JPH047768B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a seawater exchange breakwater that exchanges seawater outside a port into a port.

(Prior Art) The Japanese coastline is roughly divided into three types: coastal areas facing the open sea, open bay areas, inland seas, and closed inner bays. In particular, open bay areas, inland seas, and closed inner bays have been extensively used since ancient times because their natural topography allows for gentle natural conditions such as waves. It is widely known that most of the landfill sites, coastal factories, and ports are concentrated in these areas, and the problem of seawater pollution has become increasingly serious.

Currently, wastewater regulations have been implemented and seawater purification is gradually progressing, but the deterioration of the quality of stagnant water in closed water areas such as harbor areas is still considered a problem. In addition, in the fisheries industry, with the recent establishment of a 200 nautical mile zone, fishing patterns have been changing from distant sea to offshore to coastal, and aquaculture cages are being installed within fishing ports. From this perspective as well, water quality conservation in closed waters within fishing ports is required.

There is a conventional seawater exchange breakwater 1 that exchanges seawater outside the port into the port in order to maintain water quality within the port.
As shown in FIG. 2, a breakwater main body 2 is provided so as to partition an outside port 3 and an inside port 4, and a flow passage 5 is provided in the lower part of this breakwater main body 2 so as to communicate between the outside port 3 and the inside port 4, We are trying to exchange seawater using wave power and other means. In addition, the conventional seawater exchange breakwater 1 shown in FIG. 3 has a bellmouth-shaped portion 5A with a small loss on the outside port side 3 of the flow path 5, and a protruding portion 5B with a large loss on the inside port side 4, so that inflow due to wave force We are trying to make a difference in the amount of output. In this way, the amount of water flowing into the port 4 will be improved on average, and the flow of seawater in the port 4 will be promoted. Next, in the conventional seawater exchange breakwater 1 shown in FIG. 4, a flutter valve 6 is provided at the outlet of the flow path 5 on the port side 4, and when the water flows in, the valve 6 opens due to wave force, allowing seawater to flow in, and when it flows out, the flutter valve 6 opens. The valve 6 is closed to prevent seawater from flowing out. In this way, a unidirectional flow can always be expected toward the inside of the port 4, and the flow of seawater in the inside of the port 4 is promoted.

(Problems to be solved by the invention) However, in the structure shown in Fig. 2,
When the wave height is small compared to the water depth, the waves outside the port 3 have a sinusoidal waveform, which causes a reciprocating flow with exactly the same flow rate in the flow path 5, resulting in a problem in which the inflow volume cannot be expected. In addition, in any of the types shown in FIGS. 2 to 4, pressure changes due to waves outside the port 3 propagate directly to the inside of the port 4 through the flow path 5.
This creates new transmitted waves within the port 4, which is a fatal problem in terms of wave dissipation, which is the original purpose of the breakwater 1.

An object of the present invention is to provide a seawater exchange breakwater that can maintain the water quality of the harbor area while keeping the interior of the harbor calm.

(Means for Solving the Problems) The configuration of the present invention for achieving the above object will be explained with reference to FIGS. 1A to 1C corresponding to the embodiment. A breakwater main body 2 is provided in the upper part of the breakwater main body 2, and an entrance 8 opens on the outside 3 side of the port, and a seawater introduction groove facing 4 directions inside the port and closed at the end with a reflecting wall 9. 7 is provided in the breakwater main body 2, and the seawater introduced into each of the seawater introduction grooves 7 is reflected by the reflecting wall 9 at the end thereof.
A drainage channel 14 is provided to drain water to the bottom 13 side of the port 4 due to a water head difference H on the side, and the seawater introduction groove 7
is characterized by being comprised of a converging side wall 10 whose horizontal groove width becomes narrower toward the inside of the port 4, and a submerged bottom wall 11 submerged below the water surface 12.

(Function) Such a seawater exchange breakwater 1 has a seawater introduction groove 7.
When a wave enters the seawater inlet groove 7, the width of the seawater introduction groove 7 becomes narrower toward the four directions inside the port due to its converging side walls 10, so the water level of the seawater entering the groove 7 is adjusted to the width of the groove. As the value decreases, the value increases and reaches its maximum at the reflecting wall 9. Since the drainage channel 14 is provided at this position, the seawater in the groove 7 is drained to the bottom 13 of the port interior 4 due to the water head difference H at that time. Therefore, seawater flows into the harbor 4 from the lower part of the breakwater body using the water head difference H, so it becomes quieter, and the water quality of the harbor 4 can be maintained while keeping the harbor 4 calm.

