JP2000080623A - Permeable breakwater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve or maintain water quality in a harbor by providing a permeable breakwater for exchanging seawater in the harbor more costlessly and more efficiently as compared with a conventional permeable breakwater. SOLUTION: Open and protruded pipes 4, 4a, 4b communicating with opening parts 3, 3a, 3b are provided on permeable breakwaters 1, 1a, 1b having one or more horizontally opening parts 3, 3a, 3b of horizontally and perpendicularly different arrangement. Sea water is led through the opening parts 3, 3a, 3b and the open and protruded pipes 4, 4a, 4b to control a conducting amount of water by appropriately selecting an aperture, a shape, and a depth of the opening part 3, 3a, 3b and the open and protruded pipes 4, 4a, 4b, a direction and a length of the open and protruded pipes 4, 4a, 4b, for maintaining a water circulation in a harbor, so that the sea water can be efficiently exchanged.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission type breakwater for improving water quality by guiding water to the inside of a breakwater port inside a breakwater.

[0002]

2. Description of the Related Art In a highly closed port or fishing port, the exchange of seawater inside and outside the port is not performed smoothly, and the water quality in the port deteriorates, which is a serious problem. Especially in fishing ports where a part of the harbor is used as a farm, there is a problem that the deteriorated water quality has an adverse effect on the quality of seafood that is waiting to be shipped, and the amount of seafood shipped may decrease. .

For this reason, in recent years, the importance of seawater exchange inside and outside the port has been recognized, and a permeable breakwater that promotes seawater exchange inside and outside the port using tidal energy, and conversion of wave energy into water level difference inside and outside the port. Water-conducting breakwaters that supply seawater outside the port into the port have been actively introduced into the construction of harbors and fishing ports, and their effectiveness has been reported through field trials.

FIG. 10 is a perspective view showing an example of a conventional transparent breakwater (wave-dissipating block-covered perforated levee). FIG.
FIG. 1 is a perspective view showing an example of a conventional transmission type breakwater (seawater introduction work with a horizontal type submerged breakwater). Both of the conventional transmission breakwaters as shown in FIGS. 10 and 11 use seawater energy outside the harbor to raise the average water level outside the harbor at the breakwater, so that seawater is unilaterally supplied into the harbor. It is the one that leads to water.

[0005] In a portion below the water surface of the transmission type breakwater shown in Fig. 10, an opening is provided for allowing water to move inside and outside the port. Many breakwater blocks are installed outside the breakwater port. These wave-dissipating blocks are intended to maintain the water level outside the port higher than the water level inside the port and to ensure quietness inside the port.

The degree of the cross-sectional area of the opening (opening ratio) is a dominant parameter that determines the amount of seawater exchange. In addition, the length of the opening from the outside of the port to the inside of the port, that is, the bank width is a dominant parameter that determines the wave transmittance, and the wave transmittance can be reduced as the bank width is increased. Therefore, in order to keep the wave height of long-period transmitted waves with high transmittance low, or to maintain the calmness of the harbor at the port where large waves are dominant outside the port, measures such as setting a wide dike width are necessary. Therefore, it is necessary to reduce the wave transmittance.

On the other hand, in the transmission type breakwater shown in FIG. 11, a plurality of submerged embankments having different top-end water depths are provided at positions slightly separated from the upright embankment outside the harbor. Further, the space between the submerged embankment and the upright embankment is a retarding section. The water retarding section is defined by a partition wall corresponding to each of the submerged embankments. A water storage section is provided inside the port of the upright bank. In addition, a water pipe is provided so that water can be guided from the retarding section to the water storage section, and a water distribution pipe is provided so that water can be guided from the water storage section to the inside of the port.

[0008] In this transmission type breakwater, seawater accumulates in the water retarding portion due to the rise of the water level in the water retarding portion due to the waves propagating from the outside of the port, and the seawater flows into the water storage portion through the water conduit. Water is guided and stored in the water storage section.
Further, the water in the water reservoir flows into the port through the water distribution pipe, so that the water can be unilaterally guided to the port interior.

