JPH02167910A - Wave dissipating device - Google Patents

Abstract

PURPOSE:To make incoming waves effectively return back and to make effective wave breaking and dissipation by keeping a pontoon, having a plurality of vertical openings, submerged at a certain depth from the surface of the water and by mooring the same to the seabed with a plurality of mooring cables, to which spring devices are installed at the middle. CONSTITUTION:To a pontoon 1, a plurality of vertical openings 2, bored through from the upper side to the bottom, are provided in juxtaposition and spring devices 3 having an appropriate spring constant are interposed thereunder at the middle of mooring cables 4 that are to be anchored to the seabed 7. Then the pontoon 1 is submerged to a certain depth from the surface of the water and anchored to the seabed 7 with each of the mooring cables 4 and concrete anchors 5. Vertical bores 11 are provided on the pontoon 1 at places not interfering with the vertical openings 2 and air-contained submerged bags 12 are provided therein so that the bags are deformed by the water pressure. The bores are communicated one another with pipes 13 and the device is moored to a jacket 14. Thereby a wave dissipating device in simple construction and having high serviceability can be constructed at less costs.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to a wave canceling device that eliminates wave energy by reflecting and absorbing it.

[Conventional technology]

Conventionally, various wave dissipating devices have been proposed to ensure safe harbor waters. These are generally breakwater structures (breakwaters) in which structures and obstacles are fixed or stacked on the seabed, and are designed and constructed according to the geology of the seabed, water depth, etc. It is configured to achieve a wave-blocking effect or a wave-dissipating effect.

[Problem to be solved by the invention]

However, such conventional wave-dissipating devices produce large reflected waves, for example, at the front of the breakwater that receives the incident waves, which impedes ship navigation and increases construction costs as the water depth increases. Also.

Since such a breakwater is established on the seabed, there are problems such as poor seawater exchange rate between the front and back parts of the breakwater.

In addition, recently, in order to make more effective use of coastal areas facing the open sea, there has been an increasing need for wave-dissipating structures that have a seawater exchange function, have good wave-dissipating efficiency, and are highly economical.

This invention was made in view of the problems and needs of the prior art, and provides a wave dissipating device that suppresses the generation of reflected waves, does not cause deterioration of the seawater exchange rate, and can be obtained at low cost with a simple structure. The purpose is to obtain.

[Means to solve the problem]

The wave dissipating device according to the present invention is moored to the seabed with a plurality of mooring lines so that an impermeable pontoon or a pontoon with a plurality of vertical openings is positioned below a predetermined water surface, and a spring device is installed in the middle of these mooring lines. It has an interposed structure.

In addition, as a wave dissipating device of another invention, a plurality of submersible bags each containing an appropriate amount of air inside the membrane are provided on a pontoon so as to expand and contract according to changes in water pressure, and each of the submersible bags is connected by a communication path. Among these, a plurality of submersible bags each surrounded by a cylinder with an open top provided on a pontoon may be used.

[Effect]

The spring device in this invention lowers one end of the pontoon located at the crest of the wave when receiving the energy of the incident wave,
It acts to cause the pontoon to rotate so as to raise the other end of the pontoon located in the trough of the waves, and acts to dissipate and break the entire incident wave, thereby smoothing it.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing one embodiment of the invention, and in the same figure, l is a pontoon as a box-shaped structure, and this pontoon l has a plurality of vertical openings penetrating from the upper surface to the lower surface. As shown in FIG. 2, they are arranged in parallel. Also,
A spring device 3 having an appropriate spring constant is installed at the lower part of the pontoon 1, and this spring device 3 is interposed between a plurality of mooring lines 4 that retain the pontoon 1 on the seabed 7.

The pontoon 1 is moored to the seabed 7 by the mooring cables 4 and concrete anchors 5 so that the entire pontoon 1 is located underwater at a predetermined depth from the water surface 6.

FIGS. 3(a) and 3(b) are principle diagrams showing the details of the spring device 3, in which 3a is a spring case, 3b is a coil-shaped spring provided in the spring case 3a, and the spring device 3a is a coil-shaped spring provided in the spring case 3a.
is fixed to the lower end of a mooring line 4 connected to the pontoon 1. On the other hand, the spring 3b is placed on the bottom of the spring case 3a, and the upper end of the spring 3b is connected to the concrete anchor 5.
It is fixed to the upper end of the mooring line 4 connected to the. According to this, when the pontoon 1 rises due to waves, the spring 3b
is compressed as shown in FIG. 3(b), and acts to dissipate waves with an appropriate repulsive force. Note that depending on the state of the seabed and the water depth, it is optional to use a jacket, caisson, or the like constructed of a steel frame on the seabed in place of the concrete anchor 5 as the lower mechanism.

Next, the operation will be explained while partially comparing it with a conventional wave dissipating device that does not have the spring device 3. first.

In a conventional wave dissipating device in which the pontoon l and the mooring line 4 are directly connected. Even when receiving an incident wave, the pontoon 1 moves approximately horizontally due to the fixed length of the mooring line 4, and due to this horizontal movement, a part of the incident wave acting on the pontoon 1 is reflected and transmitted. Suppress the amplitude of wave height.

However, in this invention, since the spring device 3 is interposed in the middle of the mooring line 4, when the pontoon receives an incident wave, the pontoon moves horizontally in the same way as in the conventional case, as shown in FIG. 3 (a).
) and (b), the spring 3b in the spring device 3 expands and contracts, causing rotational movement as shown in FIG. 4.

