JPH0734428A - Wave dissipation embankment - Google Patents

Abstract

PURPOSE:To have sufficient wave dissipation by absorbing wave energy and reduce seawater change and reflected wave by having seawater flow in and out the embankment. CONSTITUTION:A wave dissipation embankment 10 is installed in a sea area for controlling, for instance, around a port. An open penetration 12 through the length 14 is provided. An air chamber 13 is disposed above the open penetration 12, in communication relation. Small holes 13 as orifice communicating to the air chamber 13 are formed on the top face 15 of the wave dissipation embankment 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a breakwater as a sea area control structure provided on the seabed of a sea area to be controlled.

[0002]

2. Description of the Related Art Sea area control structures, such as breakwaters, which are constructed in the sea area to be controlled as an outer facility, are used to secure the quietness of the harbor and to protect the harbor facilities from waves and the like. It is provided. As these sea area control structures, many impermeable structures such as upright dikes and mixed dikes have been constructed conventionally. That is,
The breakwater as such an impermeable structure has a high breakwater function by blocking passage of waves and the like.

[0003]

However, since the breakwater as the above-mentioned impermeable structure blocks not only the energy of the waves but also the flow of seawater, seawater can be easily exchanged inside and outside the breakwater. Therefore, the sea area behind the levee body will be in the same state as the closed sea area, making it difficult to secure water quality and clean the sea area, and change the flow conditions of the surrounding tidal current and river flow. There was a problem.

There is also a problem that the number of waves increases due to the influence of reflected waves from the breakwater, which adversely affects the safety of fishing boats and small boats sailing in the vicinity.

Therefore, the present invention has been made in view of such conventional problems, and has a sufficient wave-dissipating function by absorbing the energy of waves and enables the flow of seawater inside and outside the levee. It is an object of the present invention to provide a breakwater capable of easily exchanging seawater and reducing reflected waves.

[0006]

The present invention has been made to achieve the above object, and its gist is a breakwater as a sea area control structure installed on the seabed of the sea area to be controlled. The breakwater, the through-hole penetrating between the side surfaces of the breakwater, an air chamber formed above the through-opening, and the top of the breakwater communicating with the air chamber. The breakwater is characterized by having a small hole formed with an opening.

In the breakwater of the present invention, the air chamber is divided by a partition wall extending downward from the top end surface of the breakwater.
It is preferable to define a plurality of air chambers.

Further, in the breakwater according to the present invention, it is preferable that an inclined path for narrowing the opening cross-sectional area is provided at the entrance of the through opening.

[0009]

According to the breakwater of the present invention, a wave or the like moving toward the breakwater collides with the breakwater, reflects only a part thereof, and passes through the through-opening in the sea. Waves passing through this through-opening are the air as a fluid filled in the air chamber above the through-opening and the orifice formed on the top surface of the breakwater while passing through the through-opening. The action of the small holes absorbs the energy generated by the vertical movement of the waves. That is, the air in the air chamber is pressurized or depressurized by the waves moving up and down in the air chamber, while the air as the fluid is discharged or sucked in through the thin orifice, whereby the top surface of the wave breakwater is discharged. A pressure difference occurs between the upper and lower surfaces. Then, this pressure difference becomes a resistance force and absorbs the energy of a moving object, that is, the energy of waves moving up and down, by converting it into kinetic energy of air.

Further, the through opening that crosses the breakwater enables the flow of seawater and promotes the exchange of seawater inside and outside the breakwater.

Further, if the air chamber of the breakwater is divided into a plurality of air chambers by a partition wall extending downward from the upper surface thereof, wave energy can be gradually absorbed in each air chamber. As a result, the absorption efficiency of the entire breakwater can be improved, and the waves can be controlled more effectively.

Furthermore, if a slant for narrowing the opening cross-sectional area is provided at the entrance of the through-opening of the breakwater, the breakwater formed using this can converge the energy of the incident wave. The energy absorption rate of the breakwater can be improved.

[0013]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a breakwater 10 as a sea area control structure according to the present invention. The breakwater 10 is installed around a sea area to be controlled, for example, a harbor, and crosses a side surface 14 thereof. It has a through opening 12 that Further, an air chamber 13 described later is provided above these through openings 12 (see FIG. 1B), and a small hole as an orifice communicating with the air chamber 13 is provided on the top end surface 15 of the breakwater 10. 16 is formed with an opening.