[0009]

However, the above-mentioned conventional breakwater has the following problems. FIG.
In the case of a conventional transmission type breakwater as shown in FIG. 0, there is a problem that it is necessary to install the wave-breaking block, so that cost and labor are required. Furthermore, as described above, in a port where high waves prevail outside the port, it is necessary to increase the width of the levee in order to ensure calmness in the port, but in this case, the cross-sectional area of the levee body is inevitably large. There was a problem that the construction cost was high. In addition, there is also a problem that the use area inside the harbor is narrowed due to the increase of the dike width, and the available water area decreases. In addition, if the embankment width can only be reduced due to construction cost, the transmitted wave height of long-period waves increases, so this method cannot be applied to places with strong perimeter waves. Problem.

On the other hand, in the case of the conventional transmission type breakwater as shown in FIG. 11, there is a problem that the construction cost is increased because it is necessary to install a structure such as a submerged wall and a partition wall which divides the water-reservation section. . In addition, the degree of seawater exchange depends only on the amount of water transfer that depends on the water level outside the port of the upright levee, but during low waves and low tide at ports with large tidal differences, etc. However, it is difficult to keep the seawater high, so that the amount of water conveyance is reduced, and seawater in the port is stagnated because seawater is not exchanged. Also,
On the other hand, in a port with a large difference in tide, the water surface is far above the submerged levee at the time of storm surge, and there is a problem that almost no water conveyance effect can be obtained. Therefore, there is a problem that the installation place is limited in a port where the wave height of the dominant waves is small or a port where the tide level difference is large, because the significance of the installation is reduced.

It is an object of the present invention to facilitate seawater exchange by maintaining water circulation in a port, and to provide a transmissive breakwater having a seawater exchange function for achieving this object. But also. The transmission type breakwater to be provided by the present invention does not require the installation of a wave-blocking block or a submergence like a conventional transmission type breakwater in order to enhance seawater exchange in the port, and also secures the calmness in the port. For this reason, it is not necessary to increase the width of the embankment (to reduce the transmittance), so that the construction cost can be reduced. Furthermore, the significant reduction of the embankment width and embankment cross-sectional area will make it possible to secure a wide available port water area.

[0012]

According to a first aspect of the present invention, there is provided a transmissive breakwater having an opening penetrating the inside and outside of a port, wherein the breakwater communicates with the opening. It is characterized by having an opening projecting pipe projecting inside the port.

The opening may be, for example, a cylindrical one. The opening may have any other shape as long as the inside is penetrated. For example, the opening may have a square cross section. And may be cylindrical. Further, the opening area of the opening can be appropriately changed.

The open projecting tube is, for example, a cylindrical one. The open projecting tube may have any other shape as long as the inside is penetrated. May be square and cylindrical. further,
The opening area of the opening projecting tube can also be appropriately changed.

The opening and the projecting tube may be provided, for example, one by one, but may be provided by a plurality of the same number. In addition, the installation water depth of the opening and the opening projecting pipe can be appropriately changed.

Here, in order to explain the effect of the transmission type breakwater according to the present invention, an outline of the results of a hydraulic experiment using a hydraulic model will be described.

The experiment was carried out under a constant water depth while changing the diameter of the opening projecting pipe, the installation water depth, the projection length, and the installation direction (either inside the port or outside the port). The wave height of the incident wave was calculated from the data of the wave gauge installed outside the harbor using the Goda method (incident reflection separation method), and the wave height of the transmitted wave was measured by the wave height meter installed inside the harbor. In addition, the flow velocity at the center of the entrance and exit of the projecting pipe was measured using two electromagnetic flowmeters.

As a result of the experiment, it has been found that the transmittance increases as the value of the waveform gradient of the incident wave (= wave height of the incident wave / wavelength of the incident wave) decreases and as the wavelength of the incident wave increases.
Further, it was found that the transmittance value decreased with an increase in the projection length of the opening projection tube. Furthermore, it was found that, when the projecting length of the opening projecting pipe is constant, the transmittance becomes larger when the opening projecting pipe is installed so as to project inside the port.