That is, when receiving an incident wave as described above, the pontoon 1 sinks in a part located below the crest of the wave, as shown in FIG. 5, and in response to the reaction of this sinking,
Pontoon 1 tries to rise at another part on the opposite side from this position, and the other parts of pontoon 1 act to push up the water level at the trough of the waves at this time, smoothing out the wave height as a whole. It works like this. Therefore, by such movement of the pontoon 1, wave reflection and wave breaking can be performed more effectively, and the amplitude of the incident wave can be reduced.

In addition, in this embodiment, the pontoon 1 is provided with a large number of vertical openings 2 with a constant opening ratio, and by allowing some of the waves to enter and leave the vertical openings 2, it is possible to disperse the traveling wave energy. The breaking of the traveling wave and the dissipation effect due to the dispersion of its energy can be performed more effectively.

FIG. 6 is a wavelength-transmittance characteristic diagram of the conventional wave canceling device and the present invention. Curve a shows the characteristic of the present wave canceling device in which the pontoon 1 is moored to the mooring line 4 via the spring device 3. The curved line shows the characteristics of a conventional wave-dissipating device in which the pontoon 1 is directly moored by the mooring cable 4 without using the spring device 3.

According to this, in the wave canceling device of this invention, the wavelength (B/L)
The transmittance decreases significantly around 0.3 to 0.4, and gradually increases around this wavelength, but the transmittance is at least close to 0.2 compared to conventional wave breakers. It can be seen that the rate is improved. Note that the wave transmittance here is the ratio of the wave height when the case where no wave breakwater is installed is set to 1.

Further, in this invention, since the spring device i3 is interposed in the middle of the mooring line 4, it is possible to effectively alleviate the impactive tension that acts on the mooring line 4 when receiving an incident wave. . FIG. 7 shows this tension relaxation state, and when the spring device 3 is provided, as shown in FIG. 7(a), the initial value, the end value 2
For both half amplitudes, the conventional spring device 3 is not provided in Fig. 7 (
It can be seen that this is reduced to 1/3 or less compared to b).

FIG. 8 shows another embodiment of the wave canceling device according to the present invention. This is done by providing vertical tubes 1 within the wall thickness of the pontoon 1 at multiple positions that do not overlap with the vertical openings 2 of the pontoon 1, and injecting air into these vertical tubes 11 so that they deform under water pressure. Built-in submersible bags 12 are respectively provided, and among these submersible bags 12, those lined up in a line in the direction of propagation of the incident wave are connected by communication pipes 13, respectively. Further, here, a jacket 14 is used in place of the concrete anchor 5.

In the wave dissipating device having such a configuration, in addition to the wave dissipating effect of the pontoon 1 having the vertical opening 2 moored via the spring device 3, the transmittance is increased in the region of B/L 0.5 or more as shown in FIG. It acts to further reduce it.

In other words, in the wave dissipating device having the diving bag top 2, as the incident wave advances, the water pressure is low at the wave trough and high at the wave crest, so the diving bag 12 at the wave peak contracts, and the water pressure increases at the wave crest. Some diving bags 12 are enormous. For this reason.

The deformation of each of these submerged bags 12 generates an air flow within the communication tube 13, lowering the peaks of the waves and raising the troughs, and each of these deformations of the submerged bags 12 attenuates the energy of the waves. In other words, it generates a wave with a phase opposite to that of the incident wave, cancels the incident wave, and suppresses the passing wave.

In the above embodiment, the pontoon 1 is provided with the vertical opening 2, but the pontoon 1 is provided with the vertical opening 2.
It is also possible to use an impermeable structure without a In this case, it is necessary to increase the strength of these pontoons 1 and mooring lines 4 so that the load due to the energy of the incident wave does not put a burden on the strength of these pontoons 1 and mooring lines 4.

〔Effect of the invention〕

As explained above, according to the present invention, an impermeable pontoon or a pontoon having a plurality of vertical openings is moored to the seabed by a plurality of mooring lines so as to be located under a predetermined water surface, and By incorporating a spring device into the pontoon, incident waves can be effectively reflected by the pontoon to break and dissipate the waves.In addition, by incorporating the spring device as described above, the mooring line can be protected from large impact forces during stormy winds. This has the advantage that it can be avoided. In addition, since the structure as a whole has a simple shape,
Effects such as reduced construction costs and extremely high practicality can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the entire wave-dissipating device of the present invention, FIG. 2 is a plan view showing the pontoon of the wave-dissipating device, and FIG.
a), (b) A schematic sectional view of the spring device, FIG. 4 is an explanatory diagram showing the behavior of the wave dissipating device of the present invention, and FIG. 5 is an explanatory diagram showing the wave dissipating action by the wave dissipating device of the present invention. FIG. 6 is a transmittance-wavelength characteristic diagram of the present invention and a conventional wave canceling device, and FIG. 7(a). (b) is a tension characteristic diagram acting on the mooring cable in the present invention and the conventional wave-dissipating device, FIG. 8 is a sectional view showing another embodiment of the wave-dissipating device, and FIG. 9 shows the pontoon in FIG. 8. FIG. 1. Pontoon, 2. Vertical opening, 3. Spring device,
4. Mooring rope, 6. Water surface, 7. Seabed. Figure Pontoon vertical opening splash device f''' 2 Figure 6 Water surface 7 Seabed No. 611 B/L (b) Figure 7 Figure 8 Figure 9

Claims (1)

[Claims] 1) A pontoon that is impermeable or has a plurality of vertical openings is moored to the seabed by a plurality of mooring lines so as to be located below a predetermined water surface, and a spring device is interposed between the mooring lines. equipped wave dissipating device. 2) The pontoon is provided with a plurality of submersible bags each containing an appropriate amount of air so as to expand and contract in response to changes in water pressure, and each of the submersible bags are connected by a communication path. wave dissipating device.