sea area are obtained. On this basis, the aquaculture net is coupled with the breakwater, and the wave Bragg resonance principle is used to achieve the purpose of wave elimination. On the other hand, closed aquaculture cages are formed between the breakwaters, so that the manufactured flexible breakwater can better adapt to the actual sea area and meet the use requirements. This design can not only effectively improve the utilization rate of nearshore water resources, but also promote the development of aquaculture.

[0021] 2. Compared with traditional rigid breakwaters, the flexible membrane submerged breakwater with aquaculture function obtained by the present invention has many advantages. First, its construction is quick, which can not only save time and cost, but also reduce the investment of manpower and material resources. Secondly, due to the use of flexible materials, it has good environmental protection and will not have an adverse effect on the marine ecological environment. In addition, due to the use of closed aquaculture cages, it can effectively prevent the escape of fish in aquaculture, ensuring the stability and safety of aquaculture. Most importantly, this flexible membrane submerged breakwater will not affect the environment while eliminating waves, and can effectively reduce the siltation of silt and protect the stability of the coastline.

[0022] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description, claims, and drawings.

[0023] The technical solution of the present invention is further described in detail below through the drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0025] Figure 1 It is a schematic structural diagram of a flexible membrane submerged dike with aquaculture function disclosed in an embodiment of the present invention;

[0026] Figure 2 It is a schematic diagram of the principle of a flexible membrane submerged dike with aquaculture function disclosed in an embodiment of the present invention;

[0027] Figure 3 The curves of the transmission coefficient Kt after the two submerged dikes are lowered and the relative water depth kh are disclosed in the embodiments of the present invention;

[0028] Figure 4 Variation curve of horizontal wave force Fx on the breakwater facing the wave with relative water depth kh;

[0029] Figure 5 The variation curve of vertical wave force Fz on the breakwater facing the wave with relative water depth kh;

[0030] Figure 6 This is a schematic diagram of theoretical modeling in step S1 disclosed in an embodiment of the present invention.

[0031] Reference numerals:

[0032] 1. Flexible membrane submerged dike body; 2. Aquaculture net; 3. Float; 4. Heavy objects. DETAILED DESCRIPTION

[0033] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0034] A design method for a flexible membrane submerged dike with aquaculture function includes:

[0035] S1, theoretical modeling is carried out, and the breakwater evaluation factor is calculated to obtain the design parameters of the flexible membrane submerged breakwater suitable for the actual sea area.

[0036] The core of the above process is to use the boundary element method to calculate the structural hydrodynamic characteristics under arbitrary parameters. The specific equation is as follows (such as Figure 6 shown):

[0037] Under the linear wave theory, the velocity potential φ should satisfy the following governing equations and boundary conditions:

[0038]

[0039] The linearized free water surface condition is written as:

[0040]

[0041] Where K = σ 2 / g, the impermeable boundary condition is written as:

[0042]

[0043] For thin films, the boundary conditions must meet:

[0044]

[0045] P D =p i0 +iσ(ρ I φ5-ρ Oφ2)+(ρ O -ρ I )gwcosθ s ,onΓ M1 andΓ M2 (0.5)

[0046] in, P D represents the internal and external fluid dynamic pressure, E is the elastic modulus, △ represents the film thickness, θ S represents the film unit angle in static equilibrium state, L m represents the total length of the membrane, w represents the displacement of the membrane unit in the direction of the outer normal, R represents the radius of curvature of the membrane unit, T S Indicates the film tension in static equilibrium.

[0047] The far-field radiation condition of the wave is:

[0048]

[0049] Due to the irregular shape of the breakwater and the existence of second-order differential terms in the arc-shaped membrane motion equation, it is difficult to solve it using analytical methods. Therefore, the boundary element model is used to semi-analyze the above problem, in which the wave inlet and outlet boundary conditions are given based on the characteristic function expansion method, and the boundary value problem of the inner domain is converted into an integral equation using BEM. In order to reduce the computational cost and improve the model accuracy, Γ L and Γ R It is set at a position 4 times the water depth outside the breakwater, and the corresponding wave inlet and outlet velocity potential function is expressed as:

[0050]

[0051] Where R m ,,T m (m=0,1,2,...) is the unknown coefficient, k m (m=0,1,2,...) satisfies the following relationship:

[0052] σ 2 =gk m tanhk m h1,m=0,1,2...M (0.10)

[0053] Where k0 is a real number, indicating the wave number; k m (m=1,2,…) is an imaginary number, where k m = k′ m i,(m=1,2,3...M),k′ m is the equation σ 2 =―gk′ m tank′ mReal positive root of h1.

