JPH01165811A - Breakwater capable of intaking and discharging seawater - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

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) Conventionally, some seawater exchange breakwaters 1 used for water quality maintenance in ports have a breakwater main body 2 that is installed to separate an outside 3 and an inside 4 of the port, as shown in FIG. , a simple flow path 5 is provided at the bottom of the breakwater main body 2 so as to communicate between the outside 3 and the inside 4 of the port to facilitate seawater exchange using wave force, or a flow path 5 as shown in Fig. 8 is used. A bell mouth shaped part 5A with low loss is provided on the outside of the port 5, and a protruding part 5B with large loss is provided on the inside of the port, thereby creating a difference in the amount of inflow and outflow due to wave power, and increasing the amount of inflow into the port. Furthermore, as shown in Fig. 9, a flutter valve 6 is provided at the opening of the flow passage 5 on the inside of the port, and is opened when seawater enters due to wave force from outside the port, preventing it from flowing out from inside the port. These were common.

(Problem to be Solved by the Invention) 'However, in the structure shown in FIG. In this case, the flow rate will be exactly the same, reciprocating flow, and the inflow amount cannot be expected. In addition, in any of the types shown in FIGS. 7 to 9, pressure changes due to waves outside the port 3 propagate directly to the inside of the port 4 through the flow path 5, so new propagation waves are generated inside the port 4. This has become a fatal problem in terms of wave dissipation, which is the original purpose of the breakwater 1.

In view of such conventional problems, 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 gist of the present invention is to solve the above-mentioned conventional problems and achieve the intended purpose.

A breakwater was built to separate the outside of the port from the inside of the port.

A seawater introduction channel with an entrance opening on the outside of the port is provided in the upper part of the breakwater main body, and a natural vibration period adjustment storage tank is provided at the bottom of the innermost part of the seawater introduction channel, which communicates with the seawater introduction channel. A drainage channel is provided to communicate from the lower part of the storage water tank to the inside of the lower port of the breakwater main body, and the seawater introduction channel has a converging side wall whose horizontal width narrows toward the inner part. The main feature is the seawater exchange breakwater.

(Function) In this jl'j water exchange breakwater, waves that rush from outside the port collide with the front of the main body of the breakwater, some are reflected, and others enter through the opening of the seawater inlet. The invading waves enter the inner part along the converging side wall while raising the water level, become a state of disturbance, and flow into the internal storage tank while consuming energy, and then flow from the bottom of this storage tank through the drainage channel. It flows into the port.

The outflow velocity of seawater in a storage tank has a unique frequency depending on the diameter of the drainage channel, the diameter of the storage tank, and the length of the drainage channel. By shaping it in accordance with the period, it will always flow into the port in synchronization with the incoming waves.

(Example) Next, an example of implementation of the present invention will be described with reference to FIGS. 1 to 3.

This seawater exchange breakwater has a breakwater main body 11 arranged to partition an outside 3 of the port and an inside 4 of the port. This breakwater body 11
A seawater introduction channel 13 is opened on the surface (front surface 12) on the outside of the port 3 side. A storage water tank 14 is provided below the innermost part of this seawater introduction channel 13, and a drainage channel 16 is provided between the bottom of this storage water tank 14 and the lower part of the back surface 15 of the breakwater main body 11.

The seawater introduction channel 13 has a horizontally arranged ceiling wall 17, and a submerged bottom u18 that is raised toward the back and is completely submerged in water.
The seawater introduction channel 13 is surrounded by convergent side walls 19a and 19b that narrow the horizontal width of the channel toward the back.

The storage tank 14 has a seawater introduction channel 1 on the front side 12 of its upper part.
3 are in communication with each other, and due to its horizontal cross-sectional area and the diameter and length of the drainage channel 16, when seawater flows in and out through the drainage channel 16, the top and bottom of the water surface in the storage tank 14 has a unique vibration period. The natural vibration period of 172 is set in advance to be the same as the normal wave period on the outside port 3 side.

Next, the function of this seawater exchange breakwater will be explained.

Generally, as shown in FIG. 4, in two water tanks Al and A2 connected by a pipe 28A, the water surface of the water tank A1 is set at time 1=
The water surface free vibration waveform after being forcibly raised by about 101 at 0 is as shown in Fig. 5 (a), and the flow velocity waveform in the pipe at that time is as shown in Fig. 517] (b). .

