JPH07324318A - Penetrating-type wave dissipating structure - Google Patents

Abstract

PURPOSE:To obtain sufficient wave dissipating effect specially on waves of long wavelength with smaller scale structure than conventional structure regarding a penetrating type wave dissipating structure. CONSTITUTION:A submerged horizontal plate positioned below the water surface, and a vertical flat plate 2 erected near the end part on the wave lower side or wave upper side of the submerged horizontal plate 1 are supported by a supporting frame 4 erected on the sea bottom. The vertical flat plate 2 is disposed in such a way as to go through the water surface almost orthogonally to the proceeding direction of approaching waves W.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transparent wave-dissipating structure for constructing a calm water area in a harbor and for reducing the penetration of waves into the intake and discharge ports of a thermal power plant on the coast. Regarding

[0002]

2. Description of the Related Art If you want to build a pier or marina in a harbor, build an aquaculture farm, increase the operating rate of offshore construction work, or protect moored structures, make sure that the required water area It is necessary to secure the calmness of the water area by installing a wave-dissipating structure. A normal gravity breakwater not only has a limit in terms of cost with respect to an increase in water depth, but also alienates the exchange of water inside and outside the water area, and thus may be limited from the viewpoint of environmental consideration. When the water depth is relatively large or when the water exchange inside and outside the water area is emphasized, it is considered to use a transmission type wave-breaking structure that does not block the water in the depth direction at all. An example of a conventional transmissive wave-breaking structure is shown in FIGS.

FIG. 6 is a side view of a wave-dissipating structure of a type called a curtain wall, in which a vertical plate structure a is arranged so as to penetrate the water surface and reach the middle of the water depth. This type of wave-dissipating structure reduces the propagation of waves to the back by blocking the movement of water particles near the surface in the movement of water particles due to waves, and penetrates in the depth direction for waves with long wavelengths. It will be dealt with by increasing the amount. When the transmission coefficient Ct (the ratio Ht / Hi between the transmitted wave height Ht and the incident wave height Hi) as an index of the wave-dissipating performance is to be kept below 0.5, the penetration amount of the curtain wall is 1/7 times the wavelength. I know that it is necessary to some extent. Therefore, for example, 4 m for a wave with a cycle of 4 seconds and a wavelength of 25 m
A weak penetration amount is sufficient, but a penetration amount of 14 m is required for a wave having a period of 8 seconds and a wavelength of 100 m, which causes a problem that the scale of the wave-dissipating structure becomes large. Also, in this case, the permeability of water deteriorates, and although the transmission coefficient is small for waves that occur more frequently and have a shorter cycle, the reflected waves cannot be ignored, and the incident and reflected waves cannot be ignored in front of the curtain wall. There is also a problem that it hinders the navigation of vessels and work vessels in the water area where

FIG. 7 is a side view of a wave-dissipating structure of a type called a submerged horizontal plate type, in which a horizontal plate structure b is completely submerged near the water surface. This type of wave-dissipating structure consumes wave energy by utilizing the fact that a flat plate impedes the movement of water particles, the wave breaks on the flat plate, or a vortex is generated at the end of the flat plate. Although the transmission coefficient is reduced and the reflected wave is also small, the wave with a long wavelength is dealt with by increasing the width of the plate, and if the transmission coefficient is suppressed to 0.5 or less, Is required to be 1/3 to 1/4 of the wavelength. Therefore, the wavelength
There is a problem that the plate width becomes close to 30 m for a wave of 100 m and it becomes a remarkably large-scale structure.

[0005]

As described above, in the conventional transmissive wave-dissipating structure, in order to exert the wave-dissipating effect on a wave having a long wavelength, the scale becomes large and the cost is increased. There is a drawback that. In addition, water permeability may deteriorate as the scale increases. Especially in case of curtain wall, the influence of reflected wave cannot be ignored. The present invention is intended to solve the above-mentioned problems, and makes it possible to obtain a sufficient wave-dissipating effect with respect to a wave having a long wavelength with a structure having a much smaller scale than the conventional one. An object of the present invention is to provide a transmissive wave-dissipating structure capable of reducing reflected waves.

