JPH0730535B2 - Artificial reef and its installation method - Google Patents

Description

The present invention relates to an artificial reef that controls the propagation of waves near the coast and the movement of sand such as the sea floor.

[Conventional technology and its problems]

Conventionally, as a breakwater for controlling waves and sand near the coast, a method of stacking wave-dissipating blocks in the sea is generally used.

By the way, when the above method is used, the construction period is long and the construction cost is high due to the transportation of a large amount of blocks to the site and the foundation construction of the seabed at the construction site. Especially when the water depth is deep, the materials used and the like increase and the cost increases. In addition, it requires a lot of running costs because it requires continuous repairs against scouring and subsidence even after construction. In addition, it takes a lot of cost and time to move and remove the levee body when there is no sedimentation effect or when it deteriorates.

Also, because blocks are piled up, the surface of the breakwater is
It is not possible to use the breakwater itself as a space because it is dangerous because there are numerous irregularities and gaps. On the other hand, the area near the breakwater is also not able to be effectively used as a sea area for marine sports and recreation because the flow is fast and there is a danger of waves breaking and launching into blocks.

For this reason, there has been a long-felt need for artificial reefs such as breakwaters and submerged dikes that solve the above problems.

The present invention has been made to meet the above demand.

[Means for solving problems]

The artificial reef according to the present invention has a structure in which a bag made of a flexible film is fixed to the seabed by a fixing jig while being filled with a fluid such as seawater.

〔Example〕

An embodiment of the artificial reef A and its mounting construction method according to the present invention will be described below with reference to FIGS. 1 to 8.

Reference numeral 1 in the figure is a bag. The bag body 1 is made of a flexible film material such as a vinyl chloride sheet, has an upper surface that is a convex curved surface having a substantially arcuate shape, and its height is smaller than the dimension in the diameter direction when viewed in plan. Flat convex curved head 2
And the bottom wall 3. A collar 4 is provided on the outer periphery of the bottom wall 3.
The flange 4 is provided with a bolt insertion hole 5 for inserting a bolt. The height of the convex curved bag 1 is formed to be substantially the same as the water depth.

Further, the fixing jig 7 for attaching the bag body 1 and fixing it to the sea bottom 6 is formed in a ring shape by assembling the jig unit 7a made of steel or synthetic resin (FIG. 3). The outer circumference and the width thereof are substantially the same as those of the collar portion 4 of the bag body 1. Further, the fixing jig 7 is provided with a plurality of bolt holes 9 through which the anchor bolts 8 are inserted.

Next, a construction method for attaching the bag 1 to the sea bottom 6 will be described.

First, the fixing jig 7 is fixed to the sea bottom surface 6 by a plurality of anchor bolts 8 inserted into the bolt insertion holes 9 (fifth aspect).
Figure). In this case, the anchor bolt 8 is selected such that the length, the shape and the number of embedded portions of the anchor bolt 8 can surely fix the artificial reef A according to the magnitude of the external force acting on the seabed, waves, or tidal current at the construction site of the artificial reef. There is a need.

Next, the bag body 1 is spread on the fixing jig 7, and the fixing jig 7
The bolt 10 provided on the flange is inserted into the bolt insertion hole 5 of the collar 4 and fixed with a nut (Fig. 6).

Next, seawater 13 is press-fitted into the bag body 1 fixed to the fixing jig 7 through the water injection port 11 provided in the bag body 1 so that internal pressure is applied to the bag body 1 by the seawater 13. Keep (7th
Figure).

By the construction method as described above, a plurality of artificial reefs A are constructed at a constant distance from the shoreline 12 and substantially parallel to the shoreline 12 (eighth embodiment).
Figure).

According to the artificial reef A constructed in this way, when a wave is incident on the artificial reef A, the flexible bag body 1 filled with seawater 13 inside is deformed without changing its volume. As a result, a wave called a radiation wave is generated around the bag body 1 by this movement.
By interfering with this wave and the scattered wave (transmitted wave and reflected wave) generated by the incident wave, the wave transmitted around the artificial reef A is extinguished.