Further, it has been found that the smaller the diameter of the projecting tube, the more the transmission of the incident wave can be suppressed. That is, it is considered that the diameter of the opening projecting pipe corresponds to the opening ratio in the conventional transmission type breakwater. in this way,
The transmittance of the transmission type breakwater depends on the projection length of the opening projecting pipe, its diameter, and the projecting direction.

Further, it was found that the difference in transmittance with the change in the installation water depth of the opening projecting pipe became larger in the region where the incident wave waveform gradient Hi / L was larger (short-period incident wave). On the other hand, it was found that in a region where the waveform gradient Hi / L of the incident wave was small (long-period incident wave), almost no difference in transmittance due to a change in the installation water depth of the projecting pipe was observed. Therefore, it is considered that the installation water depth of the opening protruding pipe is a factor that suppresses transmission for short-period waves, but is not a main factor that suppresses transmission for long-period waves.

Further, it was found that the smaller the diameter of the projecting pipe and the shorter the projecting length of the projecting pipe, the larger the value of the maximum flow velocity at the port inner opening. That is, the amount of water conduction depends on the diameter of the projecting pipe and the length of the projecting pipe.

According to the first aspect of the present invention, water can be guided from outside the port to the port through the opening and the opening projecting pipe. The amount of water conduction depends on the diameter of the opening and the projecting tube, the projecting length of the projecting tube, the shape of the opening and projecting tube, the installation depth of the projecting opening and the projecting tube, and the quantity of the projecting opening and projecting tube. It can be adjusted by changing.

The wave transmittance is determined by the diameter of the projecting pipe,
Since it depends on the projecting length, the wave transmittance can be adjusted by appropriately changing the projecting length of the opening projecting pipe without increasing the width of the breakwater. Therefore, by setting the projecting length of the opening projecting tube large, the transmittance can be reduced, and the wave height of the transmitted wave can be suppressed even for a long-period wave having a high transmittance, so that high waves are prominent. Even in the harbor, calmness in the harbor can be maintained. On the other hand, for short-period waves, the transmittance can also be adjusted by adjusting the installation water depth. In addition, if the opening and the projecting pipe are submerged in the water, seawater can be exchanged by tide, so that the present invention can be applied to, for example, a port having a large tidal difference.

Further, since it is not necessary to increase the width of the embankment in order to reduce the transmittance, the construction cost can be reduced, and the reduction of the available port water area due to the expansion of the embankment width can be avoided. In addition, there is no need to install structures such as wave-dissipating blocks and submerged levee more than necessary for the stability of the embankment in order to reduce the transmittance and maintain the amount of seawater exchange. Can be reduced.

According to a second aspect of the present invention, there is provided a transmissive breakwater having an opening penetrating inside and outside a port, comprising an opening projecting pipe communicating with the opening and projecting outside the port. Features.

In the second aspect, the shape of the opening and the shape of the opening protruding tube are respectively the same as those of the first aspect,
It is the same as the opening projecting tube. Further, the opening area of the opening and the opening projecting tube in claim 2 can be appropriately changed.

In the second aspect, the opening portion and the opening protruding tube may be provided, for example, one by one, but may be provided by the same number of each. In addition, the installation water depth of the opening and the opening projecting pipe can be appropriately changed.

According to the second aspect of the present invention, similarly to the first aspect of the present invention, water can be guided from outside the port to the inside of the port through the opening and the opening projecting pipe. The amount of water conduction depends on the diameter of the opening and the projecting tube, the projecting length of the projecting tube, the shape of the opening and the projecting tube, the installation depth of the projecting tube and the projecting tube, and the quantity of the projecting tube and the projecting tube. It can be adjusted by changing.

Further, similarly to the first aspect of the present invention, the transmittance is reduced by setting the projecting length of the opening projecting tube to be large, and the transmitted wave is not affected by a long-period wave having a high transmittance. The wave height can be kept small, and calmness in the harbor can be maintained even in a port where high waves are dominant. On the other hand, for short-period waves, the transmittance can also be adjusted by adjusting the installation water depth.

