JPH047404A - Wave dissipation device - Google Patents

Abstract

PURPOSE:To offset incident waves by transmitted waves so as to make water surface smoother by installing a pontoon and fixing the lower section at one end of the pontoon to a post by means of a hinge structure and the lower section of the other end to another post by means of a spring device having an appropriate spring constant. CONSTITUTION:The lower section of one end of a pontoon 1 is fixed to a post 5 by means of a hinge structure 3 and the lower section of the other end is fixed to another post 5 by means of a spring device 4 having an appropriate spring constant and the entire body of the pontoon 1 is positioned underwater at a prescribed depth from water surface 7 by using a concrete block 6. The pontoon 1 receives a water pressure which varies depending upon the advance of waves and starts to make rotating motions around the hinge section. As a result, the pontoon 1 offsets incident waves by transmitted waves by producing radiated waves having a phase which is different from that of the incident waves and breaks incident waves on the pontoon 1. Accordingly, the water surface becomes smoother. Therefore, the wave dissipation action of this pontoon 1 becomes more effective than that exerted by a fixed pontoon.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a wave dissipating device that eliminates wave energy by dissipating the energy by reflection or wave breaking.

<Prior Art> Various wave dissipating devices have been proposed to ensure safe harbor waters. These are generally breakwater structures (breakwaters) in which structures and obstacles are fixed or stacked on the seabed.
In general, they have a large wave-dissipating effect, but have a disadvantage in that they have a poor seawater exchange function, and construction costs increase as the water depth increases. Various simple wave canceling devices have been proposed to compensate for this drawback, examples of which are shown in FIG. This wave dissipating device is
The pontoon 1 is mounted on support columns 9 at both ends fixed to the seabed 8.
The structure is such that the pontoon 1 is fixed below the water surface 7, and the wave-dissipating action of this device is to dissipate wave energy by breaking waves caused by the sudden shallowing of the water above the submerged pontoon 1. It is something.

<Problems to be Solved by the Invention> However, in the case of the above-mentioned fixed pontoon, waves are dissipated by breaking waves, so in order to obtain the desired wave dissipating effect, the pontoon needs to be installed near the water surface. Furthermore, the width of the embankment body also needs to be increased. As a result, a large amount of wave force acts on the pontoon, and in order to create a structure that can withstand this wave force, the structure must have a large cross section, which increases construction costs and poses an economic problem.

The present invention has been made to solve the above problems,
It is an object of the present invention to provide a wave dissipating device that reduces construction costs by simplifying the shape and configuration of the entire structure and exhibits an excellent wave dissipating function.

<Means for Solving the Problems> The present invention has been made in view of the above object, and its gist is to provide a pontoon that is placed below the water surface and has an impermeable opening or a plurality of openings, and a pontoon that is placed under the seabed. a support part for supporting and fixing, interposed between the pontoon and the support part,
The wave dissipating device includes a hinge portion for rotating the pontoon relative to the support portion in response to vertical movement of the water surface, and a spring means for returning the pontoon to a normal position.

Further, the support portion may be provided at one end of the pontoon via the hinge portion, and the support portion may be provided at the other end via the spring means.

Further, a support portion is provided at the center of the pontoon via the hinge portion, and the support portions are provided via the spring means at the front and rear ends of the pontoon with respect to the traveling direction of the incident wave. Also good.

Furthermore, the pontoon is provided with a bending mechanism that divides the pontoon into two parts, a front part and a rear part with respect to the traveling direction of the incident wave, and the support part is provided at the front end part and the rear end part, respectively, via the hinge part. At the same time, it is also possible to provide the spring means for connecting the front part and the rear part.

<Function> In the wave dissipating device according to the present invention, the pontoon disposed below the water surface receives water pressure (vertical force) that changes with the vertical movement of the water surface, that is, the progression of waves, and uses the hinge portion as a fulcrum. Begin rotational movement. Due to this rotational movement, a radiation wave having a phase different from that of the incident wave is generated to cancel the incident wave and the transmitted wave, and on the pontoon, the incident wave is broken and acts to smooth the water surface. .

<Example> A wave dissipating device A according to the present invention will be explained based on FIGS. 1 to 3.

In the figure, a box-shaped pontoon 1 has a large number of openings 2 penetrating from the upper surface to the lower surface, and is made of a material with a specific gravity equal to or lower than that of seawater, or is made of a material in which gas is injected into the inside. Appropriate buoyancy is provided by known methods. Also, at the bottom of one end of pontoon 1,
It is fixed to a stake 5 as a support section via a hinge structure 3, and the stake 5 is fixed to the lower part of the other end of the pontoon 1 via a spring device 4 having an appropriate spring constant.