At this time, the bag 1 is filled with seawater 13,
For example, the mass of the bag body 1 as a whole (bag body 1 + seawater 13) is significantly increased (about 1000 times) as compared with the case of filling the bag body 1 with a gas such as air. As a result, as described above, in the artificial reef A that is designed to perform the wave-dissipating action by the movement of the bag body 1, the force acting on the surrounding seawater by the movement of the bag body 1 (“action force” = “mass”). ”ד acceleration ”) is overwhelmingly large, and it is possible to easily and efficiently generate a radiation wave along with the movement of the bag body. This makes it possible to eliminate the artificial reef using the interference effect of this wave. The wave efficiency can be increased.

Further, when the bag body 1 is filled with air, a large buoyancy (upward force) acts on the bag body 1 when the bag body 1 is installed on the sea bottom 6, and it is difficult for the bag body 1 to move horizontally when a wave is incident. There is a problem. This problem becomes more remarkable as the internal pressure increases. On the contrary, when the internal pressure becomes low, the gas is compressed by the wave force and the volume of the bag body 1 is reduced, so that the function of generating the radiation wave becomes low.

On the other hand, according to the artificial reef and the method of mounting the artificial reef of the above-described embodiment, since the bag body 1 is press-filled with the seawater 13 and the internal pressure is applied, the seawater 13 in the bag body 1 is compressed by the surrounding water pressure. It will not be done. Therefore, compared with the case where the bag body 1 is filled with air, as well as when the bag body 1 is simply filled without press-fitting, the responsiveness to the incident wave is excellent and the radiation wave is efficiently generated. Thus, the waves passing around the artificial reef A can be canceled. Since the bag body 1 is made of a flexible film, it can be easily transported in a folded state, and the transportation cost is low. Further, also in the case of mounting and fixing, it is sufficient to fix the fixing jig 7 with the anchor bolts 8 without particularly performing the basic construction such as earthmoving and mound construction, and the bag body 1 may be filled with seawater. Therefore, the construction period is extremely short, the material cost is low, and the material used is only slightly increased even in the deep water, so the cost is remarkably reduced.

In addition, the shape is a flat convex curved surface whose upper surface is a convex curved surface with a substantially arcuate shape in side view and whose height is smaller than the radial dimension when viewed in plan. No need for continuous repairs.

Further, since the bag body 1 is formed of a flexible film and has a smooth curved body, there is no danger in the vicinity of the artificial reef and it can be widely used for marine leisure and the like, so that the sea floor can be effectively used.

Also, when moving the artificial reef, it can be easily moved and removed by discharging the seawater 13 and removing the fixing device such as anchor bolts, and injecting air into the bag 1 to move it floating. It is also convenient.

The material of the bag body 1 is not limited to vinyl chloride, but may be synthetic resin such as polyethylene or rubberized cloth.

Further, the bag body may be fixed to the seabed 6 directly by the anchor bolt 8 from the collar portion 4 of the reinforced bag body without using the ring-shaped fixing jig 7.

Further, the shape of the bag body 1 is not limited to a circular shape in plan view, and may be an elliptical shape (B) or an oval shape (C) in plan view as shown in FIGS. 9 and 10, respectively. Good. In addition, a spherical bag is used without providing the bottom wall 3, and when the fixing jig 7 is attached, the upper side is the seawater filling portion, and the other portions are folded in the ring of the fixing jig 7. It may be in a closed state.

Further, as the fluid, not only seawater but also one having a larger specific gravity than seawater such as sand and mud can be mixed or filled to increase the stability of the artificial reef.

Also, the height, width, shape, interval, etc. of the artificial reef from the sea bottom can be set in accordance with the purpose such as control of waves and drift sand in consideration of the wave wavelength and tidal current of the construction site. .