[0054] Vertical characteristic function f(k m ,z)(m=0,1,2,...) can be written as:

[0055]

[0056] The inner product of the vertical characteristic function is defined as follows:

[0057]

[0058] in:

[0059]

[0060] Using the orthogonality of the characteristic function, the unknown coefficient R can be obtained m and T m as follows:

[0061]

[0062] in represents the velocity potential when the expansion term m=M, and R m and T m Substituting into the import and export boundary conditions, we can get:

[0063]

[0064] In summary, we have given the boundary conditions of the entire solution domain, and this boundary condition is only related to the velocity potential, and the other unknowns are known. Using Green's second theorem, the solution of the Laplace equation can be transformed into the following boundary integral equation:

[0065]

[0066] in, is the source point, represents the fixed angle coefficient; Γ represents the boundary of the solution area, which is directional and stipulates that when moving along the positive direction of Γ, the solution domain is always on the left hand side; is the Green function that satisfies the Laplace equation, which is written as:

[0067]

[0068] in, n represents the external normal direction of the element.

[0069] Wave transmission coefficient K t and reflection coefficient K r The definition is as follows:

[0070]

[0071] Similarly, the energy loss K d The definition is as follows:

[0072]

[0073] The wave force F on the submerged reef can be expressed by the integral of the surface pressure on the membrane boundary:

[0074]

[0075] In the formula, n=(n x , n z ) is the unit normal vector of the object surface; F x is the horizontal wave force, F z is the vertical wave force.

[0076] The above equations can be used to calculate the hydrodynamic characteristics of the breakwater.

[0077] By comprehensively considering the influence of structural stress, wave-breaking characteristics, and structural dimensions, a comprehensive evaluation system is established. The relevant evaluation equations are as follows:

[0078] According to the transmission coefficient K t , Energy dissipation coefficient K d , horizontal wave force F x and vertical wave force F z , the average of the design high water level and the design low water level is used as the water depth used for calculation, and the wave transmission K is obtained by ti and culvert flow Q i , the water bag breakwater evaluation factor J is calculated:

[0079]

[0080] Where: K t represents the wave transmission coefficient, S(fi) represents the spectral density function of the irregular wave, A i represents the amplitude of the component wave, ρ represents the fluid density, g represents the acceleration due to gravity, h represents the water depth, and f represents the frequency.

[0081] Considering the actual engineering application, the comprehensive evaluation value J under the action of irregular waves can be calculated as follows:

[0082]

[0083] In the following calculations, it is assumed that S(f) satisfies the JONSWAP spectrum, which can be expressed as:

[0084]

[0085] Among them, fpk is the spectrum peak frequency, T pk is the spectrum peak period. In the following calculations, it is assumed that the effective wave height H 1 / 3 =0.5m;γ=3.3;σ pk =0.07(f <f pk );σ pk =0.09(f>f pk ); the frequency f range is 0.070Hz-0.333Hz; the peak frequency f pk =0.166H Z , the number of waves N = 50.

[0086] Through the above equation, when the water depth h is determined and the structure size R is preliminarily determined, the maximum J calculated is the optimal design solution.

[0087] S2, after manufacturing the corresponding flexible membrane submerged dike body 1 by using the above parameters, it is coupled with the aquaculture net 2 to form a flexible membrane submerged dike with aquaculture function.