(Example) Examples of the present invention will be described in detail below with reference to FIGS. 1A to 1C. Seawater exchange breakwater 1 of this example
has a breakwater main body 2 that is provided to separate an outside port 3 and a port inside 4. In the upper part of the breakwater main body 2, a seawater introduction groove 7 opens an entrance 8 on the outside 3 side of the port, faces 4 directions inside the port, and extends in the longitudinal direction of the breakwater main body 2 so that the end becomes a reflecting wall 9. They are installed in parallel. Moreover, these seawater introduction grooves 7 have a convergent side wall 10 whose horizontal groove width becomes narrower toward the inner port 4 side, and a waveguide slope portion 1 at the bottom of the inlet 8.
1 A submerged bottom wall 1 submerged below the water surface 12
1. Further, the breakwater main body 2 is provided with drainage channels 14 for draining seawater introduced into each seawater introduction groove 7 to the bottom 13 side of the groove 4 by a water head difference H on the reflecting wall 9 side at the end thereof. . Groove 7
A top plate 15 for preventing waves from overtopping is provided on the ceiling at the far end.

In such a seawater exchange breakwater 1, a waveguide slope portion 11A is provided at the lower part of the entrance 8 of each seawater introduction groove 7, so that incident waves are efficiently directed to the submerged bottom wall 11.
be led upwards. The seawater that has entered each seawater introduction groove 7 in this way forms a converging side wall 10 whose groove width becomes narrower as it goes toward the inner port 4 side, so that the outermost reflecting wall 9 As it approaches , it gradually rises as shown by the broken line, and the maximum head difference H is shown at the reflecting wall 9. Utilizing this water head difference H, the seawater in the groove 7 is drained to the bottom 13 side of the harbor 4 through the drainage channel 14. Groove 7
Since the top plate 15 for preventing wave overtopping is provided at the end of the wave, overtopping of waves caused by rising waves is prevented.

(Effects of the Invention) As explained above, since the seawater exchange breakwater according to the present invention uses a seawater introduction groove having a converging side wall, a considerable water head difference is obtained at the end reflecting wall due to the converging action. This allows water to be guided efficiently even in small waves. In the present invention,
This water head difference is used to drain water to the bottom of the port through the drainage channel, so the inflow of seawater into the port becomes quieter, making it possible to maintain the water quality within the port while keeping the port calm. Furthermore, there is a waveguide slope section at the bottom of the entrance of the seawater introduction groove, which can efficiently guide waves onto the submerged bottom wall. Moreover, since the submerged bottom wall is always submerged, the amount of introduced water can be adjusted to the target sea area. It has the advantage of not being affected by tidal differences.

[Brief explanation of drawings]

FIG. 1A is a plan view of an embodiment of a seawater exchange breakwater according to the present invention, FIG. 1B is a sectional view taken along the line X-X of FIG. 1A, FIG. Figures 4 through 4 are cross-sectional views showing three types of conventional breakwaters. 1... Seawater exchange breakwater, 2... Breakwater main body, 3
...Outside the port, 4...Inside the port, 7...Seawater introduction ditch, 8...
...Entrance, 9...Reflection wall, 10...Convergence side wall, 1
1A... Waveguide slope portion, 11... Submerged bottom wall, 12...
...Water surface, 13...Bottom, 14...Drainage channel, 15...
...Top plate to prevent overtopping waves.

Claims (1)

[Claims] 1 A breakwater main body is provided to separate the outside of the port from the inside of the port, and a seawater introduction groove is provided in the upper part of the breakwater main body with an entrance opening on the outside of the port and facing toward the inside of the port and closed at one end with a reflecting wall. The breakwater main body is provided with a drainage channel for draining the seawater introduced into each of the seawater introduction grooves to the bottom side of the port by a water head difference on the reflecting wall side at the end thereof, and the seawater introduction grooves are horizontal. A seawater exchange breakwater comprising: a converging side wall whose groove width narrows toward the inner side of the port; and a submerged bottom wall submerged below the water surface.