〔The invention's effect〕

As described above, the artificial reef according to the present invention has a structure in which the liquid body such as seawater is filled in the bag body.
As a result, when a wave is incident on the artificial reef, the flexible bag body is filled with fluid inside and deforms without changing its volume, and this movement causes the bag body to move. Radiation waves can be generated in the vicinity to cancel the waves.

At this time, for example, compared with the case of filling the bag body with gas such as air, the mass of the entire bag body is remarkably large, and the force acting on the surrounding seawater due to the movement of the bag body becomes overwhelmingly large. Since its movement is not hindered by buoyancy, it is possible to easily and efficiently generate a radiation wave and enhance the wave-elimination efficiency of the artificial reef.

Further, since fluid such as seawater is press-fitted and filled into the bag to apply an internal pressure, the fluid in the bag is not compressed by the surrounding water pressure. Therefore, compared with not only filling the bag with air but also simply filling it without pressurizing the fluid, the response to the incident wave is excellent and the radiation wave is generated efficiently. You can break the wave.

In addition, the shape of this artificial reef is a flat convex curved surface whose upper surface is a convex curved surface having an arc shape or an elliptic arc shape in a side view, and whose height is smaller than the radial dimension when viewed in plan. Since there is no scouring, there is little need for continuous repairs.

Furthermore, since this artificial reef is made of a flexible membrane bag, it uses few materials and is easy to transport. Moreover, its construction does not require foundation work such as earthmoving and mound, and the bag body Since it only has to be connected to the fixing jig, the construction period is short and the cost is extremely low.

Further, since the bag body does not have a hard uneven surface like a concrete block, it is safe to hit the body and the sea area can be widely used for marine sports, recreation and the like.

In addition, the bag can be easily formed in various shapes and sizes, and because the installation and fixing construction method is simple, there is no restriction on the construction space, topography, etc., so it can be easily constructed anywhere. It is possible to obtain the effect that the effective use of the sea area can be measured.

In addition, even if it is necessary to move or remove the artificial reef due to a change in the use of the sea area, the artificial reef can be easily moved and removed at a low cost in a short period of time.

[Brief description of drawings]

1 to 8 show an embodiment of the artificial reef A according to the present invention. FIG. 1 is a plan view of the bag 1, and FIG.
Sectional view taken along line II-II of the figure, FIG. 3 is a plan view of a fixing jig, FIG. 4 is sectional view taken along line IV-IV of FIG. 3, and FIGS. 5 to 7 are artificial reefs. Fig. 5 shows the mounting sequence of A, Fig. 5 is a side sectional view showing a state in which a fixing jig is fixed to the sea bottom, and Fig. 6 shows a state in which a bag is attached and fixed to this fixing jig. A side sectional view, FIG. 7 is a side sectional view showing a state in which seawater is injected and filled in the bag body, and FIG. 8 is an artificial reef A on the shoreline 12.
And FIG. 9 and FIG. 10 are plan views showing a modified example of the above-mentioned embodiment, which are parallel to each other. A, B, C ... Artificial reef, 1 ... Bag, 7 ... Fixing jig.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Akihiko Hirayama 2-16-1, Kyobashi, Chuo-ku, Tokyo Shimizu Construction Co., Ltd. (72) Inventor Satoshi Kiyokawa 2-16-1, Kyobashi, Chuo-ku, Tokyo Shimizu Construction company (56) References JP-A-58-69909 (JP, A) JP-A-54-164325 (JP, A)

Claims (2)

[Claims] 1. A bag body made of a flexible film, the upper surface of which is a convex curved surface having an arc shape or an elliptic arc shape in a side view, and the height of which is smaller than the radial dimension in a plan view. , Its top is located in the water and is fixed to the seabed,
An artificial reef characterized in that a liquid fluid such as seawater is press-filled into the bag body and an internal pressure is applied to the bag body. 2. A step of fixing the artificial reef fixing jig to the seabed, a step of attaching and fixing a bag body made of a flexible film to the fixing jig, and a bag body made of a flexible film. A method of mounting an artificial reef, comprising the steps of press-filling a liquid fluid such as seawater and applying internal pressure to the bag.