[0088] like Figure 1 As shown, it is a schematic diagram of the structure of a flexible membrane submerged dike with aquaculture function provided by an embodiment of the present invention, wherein the structure includes a farming net 2 and two flexible membrane submerged dike bodies 1 connected to the farming net 2 and arranged side by side at the bottom of the farming net 2, wherein the flexible membrane submerged dike body 1 is arranged on the seabed, and a plurality of weights 4 connected to the non-flexible membrane submerged dike body 1 area at the bottom of the farming net 2 is provided, and a plurality of buoys are provided on the top of the farming net 2, and the bottom of the farming net 2 is fixed by the weights 4 and the flexible membrane submerged dike body 1, and the buoys pull the top of the farming net 2 under the action of buoyancy, so that a semi-closed cage structure with an opening facing the sea surface is formed between the farming net 2 and the flexible membrane submerged dike body 1, and the interior of the cage structure is a farming area.

[0089] The flexible membrane submerged dike body is composed of several sections, each of which is filled with pure water or a water-sand mixture. The structural density of pure filled water is close to that of seawater, and the relative density of the filled water-sand mixture is controlled at 1600-2000kg / m3 (to ensure that the structure can be deformed. In the case of pure sand, the structure is similar to rigidity). This is achieved by adjusting the water-sand ratio to ensure that the overall structure does not move under the action of waves or water currents.

[0090] The structure obtained by the above embodiment not only has the effect of breaking waves, but also can be used to breed fish inside the breeding area. On the other hand, since a flexible membrane submerged dike is used, it will not affect the environment while breaking waves, and can effectively reduce siltation and protect the stability of the coastline.

[0091] like Figure 2As shown in the figure, it is a schematic diagram of the principle of the flexible membrane type submerged breakwater provided by the embodiment of the present invention. Under the action of sea waves, the wave surface of the sea waves has different wave heights at different times. In this process, the float 3 will rise and fall with the wave surface. In order to keep the float 3 floating on the sea surface all the time, the flexible membrane type submerged breakwater body 1 is designed to be elastic and can change its shape following the state of the sea waves. At the same time, the height of the aquaculture net 2 is greater than the extreme high water level plus twice the significant wave height. During the continuous change of the wave surface height, the float 3 always floats on the sea surface. While dissipating waves, the aquaculture net 2 is pulled to keep the aquaculture net 2 in an open state, and the porous structure of the aquaculture net 2 is used to attenuate the waves. By converting wave energy into structural kinetic energy and under the synergistic effects of wave reflection, friction, energy conversion, and breaking, etc., the wave height behind the breakwater is reduced, and the shelter effect of the water area behind the breakwater is realized.

[0092] Liquid is injected into the flexible membrane type submerged breakwater body 1 to make it have a relative pressure inside, such as Figures 3 to 5 As shown, it can be seen that the relative pressure p inside the flexible membrane type submerged breakwater body 1 i0 / ρgh ranges from 0.05 to 0.1 (the value represents the softness of the flexible membrane type submerged breakwater body 1, and the larger the value, the more rigid the structure of the flexible membrane type submerged breakwater body 1), and a better wave dissipation effect can be produced (at this time, 0.6 < kh < 2.5). Among them, in Figure 3 : Kt represents the transmission coefficient behind the breakwater (the smaller it is, the better the wave dissipation effect), and kh represents the dimensionless water depth.

[0093] It should be understood that the specific order or hierarchy of steps in the disclosed process is an example of an exemplary method. Based on design preferences, it should be understood that the specific order or hierarchy of steps in the process can be rearranged without departing from the protection scope of the present disclosure. The appended method claims present the elements of various steps in an exemplary order and are not intended to be limited to the specific order or hierarchy described.

[0094] In the above detailed description, various features are combined in a single embodiment to simplify the present disclosure. This method of disclosure should not be interpreted as reflecting the intention that the embodiments of the claimed subject matter require more features than those clearly stated in each claim. On the contrary, as reflected in the appended claims, the present invention is in a state with fewer features than all the features of the disclosed single embodiment. Therefore, the appended claims are hereby clearly incorporated into the detailed description, where each claim stands alone as a separate preferred embodiment of the present invention.

