JPH0569929B2 - - Google Patents

Description

[Detailed description of the invention] Industrial applications The present invention relates to a wave-dissipating module.

Conventional technology As a conventional wave-dissipating wall such as a breakwater, for example, Japanese Patent Application No. 61-214918 (Japanese Patent Application No. 63-70706)
As disclosed in , it is known that a plurality of wave-dissipating pipe-like structures are stacked vertically and horizontally, with an opening at one end located on the outside of the bay and an opening at the other end located inside the bay. . Here, the pipe-like structure is generally one in which a wave dissipating pipe made of cast iron or the like and having an irregular cross section is buried inside a square columnar concrete block. According to such a configuration, when waves traveling from the outside of the bay pass through the wave-dissipating tube, they are attenuated due to changes in the cross-sectional area of the passage within the wave-dissipating tube.

Problems to be Solved by the Invention However, in the conventional configuration, if the cross-sectional area of the flow path of the wave-dissipating tube is increased to make it easier for waves to enter the wave-dissipating tube and to lower the reflectance of waves,
There was a problem that the transmittance of waves increased and the wave-dissipating effect weakened.

SUMMARY OF THE INVENTION An object of the present invention is to provide a wave-dissipating module that reduces wave reflectance and wave transmittance.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention has a wave-dissipating hole in which a narrow passage portion having a smaller cross-sectional area than the opening is formed, and one end side of the wave-dissipating hole is In the wave-dissipating module, which is arranged with its opening facing the direction of wave propagation, the narrow passage is formed by a thin plate-shaped annular protrusion.

Another preferable configuration of the present invention is that an annular inclined surface portion continuing to the inner circumferential surface of the wave-dissipating hole is provided on one side of the annular protrusion portion corresponding to the wave inflow direction.

Furthermore, another favorable configuration of the present invention is that annular inclined surface portions continuing to the inner circumferential surface of the wave-dissipating hole are provided on both sides of the annular protrusion in the axial direction of the wave-dissipating hole.

Furthermore, in another preferred configuration of the present invention, narrow passages formed by annular protrusions are provided at both ends of the wave-dissipating hole, and narrow passages formed by annular protrusions are provided on both sides of the respective annular protrusions on the inner circumferential surface of the wave-dissipating hole. A continuous annular inclined surface portion is provided.

Furthermore, another favorable configuration of the present invention is that the wave-dissipating hole is provided with a plurality of annular protrusions, and the flow path diameter of the narrow passage portion formed by each annular protrusion is set to an arbitrary and appropriate size. It is something.

Furthermore, another preferable configuration of the present invention is that the narrow passage portion formed by the annular protrusion is provided at a position eccentric to the axis of the wave-dissipating hole.

Effect With the above configuration, the wave-dissipating hole has a small channel cross-sectional area at the narrow passage portion and a large channel cross-sectional area before and after the narrow passage portion, so that the wave-dissipating hole has a shape that changes as the channel cross-sectional area expands and contracts. . Therefore, waves flowing into the wave-dissipating hole from the opening are absorbed, attenuated, and dissipated by expanding and contracting the cross-sectional area of the channel. In particular, when passing through a narrow passage, the flow of waves is disturbed by the resistance of the annular protrusion, which is plate-shaped and has a surface perpendicular to the axis of the wave-dissipating hole. A separation vortex is generated at the inner peripheral edge of the For this reason, the wave after passing through the narrow passage has its wave energy absorbed by the change in the cross-sectional area of the flow passage, and is also subjected to resistance by the separated vortices, increasing the wave dissipation efficiency. It will be done. In addition, in addition to the wave-dissipating effect caused by the change in the cross-sectional area of the flow path of the wave-dissipating hole, waves are also subjected to a wave-dissipating effect caused by the resistance caused by the separated vortices, which increases the reflectance of waves in the wave-dissipating module. The resistance of the separated vortices reduces the wave transmittance in the wave-dissipating module without causing a reduction in the cross-sectional area of the flow path.

