JPH0619125B2 - Submersible wave-dissipating structure - Google Patents

Description

TECHNICAL FIELD The present invention relates to a submerged wave-dissipating structure for controlling the propagation of waves near the coast and the movement of sand such as the sea floor.

“Conventional technology” Conventionally, as submerged wave-dissipating structures (submerged dikes) that control waves and sand near the coast, there are methods that use caisson construction or methods that pile up wave-dissipating blocks in the sea. It is common.

"Problems to be solved by the invention" However, the so-called rigid structure submerged dike constructed with caisson or wave-dissipating block in this way breaks the wave on this crown and is disturbed by this break. By continuing on a wide zenith, the wave energy is lost and the wave is extinguished. Therefore, in order to obtain a sufficient wave-dissipating effect with such a submerged dike, it is necessary to raise the crown of the submerged dike to near the water surface and to make the crown width extremely large.
There was a problem that the size of the submerged dike became very large and unreasonable and hindered the navigation of ships.

In addition, caisson to be a submerged embankment and a large amount of wave-dissipating blocks must be transported to the site, and in addition, foundation construction such as seabed leveling and mound at the construction site is required, and if the water depth is deep, Since the amount of materials used, etc. will increase significantly, the construction period will be prolonged and the cost will be high.Moreover, there will be a lot of running cost since continuous repairs against scouring and subsidence are required after construction. was there.

Furthermore, if it is necessary to move or remove the submerged dike when it does not have the effect of sedimentation or is deteriorated after the submerged dike installation, the work will take a very long time and cost. There were also problems.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a submerged wave-dissipating structure having an excellent wave-dissipating effect and being easily installed.

"Means for solving problems" Therefore, in the present invention, a bag body made of a sheet-shaped flexible material installed on the seabed ground, a fluid injected into the bag body to inflate it, and the bag The anchor tube is provided along the bottom edge of the body and is filled with a filler such as earth and sand, and the anchor tube is embedded in the seabed, and the top end of the bag body is further provided. The above problem is solved by constructing a submerged wave-dissipating structure in which the ratio of the water depth to the water depth at the installation location is set to 0.4 or more.

[Operation] According to the present invention, when an incident wave arrives at the submerged wave-dissipating structure, the energy of the incident wave is transmitted to the submerged wave-dissipating structure, and the submerged wave-dissipating structure is As a result of the deformation, a radiation wave is radiated from the submerged wave-dissipating structure, and the wave is extinguished by the interference between the radiation wave and the incident wave. at the same time,
The incident wave is also extinguished by consuming the energy of the incident wave in deforming the submersible wave-dissipating structure.

[Examples] Examples of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing a submerged wave-dissipating structure according to an embodiment of the present invention. In the figure, reference numeral 1 is a flexible submerged dike (submersible wave-dissipating structure) installed on a sandy seabed G. This flexible submerged dike 1 is the outer shell of the flexible submarine 1. The bag 2 to be made,
It is roughly composed of seawater (fluid) 3 which is injected into the bag body 2 to inflate them.

The bag body 2 is made of a sheet-shaped flexible material such as a rubber sheet or a vinyl chloride sheet, and has a flat top plate 4 having a convex shape and a curved upper surface, and a bottom plate 5 in contact with the seabed G. These edge portions are welded and integrally joined. Inside the bag body 2, as described above, the seawater 3
Is injected and sand (filler) 6 is filled at the bottom. A filling valve 7 for injecting and filling seawater 3 and sand 6 therein and a discharge valve 8 for discharging the excess seawater 3 injected inside are provided below the top plate 4, respectively. There is. As the bottom plate 5 of the bag body 2, it is preferable to use a highly flexible sheet that can follow the unevenness of the seabed particularly better than the top plate 4 and the like.
Further, the flexible material forming the bag body 2 is not limited to the rubber and vinyl chloride described above, and may be a synthetic resin such as polyethylene or a rubberized cloth. Furthermore, bag 2
Examples of the shape include, but are not limited to, a circular shape in plan view, an elliptical shape, an oval shape, and the like. However, when the bag body 2 has a longitudinal direction such as an elliptical shape or an oval shape, it is preferable that the longitudinal direction be substantially orthogonal to the traveling direction of the incident wave W that has arrived along the sea surface S.

In addition, hollow anchor tubes 10 and 10 are attached along the bottom edge of the bag body 2, that is, at the peripheral edge of the joint between the top plate 4 and the bottom plate 5, along the same. The anchor tube 10 is made of the same flexible material as the bag body 2, and has the same sand (filler) as the earth and sand of the seabed G therein.
It is buried in the seabed ground G outside the bottom edge of the bag body 2 in a state in which 11 and 11 are filled. This anchor tube 1
No. 0 is provided with an injection valve 12 for injecting and filling the sand 11 and an exhaust valve (not shown) for exhausting excess fluid such as seawater. The anchor tube 10 need not be provided so as to continuously surround the entire bottom edge portion of the bag body 2, but may be provided at appropriate intervals. Similarly, the anchor tube 10 may be integrally manufactured with the bag body 2, or may be separately manufactured and connected by a connecting means such as a bolt or a nut.