[0095] Those skilled in the art will also appreciate that the various illustrative logic blocks, modules, circuits, and algorithmic steps described in conjunction with the embodiments herein can all be implemented as electronic hardware, computer software, or a combination thereof. In order to clearly illustrate the interchangeability between hardware and software, various illustrative components, blocks, modules, circuits, and steps are generally described above around their functions. Whether such functions are implemented as hardware or software depends on specific applications and the design constraints imposed on the entire system. A skilled person can implement the described functions in an alternative manner for each specific application, but such implementation decisions should not be interpreted as departing from the scope of protection of the present disclosure.

[0096] The steps of the method or algorithm described in conjunction with the embodiments herein may be directly embodied as hardware, a software module executed by a processor, or a combination thereof. The software module may be located in a RAM memory, a flash memory, a ROM memory, an EPROM memory, an EEPROM memory, a register, a hard disk, a mobile disk, a CD-ROM, or any other form of storage medium well known in the art. An exemplary storage medium is connected to the processor so that the processor can read information from the storage medium and can write information to the storage medium. Of course, the storage medium may also be an integral part of the processor. The processor and the storage medium may be located in an ASIC. The ASIC may be located in a user terminal. Of course, the processor and the storage medium may also be present in a user terminal as discrete components.

[0097] For software implementation, the techniques described in this application can be implemented with modules (e.g., procedures, functions, etc.) that perform the functions described in this application. These software codes can be stored in a memory unit and executed by a processor. The memory unit can be implemented within the processor or outside the processor. In the latter case, it is coupled to the processor in a communication manner via various means, which are well known in the art.

[0098] The above description includes examples of one or more embodiments. Of course, it is impossible to describe all possible combinations of components or methods for the purpose of describing the above embodiments, but it should be recognized by those skilled in the art that the various embodiments may be further combined and arranged. Therefore, the embodiments described herein are intended to cover all such changes, modifications and variations that fall within the scope of protection of the appended claims. In addition, with respect to the term "comprising" used in the specification or claims, the word is covered in a manner similar to the term "including", just as "including," is explained as a transitional word in the claims. In addition, any term "or" used in the specification of the claims is intended to mean "non-exclusive or".

Claims

1. A flexible membrane submerged dike with aquaculture function, characterized in that: include: A breeding net, and two flexible membrane submerged dike bodies connected to the breeding net and arranged side by side at the bottom of the breeding net; A plurality of weights connected to the non-flexible membrane-type submerged dike body at the bottom of the aquaculture net are provided; A semi-enclosed cage structure with an opening facing the sea surface is formed between the aquaculture net and the flexible membrane submerged dike body, and the interior of the cage structure is a breeding area; The top of the aquaculture net is equipped with a number of floats that float on the sea surface; The flexible membrane submerged dike is composed of several sections, each of which is filled with pure water or water-sand mixture. The structural density of the pure water is close to that of seawater, and the relative density of the water-sand mixture is controlled at 1600-2000 kg / m 3 .

2. A flexible membrane submerged dike with aquaculture function as claimed in claim 1, characterized in that: Flexible membrane submerged dikes are elastic and can change their shape according to the state of the waves.

3. A flexible membrane submerged dike with aquaculture function as claimed in claim 1 or 2, characterized in that: Liquid is injected into the flexible membrane submerged dike body to give it a relative pressure.

4. A flexible membrane submerged dike with aquaculture function as claimed in claim 3, characterized in that: Relative pressure p inside the flexible membrane submerged dike i0 The range of / ρgh is: 0.05-0.1; Among them, p i0 represents the actual pressure inside the flexible membrane submerged dike body; ρgh represents the water pressure, where ρ is the seawater density, g is the gravitational acceleration, and h is the water depth.

5. The flexible membrane submerged dike with aquaculture function as claimed in claim 3, characterized in that: The height of the aquaculture net is greater than the extreme high water level plus twice the effective wave height to keep the buoys always floating on the sea surface.

6. A method for designing a flexible membrane submerged dike with aquaculture function, characterized in that: The following steps are involved: Conduct theoretical modeling and calculate the breakwater evaluation factors to obtain the design parameters of the flexible membrane submerged breakwater suitable for the actual sea area; After the corresponding flexible membrane submerged dike body is manufactured using the above parameters, it is coupled with the aquaculture net to form a flexible membrane submerged dike with aquaculture function.

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