Also in the breakwater of the embodiment of the present invention, such communication 2
It is based on the principle of movement of water in an aquarium, and the aquarium A2 is
If it is a water body (infinite cross-sectional area), the water tank A1 is the storage tank 14.
Corresponding to this, the water surface natural vibration period (St) is approximated by the following equation.

S t=2π (A□/A)・(Q/g)...
...(1) Here A If 172 of the natural vibration period Ts of the water surface of the storage tank 14 of the breakwater main body 11 of this embodiment, which is determined by equation (1), matches the period of the incident wave introduced into the seawater introduction channel 13 from the outside port 3, the storage tank The water surface vibration time series waveform of No. 14 is schematically shown in Fig. 6 (a), and the water surface vibration time-series waveform of No. 14 is shown schematically as shown in Fig. 6 (a).
The flow velocity time-series waveform in Figure 6 (b) is shown in Figure 6 (b). The water level reaches its maximum, after which it shifts to free vibration again. Therefore, the flow velocity in the drainage channel 16 reaches a maximum at Ts/4 and reaches zero at Ts/2, and the flow velocity always fluctuates on the positive side, that is, on the inflow side, so that seawater can always flow in.

Furthermore, when we examined the wave height transmissibility and reflectance of the breakwater in this example, we found that the wave height transmissibility is 5% when the natural vibration period of the water surface of the water tank 14 is 1/2 synchronized with the period of the incident wave, as described above. It was confirmed through experiments that the reflectance was approximately 30%. In addition, as an index to evaluate the ability of this type of breakwater, energy loss (
Kloss).

K1oss= l−K r”−K t”−・−・・(
2) Here Kr: Reflectance Kt: Wave height transmissibility In the breakwater of this example, when the seawater exchange effect is maximum, K
r=°0.30. If Kt=0.05, K1oss
= 0,953, and it is considered that 95% of the wave energy is converted to flow energy.

It has the effect of wave reduction and low transmitted wave.

(Effects of the Invention) The seawater exchange breakwater of the present invention is constructed as described above, and is provided with a seawater introduction path having a converging side wall, and a storage tank for adjusting the natural vibration period is provided in the inner part of the seawater introduction path, so that it can be easily accessed from outside the port. Most of the waves that hit the ocean are converted into energy and consumed by the flow in the seawater introduction channel, and
The waves introduced into the storage tank are discharged to the inside of the port by natural flow, so the seawater exchange occurs while maintaining the calm inside the port. By matching the cycle of the incident waves, seawater from outside the port is constantly introduced into the inside of the port, creating a lively seawater exchange.

[Brief explanation of the drawing]

Fig. 1 is a vertical cross-sectional view showing a breakwater as an example of an embodiment of the present invention, Fig. 2 is a front view of the same, Fig. 3 is a cross-sectional view taken along the line mm in Fig. 1, and Fig. 4 is the same embodiment. 5(A) is a graph showing the water surface free vibration waveform of the communicating 2 tanks in FIG. 4, and (B) is a graph showing the flow velocity waveform in the pipe. Figure 6 (a) is a graph showing the water surface vibration time series waveform of the storage tank, Figure 6 (b) is a graph showing the flow velocity time series waveform of the drainage channel, and Figures 7 to 9 are graphs showing the time series waveform of water surface vibration in the water tank.
It is a longitudinal cross-sectional view showing an example of the type. 11... Breakwater main body, 13... Seawater introduction channel, 14... Storage tank, 16... Drainage channel, 18... Submerged bottom Wall, 19a, 19b...
... Convergence side wall.

Claims (1)

[Claims] A breakwater main body is provided to separate the outside of the port from the inside of the port, and a seawater introduction channel with an entrance opening on the outside of the port is provided at the top of the breakwater main body, and the seawater introduction channel is located at the bottom of the innermost part of the seawater introduction channel. A storage water tank for natural vibration period adjustment is provided which communicates with the waterway, and a drainage channel is provided to communicate from the lower part of the storage tank to the inner side of the port at the bottom of the breakwater main body, and the seawater introduction channel has a horizontal road width. A seawater exchange breakwater characterized by having a convergent side wall that narrows toward the inner part.