Further, since it is not necessary to increase the width of the bank to reduce the transmittance, the construction cost can be reduced, and the reduction of the available water area in the port due to the wide bank can be avoided. In addition, there is no need to install structures such as wave-dissipating blocks and submerged levee more than necessary for the stability of the embankment in order to reduce the transmittance and maintain the amount of seawater exchange. Can be reduced.

However, in the second aspect of the present invention,
Since the opening projecting pipe projects to the outside of the harbor, the wave transmittance can be made smaller than in the case where the opening projecting pipe projects to the inside of the port.

According to a third aspect of the present invention, there is provided a transmission type having a first opening penetrating inside and outside a port, and a second opening arranged at a different horizontal position from the first opening. A breakwater, wherein the first opening is connected to the first opening and projects to the inside of the port; and the second opening is connected to the second opening and projects to the outside of the port. , Is provided.

The shapes of the first and second openings and the first and second opening projecting tubes in the third aspect are the same as those of the first and second openings in the first and second aspects, respectively. It is. Further, the first and second openings,
The opening area and installation water depth of the first and second opening projecting pipes can also be appropriately changed.

The first opening and the first opening protruding tube may be provided, for example, one by one, but may be provided by the same number of a plurality each. When both the first opening and the first opening projecting pipe are provided, a shape, a size, and an installation water depth can be appropriately changed. The same applies to the second opening and the second opening projecting tube.

According to the third aspect of the present invention, the first opening and the first opening protruding tube have the same effects as the first aspect of the invention, and the second opening and the first opening protruding tube have the same functions. The second opening projecting tube has the same effect as the second aspect of the invention.

Further, since the open projecting pipe projecting inward from the port has a higher wave transmittance and a larger amount of water flowing into the port than the open projecting pipe projecting outward from the port, the first open projecting pipe is used. The flow of water in the port can be generated along the flow of water conducted from the port. Here, in the second opening and the second opening protruding pipe, it is possible to control the amount and direction of water flowing into and out of the port. Therefore, the circulation of water in the port can be maintained, and the exchange of water in and out of the port can be performed smoothly.

According to a fourth aspect of the present invention, there is provided the transmission breakwater according to the third aspect, wherein the first projecting pipe has a larger diameter than the second projecting pipe. I have.

According to the fourth aspect of the present invention, since the diameter of the first projecting pipe is larger than that of the second projecting pipe, the amount of water conducted from the first projecting pipe is smaller. And water can be more smoothly circulated in the harbor,
Seawater exchange is also effective.

[0039]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will be described below with reference to FIGS.

FIG. 1 is a schematic perspective view showing a transmission type breakwater according to the present invention, FIG. 2 (a) is a schematic front view showing a transmission type breakwater according to the present invention, and FIG. 2 (b) is a side view of FIG. FIG. 3 is a schematic plan view showing an application example of the transmission type breakwater according to the present invention.

As shown in FIG. 1, the transmission breakwater 1
Is generally constituted by an embankment body 2, an opening 3 penetrating the embankment body 2 into and out of the port, and an opening projecting pipe 4 communicated with the opening 3. The opening 3 is, for example, cylindrical. The opening projecting tube 4 is also, for example, cylindrical.

The transmission type breakwaters 1a and 1b similar to the transmission type breakwater 1 are provided at different horizontal positions, for example, as shown in FIG. Transmissive breakwater 1a
The projecting pipe 4a projects from the inside of the harbor and is a transparent breakwater 1b.
The opening projecting pipe 4b projects outside the port. The opening projecting tube 4a has a larger diameter than the opening projecting tube 4b. Further, the opening 3a also has a larger diameter than the opening 3b.

Here, before describing the operation and effect of the transmission type breakwater according to the present invention, details of hydraulic experiment results using a hydraulic model will be described.