[0006]

In order to achieve the above-mentioned object, in the present invention, a submerged horizontal plate which is developed in a horizontal direction substantially orthogonal to the direction in which waves enter is completely parallel to the water surface and completely submerged. And a vertical flat plate that is erected and fixed upwards so as to penetrate the water surface near the end on the wave upper side or wave lower side of the submerged horizontal plate. Has become. That is, the transmission type wave-dissipating structure of the present invention is provided with a support frame which is erected on the seabed and allows the permeation of seawater, and a submerged horizontal plate which is supported by the support frame and is located below the water surface. It is characterized in that a vertical plate is erected upright near the end of the water horizontal plate on the wave lower side or the wave upper side so as to pass through the water surface substantially orthogonal to the traveling direction of the incoming wave.

Further, in the transmission type wave-dissipating structure of the present invention, a plurality of partition plates for connecting the submerged horizontal plate and the vertical flat plate are arranged at intervals along the traveling direction of the incoming wave. It is characterized by being installed.

In the transmission type wave-dissipating structure of the present invention, the partition plate is formed in the shape of a right triangle having a hypotenuse obliquely inclined from the vicinity of the upper edge of the vertical flat plate to the vicinity of the edge of the submerged horizontal plate. It is characterized by

Further, the transmission type wave-dissipating structure of the present invention is characterized in that the width of the submerged horizontal plate is set larger than the height of the vertical flat plate.

Furthermore, the transmission type wave-dissipating structure of the present invention is
A projecting member is attached to an end of the submerged horizontal plate on which the vertical flat plate is not erected so as to prevent a flow along an upper surface or a lower surface of the submerged horizontal plate.

Further, in the transmission type wave-dissipating structure of the present invention, near the end of the submerged horizontal plate on which the vertical flat plate is not erected, above the submerged horizontal plate and below the water surface. It is characterized in that the plate structure is provided at the position.

Furthermore, the transmission type wave-breaking structure of the present invention is
It is characterized in that the plate structure is disposed so as to be positioned below the water surface and away from the submerged horizontal plate on the wave upper side.

[0013]

In the transmission type wave-dissipating structure of the present invention described above, when the vertical flat plate is erected near the wave-side end of the submerged horizontal plate,
The incoming wave propagating on the water surface is reflected once by the vertical flat plate in order to pass along the upper surface of the submerged horizontal plate, returns on the submerged horizontal plate, and then passes under the submerged horizontal plate. Perform the action of going. Then, in the case of a returning wave, the operation of tracing the reverse path described above is performed. In this way, a part of the wave is delayed in phase, and a part of the energy of the wave is consumed by moving the water on the submerged horizontal plate, so that the transmitted wave is attenuated.

Also, when the vertical flat plate is erected near the end of the submerged horizontal plate on the wave upper side, the transmitted wave is sufficiently attenuated by the synergistic action on the waves of the vertical flat plate and the submerged horizontal plate. . Then, when a plurality of partition plates that connect the submerged horizontal plate and the vertical flat plate are arranged in parallel with each other in parallel with the traveling direction of the wave, the movement of the wave along the submerged horizontal plate described above. The operation is smoothly performed, and the joint strength between the submerged horizontal plate and the vertical flat plate is increased.

Further, since the partition plate is formed in the shape of a right-angled triangle having a hypotenuse inclined from the vicinity of the upper edge of the vertical flat plate to the vicinity of the edge of the submerged horizontal plate, the mounting strength of the partition plate itself is improved. Be properly maintained. Furthermore, the projecting member or the plate structure according to claims 5 to 7 uses a flow around the submerged horizontal plate to generate a vortex,
It acts to reduce the energy of the waves. Further, since the projecting member or the plate structure does not hinder the resonance phenomenon on the submerged horizontal plate and is arranged at a location where the flow is fast, the above-mentioned action is remarkably performed.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A transmission type wave-breaking structure as one embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view thereof, and FIG.
3 (a) to 3 (c) are schematic side sectional views of the first modification, and FIG.
(a) ~ (c) is a schematic side sectional view of the second modified example, Fig. 5 (a) ~
(e) is a schematic side sectional view of the third modification.