As shown in FIG. 1A, the breakwater 10 is in the form of a rectangular parallelepiped in which wall plates made of reinforced concrete that form six sides are arranged in parallel. A through opening 12 with a rectangular cross section that penetrates the breakwater 10 between the wall plates.
Is provided. Further, as shown in FIG. 1B, an air chamber 13 is formed above the through opening 12 so as to be covered with the other five wall plates except the lower wall plate. The partition 13 is divided into a plurality of air chambers 13a, 13b, and 13c that are continuous in the extension direction of the through opening 12 by a partition wall 18 that extends downward from the lower surface of the top end surface 15. Further, the air chambers 13 are provided on the top end surface 15.
Small holes 16 are provided in communication with a, 13b, and 13c, respectively, through which air flows between the air chamber 13 and the outside air.

As an example of construction of the breakwater 10, as shown in FIG. 2, a large number of the breakwaters 10 are continuously arranged along the sea area to be controlled, for example, around the shore. In this construction, for example, the breakwater 10 having the above-described structure manufactured on land,
It can be easily installed by towing it to the installation location, transporting it, and submerging it in the sea. Since the entire shape of each breakwater 10 is basically based on a caisson, it can be easily constructed by the same work process as a normal caisson installation work.

According to the breakwater 10 of this embodiment thus constructed, the energy of waves or the like passing through the breakwater 10 can be effectively absorbed. That is, the waves moving toward the breakwater 10
Only a part of it collides with the breakwater 10, and most of it passes through the underwater through-opening 12.
While passing through, the energy is absorbed by the air in the air chamber 13 and the action of the small holes 16 as orifices. In addition, since waves and tidal currents moving toward the breakwater 10 can flow through the through opening 12,
Seawater can be easily exchanged between the inside and outside of the breakwater 10, and the waves are reflected only partially by the breakwater 10, so that the reflected waves can be easily reduced.

FIG. 3 shows a breakwater 20 according to another embodiment of the present invention. In this breakwater 20, the partition walls 22a and 22b for partitioning the air chamber 21 and the wall plates 23 and 24 on both side surfaces are arranged so that these water-falling water is gradually lowered from the wave inlet side toward the wave outlet side. It is provided in. According to this structure, each air chamber 21a,
Since the natural periods of 21b and 21c are different, the peaks of the energy absorption efficiency in each of the air chambers 21a, 21b, and 21c are not concentrated, and the absorption efficiency can be improved for waves in a wide frequency band. Therefore,
The energy of waves can be absorbed more efficiently.

Further, FIG. 4 shows a breakwater 30 according to still another embodiment of the present invention. The breakwater 30 has a mound 32 having a slope 31 and an inclined ceiling 33 for narrowing the opening cross-sectional area at the entrance of the through opening. According to this structure, the energy of the waves can be more efficiently absorbed by converging the energy of the waves.

In each of the above embodiments, the partition wall 18,
Alternatively, the extension length of 22a, 22b downward, the partition wall 1
8 or 22a, 22b, the size of the small holes 16, the position of the small holes 16 and the like are appropriately set according to the wave height and wavelength in the sea area, thereby achieving a wave-eliminating effect corresponding to any sea condition. Obtainable. Further, if a turbine, a generator or the like is attached to the breakwater 10, the energy of the waves can be effectively used for wave power generation or the like.

[0020]

As described above, according to the breakwater according to the present invention, it is possible to obtain a sufficient wave-dissipating effect by absorbing the energy of the waves, and at the same time, the through opening that crosses the breakwater is used. The flow of seawater can be enabled to promote the exchange of seawater inside and outside the breakwater, and the quality of water in the area behind the breakwater can be secured and the area can be purified.

Further, the reflected waves from the breakwater can be reduced, and the safety of fishing boats and small vessels traveling in the vicinity can be achieved.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a breakwater according to the present invention.

FIG. 2 is an explanatory diagram showing an example of construction of a breakwater according to the present invention.

FIG. 3 is a schematic sectional view showing a modified example of the breakwater according to the present invention.

FIG. 4 is an explanatory view showing another embodiment of the breakwater according to the present invention.

[Explanation of symbols]

 10 Breakwater 12 Through opening 13 Air chamber 16 Small hole

Claims (3)

[Claims] 1. Installed on the seabed of the area to be controlled,
A breakwater as a sea area control structure, wherein the breakwater is
A through-opening penetrating between the side surfaces of the breakwater, an air chamber formed above the through-opening, and a small hole formed on the top end surface of the breakwater in communication with the air chamber. A breakwater characterized by having. 2. The breakwater according to claim 1, wherein the air chamber is divided into a plurality of air chambers by a partition wall extending downward from a top end surface of the breakwater. 3. The through opening has an oblique path at an entrance thereof for narrowing an opening cross-sectional area.
Alternatively, the breakwater according to claim 2.