Next, the wave-dissipating principle of the submersible wave-dissipating structure made of a flexible material according to the present invention will be described.

As shown in FIG. 2, a flexible structure submerged FM in which a fluid such as seawater is injected into a bag made of a flexible material is a seabed G.
Suppose it is installed above. At this time, flexible structure dike F
When the incident wave W arrives along the sea surface S toward M,
The energy of this incident wave W is transmitted to the flexible structure submerged FM, and the flexible structure submerged FM is deformed as shown by the dotted line in FIG. Then, as the flexible structure submerged FM is deformed, a radiated wave R is emitted from the flexible structure submerged FM itself toward the sea surface S as indicated by an arrow A in the figure, and the radiated wave R and the incident wave W are separated from each other. The wave is extinguished by the interference. At the same time, the energy of the incident wave W is consumed to deform the flexible structure submerged FM, and the energy of the incident wave W is attenuated, so that the incident wave W is extinguished.

Therefore, the flexible structure submerged FM made of a flexible material breaks the incident wave at the top of the submerged dike like the conventional rigid structure submerged dike as described above, and causes the disturbance due to the breaking wave in the width direction of the submerged dike. Since it is not necessary to perform wave-dissipation by continuing over the entire length, it is possible to deepen the water depth at the top of the flexible structure FM dike, and to make the dike width direction small. Become. This will be clarified by the experimental results shown below.

FIG. 3 shows the relative bank width ratio D / L of the flexible structure submerged dike (D: width of the flexible structure submerged dike, L: wavelength of the incident wave) and the transmittance Kt of the incident wave.
It is a figure which shows the result of having calculated | required the relationship with (namely, the wave-dissipating effect of the flexible structure submerged bank) about the conventional rigid structure submerged bank and the flexible structure submerged bank FM which consists of a flexible material. At this time, the submergence rate R / h of each flexible structure dike (R: top end water depth of flexible structure dike, h: water depth of sea area where flexible structure submerged was installed) is /H=0.18, flexible structure submersible made of flexible material is R
/H=0.5. It can be understood that the flexible structure FM made of a flexible material has an excellent wave-dissipating effect even if the submerged rate R / h is large and the relative bank width ratio D / L is small.

FIG. 4 is a diagram showing a change in the wave-dissipating effect when the submersion rate R / h of the flexible structure submerged bank FM made of a flexible material is changed. It is understood that even if the submersion rate R / h is increased, the wave-dissipating effect by the flexible structure FM is not attenuated, but rather the wave-dissipating effect is increased within a certain relative bank width ratio D / L. it can. According to the results of experiments conducted by the present inventors, the submersion rate R / h of the flexible structure submersible FM made of a flexible material is R / h ≧ R / h ≧ in consideration of conditions such as not hindering the navigation of a ship. It is preferably 0.4. In the conventional rigid structure submerged dike, it has been found from the experimental result that the transmittance Kt≈1.0, that is, the wave-dissipating effect is hardly obtained when the submersion rate R / h ≧ 0.5.

Fig. 5 shows the incident wave height Hi = 2 in the sea area with water depth h = 20m.
The cross-section of a conventional rigid structure submerged dike M, which can reduce the transmitted wave height Ht of a wave having an incident wavelength L of 100 m, to 1 m or less, and a flexible submerged dike FM made of a flexible material. As is clear from this figure, the cross-sectional area required to obtain the same wave-dissipating performance is 1 for the flexible structure submerged FM made of flexible material.
It can be understood that it can be as small as / 8 or less.

As explained below, the flexible structure submerged dike 1 according to the present invention is
Since the bag body 2 made of a sheet-shaped flexible material is installed on the seabed, and the seawater 3 is poured into the inside of the bag body 2 to inflate it, seawater is stored at a predetermined installation place. By injecting into the bag body 2 or the like, the work of transporting, installing, moving, removing, etc. becomes much more efficient than the conventional rigid structure submerged dike. Further, the flexible structure submerged dike 1 obtains a wave-dissipating effect by utilizing its own flexibility, and is smaller in scale than the conventional disintegration due to the wave breaking like a rigid structure dike. Even if there is, its wave-dissipating effect is great,
Therefore, it is possible to control the waves even when the top of the flexible structure submerged submergence is sufficiently submerged. For this reason, by installing the flexible structure submerged dike 1 in the sea, the installed sea area can be effectively used.