The experiment was performed using a two-dimensional wave-making water tank (length 65 m × width 1.0 m × height 1.6 m). The acrylic hydraulic model had a size of 1/20 of the assumed actual scale. Table 1 shows the specifications of the hydraulic model.

[Table 1] FIG. 4 is a schematic side view showing a hydraulic model and the like used in the hydraulic experiment. The hydraulic model is installed at a point 30 m from a wave plate (not shown).
And through the opening 51 only. In order to prevent a significant rise in the water level inside the harbor due to the transmission of waves, a water-blocking wall 52 capable of overflowing was installed at a position 25 m behind the model, and a wave-absorbing material 53 was installed in front of the wall. Table 2
Shows the experimental conditions.

[Table 2] The experiment was carried out under a constant water depth (h = 40 cm).
The measurement was performed by changing the aperture d of 0, the installation depth hs, the projection length l, the projection direction (either inside the port or outside the port), and the conditions of the incident wave. Wave height meter 57,5 installed outside the port
The wave height Hi of the incident wave was calculated from the data of No. 8 using the Goda method (incident reflection separation method), and the wave height Ht of the transmitted wave was measured by the wave height meter 54 installed inside the port. Further, the flow velocity at the center of the entrance and exit of the projecting pipe 50 was measured using two electromagnetic flowmeters 55 and 56. Further, wave pressure gauges were embedded at predetermined intervals above and below the opening protruding tube 50 and the opening 51, and pressure distribution was measured. Data collection was performed at a sampling frequency of 50 Hz for 90 seconds.

FIG. 5 shows the diameter d of the projecting pipe 50 of the hydraulic model.
FIG. 9 is a diagram showing experimental results when the setting water depth is 16 cm and the installation water depth hs is 18 cm. FIG. 5 shows the transmittance Kt when the protrusion length l and the protrusion direction are changed as experimental parameters.
The relationship between (= Ht / Hi) and the waveform gradient Hi / L of the incident wave is plotted. From FIG. 5, the waveform gradient H of the incident wave is shown.
It can be seen that the transmittance Kt increases as the value of i / L decreases and as the wavelength L of the incident wave increases. In particular, on the long-period wave side, the wave height Ht of the transmitted wave is equal to the wave height Hi of the incident wave.
It has been reduced to less than a percentage, and it can be judged that the calmness inside the port is sufficiently maintained. In addition, not only does the value of the transmittance Kt decrease with an increase in the projection length l, but also the transmittance increases when the sum of the lengths of the opening projecting tube 50 and the opening 51 (= l + B) doubles. It was also confirmed that it was reduced to about 1/2. Further, when the projection length l is constant, the transmittance Kt is larger when the opening projecting pipe 50 is installed so as to project inside the port. In other words, it is considered that the transmittance Kt largely depends on the protrusion length l, the sum of the lengths of the opening protrusion tube 50 and the opening 51 (= 1 + B), and the protrusion direction.

FIG. 6 is a diagram plotting the transmittance characteristics when the projecting length 1 of the opening projecting pipe 50 of the hydraulic model is 0 cm for each of the aperture d and the installation water depth hs. Focusing on the transmittance Kt when the diameter d of the opening projecting tube 50 is 16 cm,
The value of the transmittance Kt decreases as the installation water depth hs increases. Further, the difference in transmittance Kt accompanying a change in the installation water depth hs increases in a region where the waveform gradient Hi / L of the incident wave is large (an incident wave having a short period). On the other hand, in a region where the waveform gradient Hi / L of the incident wave is small (long-period incident wave), the above difference is hardly recognized. Therefore, it is considered that the installation water depth hs of the opening projecting pipe 50 is not a main factor for suppressing transmission of long-period waves.

