JPS5914123B2 - floating wave bank - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a floating wavebank, and an object of the present invention is to provide a floating wavebank that has a simple configuration and can obtain an appropriate wave-dissipating effect.

Conventionally, fixed breakwaters such as rubble stone breakwaters and vertical breakwaters have been well known as breakwaters for the purpose of breaking or dissipating waves in the ocean.

These breakwaters are generally constructed with a strong foundation on the seabed, and although they can be expected to have a certain degree of breakwater effect, the construction work on the seabed and at sea is fraught with various difficulties.
Moreover, it is well known that construction requires a large amount of money and many days.

Furthermore, such fixed breakwaters also have the problem of blocking the exchange of seawater between the open ocean and the inland sea, which are separated by the breakwater, and promoting seawater pollution in the inland sea.

Particularly in recent years, efforts have been made to expand the use of the ocean for marine resource development (e.g., artificial fishing grounds) and marine leisure in ports and other areas of the ocean. Alternatively, proposals for wave-dissipating levees are desired.

The present invention was devised in view of the above-mentioned current situation, and an object of the present invention is to provide a floating breakwater that can be easily floated at a suitable location in the ocean and can obtain an appropriate wave-dissipating effect.

For this reason, the present invention configures a pontoon type floating body to have a weight distribution according to the shape of the floating body such that one center of gravity is set at a position above the center of gravity position where the natural period of rolling and the natural period of up and down coincide. The basic principle is that the floating body is placed so that its length direction is approximately perpendicular to the direction of wave propagation, and that the floating body is floated on the sea so that its center of gravity is located on the extension line of the mooring line. Characteristics.

Next, one embodiment of the present invention will be specifically described based on the drawings.

FIG. 1 shows a floating wavebank according to the present invention, 1
is a pontoon type floating body (hereinafter simply referred to as a floating body).

), 2.2 is a mooring cable, and the floating body 1 is configured to have a fixed length.

Therefore, the floating body 1 is set at a position such that its center of gravity G is longer than the natural rolling period of the floating body.

In other words, the natural period of vertical heave is almost determined by the shape of the floating body, but the natural period of rolling is determined by the position of the center of gravity of the floating body.

In other words, it depends on the weight distribution, and the higher the center of gravity is, the longer the rolling period will be.

Therefore, in one aspect of the present invention, by taking into account the weight distribution of the floating body, its center of gravity G is set at a position above the center of gravity position where the natural period of rolling coincides with the natural period of vertical shaking.

The floating body 1 is moored by mooring cables 2, 2 each of which has one end anchored to an anchor (not shown) installed on the seabed. The other ends of the mooring cables 2, 2 are anchored to both sides of the lower part of the floating body 1 in the width direction, so that the floating body 1 is floated on the sea.

The mooring ropes 2, 2 are anchored to the floating body 1 in such a way that their extension lines pass through the center of gravity G of the floating body 1, thereby mooring the floating body 1. , by considering the locking position of 2.

The rolling restoring moment of the floating body 1 can be made sufficiently small.

According to the floating road embankment configured as described above, by considering the weight distribution of the floating body 1, the natural rolling period of the floating body 1 is configured to be longer than the natural period of vertical shaking, and the floating body 1 Since the coefficient of restoration of the mooring lines 2, 2 with respect to the rolling motion of the floating body 1 is sufficiently small, the floating body 1 causes a oscillation that reduces the transmitted waves, thereby achieving an effective wave-dissipating effect. The wave-dissipating effect is shown in Figure 2.

Figure 2 shows the wave transmittance ζT/ζI for the wave-dissipating bank, which has a wave-dissipating effect according to the wave wavelength λ, where ζT is the incident wave amplitude, ζI is the transmitted wave amplitude, and B is the floating body width. show.

In the figure, the broken line a shows the case of a floating wavebank according to the present invention, and the solid line a shows the case of the floating wavebank according to the present invention, and the solid line a shows the case of the floating wavebank according to the present invention.
' is anchored to the upper ends of both sides of the floating body 1, and the chain line C indicates that the center of gravity of the floating body 1 is set downward, and the natural rolling period of the floating body 1 is configured to be shorter than the natural period of vertical shaking. Each case is shown below.

As is clear from the figure, in the case of solid line C or solid line 2, a transmittance of 0.5 or less can be seen until the wavelength λ of the wave is approximately twice the width of the floating body B, but if the wavelength λ is larger than that, It can be seen that, whereas the performance of the floating body deteriorates significantly, the one according to the present invention can obtain a good wave-dissipating effect even for waves about four times the width of the floating body B.

In this embodiment, a pontoon-type floating body with a cross-sectional shape as shown in FIG. The anchoring position of the mooring line is selected accordingly.

According to the floating wavebank of the present invention as described above.

The pontoon type floating body 1 is configured to have a weight distribution such that the center of gravity G is set at a position above the center of gravity position where the natural rolling period and the natural period of up and down coincide with each other according to the shape of the floating body, and the pontoon type floating body 1 1 so that its length direction is approximately perpendicular to the direction of wave propagation, and the mooring rope 2
By floating the pontoon type floating body 1 on the sea so that its center of gravity is located on the extension line of . Furthermore, since it can be installed and maintained at low cost, it is an invention with high industrial value.

[Brief explanation of the drawing]

FIG. 1 is a side view showing an embodiment of a floating wavebank according to the present invention. FIG. 2 shows the wave-dissipating effect of the floating levee according to the present invention in comparison with other wave-dissipating levees. FIG. 3 is a side view showing floating waves that produce the wave-dissipating effect indicated by the solid line in FIG. 2. FIG. In the figure, 1 is a floating body and 2 is a mooring cable. −11=

Claims (1)

[Claims] 1. On a floating breakwater consisting of a floating body and a mooring line for mooring it, the pontoon-type powder is placed at a position where the center of gravity is above the position of the center of gravity where the natural period of rolling and the natural period of heave coincide, depending on the shape of the floating body. The pontoon type floating body is arranged so that its length direction is substantially perpendicular to the direction of wave propagation, and
A floating breakwater is a pontoon-type floating body that is floated on the sea so that its center of gravity is located on the extension of the mooring line.