JP4229441B2 - Artificial leaf with adjustable buoyancy - Google Patents

Description

  The present invention relates to an artificial leaf that can be brought into a neutral buoyancy state so as to be immersed in water and to automatically keep the top end at a certain depth from the water surface.

  There is a floating breakwater using floating bodies as a wave-dissipating structure. Even if there is a change in tide level, the relative position with respect to the water surface does not always change, and foundation work such as mound is not necessary. However, because the structure is exposed on the surface of the water, the connection part of the wave-dissipating structure may be damaged by high waves, or the mooring line etc. may be damaged to fix the wave-dissipating structure in a fixed position to prevent movement. May occur.

  In addition, since the wave-dissipating structure exists only near the water surface, it cannot cope with long-period waves, and wave energy passes through the water space under the floating structure and reaches the shore side. However, it is difficult to maintain the quietness of the water area behind the wave-dissipating structure, and the wave-dissipating performance is generally low. For this reason, in order to improve the wave-dissipating performance, it is necessary to arrange a plurality of units of the wave-dissipating structure in parallel to cope with long-period waves, which increases the construction cost. In addition, since the sedimentation effect cannot be expected at all, it cannot be used for the purpose of preventing coastal erosion and stabilizing the coast. Furthermore, since the structure is exposed on the water surface, the landscape on the coast is damaged.

On the other hand, artificial reefs are increasingly used as wave-absorbing structures in recreational spaces for the purpose of stabilizing beaches and forming calm seas.
Artificial reefs install multiple blocks made of concrete on a rubble mound, etc. (Patent Document 1) or install a large wave-dissipating structure to reduce wave energy by generating breaking waves accompanying changes in water depth. The present inventor has proposed an artificial leaf that generates a breaking wave shown in Patent Document 2 and Patent Document 3 and rushes into the box to attenuate wave energy to obtain a calm water area.
JP-A-8-3965 Japanese Patent Laid-Open No. 11-13040 JP 2002-242150 A

The artificial reef is designed so that the top of the artificial reef is submerged in the water even when the tide level changes and becomes low, so the top of the artificial reef is designed to be at least about 50 cm below the low water level. It is common. On the other hand, in places where sea level fluctuations are large, the water depth to the top of the sea is too high at high tide, and a sufficient wave-dissipating effect cannot be obtained.
In addition, when the water level rises due to future structure subsidence or global warming, the top water depth may be deeper than at the time of planned design, and it becomes impossible to secure a predetermined wave-dissipating performance.
From the aspect of wave energy attenuation, the wave attenuation effect by artificial reef is not very large, and if the water depth at the top edge cannot be maintained properly, sufficient wave extinction effect cannot be obtained, so the width of the top edge is reduced. It must be wide and have a large cross section to obtain a sufficient wave-dissipating effect, which not only increases the construction cost, but also may change various environments in the sea area. As the amount of water rising behind the structure increases due to the incoming waves, a rip current will occur near the shoreline, and the sedimentation effect may not be expected.

The artificial leaf of the present invention is an artificial leaf that is neutral in water so that it can respond to changes in the tide level, and uses the wave-dissipating function of the trap-type double leaf. A buoyancy adjustment chamber is provided, and the front surface of the buoyancy adjustment chamber is made lower than the top end of the box to form a double leaf structure. A slit is formed, and the wave is quenched by capturing the water mass by the vertical disturbance around the slit and the hollow area inside.
In order to make the structure in a state of neutral buoyancy, floating bodies that can adjust buoyancy are provided at the front and rear of the box. Neutral buoyancy is obtained by pouring water, and the artificial reef is maintained at a predetermined position in the water. Is.
Further, by providing a wall extending downward in front of the wave-dissipating structure, long-period waves are wave-dissipated, and the water mass passing through the lower part of the box is reduced.

As shown in FIGS. 1 and 2, the artificial leaf 1 is a floating body and a bottom plate 4 serving as a lower leaf, a box 2 having an open top surface serving as an upper leaf installed on the upper plate, and a front and rear of the box. It is composed of buoyancy adjustment chambers 31 and 32.
The bottom plate 4 is a watertight concrete floating body, and the box 2 formed on the bottom plate 4 is also made of concrete and has an open top surface. The bottom plate 4 is a lower leaf and the box 2 is an upper leaf to form a double leaf having a two-stage structure.
The offshore side end of the buoyancy adjusting chamber 31 provided in front of the box 2 is an upright wall 10, and the opening 11 is formed at the lower end of the upright wall 10. The inside of the box 2 is partitioned by a partition wall 12 and reinforced. On the upper surface of the box 2, slit plates 13, 13 that are inclined downward by 30 degrees with respect to the traveling direction of the waves are arranged between the partition walls 12 at intervals, and between the slit plates 13, the inclined slits 14, 14 is formed.

The buoyancy adjustment chambers 31 and 32 made of concrete before and after the box 2 and having a watertight structure are formed integrally with the box 2 or separable. The buoyancy adjusting chambers 31 and 32 are provided with valves (not shown) for water injection or drainage in order to adjust the buoyancy so that the artificial reef is in a neutral buoyancy state as a whole.
For the buoyancy adjustment chambers 31 and 32, it is possible to use an abandoned ship such as a trolley, and the trolley is cut to an appropriate size to close the front and back to form a buoyancy adjustment chamber. The front and rear are connected and integrated with a connecting bracket or the like. When this buoyancy adjustment chamber is corroded and can no longer function as a floating body, it is removed and replaced with a new one.