This pontoon 1 is installed on the seabed 8 using concrete blocks 6 so that the entire pontoon 1 is located underwater at a predetermined depth from the water surface 7.

The surplus buoyancy of the pontoon 1 has the function of keeping the tension coil spring in an appropriately expanded state (if a compression coil spring is used, in an appropriately compressed state) in a stationary state, and promoting the rotational movement of the pontoon 1 due to the incident wave 10. At the same time,
It also acts as a restoring force against the force pushing down the pontoon 1.

The spring device 4 acts as a restoring force against the force pushing up the pontoon 1, and also has the effect of mitigating the impact force.

The opening 2 of the pontoon 1 contributes to reducing wave energy loss and vertical force due to vortices generated around the opening due to the rotational movement of the pontoon 1.

Next, the wave-dissipating operation of the wave-dissipating device A will be explained while partially comparing it with the conventional wave-dissipating device shown in FIG. 7.

First, in the conventional wave absorbing device in which the pontoon 1 and the support column 9 are directly fixed, even if the pontoon 1 receives the incident wave 10, the pontoon 1
does not rotate, but suppresses the amplitude of the transmitted wave 11 by reflection, wave breaking, wave splitting (conversion from long wavelength to short wavelength), etc. On the other hand, the wave dissipating device A includes a hinge structure 3 and a spring device 4, and when the pontoon 1 receives the incident wave 10, it rotates about the hinge structure 3 as a fulcrum.

In other words, when the peak of the incident wave 10 reaches the top of the pontoon 1, the entire pontoon 1 tries to sink due to water pressure (vertical force), but the end on the hinge structure side is restrained from vertical movement. , the pontoon 1 sinks due to the contraction of the opposite spring device 4 (FIG. 2a). Next, when the trough of the incident wave 10 reaches the top of the pontoon 1, the water pressure becomes low, so the entire pontoon 1 tries to float due to the restoring force due to its excess buoyancy, but the end on the hinge structure side Since the movement is restricted, the opposite spring device 4 expands, causing the pontoon 1 to float (FIG. 2b). Each of the above operations occurs alternately as the wave progresses. Therefore, the pontoon 1 performs a rotational movement using the hinge structure 3 as a fulcrum, and this movement generates a radiation wave 12. Since this radiation wave 12 has a different phase from the incident wave 10 and the transmitted wave 11,
They cancel each other out, and the amplitude of the transmitted wave 11 is reduced (third
figure).

In this embodiment, the pontoon 1 is provided with a large number of openings 2 having a constant aperture ratio, and by moving the openings 2 up and down, it is possible to generate a vortex around the openings and cause energy loss of the incident wave 10. can.

This opening 2 also contributes to reducing vertical force.

In the wave-dissipating device A, even if the incident direction of the waves shown in FIG. 1 is opposite, the pontoon 1 moves in the same manner as described above, and the same wave-dissipating effect can be expected.

Furthermore, as shown in FIG. 4a, the wave dissipating device A can be arranged such that the pontoon 1 is inclined at a predetermined angle θ° toward the water surface using the hinge structure 3 as a fulcrum.

In this case as well, when receiving the incident wave 10, the pontoon 1 performs a rotational movement using the hinge structure 3 as a fulcrum, and this movement generates a radiation wave 12, which cancels out the transmitted wave 11 and reduces the amplitude of the transmitted wave 11. let Also, pontoon 1
As the incident wave 10 advances above the pontoon, the water depth becomes gradually shallower, and the pontoon 1 also dissipates wave energy by the wave breaking action caused by the shallower water depth.

Alternatively, as shown in FIG. 4b, the pontoon 1 may be tilted in the same manner, and the hinge structure 3 may be provided at the front end in the direction of wave propagation, and the spring device 4 may be provided at the rear end. In this case as well, the wave-dissipating device operates in the same way as the wave-dissipating device shown in FIG. 4a, and exhibits the same wave-dissipating effect.

Further, another embodiment is shown in FIG. The wave dissipating device B is configured such that a hinge structure 3 is provided at the lower center of the pontoon 1, and spring devices 4 are provided at the lower portions of the front and rear ends of the pontoon 1 in the wave traveling direction. The pontoon 1 in this wave dissipating device B performs a rotational movement with the hinge structure 3 as a fulcrum as the wave advances, and the radiated wave 12
is generated, and the amplitude of the transmitted wave 11 is reduced as described above.

