JPH0451603B2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a sea area control structure with transparent horizontal plates that is installed offshore of a beach to control huge waves and create a calm sea area. .

(Prior Art) As a structure of this type, there is an offshore breakwater that is constructed by stacking concrete blocks and has both a beach nourishing effect and a wave-breaking effect to some extent.

(Problems to be Solved by the Invention) However, the detached breakwater has a large cross section in deep water, which not only causes economical problems, but also makes it impossible to expect the desired effects. Therefore, there is a problem in that the usable water area behind the breakwater is limited. Moreover, since the detached breakwater protrudes above the sea surface, there is not only the risk of spoiling the scenery, but also the problem that the detached breakwater is likely to collapse due to scouring in front of the detached breakwater.

An object of the present invention is to provide a sea area control structure with slits that can provide a sufficient wave-dissipating effect, can create a calm sea area, and does not spoil the scenery.

(Means for Solving the Problems) The sea area control structure with a transparent horizontal plate of the present invention has a bottom wall, four vertical walls surrounding the bottom wall, and a submerged depth from a still water surface and a water depth. a box-shaped wave-dissipating underwater structure body installed in the sea, having a transparent horizontal plate with a height of 0.1 to 0.2 and located below the sea surface;
The main body of the wave-dissipating underwater structure is partitioned into a plurality of water retarding chambers by a vertical partition wall between the front wall and the rear wall, and the height of the top of the front wall, the partition wall, and the rear wall is is near the still water surface, and the front wall, partition wall, and rear wall have an opening ratio of 25 to 30% to allow seawater to pass through.
A structure is characterized in that a large number of slits are formed, and the permeable horizontal plate has a large number of slits with an opening ratio of 15 to 18% that eject the seawater in the water retarding chamber as a vertical jet. do.

(Function) With this structure, the incident wave is introduced into the water retarding chamber through the slit and is disturbed within the water retarding chamber. A part of the incident wave entering the water retarding chamber is ejected as a vertical jet from the slit in the transparent horizontal plate.

The vertical jet from the slit in this transparent horizontal plate is
It collides with the incident wave passing above the transparent horizontal plate, breaking the incident wave and attenuating it. Further, the remaining incident waves that entered the water retarding chamber are attenuated in the water retarding chamber and are discharged from the slit in the rear wall.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings. 1 to 4 show a first embodiment of the present invention.

As shown in the figure, the sea area control structure with transparent horizontal plates of this embodiment has a rectangular bottom wall 1, four vertical walls 2, 3, 4, 5 surrounding the bottom wall 1, and sea surface A box-shaped wave-dissipating underwater structure main body 8 is installed in the sea and has a transparent horizontal plate 7 located at a height below 6.
It is equipped with In this embodiment, the bottom wall 1 is installed on the seabed surface 9. The interior of the wave-dissipating underwater structure main body 8 is partitioned into a plurality of water retarding chambers 11 and 12 by a vertical partition wall 10 that partitions the front wall 2 and the rear wall 4 thereof. The front wall 2, the partition wall 10, and the rear wall 4 have a large number of slits 13, 1 through which seawater passes.
4 and 15 are formed horizontally.
Further, a large number of slits 17 are formed in the transparent horizontal plate 7 to eject the seawater in the water retarding chambers 11 and 12 as vertical jets 16. In this case, the aperture ratio ε ₁ of the front wall 2, the partition wall 10, and the rear wall 4 (ratio of slits to the plate area) and the aperture ratio ε ₂ of the transparent horizontal plate 7 are different as ε ₁ > ε ₂ . ing.

The wave-dissipating effect of such structures can be determined from the results of underwater model experiments: (a) The water depth at the top of the vertical walls 2, 10, 4 is near the still water surface (b) The submergence depth d of the transparent horizontal plate 7 ( The ratio d/h of the submersion depth from the still water surface to the water depth h is between 0.1 and 0.2 (c) The aperture ratio ε ₁ and ε ₂ are respectively ε ₁ = 25 to 30%, ε ₂ =
15 to 18% (d) The ratio B/L of the structure body width B to the wavelength L is 0.1
It becomes noticeable when it is between ~0.2.