First, the transmissive wave-dissipating structure shown in FIG. 1 will be described. Reference numeral 1 denotes a submerged horizontal plate disposed at a position of a depth d below the water surface. A wave-dissipating structure is formed between the submerged horizontal plate 1 and a vertical flat plate 2 that is erected on the wave-side end of the submerged horizontal plate 1. This support frame is erected on the seabed so as to allow the permeation of seawater. It is supported by 4.
In this way, the vertical flat plate 2 is provided so as to penetrate the water surface substantially orthogonal to the traveling direction 5 of the incoming wave W, and the ratio of the submerged depth d of the submerged horizontal plate 1 to the width B (d / B) is 1/2
It is set to about 1/3.

A plurality of partition plates 3 connecting the submerged horizontal plate 1 and the vertical flat plate 2 are arranged side by side along the traveling direction 5 of the incoming wave W at intervals. Each partition plate 3 is formed in the shape of a right triangle having a hypotenuse 3a that obliquely extends from near the upper edge of the vertical flat plate 2 to near the edge of the submerged horizontal plate 1. The support frame 4 is composed of an elongated member such as a steel frame or an iron pipe, which enhances the water permeability. Here, the longitudinal direction 6 of the wave-dissipating structure is arranged orthogonal to the traveling direction 5 of the incoming wave W. Figure 1
The symbol B in the figure indicates the width of the submerged horizontal plate 1, and the symbol D indicates the vertical plate 2.
, The reference numeral s indicates the freeboard portion of the vertical flat plate 2, and the reference numeral 10 indicates the water surface.

Since the transmission type wave-dissipating structure of this embodiment is constructed as described above, the ingress wave W propagating on the water surface is obtained.
Is an operation of passing along the upper surface of the submerged horizontal plate 1, once reflected by the vertical flat plate 2, returned over the submerged horizontal plate 1, and then passed under the submerged horizontal plate 1. Do. Then, in the case of a returning wave, the operation of tracing the reverse path described above is performed. In this way, a part of the wave is delayed in phase, and by moving the water on the submerged horizontal plate 1, a part of the wave energy is consumed, so that the transmitted wave is attenuated.

Also, when the vertical flat plate is erected near the end of the submerged horizontal plate on the wave upper side, the transmitted wave is sufficiently attenuated due to the synergistic action on the wave of the vertical flat plate and the submerged horizontal plate. . When a plurality of partition plates 3 for connecting the submerged horizontal plate 1 and the vertical flat plate 2 are arranged in parallel with each other in parallel with the traveling direction of the wave, the wave along the above-mentioned submerged horizontal plate 1 is generated. The movement is smoothly performed, and the joint strength between the submerged horizontal plate 1 and the vertical flat plate 2 is increased.

Further, the partition plate 3 is formed in the shape of a right triangle having a hypotenuse 3a obliquely running from the vicinity of the upper edge of the vertical flat plate 2 to the vicinity of the edge of the submerged horizontal plate 1, so that the partition 3
The mounting strength of the plate itself can be maintained appropriately. Figure 2
(a) and (b) show the wave-dissipation performance curves for regular waves obtained by simulation calculations and tank experiments. The abscissa represents a value obtained by making the wavelength λ of the incoming wave (regular wave) dimensionless by the width B of the submerged horizontal plate 1, and the ordinate represents the wave transmission coefficient.

FIG. 2 (a) shows the case where the ratio of the submerged depth d of the submerged horizontal plate 1 to the width B is 1/3, and the wavelength λ when the transmission coefficient is 0.5 or less. The maximum value of is 18 times the width B of the submerged horizontal plate 1. Further, FIG. 2B shows the case where the ratio of the submerged depth d of the submerged horizontal plate 1 to the width B is 1/2, but the maximum value of the wavelength λ at which the transmission coefficient is 0.5 or less. Is approximately 12 times the width B of the submerged horizontal plate.

