JPH0733649B2 - Bottomless type wave-dissipating structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention can be installed offshore such as a coast to perform wave-dissipation, and at the same time, can effectively control the sea area behind by a seawater exchange function. It relates to a bottom slab type wave-dissipating structure.

[Prior art and problems to be solved]

Conventionally, there are many places where erosion occurs due to waves on the open ocean coast, and as a erosion prevention measure, for example, a rubble mound 1 is formed in the sea near the coastline in parallel with the shoreline, and this rubble mound is formed. Widely adopted are breakwaters constructed by combining a large number of wave-dissipating blocks 3 on one (see Fig. 4).

On the other hand, in order to deal with the increasing desire for coastal recreation in recent years, it is possible to secure a quiet backwater area that can be easily constructed even if it faces the open sea with a considerable depth of water and severe waves, Furthermore, it is desired that the structure is one that can appropriately preserve water quality and ecology.

However, if the above-mentioned breakwater is installed in deep water and in a large wave area, there are the following problems.

The shape of the breakwater is a trapezoidal cross section with a certain slope (1: 1 to 1: 2) in order to ensure the stability of the wave-dissipating block 3 itself, and from the sea surface to the top. The height of the is usually approximately constant with respect to the incident wave height H (0.5H to 0.6H)
As the water depth increases, the seams will be separated from the embankment center and become a large cross section. On the other hand, effective wave-dissipation takes place near the sea surface, where the energy of the incident wave is the largest, so the deeper the water becomes, the more uneconomical it becomes (see Fig. 4).

In general, when the depth of water becomes large, the incident wave also becomes large, so a large-weight wave-dissipating block is used to counter it, but the larger the block, the more difficult the installation work becomes and the greater the possibility of damage to the block.

If the waves are severe enough to exceed the top, maintenance will be required because the wave-dissipating block on the inside shoulder of the dam will become unstable and scattered.

Under such circumstances, as shown in FIG. 5, a caisson 7 made of concrete or the like is installed on the rubble mound 1 to propose it. This caisson 7 has an economical cross-sectional shape and facilitates installation work, etc. However, when a wave pressure such as a powerful breaking wave acts on the front side, a large lifting pressure corresponding to it also acts on the bottom side, and this caisson 7 Since the friction coefficient between the bottom surface and the rubble mound 1 is smaller than the friction coefficient between the rubble stones, the stability becomes low. Therefore, it has been devised that a slit is formed on the front surface of the caisson 7 and a cavity (water-retaining portion) is provided inside to reduce the hydraulic pressure acting on the front surface, but the lifting pressure does not decrease so much, and moreover, from the front slit. The wave that penetrates into the cavity is reflected on the back surface, causing phase interference of the wave, and this phase interference varies depending on the ratio of the wavelength of the incident wave to the caisson cavity width, so it is appropriate considering the irregularity of the wave at the installation site. There was a problem that it was difficult to determine the appropriate width dimension.

[Means for solving problems]

In view of this, in the present invention, a cellular box having a large number of slits provided on the opposing side walls and an open top and bottom is prepared, and the cellular box is installed on a submerged foundation mound to dissipate the wave therein. Stabilizing the wave-dissipating structure and wave-dissipating by adopting a structure in which the blocks are packed and the wave permeability is maintained, and these wave-dissipating blocks are grounded to the foundation mound through the open bottom. It is intended to expand the effect area.

Further, in this case, if a plurality of chambers are provided inside the cellular box and a large number of slits are also provided in the partition walls that partition these chambers, the durability of the wave-dissipating structure and the wave-dissipating performance can be further improved. This is preferable because it is possible.

[Action]

In the bottomless plate type wave-dissipating structure according to the present invention, since the bottom and top of the originally non-permeable cellular box are opened and a large number of slits are provided in the opposite side walls for the passage of waves, the entire structure is provided. The maximum simultaneous external force acting on is reduced, and since the wave-dissipating block is directly grounded to the foundation mound, the friction coefficient with the mound is increased and the stability is improved. .

〔Example〕

Next, preferred embodiments of the bottomless wave-dissipating structure according to the present invention will be described in detail below with reference to the accompanying drawings.

1 to 3, a bottomless plate type wave-dissipating structure 10 according to the present invention has a rectangular parallelepiped cellular box 14 in which a large number of chambers 12 are formed by using concrete or the like as a material and a bottom 16 and a top are opened. And a plurality of horizontally extending slits 22 are provided in each side wall portion 18 and partition wall 20 of the cellular box 14, and the cellular box 14 is formed on the rubble mound A previously formed in water. It is configured by installing a large number of wave-dissipating blocks 24 inside each room 12 while maintaining the transparency of the incoming waves, and further grounding these wave-dissipating blocks 24 directly to the rubble mound A. ing.