Furthermore, by providing an annular slope on one side of the annular protrusion, the flow of waves that have entered the inside of the wave-dissipating hole is smoothly guided to the narrow passage, reducing the reflectance of waves at the wave-dissipating module. Ru.

In addition, by providing annular inclined surfaces on both sides of the annular protrusion, waves can be dissipated by smoothly guiding the flow of waves into the narrow passage in response to waves flowing in both directions from the openings at both ends of the wave-dissipating hole. The reflectance of waves on the module can be reduced.

Furthermore, by providing the annular protrusions at both ends of the wave-dissipating hole, it is possible to perform a wave-dissipating action in response to waves propagating in both directions toward the openings at both ends of the wave-dissipating hole. In addition, waves in each direction are subjected to double wave-dissipating effects by the annular protrusion located on the inflow side and the annular protrusion located on the outflow side, so the wave-dissipating efficiency as a wave-dissipating module is synergistic. It is raised to

In addition, by providing a plurality of annular protrusions in the wave-dissipating hole and setting the flow path diameter of each channel to an appropriate size, waves flowing into the wave-dissipating hole can be
The wave-dissipating effect of the annular protrusion is applied in multiple stages, synergistically increasing the wave-dissipating efficiency of the wave-dissipating module, and the channel diameter of the narrow passage section is set to an appropriate size to reflect waves. rate can be reduced.

In addition, by providing the narrow passage at a position eccentric to the axis of the wave-dissipating hole, the effect of disrupting the flow of waves flowing into the wave-dissipating hole by the annular protrusion is improved, further reducing transmittance. be done.

Embodiment Hereinafter, an embodiment of the present invention will be described based on the drawings. In FIG. 1, a wave-dissipating module 1 has a wave-dissipating hole 2 extending axially through the cast iron pipe 3, and a concrete block 4 having a rectangular cross section is formed around the cast iron pipe 3. Note that the pipe is not limited to the cast iron pipe 3, but may be other metal pipes, resin pipes, concrete pipes, etc. In the middle of the cast iron pipe 3, an annular protrusion 5 is provided along the inner circumference of the pipe, and this annular protrusion 5 allows openings 2a, 2b at both ends of the wave-dissipating hole 2 to be formed in the middle of the wave-dissipating hole. A narrow passage portion 6 having a smaller flow passage cross-sectional area is formed. The annular protrusion 5 has a thin plate shape, and the inner peripheral edge 7 is formed into an angular shape. Further, on one side of the annular protrusion 5, an annular inclined surface portion 8 is provided which continues to the inner circumferential surface of the cast iron pipe 3, and the wave dissipating module 1 has an opening 2 on the side where the annular inclined surface portion 8 is provided.
It is arranged with a facing the direction in which the waves 9 propagate.

Hereinafter, the effects of the above configuration will be explained. First, the wave-dissipating hole 2 has a small flow cross-sectional area at the narrow passage portion 6 and a large flow passage cross-sectional area before and after the narrow passage portion 6, so that the wave-dissipating hole 2 has a shape that changes as the flow passage cross-sectional area expands and contracts. . Therefore, the waves 9 flowing into the wave-dissipating hole 2 through the opening 2a have their wave energy absorbed, attenuated, and dissipated by expanding and contracting the cross-sectional area of the channel. In particular, when passing through the narrow passage section 6, the wave 9 receives resistance from the annular protrusion section 5 which is plate-shaped and has a surface perpendicular to the axis of the wave-dissipating hole, and its flow is disturbed. A separation vortex 10 is generated at the inner circumferential edge 7 of the annular protrusion 5 . For this reason, the wave after passing through the narrow passage section 6 has its wave energy absorbed by the change in the cross-sectional area of the channel, and is also subjected to resistance by the separation vortex 10, which reduces the wave dissipation efficiency. It can be further enhanced. Therefore, by giving the waves 9 a wave-dissipating effect by the separated vortices 10, the waves 9 can be dissipated without increasing the reflectance of the waves 9 in the wave-dissipating module 1.
can reduce the transmittance of Note that reflectance=(reflected wave height−incident wave height)/incident wave height, and transmittance=transmitted wave height/incident wave height.