From the above, the submerged depth of the submerged horizontal plate 1 is changed due to the tide level change, and the ratio of d and B is 1/2 to 1/1 /.
Even if it changes within the range of 3, for example, a period of 8 seconds, a wavelength of 100
For an incoming wave of m, a considerably small wave-dissipating structure with a width of the submerged horizontal plate 1 of about 8 m and a submerged depth of about 2.7 to 4 m is sufficient. At a period of 6 seconds and a wavelength of 56 m, the width may be about 5 m, and at a period of 12 seconds and a wavelength of 225 m, the width needs to be about 20 m. Although the submerged horizontal plate 1 and the vertical flat plate 2 are simple plates in this embodiment, they may have a steel plate structure having a certain thickness or a block structure covered with concrete.

In the illustrated example, the submerged horizontal plate 1 and the vertical flat plate 2 have an L-shaped cross-section, but a slight protrusion from the submerged horizontal plate 1 or the vertical flat plate 2 is acceptable. Further, in the illustrated example, the vertical flat plate 2 is replaced by the submerged horizontal plate 1.
Although it is provided at the lower end of the wave, it has been confirmed by calculation and experiment that the same effect can be obtained at the upper side of the wave. When the vertical flat plate 2 is provided at the end of the submerged horizontal plate 1 on the wave side,
In FIG. 1, the incoming wave is represented by the symbol W '.

Here, the submerged horizontal plate 1 and the vertical flat plate 2 described above are used.
The principle of the wave-dissipating action in the transmission-type wave-dissipating structure composed of and will be described. The wavelength λ of the wave is expressed as in [Equation 1] using the wave period T when the water depth is large.

[Equation 1] Where g is gravitational acceleration and π is the circular constant

On the other hand, when the water depth is very small, the wavelength λ _h considering the influence of the water depth h is expressed by the formula [2].

## EQU2 ## λ _h = T√ (gh) Therefore, the smaller the water depth, the shorter the wavelength.

The present invention utilizes the so-called resonance phenomenon which occurs on the submerged horizontal plate in which the antinode of the wave is generated on the front surface of the vertical flat plate and the node of the wave is generated on the other end of the submerged horizontal plate to dissipate the energy of the incident wave. , The transmission coefficient is reduced. That is, when the wavelength on the submerged horizontal plate is four times the width of the submerged horizontal plate, the formula [3] is obtained.

4B = λ _d where λ _d is the wavelength on the submerged horizontal plate, and B is the width of the submerged horizontal plate.

In the structure type of the transmission type wave-dissipating structure described above, the apparent water depth h on the submerged horizontal plate is regarded as the submerged depth d of the submerged horizontal plate. Substituting the water depth h in the formula with d and substituting it in the formula [3],
When the relationship between the width B and the wave period T at resonance is obtained, [Equation 4]
The formula holds.

[Equation 4]

Since the equation (4) is an approximate equation that does not take into consideration the movement of water outside the other end of the submerged horizontal plate, it is actually corrected to the following equation (5). It is considered to be.

[Equation 5] Since the water outside the other end of the submerged horizontal plate works as a mass, the resonance period needs to be corrected longer, and therefore α is considered to be a value larger than 1.

In the offshore wave (incoming wave), the equation [1] is established between the wave period and the wavelength.
Eliminating T by the equations and ## EQU6 ## eventually yields the equation [6].

[Equation 6]

For example, if α is 1.5, B / d is 2
At that time, a resonance phenomenon occurs when λ / B is about 11.5. In other words, the wave-dissipating performance can be demonstrated with a structure having a width of about 1/12 or less with respect to the wavelength of the incoming wave.