The bottomless plate type wave-dissipating structure according to the present invention having such a configuration
Since 10 has a rectangular cross-sectional shape, the deeper the water depth is, the more economical it becomes (see Fig. 2). Also, since the wave-dissipating block 24 is packed inside the cellular box 14, a small-weight block may be used for installation work and maintenance. Not only is it simpler, but unlike the case where rubble stones are filled, suitable permeability can be easily maintained.

On the other hand, the wave acting on the cellular box 14 is the wave entering inside through each slit 22 together with the wave extinguishing due to the reflection on the front surface of the wave breaking block 24 that has passed through the slit 22 of the partition wall 20 or is packed inside. Since the energy is lost due to the disturbance of the water particles before passing through the gap, not only the wave is preferably canceled but also the disadvantage caused by the phase interference of the waves can be avoided.

Further, since a part of the horizontal wave force acting on the cellular box 14 passes through the slit 22, the wave force acting on the front surface is small as compared with FIG. 5, and the bottom 16 is open, so that the cellular box body is open. The lift force acting on 14 is also small, and since this lift force does not act simultaneously with the horizontal wave force, the maximum simultaneous external force acting on the entire structure 10 becomes small, and further, the wave-dissipating block 24 in the cellular box 14 is placed in the mound A. Since the ground contact is made in the state of biting, the sliding resistance of the entire structure also increases, and thus the stability against waves is improved (see FIG. 3).

In the present embodiment, the top of the cellular box 14 is set on the still water surface, but if it is necessary to keep a view of the sea area behind the structure, or if a habitat for aquatic products is required, this It can also be configured as a so-called submerged type in which the crown is set below the level of still water. Note that the wave-dissipating action in this case is performed by the loss of wave energy due to the disturbance of water particles when passing through the gap of the wave-dissipating block through the slit and the wave breaking on the top of the structure.

Further, the slits 22 extend in the horizontal direction of the side wall portions 18 and the partition walls 20 of the cellular box 14, but it goes without saying that they may extend in the vertical direction.

〔The invention's effect〕

As described above, since the bottomless plate type wave-dissipating structure according to the present invention uses the cellular box whose bottom and top are open, the lift is small, and the wave-dissipating block is used as the basic mound. Since it was grounded directly to improve stability,
It can be easily constructed even if it faces the open sea where the water depth is considerably large and the waves are severe, and since the wave-dissipating performance is high, a quiet backwater area can be secured.

In addition, the partition wall slits that partition the side wall and the chamber of the cellular box with the bottom and top open are formed, and the wave-dissipating block is filled inside to maintain the permeability, which is excellent in the function of exchanging seawater. Not only can water quality and ecology be favorably conserved, inconveniences due to wave phase interference can be avoided as much as possible, and durability can be improved, and other advantages are provided.

The preferred embodiment of the bottomless wave-dissipating structure according to the present invention has been described above. However, the present invention is not limited to this embodiment, and various designs can be made within the scope not departing from the spirit of the present invention. Of course, changes can be made.

[Brief description of drawings]

1 is a partial cross-sectional explanatory view showing a preferred embodiment of a bottomless plate type wave-dissipating structure according to the present invention, and FIG. 2 is a cross-section taken along line II-II of the bottomless plate-type wave-dissipating structure shown in FIG. FIG. 3 is an explanatory view showing the relationship between the wave pressure acting on the bottomless plate type wave-dissipating structure shown in FIG. 1 and the lifting pressure, and FIG. 4 is a cross-sectional explanatory view showing the conventional wave-dissipating structure. FIG. 5 is a cross-sectional explanatory view showing the same relationship as FIG. 3 of another conventional wave-dissipating structure. 10 …… Bottomless type wave-dissipating structure, 12 …… Chamber, 14 …… Cellular box, 18 …… Side wall, 20 …… Partition, 22 …… Slit, 24
…… Disappearing block.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yuji Noguchi 28-37 Izumi, Abiko City, Chiba Prefecture 72-37 Inventor, Yamamoto Man 667-30, Jinmachi, Tsuchiura City, Ibaraki Prefecture (72) Kei Kei Watanuki, Tsuchiura City, Ibaraki Prefecture Wakamatsucho 4002-22 (72) Inventor Kazukiro Nishikori 5-22-15 Shirayama, Toride-shi, Ibaraki (72) Inventor Ichiro Nishiwaki 2-11-9 Koteshi-cho, Tokorozawa, Saitama Prefecture (56) References JP 64 -75706 (JP, A) JP-B 47-48735 (JP, B1)

Claims (2)

[Claims] 1. A cellular box which is provided with a large number of slits on opposite side walls and whose top and bottom are open. This cellular box is installed on a submerged foundation mound, and a wave-dissipating block is provided therein. A bottomless plate type wave-dissipating structure characterized by being padded and maintaining wave permeability and further grounding these wave-dissipating blocks to the foundation mound through the open bottom. 2. The bottomless plate type wave-dissipating structure according to claim 1, wherein a plurality of chambers are provided inside the cellular box, and a large number of slits are also provided in partition walls that partition these chambers.