Further, the flexible tube 1 is attached with anchor tubes 10 and 10 along the bottom edge of the bag body 2, and the anchor tubes 10 and 10 are attached to the seabed G.
It is buried inside. Therefore, this anchor tube 1
0 and 10 not only fix and fix the entire flexible structure submerged dike 1 to the seabed G, but also the place where scour is most likely to occur even when installed, that is, the ground G at the bottom edge of the bag 2. Protect. As a result, scouring around the flexible structure submerged dike 1 is prevented, which simplifies management and repair work after installation and reduces maintenance costs.

In addition, this flexible structure submerged dike 1 includes anchor tubes 10 and 10
Since it is fixed to the seabed G by means of it, the installation work is much simpler and quicker than the flexible structure submerged dike which is fixed and fixed by an ordinary anchor as mentioned above.
The cost can be reduced.

Due to the existence of the anchor tubes 10 and 10, the ground G ′ surrounded by the anchor tubes 10 and 10,
That is, the ground G'of the portion where the bottom plate 5 of the flexible structure submersible 1 contacts
Since the ground and the other part of the ground G are cut off, the lift force acting on the bottom plate 5 of the flexible structure submerged dike 1 is reduced as the wave passes, so that the flexible structure submerged dike 1 is used as a small anchor. Can be fixed.

The details of the submersible wave-dissipating structure of the present invention are not limited to those in the above-described embodiment, and various modifications are possible. As an example, the flexible structure submerged bank 1 is not limited to the configuration of only one bag body 2, and may be a configuration in which a large number of bag bodies are arranged in series. Further, the fluid filled and filled in the bag body 2 may be a fluid other than seawater 3 such as air. Similarly, the filling material filled in the bottom portion of the bag body 2 is not only sand 6 but also specific gravity more than seawater 3 such as sand muddy water. However, the filler may be omitted. Further, if the anchor tube 10 is made of a water-permeable material such as so-called geotextile, the discharge valve described above can be omitted.

[Advantages of the Invention] As described in detail above, according to the present invention, a bag body made of a sheet-like flexible material installed on the seabed ground and the bag body is inflated by being injected into the bag body. Since the submersible wave-dissipating structure is composed of the fluid and the fluid, the fluid can be injected into the bag only at the time of installation, which makes the installation work very efficient. In addition, since the submersion type wave-dissipating structure utilizes the flexibility of itself to obtain the wave-dissipating effect, the wave-dissipating effect is large even on a small scale. Waves can be controlled even when the edges are fully submerged. Therefore, the sea area where the submerged wave-dissipating structure is installed can be effectively used.

In addition, along the bottom edge of the bag installed on the seabed,
An anchor tube filled with a filler such as earth and sand is disposed inside and the anchor tube is embedded in the seabed ground, so that the anchor tube fixes the entire submerged wave-dissipating structure to the seabed ground. At the same time, the ground at the bottom edge of the bag body is protected. This prevents scouring around the submerged wave-dissipating structure, which simplifies post-installation management and repair work and reduces maintenance costs. At the same time, the installation work becomes much easier and quicker than the fixing by an anchor or the like, and the cost can be reduced.

Also, because the ratio of the water depth at the top of the bag to the water depth at the installation location is set to 0.4 or more, the relative bank width ratio (the width of the bag and the wavelength of the incident wave is The good wave-dissipating efficiency can be obtained despite the small value (ratio to ratio), and it is better to use a small bag than a large bag to compare which aspects of manufacturing, installation, transportation, etc. However, since it is obvious that the cost can be kept low, there is an excellent effect that a good wave-dissipating efficiency can be obtained while keeping the cost low.

[Brief description of drawings]

FIG. 1 is a sectional view showing a submerged wave-dissipating structure which is an embodiment of the present invention, and FIGS. 2 to 5 are views for explaining the principle of the submersible wave-dissipating structure. . G: submarine ground, 1 ... flexible structure dike, 2 ... bag, 3 ...
… Seawater (fluid), 10 …… Anchor tube, 11 ……
Sand (filler).

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Seiji Ichii 2-16-1 Kyobashi, Chuo-ku, Tokyo Shimizu Construction Co., Ltd. (72) Inventor Yutaka Katsura 2-16-1 Kyobashi, Chuo-ku, Tokyo No. Shimizu Construction Co., Ltd. (72) Inventor Tadashi Ono 2-161-1 Kyobashi, Chuo-ku, Tokyo Shimizu Construction Co., Ltd. (72) Inventor Katsumi Shimizu 2-16-1 Kyobashi, Chuo-ku, Tokyo Shimizu Corporation (56) References JP-A-62-141209 (JP, A) JP-A-59-8831 (JP, A)

Claims (1)

[Claims] 1. A bag body made of a sheet-shaped flexible material installed on the seabed, a fluid injected into the bag body and inflating the bag body, and disposed along the bottom edge of the bag body. With an anchor tube filled with a filler such as earth and sand inside, the anchor tube is embedded in the seabed ground, further, the water depth of the top of the bag and the water depth of its installation location A submerged wave-dissipating structure characterized in that the ratio is set to 0.4 or more.