From the above, in the structure type of the above-mentioned transmission type wave-dissipating structure, a space opened on one side for causing a resonance phenomenon is formed by a combination of a vertical flat plate and a submerged horizontal plate, and further a submerged horizontal plate. The scale of the structure can be reduced by shortening the wave length by making the submersion depth of shallow. Since the exact solution for α is unknown, the effect of the structural form according to the present invention can be estimated by obtaining the fluid phenomenon around the structure using a numerical calculation method. The effect was confirmed by a water tank experiment, and an example of the result is as described above.

If B / d is increased so as to be effective for a wave as long as possible, a wave having a short wavelength is easily transmitted. Based on experimental results, 2-3 is suitable as B / d, and considering the freeboard part s and the tide difference, the width of the submerged horizontal plate 1 (that is, B) is the height of the vertical flat plate ( It is appropriate that the sum of d and the freeboard s = D) is slightly more than 1 to 2 times.
In principle, it is significant to place the vertical flat plate 2 at the end of the submerged horizontal plate 1, which may be on the wave side or the wave side.

Next, each modification shown in FIGS. 3 to 6 will be described. In each of these modified examples, means for reducing the reflected wave reflected by the vertical flat plate in the transmission type wave-dissipating structure having the above-mentioned configuration is added. That is, in the first modified example of FIG. 3, in order to prevent the flow along the upper surface or the lower surface of the submerged horizontal plate 1 at the end of the submerged horizontal plate 1 where the vertical flat plate 2 is not erected, 7 is attached. Reference numeral 10 indicates the water surface.

As shown in FIG. 3 (a), the projecting member 7 is provided so as to project above the submerged horizontal plate 1, or as shown in FIG.
As shown in (b), the submerged horizontal plate 1 is provided so as to project downward. Also, as shown in FIG. 3 (c),
The protruding member 7 is provided so as to protrude both above and below the submerged horizontal plate 1, but in any case, the protruding member 7 is used to generate a vortex by utilizing the flow around the wave-dissipating structure. As a result, the action of reducing the energy of the wave is performed.

Therefore, in order to allow the projecting member 7 to effectively perform the above-mentioned action, the projecting member 7 does not hinder the above-mentioned resonance phenomenon on the submerged horizontal plate 1 and has a high flow rate, that is, submerged water. The horizontal flat plate 1 is provided at the end of the side where the vertical flat plate 2 is not erected. In the second modified example of FIG. 4, in the vicinity of the end of the submerged horizontal plate 1 on which the vertical flat plate 2 is not erected, the submerged horizontal plate 1 is located above the submerged horizontal plate 1 and below the water surface 10, and has a plate structure. A body 8 is provided.

The plate structure 8 has substantially the same function and effect as the projecting member 7 in the above-mentioned first modified example.
It is attached vertically to the submerged horizontal plate 1 as shown in FIG. 4 (a), or is attached so as to be inclined with respect to the submerged horizontal plate 1 as shown in FIG. 4 (b). . See also FIG.
In the case of a plate structure having a T-shaped cross section as shown in (c), almost the same action and effect can be obtained. In the third modification of FIG. 5, the plate structure 9 is provided so as to be separated from the submerged horizontal plate 1 to the wave upper side and to be located below the water surface 10.

As shown in FIGS. 5 (a), 5 (b) and 5 (c), this plate structure 9 is arranged vertically or inclined with respect to the submerged horizontal plate 1, or has a T-shaped cross section. In addition to
As shown in (d) and (e), a plurality of water vapors are arranged at substantially the same water depth as the vertical shape or at different water depths in an oblique direction. In either case, by providing the plate structure 9, Three
The modified example can also provide the same operational effect that the reflected wave can be reduced as in the case of the first modified example in which the protruding member 7 is provided.

[0039]

As described in detail above, according to the transmissive wave-breaking structure of the present invention, the following effects and advantages can be obtained. (1) It is possible to reduce transmitted waves with a structure smaller than conventional ones for long wavelength waves, which not only reduces cost but also improves the permeability of the flow around the structure.
An extremely useful effect can be obtained industrially. (2) By installing additional structures to reduce reflected waves,
This makes it possible to prevent navigation of vessels and work vessels in front of the wave-dissipating structure.