Yet another embodiment is shown in FIG. 6a. The pontoon 1 of the wave absorber C has a front end 1a and a rear end 1 in the direction of propagation of the incident wave.
1b, and each is connected by a hinge structure 3c. Further, spring devices 4a and 4b are provided on the upper and lower surfaces of the pontoon 1, respectively, to connect the front end side 1a and the rear end side 1b of the pontoon 1. When the specific gravity of the pontoon 1 is set to approximately 1, the pontoon 1 of the wave dissipating device C becomes approximately horizontal in still water.

When the peak of the incident wave 10 comes directly above the pontoon 1 due to the progression of the wave, the pontoon 1 moves to the central hinge structure 3c.
At this time, the spring device 4a attached to the upper surface of the pontoon 1 contracts, and the spring device 4b attached to the lower surface of the pontoon 1 expands. In addition, if the valley of the wave resistance 1o comes directly above the pontoon 1, the spring device 4a
, 4b serve as restoring forces, and the central hinge structure 3c is pushed upward (the state shown by the broken line in FIG. 6b). By repeating this operation as the wave advances, the radiation wave 12 described in the wave canceling device A is generated, and the amplitude of the transmitted wave 11 is reduced.

Although the pontoons 1 of the wave breakers B and C shown in the above-mentioned embodiments are not provided with the openings 2, it is of course possible to provide them, and the openings 2 can be moved up and down. As described above, the energy of the incident wave 10 can be lost by generating a vortex around the wave 2.

Furthermore, each pontoon 1
moves in the same way as in the forward direction, and exhibits the same wave-dissipating effect.

Further, although the piles 5 are used as an example of a support part for supporting and fixing the pontoon 1 to the seabed in this embodiment, any other material such as a mooring cable can be used as long as it can moor the pontoon to the seabed. It is not limited.

<Effects> The wave dissipating device according to the present invention includes a pontoon that is opaque or has a plurality of openings, a support section that supports and fixes the pontoon to the seabed, and a hinge section that can rotate the pontoon with respect to the support section. and a spring means for returning the pontoon to its home position, so that the pontoon can be rotated about the hinge part as a fulcrum due to changes in water pressure due to vertical movement of the water surface as the incident wave advances. Since a radiated wave having a phase different from the transmitted wave is generated to cancel the incident wave and the transmitted wave, the wave canceling effect can be performed more efficiently than when a fixed pontoon is used as in the past.

Further, since the spring means is employed, it is possible to avoid a large impact force being applied to the support portion that supports and fixes the pontoon in the event of a strong wind or the like.

Furthermore, since the structure as a whole is simple in shape and configuration, construction costs can be reduced and a highly practical wave dissipating device can be provided.

[Brief explanation of drawings]

FIG. 1 is a side view showing a wave dissipating device A according to the present invention, and FIG.
, 2b is a side view illustrating the wave-dissipating operation of the wave-dissipating device A, and FIG. 3 is a schematic conceptual diagram showing a mechanism for canceling incident waves and transmitted waves by radiation waves generated by the wave-dissipating device A. Figures 4a and 4b are side views showing another embodiment of the wave absorbing device A, Figures 5a and 5b are side views showing another wave absorbing device B according to the present invention, and Figures 6a and 6b are side views showing another embodiment of the wave absorbing device A. FIG. 7 is a side view showing still another wave-dissipating device C, and FIG. 7 is a side view showing a conventional wave-dissipating device. 1. Pontoon, 2. Opening, 3. Hinge structure, 4. Spring device, 5. Pile (supporting portion). Ma Gumi Co., Ltd. Toyo Construction Co., Ltd. Wakachiku Construction Co., Ltd. Ijima Takeshizake Ikane Sakakane Saka

Claims (1)

[Scope of Claims] 1) A pontoon that is disposed below the water surface and is impermeable or has a plurality of openings, a support part that supports and fixes the pontoon to the seabed, and a pontoon that is interposed between the pontoon and the support part. A wave dissipating device comprising: a hinge portion for rotating the pontoon relative to the support portion in response to vertical movement of the water surface; and spring means for returning the pontoon to a home position. 2) The wave dissipating device according to claim 1, wherein the hinge portion is provided at one end of the pontoon, and the spring means is provided at the other end. 3) A support section is provided at the center of the pontoon via the hinge section, and the support sections are provided at the front and rear ends of the pontoon with respect to the traveling direction of the incident wave via the spring means, respectively. The wave dissipating device according to claim 1. 4) The pontoon is provided with a center bending mechanism that divides the pontoon into two parts, a front part and a rear part with respect to the traveling direction of the incident wave, and the support part is provided at the front end part and the rear end part, respectively, via the hinge part. 2. The wave dissipating device according to claim 1, further comprising the spring means for connecting the front part and the rear part.