  As shown in FIG. 2, the artificial leaf 1 connects a plurality of single bodies to form a wave-dissipating structure, and therefore the connecting tool is installed at an appropriate position. Further, a long-period wave blocking wall 6 extending downward is provided near the front end of the bottom plate 4. The blocking wall 6 may be provided on the center side of the bottom plate 4, or may be integrated with the bottom plate 4, or may be separately assembled and assembled at the site where the wave-dissipating structure is installed.

The artificial reef 1 having the buoyancy adjustment chambers 31 and 32 is launched from the dock or the coast and towed to the installation point. The buoy 5 is attached to the artificial leaf 1 through the coupling body 51. Water is poured into the front and rear buoyancy adjustment chambers 31 and 32 so that the artificial leaf 1 is maintained in a horizontal state, and the buoyancy is slightly settled as a buoyancy slightly smaller than the neutral buoyancy.
The connecting body 51 that connects the buoy 5 and the artificial leaf 1 defines the depth from the water surface to the top edge, has a large rigidity, and the length is appropriately selected from about 0.5 to 1.5 m. To do.
The anchor cord 52 and the anchor 53 are attached before and after the artificial leaf 1 to complete the installation. Subsequently, another artificial leaf 1 is set to a predetermined depth and connected.
Since the artificial leaf 1 which is a wave-dissipating structure is in a state of almost neutral buoyancy, the buoyancy required for the buoy 5 is small, and thus the volume can be reduced, so that the structure exposed on the water surface can be small. , Hardly disturb the landscape. Moreover, by making the length of the coupling body 51 adjustable, the water depth at the top end of the artificial leaf 1 can be changed, and the top end water depth according to the wave at the installation location of the wave-dissipating structure can be obtained.

Waves traveling from offshore are amplified as the water depth becomes shallower, amplified in the bottom plate 4 as the lower leaf, and further, breaking waves are generated by a sudden decrease in water depth in the upright wall 10 of the box 2. The breaking wave enters the upper surface of the box 2, passes through the inclined slit 14, and is reduced in the space inside the box. Further, the blocking wall 6 prevents long-period waves from moving under the bottom plate 4.
The wave energy transmitted to the shore side by the artificial reef is reduced, and a calm water area is obtained on the shore side, and accordingly, the generation of water flow from the shore to the offshore is suppressed, so the movement of sand on the seabed is reduced. Coastal erosion is prevented.

The example shown in FIG.3 and FIG.4 reduces the damage of a connection part by suppressing the movement of the artificial leaf 1 and the rocking | fluctuation to the front-back direction of the artificial leaf 1 by a wave.
Therefore, through holes 22 are formed in the front and back of the box 2 and the bottom plate 4 of the artificial leaf, and a pile 54 is driven into the through hole 22, and a cushioning body such as rubber (illustrated) is formed between the through hole 22 and the pile 54. In this case, the artificial leaf 1 is held at a fixed position and moved up and down along the pile 54 in accordance with changes in the tide level.

As described above, the artificial leaf of the present invention is in a state of neutral buoyancy in water so that it can cope with changes in tide level, and the top of the artificial leaf is automatically adjusted to a certain depth from the water surface. An artificial reef that utilizes the wave-dissipating function of a trap-type double-leaf, and the wave-dissipation can be performed efficiently and a calm water area can be formed.
A buoyancy adjustment chamber is provided at the front and rear of the box with the top open, and the bottom plate and box have a double leaf structure, and the box is formed with an oblique slit whose back is lower than the wave traveling direction. However, the vertical disturbance around the slit and the trapping of the water mass by the hollow area inside the wave cause quenching.
Since the artificial leaf is in a state of neutral buoyancy, the buoyancy of the buoy for maintaining it at a predetermined position in the water may be small, the structure exposed on the water surface is small, and the landscape is not hindered.
In addition, by providing a blocking wall that extends below the artificial reef, the water mass that passes under the bottom plate is reduced, preventing the transmission of long-period waves to the shore side, and a calm water area is obtained. It is done.

Sectional drawing of the Example of an artificial leaf. The top view of the Example of an artificial leaf. Sectional drawing of the artificial leaf fixed so that vertical movement was possible with the pile. The top view of the artificial leaf fixed so that it could move up and down with a pile.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Artificial leaf 13 Slit board 14 Slit 2 Box 31 and 32 Buoyancy adjustment chamber 4 Bottom plate (floating body)
5 Buoy 51 Linkage 53 Anchor 54 Pile

Claims (4)

A double-leaf structure in which a box with an open top surface is provided on the bottom plate, which is a floating body, and a buoyancy adjustment chamber is provided at the front and rear of the box, and the top surface of the buoyancy adjustment chamber at the front is boxed It has a double-leaf structure that is lower than the top of the top, and a box with an open top surface is provided with a plurality of slit plates that are inclined downward with respect to the wave traveling direction. Artificial reef that is always immersed in water. 2. The artificial leaf according to claim 1, wherein the buoy is connected through a rigid connecting body. 3. The artificial leaf according to claim 1, wherein the front and rear buoyancy adjustment chambers are separably provided in the box. The artificial leaf according to any one of claims 1 to 3, wherein a through hole is formed in the bottom plate or the buoyancy adjustment chamber, and a pile reaching the water bottom is placed in the through hole so that the whole can be moved up and down.

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