Furthermore, the annular inclined surface portion 8 smoothly guides the flow of waves 9 to the narrow passage portion 6, thereby further reducing the reflectance.

Next, in the one shown in FIG. 2, annular inclined surface portions 8 are provided on both sides of the annular projection portion 5. According to this configuration, water flows in from the openings 2a and 2b at both ends of the wave-dissipating hole 2. With respect to the bidirectional waves 9, the flow of the waves 9 is smoothly guided to the narrow passage section 6 by the annular slope section 8, and the reflectance of the waves 9 at the dissipation module can be reduced.

Next, in the one shown in FIG. 3, annular protrusions 5 are provided at both ends of the wave-dissipating hole 2. According to this configuration, the annular protrusions 5 are provided at both ends of the wave-dissipating hole 2. A wave-dissipating action can be performed in response to waves 9 propagating in both directions. Moreover, the annular protrusion 5 where the waves 9 in each direction are located on the inflow side.
Since the wave-dissipating effect is doubled by the annular protrusion 5 located on the outflow side and the wave-dissipating effect, the wave-dissipating efficiency as a wave-dissipating module is synergistically enhanced.

Next, what is shown in FIG. 4 is one in which a plurality of annular protrusions 5 are provided in the wave-dissipating hole 2, and the flow path diameter in each narrow passage part 6 is set to any appropriate size. According to this configuration, the wave-dissipating action of the annular protrusion 5 is applied to the waves 9 flowing into the wave-dissipating hole 2 in multiple stages, and the wave-dissipating efficiency of the wave-dissipating module 1 is synergistically increased. At the same time, the flow path diameter of the narrow passage portion 6 is set to an appropriate size to prevent waves 9.
can reduce the reflectance of

Furthermore, in the case shown in FIGS. 5a, b, and c, the narrow passage portion 6 is provided at a position eccentric to the axis of the wave-absorbing hole 2. According to this configuration, the wave-absorbing hole The effect of disturbing the flow of waves 9 flowing into the wave breaking module 2 by the annular protrusion 5 is improved, and the transmittance of the wave dissipating module 1 is further reduced.

In any of the above embodiments,
The thinner the wall thickness of the annular protrusion 5, the better. However, industrially, the materials used and the wall thickness must be determined in consideration of strength, corrosion resistance, erosion resistance, etc. In addition, from a hydraulic point of view, a wall thickness of 100 mm or less is desirable.

As shown in FIG. 6, the shapes of the annular protrusion 5 and the annular inclined surface 8 are such that A/B>0.10, tanθ
=B/l and θ<60° is standard.

Next, the results of experiments conducted using the wave-dissipating module 1 of the present invention will be explained.

What is shown in FIG. 7a is an experimental model of the wave-dissipating module 1 formed according to the present invention, and the wave-dissipating hole 2 has a diameter of 1000 mm and a total length of 3000 mm. Further, the annular protrusion 5 and the annular inclined surface 8
The shape is formed such that A/B=0.32 and θ=45°, and the flow path in the narrow passage portion 6 has a diameter of 500 mm. Furthermore, the one shown in Fig. 7b is an experimental model of a conventional wave-dissipating module, in which the narrow passage is simply formed by an inclined surface of θ = 45° without providing an annular protrusion in the narrow passage. . Other components are the same as those in FIG. 7a. And wave height (H) 0.5-6.0m, wavelength
Assuming the conditions of (L) 30 to 150 m and water depth (h) 5 to 20 m, we experimented with both of the above wave-dissipating modules at a similarity rate of 1/10 in an aquarium with a length of 50 m, width of 1 m, and depth of 1.5 m. The results are shown in Figure 8. Here, reflectance (KR) and transmittance (KT) are as defined before.