FIG. 7 shows the projection length l of the opening projection pipe of the hydraulic model.
It is a figure which shows the transmittance | permeability characteristic at the time of = 20cm. FIG. 7 shows an experimental result when d and hs are changed as experimental parameters as in FIG. It is recognized that the transmittance characteristics when the aperture is d = 10 cm are halved compared to the characteristics when d = 16 cm. From this fact, it is considered that the diameter d of the opening projecting pipe 50 is an effective parameter for suppressing transmission of an incident wave, and corresponds to an aperture ratio in a conventional transmission type breakwater. From the above experimental results,
It is apparent that the transmittance Kt of the transmission type breakwater greatly depends on the projection length l of the opening projection pipe 50, its diameter d, and the installation direction.

FIG. 8A shows the maximum flow velocity Vx and the waveform gradient Hi of the incident wave at the port inner opening when the shape and the installation conditions of the opening projecting pipe 50 are changed as parameters.
/ L is plotted. The maximum flow velocity Vx at the port inside opening is the maximum value obtained by subjecting the data not affected by the re-reflected wave from the wave plate to the moving average processing at the wave period T. From the figure, it can be confirmed that when Hi is constant, the maximum flow velocity Vx at the port inner opening increases as the value of the waveform gradient Hi / L of the incident wave decreases, that is, as the wavelength L of the incident wave increases. Also,
As the wave height Hi of the incident wave increases, the value of the maximum flow velocity Vx at the port inner opening also increases, and it is also understood that the flow velocity at the port inner opening depends on the energy of the water particles of the incident wave. Focusing on the difference in the shape of the opening projecting tube 50,
When the diameter d and the total length (= 1 + B) become smaller, the value of the maximum flow velocity Vx at the port inside opening increases. This can be interpreted as that the flow rate of the incident wave under the same conditions is reduced depending on the friction loss and the volume of seawater in the pipe when passing through the pipe 50. The qualitative tendency of the maximum flow velocity Vx at the port inner opening with respect to the waveform gradient Hi / L of the incident wave is shown in FIG.
And the dimensionless flow velocity Ut (the dimensionless amount obtained by dividing the maximum flow velocity Vx at the port inside opening by the horizontal maximum flow velocity (Uimx) of water particles at the center of the port outside opening of the traveling wave based on the small amplitude wave theory) The relationship with the waveform gradient Hi / L can be similarly confirmed. In particular, the waveform gradient Hi / L of the incident wave
Focusing on the incident wave on the long cycle side where is smaller than 0.02,
The maximum flow velocity Vx at the port inside opening is 1.10 of Uimx.
The characteristic of the maximum flow velocity Vx at the port inner opening is Uimx based on the small amplitude wave theory.
It is considered that some factors cannot be explained by themselves. Further, with the increase in the installation water depth hs of the opening projecting pipe 50, the maximum flow velocity Vx at the port inside opening is shown from FIG.
Is found to decrease. This is probably because the larger the installation depth hs, the smaller the Uimx in the opening outside the port.

FIG. 9 is a diagram showing the relationship between Vm and η / h when the shape of the opening of the opening projecting tube 50 and the installation conditions are kept constant. Here, Vm is the flow velocity obtained by averaging the flow velocity at the port inside opening for each incident wave, and η is the water level obtained by averaging the height from the still water surface to the free water surface outside the port for each incident wave. Based on FIG. 9 in which the period T of the incident wave is adopted as an experimental parameter, it can be seen that Vm has a tendency to increase as η / h increases and the wave period T decreases.

According to the transmission type breakwaters 1a and 1b according to the present invention, the openings 3a and 3b and the opening projecting pipe 4 are provided.
Water can be guided from outside the port to the inside of the port through a and 4b. Therefore, the seawater can be exchanged in the port, and the water quality in the port can be improved.

Further, as can be inferred from the above experimental results, the amount of water can be adjusted by appropriately changing the diameters of the projecting pipes 4a and 4b and the projecting lengths of the projecting pipes 4a and 4b.