Figure 5 shows the results of the underwater model experiment. The horizontal axis of the figure is made dimensionless by the ratio B/L of the structure body width B and the wavelength L, and the vertical axis is Kt, which is the wave height transmissibility (ratio of the wave height of the transmitted wave 19 to the wave height of the incident wave 18), and Kr, which is the ratio of the wave height of the transmitted wave 19 to the wave height of the incident wave 18. Reflectance (ratio of the wave height of the reflected wave to the wave height of the incident wave 18),
K ² _L is the energy loss rate. The triangle mark in the diagram,
The circles and squares are the transmittance, reflectance and energy loss rate, respectively, and the white and black marks are ε ₁ = 30%, ε ₂ = 18% and ε ₁ = 26%, ε _{2 respectively.}
= 18%.

From this result, the transmittance Kt is less than 0.6 and the reflectance Kr
is less than 0.3, and the energy loss rate K ² _L is more than 0.5.
It can be seen that the wave dissipation effect is high.

The resistance to sliding and overturning of this structure due to wave forces can be achieved by providing a filling sand storage chamber 18 under the structure body 8 as shown in FIG. 6, or by constructing a structure as shown in FIG. It can be activated by fixing the object body 8 below the seabed surface 9 with stakes 19.

If the scour is significant, the structure body 8 may be raised using stakes 19 as shown in FIG.

(Effects of the Invention) The present invention has the following effects by having the above configuration.

By setting the height of the transparent horizontal plate to a height below the sea surface where the ratio of the submerged depth from the still water surface to the water depth is 0.1 to 0.2, when waves pass over the main body of the wave-dissipating underwater structure, , the flow velocity near the transparent horizontal plate is slowed down due to the roughness of the transparent horizontal plate, while the wave ridge tries to pass at the wave speed, so the relative speed difference becomes large and wave breaking occurs, resulting in energy It is possible to increase the dissipation effect of waves and ensure wave dissipation.

The height of the tops of the front wall, partition wall, and rear wall was set close to the still water surface so that the waves would overflow from the top.Since the wave power of the waves does not act above the water surface, the wave power is The structure can be reduced by about 40%.

The front wall, partition wall, and rear wall have slits with an aperture ratio of 25 to 30% that allow seawater to pass through, and the transparent horizontal plate has many slits with an aperture ratio of 15 to 18% that are smaller than the above slits to prevent water from flowing. A part of the incident wave that enters the room flows vertically from the slit in the transparent horizontal plate, collides with the incident wave passing above the transparent horizontal plate, and forcibly breaks and disturbs the incident wave, resulting in wave energy. can be dissipated more efficiently.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional explanatory view of an embodiment of the structure according to the present invention in use, FIGS. 2 to 4 are perspective views, front views, and plan views of the structure shown in FIG. 1, and FIG. 6 to 8 are measurement data distribution diagrams of wave height transmittance, reflectance, and energy loss rate with respect to the ratio of body width and wavelength in the underwater model experiment of the structure of this example.
The figure is a vertical sectional view showing three other embodiments of the present invention. 1... Bottom wall, 2... Front wall, 4... Rear wall, 6... Sea surface, 7... Transparent horizontal plate, 8... Wave-dissipating underwater structure body,
10... Partition wall, 11, 12... Water retarding room, 13-15
...Slit, 16...Vertical jet, 17...Slit.

Claims (1)

[Claims] 1 The ratio of the submersion depth from the still water surface to the water depth of the bottom wall, the four vertical walls surrounding the bottom wall, and the water depth is 0.1.
The main body of the wave-dissipating underwater structure is equipped with a box-shaped wave-dissipating underwater structure that is installed in the sea and has a transparent horizontal plate with a height of ~0.2 below the sea surface. The front wall, the partition wall, and the rear wall are partitioned into a plurality of water retarding chambers by a vertical partition wall, and the top heights of the front wall, the partition wall, and the rear wall are near the still water surface, and the front wall, the partition wall, and the rear wall are separated from each other. A large number of slits with an aperture ratio of 25 to 30% are formed on each side wall to allow seawater to pass through.
The sea area control structure with a transparent horizontal plate is characterized in that the transparent horizontal plate has a large number of slits with an opening ratio of 15 to 18% that eject the seawater in the water retarding chamber as a vertical jet.