JPS6225607A - Breakwater - Google Patents

Abstract

PURPOSE:To reduce the energy of waves with good efficiency by a method in which water paths are formed piercingly in the wall of a breakwater by varying the cross sectional areas of the water paths from the front opening to the back opening. CONSTITUTION:Waves which collide with the concrete wall face A of a breakwater form reflecting waves possessing the entire energy reflected immediately. Waves which collide with the reduced diameter path 2 easily go into the water path 1 but small amounts of waves are discharged from the back side B because the waves are consolidated due to the reduced diameter of the tip portion. Waves which collide with the increased diameter path 3 can not go into the water path 1 easily, but the water coming into the path 3 goes out from the back side B easily. Since the reflected waves possessing three kinds of different energies have many kinds of phase differences due to different generating times, they breakby cancelling each other and the energy of waves can thus be damped.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a breakwater for reducing the energy of waves.

<Conventional technology> Conventionally, breakwaters have been designed to reduce the energy of waves.
A number of improvements have been made.

For example, a breakwater is made up of a front wall and a rear wall with a large number of holes of equal diameter, and a water retarding chamber is provided between the front wall and the rear wall.
It is hoped that by diffusing the wave energy in the water retarding chamber, the energy will be reduced.

<Object of the present invention> An object of the present invention is to provide a breakwater that can efficiently (reduce) the energy of waves.

<Example> An example of a breakwater according to the present invention will be described below with reference to the drawings.

(A) Structure of breakwater The breakwater of the present invention is formed of a wall such as concrete, and among the wall surfaces of the wall, the surface on which waves crash is the front surface A, and the opposite surface is the rear surface B.

A water passage 1 is provided on the wall of this breakwater, penetrating from the front A to the back B.

(b) Water channel The water channel 1 is formed so that its cross-sectional area gradually changes from the front surface A to the back surface B.

For example, as shown in Fig. 1.2, a water passage 1 having circular cross-sectional openings with two different hole diameters is installed on the front surface A, and the inner diameter of the water passage 1 is changed from the front surface A to the rear surface B. The path that decreases is defined as a reduced path 2, and the path that increases conversely is defined as an increased path 3.

(c) Reduced path path The reduced path path 2 is a passageway 1 in which the diameter of the opening on the back side B of the breakwater is smaller than that on the front side A, and the cross-sectional area gradually decreases from the front side A to the back side B.

2) Path expansion path The path expansion path 3 is a passageway 1 in which the diameter of the opening at the rear surface B is larger than that at the front surface A, and the cross-sectional area gradually increases from the front surface A toward the rear surface B.

Function> The breakwater of the present invention functions as follows to reduce wave energy.

(b) Wave attenuation effect in front of the breakwater On the front A,
The concrete wall surface, the opening of the reduced path 2, and the opening of the increased path 3 are located, and the waves that hit each part are as follows.

[Concrete wall surface 1] All of the energy of the wave that hits the concrete wall surface is immediately reflected, forming a reflected wave that retains all of the energy.

[Reduced path path 1 Waves that hit the reduced path path 2 easily enter the launch path 1 because the opening is large.

However, since the diameter of the incoming wave decreases at the tip and the water is consolidated, the number of waves discharged from the back surface B is small.

As a result, energy is reflected with a time difference and considerably reduced compared to the wave reflected by the concrete cross-section, forming a reflected wave that retains this energy.

[Increased route 1 Waves that hit the increased route 3 section cannot easily enter the launch channel 1 because the opening is small;
The waves that enter the water are not consolidated because the diameter of the channel is increased.

Therefore, the water that has entered from the increased path 3 is easily discharged from the rear surface B side.

Eventually, some of the energy will be absorbed, and the energy of the wave near the entrance will be reflected, forming a reflected wave that carries this energy.

[Cancellation of Reflected Waves] As described above, the three types of reflected waves having different energies have different generation times.

Therefore, the plurality of reflected waves have different wavelengths, resulting in many types of phase differences.

As a result, the waves cancel each other out between the impinging waves and the reflected waves by wave decomposition and superposition, and the energy of the waves can be attenuated.

(b) Wave attenuation effect on the back side of the breakwater The openings of the path reducing path 2 and the openings of the path increasing path 3 are located on the back side B, and the openings of the path increasing path 3 are located on the back side B.
A portion of the wave entering from the opening exits from each opening as described above.

Immediately before being discharged from the passageway 1, the wave energy moves while being attenuated by the expansion and contraction of the cross-sectional diameter of the passageway 1.

Furthermore, there is a difference in the time and energy of the ejected waves between the reduced path path 2 and the increased path path 3.

Therefore, many types of phase differences will still occur,
The waves cancel each other out through wave decomposition and superposition, and the energy of the waves can be attenuated.

Other Examples> As the passageway 1 of the breakwater, one formed as follows can also be adopted.

(A) The openings on the front surface A and the rear surface B of the water passage 1 may have various shapes such as polygons such as triangles and quadrangles, and ellipses.

Furthermore, these shapes can be formed alone or in combination.

(b) The cross-sectional shape of the water passage 1 at the front surface A is made equal;
It is also possible to form the back surface B to have a different cross-sectional shape.

(c) The number of water passages 1 may be different if the openings have different shapes.

(iv) It is also possible to form the passageway 1 by gradually changing the diameter of the passageway 1 from the inlet side, and then narrowing it down gradually.

In other words, the diameter of the flow path is maximized midway between the inlet and the outlet.

Alternatively, after narrowing down the flow path, the flow path may be gradually enlarged so that the flow path diameter becomes the minimum halfway between the inflow port and the discharge port.

(e) As shown in FIG. 3, it is also conceivable to provide a plate-shaped resistance member 4 protruding from the inner circumferential surface of the water passage 1.

When the resistance member 4 is, for example, a plate-like object, the plate-like object is arranged parallel to the flow path, or intersected with the flow path, or a combination thereof.

By providing the resistance member 4, it is possible to improve the wave-dissipating efficiency of waves passing through the water passageway 1.

Effect> The passageway of the breakwater of the present invention is formed of a reduced-path path and an increased-path path.

Therefore, it is possible to efficiently cancel waves at the front and rear sides of the breakwater by using various types of phase differences, and furthermore, it is possible to expect losses due to expansion and contraction of the cross section of the water passage.

As a result, wave energy can be efficiently attenuated.

[Brief explanation of the drawing]

Figure 1: Perspective view of the breakwater of the present invention Figure 2: Cross-sectional view of the breakwater Figure 3: Explanation of other embodiments 1: Water passage 2: Reduced route 3: Increased route A: Front side
B: Back

Claims (1)

[Claims] A breakwater in which a water passage passes through the wall of the breakwater, and the cross-sectional area of the water passage changes from the front opening to the rear opening.