Since the transmittance of the waves depends on the diameter and the projecting length of the projecting pipes 4a and 4b, the projecting length of the projecting pipes 4a and 4b can be appropriately changed without increasing the width of the breakwater. The wave transmittance can be adjusted. Therefore, the opening projecting pipe 4
By setting the protrusion lengths of a and 4b large, the transmittance can be reduced, and the wave height of the transmitted wave can be suppressed even for a long-period wave having a high transmittance, and even in a port where high waves are dominant. The calm in the harbor can be maintained. On the other hand, for short-periodic waves, the transmittance can also be adjusted by adjusting the installation depth of the opening projecting pipes 4a and 4b.

Further, since it is not necessary to increase the width of the embankment to reduce the transmittance, the construction cost can be reduced, and the reduction of the available port water area due to the expansion of the embankment width can be avoided. In addition, there is no need to install structures such as wave-dissipating blocks and submerged levee more than necessary for the stability of the embankment in order to reduce the transmittance and maintain the amount of seawater exchange. Can be reduced.

In addition, an opening projecting pipe 4b projecting outside the port
Since the opening projecting pipe 4a projecting more toward the inside of the port has a higher transmittance and a large amount of water flowing into the port inside, the flow of water in the port along the flow of water guided from the opening projecting pipe 4a is reduced. (Arrow A in FIG. 3). In addition, the water flow in the port including the amount of water conducted from the opening projecting pipe 1a can control the flow of water to the inside or outside of the port in the opening projecting pipe 1b. Therefore, the circulation of water in the port (circulation in the port) can be performed smoothly, and the exchange of water inside and outside the port can be effectively performed. Further, the opening projecting tube 1a is
By making the diameter larger than that of the opening projecting pipe 1b, the inflow from the opening projecting pipe 1a becomes larger than that of the opening projecting pipe 1b, so that the water can be more smoothly circulated in the port. , Seawater exchange is promoted. Therefore, it is possible to effectively improve or maintain the water quality in the port.

In the above embodiment (FIG. 3),
Although the first opening, the first opening protruding tube, the second opening, and the second opening protruding tube are provided one by one,
These numbers can be changed as appropriate. Furthermore, it is also possible to change the amount of water introduction by changing the length, shape, and installation water depth of the first and second openings and the first and second opening projecting pipes. In addition, for one opening, both an opening projecting pipe projecting inside the port and an opening projecting tube projecting outside the port may be provided. In this case, the length of the opening projecting pipe projecting to the inside of the port and the length of the opening projecting pipe projecting to the outside of the port may be the same, or a difference may occur. Further, when both the first opening projecting tube and the second opening projecting tube are provided as in the embodiment, it is necessary to make the first opening projecting tube larger in diameter than the second opening projecting tube. However, for example, the diameter may be the same, and in some cases,
The second projecting tube may have a larger diameter. That is,
The arrangement and shape of the opening and the opening projecting pipe can be appropriately changed according to the installation sea area, the shape of the port, the demands of the manager and the user, and the like.

[0056]

According to the transmission type breakwater according to the first aspect of the present invention, water can be guided from outside the port into the port through the opening and the projecting pipe. Therefore, the seawater can be exchanged in the port, and the water quality in the port can be improved or maintained. The amount of water conduction depends on the diameter of the opening and the projecting tube, the projecting length of the projecting tube, the shape of the opening and projecting tube, the installation depth of the projecting opening and the projecting tube, and the quantity of the projecting opening and projecting tube. It can be adjusted by changing.

The transmittance can be adjusted by appropriately adjusting the projection length of the opening projection tube. For example, the degree of calmness in a harbor can be maintained even in a place where waves are strong. For short-period waves, the transmittance can also be adjusted by adjusting the installation water depth.

In addition, if the opening and the projecting pipe are submerged in the water, seawater can be exchanged by the tide, so that the present invention can be applied to, for example, a port having a large difference in tide level.

Further, since it is not necessary to increase the width of the embankment in order to reduce the transmittance, the construction cost can be reduced, and the reduction of the available port water area due to the expansion of the embankment width can be avoided. In addition, there is no need to install structures such as wave-dissipating blocks and submerged levee more than necessary for the stability of the embankment in order to reduce the transmittance and maintain the amount of seawater exchange. Can be reduced.