As is clear from FIG. 8, according to the wave-dissipating module formed based on the present invention, the wave-dissipating efficiency is increased by reducing the transmittance while reducing the reflectance overall compared to the conventional one. be able to.

Next, the one shown in Fig. 9a is an experimental model of the present invention with a total length of 3000 mm, and the one shown in Fig. 9b is a combination of two of the ones in Fig. 9a, with a total length of 3000 mm.
It is set to 6000mm. And Figure 10 shows
This figure shows the results of experiments using both of the wave-dissipating modules described above. However, with regard to the one shown in FIG. 9b, two types of experiments were conducted: one in which the total length was simply 6000 mm, and one in which annular protrusions were provided at both ends of the wave-dissipating hole.

As is clear from FIG. 10, by lengthening the wave-dissipating hole and providing annular protrusions at both ends, the transmittance can be further reduced, although the reflectance is increased somewhat. Furthermore, when installing the actual product, efficient wave dissipation can be achieved by appropriately combining wave dissipating modules in consideration of the installation conditions.

Effects of the Invention As described above, according to the present invention, by forming a narrow passage portion in the wave-dissipating hole using a plate-shaped annular protrusion, transmittance can be reduced without increasing reflectance. The wave-dissipating efficiency of the wave-dissipating module can be improved.

[Brief explanation of drawings]

FIG. 1 is an overall sectional view showing an embodiment of the present invention;
FIG. 2 is an overall sectional view showing another embodiment of the present invention;
FIG. 3 is an overall sectional view showing still another embodiment of the present invention, FIG. 4 is an overall sectional view showing still another embodiment of the invention, and FIGS. 6 is an enlarged sectional view of the annular protrusion, FIG. 7a is a diagram showing an experimental model of the wave-dissipating module of the present invention, and FIG. 7b is an experiment of the conventional wave-dissipating module. Figure showing the model, Figure 8 is Figure 7a
FIG. 9a is a diagram showing one experimental model of the wave-dissipating module of the present invention, and FIG. 9b is a diagram showing another experimental model of the wave-dissipating module of the present invention. Figure 10 shows the 9th
FIG. 9 is a diagram showing experimental results using the experimental models of FIG. 9a and FIG. 9b. 1... Wave-dissipating module, 2... Wave-dissipating hole, 3...
Cast iron pipe, 4... Concrete block, 5... Annular protrusion, 6... Narrow section, 7... Inner peripheral edge, 8
... Annular inclined surface portion, 9 ... Waves, 10 ... Separated vortex.

Claims (1)

[Claims] 1. A wave-dissipating hole in which a narrow passage portion having a flow passage cross-sectional area smaller than the opening is formed, and the opening at one end of the wave-dissipating hole is arranged with the opening on one end side facing the wave propagation direction. A wave-dissipating module characterized in that the narrow passage portion is formed by a thin plate-shaped annular protrusion. 2. The wave-dissipating module according to claim 1, characterized in that an annular inclined surface portion continuing to the inner circumferential surface of the wave-dissipating hole is provided on one side of the annular protrusion corresponding to the wave inflow direction. 3. The wave-dissipating module according to claim 1, wherein an annular inclined surface portion continuing to the inner circumferential surface of the wave-dissipating hole is provided on both sides of the annular protrusion in the axial direction of the wave-dissipating hole. 4. Narrow passages formed by annular protrusions are provided at both ends of the wave-dissipating hole, and annular inclined surface portions continuing to the inner peripheral surface of the wave-dissipating hole are provided on both sides of each annular protrusion. The wave-dissipating module according to claim 1. 5. The wave-dissipating device according to claim 1, wherein the wave-dissipating hole is provided with a plurality of annular protrusions, and the flow path diameter of the narrow passage portion formed by each annular protrusion is set to any appropriate size. Module. 6. The wave-dissipating module according to claim 1, wherein the narrow passage portion formed by the annular projection is provided at a position eccentric to the axis of the wave-dissipating hole.