[Brief description of drawings]

FIG. 1 is a perspective view showing an overall configuration of a transmission type wave-breaking structure as one embodiment of the present invention.

FIG. 2 (a) is a graph showing the wave-dissipating performance of the transmission-type wave-dissipating structure of FIG. 1 against regular waves. (b) A graph showing the wave-dissipating performance of the transmission-type wave-dissipating structure of FIG. 1 against regular waves.

FIG. 3 (a) is a schematic side sectional view of a first modification of the transmission-type wave-breaking structure of FIG. (b) A schematic sectional side view of the 1st modification of the transmission type wave-breaking structure of FIG. (c) A schematic side sectional view of a first modified example of the transmission type wave-dissipating structure of FIG. 1.

FIG. 4 (a) is a schematic side sectional view of a second modification of the transmissive wave-breaking structure of FIG. (b) A schematic side sectional view of a second modification of the transmission-type wave-breaking structure of FIG. 1. (c) A schematic side sectional view of a second modification of the transmissive wave-breaking structure of FIG. 1.

5 (a) is a schematic side cross-sectional view of a third modified example of the transmissive wave-breaking structure in FIG. 1. FIG. (b) The schematic side sectional view of the 3rd modification of the transmission type wave-breaking structure of FIG. (c) A schematic side sectional view of a third modification of the transmission-type wave-breaking structure of FIG. 1. (d) A schematic side sectional view of a third modification of the transmission-type wave-breaking structure of FIG. 1. (e) A schematic side sectional view of a third modified example of the transmission type wave-dissipating structure of FIG. 1.

FIG. 6 is a side view showing a curtain wall type as an example of a conventional transmission type wave-dissipating structure.

FIG. 7 is a side view showing a submerged horizontal plate type as another example of the conventional transmission type wave-dissipating structure.

[Explanation of symbols]

 1 Submerged horizontal plate 2 Vertical flat plate 3 Partition plate 3a hypotenuse 4 Support frame 5 Direction of incoming wave 6 Longitudinal direction 7 Projection member 8, 9 Plate structure 10 Water surface

Claims (7)

[Claims] 1. A support frame, which is erected on the sea floor and allows permeation of sea water, and a submerged horizontal plate which is supported by the support frame and is located below the water surface. A transmissive wave-dissipating structure, in which a vertical flat plate is erected near the end on the upper side of the wave so as to penetrate the water surface substantially orthogonal to the traveling direction of the incoming wave. 2. The transmission type wave-dissipating structure according to claim 1, wherein a plurality of partition plates connecting the submerged horizontal plate and the vertical flat plate are spaced from each other so as to extend along the traveling direction of the incoming wave. A transmissive wave-dissipating structure characterized by being installed side by side. 3. The transparent wave-dissipating structure according to claim 2, wherein the partition plate has a right-angled triangle having a hypotenuse obliquely extending from near the upper edge of the vertical flat plate to near the edge of the submerged horizontal plate. A transmissive wave-dissipating structure characterized by being formed into a shape. 4. The transparent wave-dissipating structure according to claim 1, wherein a width of the submerged horizontal plate is set larger than a height of the vertical flat plate. Transparent wave-dissipating structure. 5. The transmissive wave-dissipating structure according to claim 1, wherein the submerged horizontal plate is provided at an end of the submerged horizontal plate on which the vertical flat plate is not erected. A transmissive wave-dissipating structure, wherein a protruding member is attached to prevent the flow along the upper surface or the lower surface of the. 6. The transmissive wave-dissipating structure according to any one of claims 1 to 4, wherein the submerged horizontal plate is near the end of the submerged horizontal plate on which the vertical flat plate is not erected. A transparent wave-dissipating structure, wherein a plate structure is provided above the plate and below the water surface. 7. The transparent wave-dissipating structure according to claim 1, wherein the plate structure is arranged so as to be located above the submerged horizontal plate on the wave upper side and below the water surface. A transmissive wave-dissipating structure characterized by being installed.