According to the transmission type breakwater according to the second aspect of the invention, substantially the same effects as those of the first aspect of the invention can be obtained. However, in the second aspect of the invention, since the opening projecting pipe projects to the outside of the port, the transmittance can be made smaller than when the opening projecting pipe projects to the inside of the port as in the first aspect of the invention. .

According to the transmission type breakwater according to the third aspect of the present invention, the open projecting pipe projecting inward from the port has a higher transmittance than the open projecting pipe projecting outward from the port, and the amount of water introduced into the port is improved. Because there are many, the flow of water in the port can be generated along the flow of water guided from the first opening projecting pipe, so that water circulation in the port is maintained, and Exchange of water can be performed smoothly. Therefore, improvement or maintenance of water quality can be effectively performed.

According to the transmission type breakwater according to the fourth aspect of the present invention, since the first opening projecting pipe has a larger diameter than the second opening projecting pipe, the first opening projecting pipe has a larger diameter than the second opening projecting pipe. Also, since more water enters the port through the first opening projecting pipe, the water can be more smoothly circulated in the port. Therefore, improvement or maintenance of water quality can be performed more effectively.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing a transmission type breakwater according to the present invention.

FIG. 2A is a schematic front view showing a transmission type breakwater according to the present invention, and FIG. 2B is a side view of FIG.

FIG. 3 is a schematic plan view showing an application example of a transmission type breakwater according to the present invention.

FIG. 4 is a schematic side view showing a hydraulic model and the like used in a hydraulic experiment.

FIG. 5 is a view showing an experimental result in a case where a diameter of an opening projecting pipe of a hydraulic model is 16 cm and an installation water depth is 18 cm.

FIG. 6 is a diagram in which the transmittance characteristics when the protrusion length of the opening protrusion pipe of the hydraulic model is 0 cm are plotted for each diameter and installation water depth.

FIG. 7 is a diagram showing transmittance characteristics when the opening length of the opening projecting pipe of the hydraulic model is 20 cm.

8A is a diagram showing the relationship between the maximum flow velocity and the incident wave waveform gradient at the port inside opening when the shape of the projecting pipe and the installation conditions are changed, and FIG. FIG. 9 is a diagram showing a relationship between a maximum velocity at an inner port opening and a dimensionless quantity obtained by dividing a maximum velocity of a water particle at a center of an outer port opening of a traveling wave based on a small amplitude wave theory) and a waveform gradient of an incident wave. .

FIG. 9 is a graph showing the flow rate of the incident wave 1 at the port inner opening when the shape and installation conditions of the opening of the projecting pipe are constant.
It is a figure which shows the relationship between the flow velocity averaged for every wave, and the value which divided the water level which averaged the height from the still water surface outside a port to the free water surface for every incident wave by the water depth.

FIG. 10 is a perspective view showing an example of a conventional transmission type breakwater (wave-dissipating block-covered perforated breakwater).

FIG. 11 is a perspective view showing an example of a conventional transmission type breakwater (seawater introduction work with side-by-side submerged levee).

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 transmission type breakwater 1a transmission type breakwater 1b transmission type breakwater 3 opening 3a first opening 3b second opening 4 opening projecting tube 4a first opening projecting tube 4b second opening projecting tube

Claims (4)

[Claims] 1. A transmission type breakwater having an opening penetrating both inside and outside a port, comprising: an opening projecting pipe communicating with the opening and protruding inside the port. . 2. A penetrating breakwater having an opening penetrating inside and outside a port, comprising: an opening projecting pipe communicating with the opening and protruding outside the port. . 3. A first opening penetrating inside and outside the port,
A transmissive breakwater having the first opening and a second opening arranged at a different horizontal position, wherein the first opening is communicated with the first opening and protrudes inside the port. A transmission type breakwater, comprising: a pipe; and a second opening protruding pipe that is communicated with the second opening and protrudes outside the port. 4. The apparatus according to claim 3, wherein said first projecting pipe has a larger diameter than said second projecting pipe.
The see-through breakwater described.