JPS62276113A - Wave breaking structure - Google Patents

Abstract

PURPOSE:To raise the wave breaking effect of a wave breaking structure by a method in which the interval between at least three rows of equidistant upright walls and the final wall is regulated to a given multiple of the wavelength of waves and also the area of the through openings of the top and middle walls is specified. CONSTITUTION:Three rows of upright walls 4a, 4b, and 4c are formed at a fixed interval on the base 3 on the seabed ground 8 to form water-retarding areas 5a and 5b. Rectangular holes 7 are formed among a plurality of columns 6 formed in the middle wall 4b and the top wall 4a to make up a wave breaking structure 1. The interval between the wall 4a and the final wall 4c is regulated to about 0.2-0.25 times the wavelength of incoming waves, and the area of the hole 7 under water surface 2 is also regulated to an opening ratio divided by the whole area of the upright wall 4 under water surface 2. The opening ratio is 0.3-0.4 for the wall 4a and 0.1-0.2 for the wall 4b. The intervals between the walls in the water-retarding areas 5a and 5b are almost equalized.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention "Field of Industrial Application" This invention is for dissipating waves that attack ports and coasts! ! Q Regarding the wave-dissipating structure installed.

"Prior Art" Generally, wave-dissipating structures are sometimes installed in ports and coasts for the purpose of calming the sea areas around them. Conventionally proposed wave-dissipating structures with low reflectance include, for example, two rows of serial walls forming one water retarding section between them, and the top upright wall having a transparent structure. Are known. According to this wave-dissipating structure, when an incoming wave passes through the leading upright wall, its direction of travel is disturbed, reducing the wave's energy, which is further reflected by the trailing upright wall. The waves that have entered the retarding portion and the waves that have entered the retarding portion cancel each other out due to their respective phase differences within the retarding portion. Therefore, by appropriately selecting the width of this water retarding section, it is possible to realize a wave-dissipating structure with low reflectance.

[Problems to be Solved by the Invention] By the way, since the conventional Urahami structure with low reflectance is composed of one water retarding section and one upright wall of a transparent structure, the width of the water retarding section is It shows a significant wave-dissipating effect only for waves with a specific period, where is approximately multiplied by a constant. Therefore, waves with a wide range of periods come! There was a problem in that the desired wave-dissipating effect could not be achieved in actual sea areas.

This invention deals with the problem of how to realize a wave-dissipating structure that can be expected to have a good Urahami effect against waves with a wide range of periods.

"Means for Solving the Problems" This invention provides at least three rows of upright walls to form a plurality of water retarding sections therebetween, and at least the first and middle upright walls of the upright walls are made up of columnar rows. In a wave-dissipating structure having a transmission structure, the distance between the leading upright wall and the rearmost upright wall is 0.2 to 0.2 of the wavelength of the incoming wave.
0.25 times, and the value of the aperture ratio of the top upright wall is 0.25.
3 to 0°4, the aperture ratio of the intermediate upright walls to be within the range of 0.1 to 0.2, and the wall spacing in the water retarding portion between each of the upright walls to be approximately equal. The above-mentioned problems are solved by configuring a wave-dissipating structure like this.

Here, the wave-dissipating structure preferably has a box-shaped caisson configuration.

"Operation" In the present invention, when an incoming wave passes through the leading and intermediate upright walls, the traveling direction of the wave is disturbed before and after the wave, thereby reducing its energy. Furthermore, within the water retarding parts between the upright walls, the reflected waves and the waves entering each water retarding part cancel each other out due to their respective phase differences.
This reduces reflected waves. In particular, when the wave wavelength is short, the water retarding parts between the leading and middle upright walls cancel each other out, and when the wave wavelength is long, the water retarding parts work together to cancel each other out.

"Embodiments" Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing a wave-dissipating structure according to a first embodiment of the present invention. In FIG. 1, reference numeral 81 is a wave-dissipating structure, and this wave-dissipating structure 1 is constructed by placing its base 3 on the seabed ground 8 in the sea surface 2 where waves attack from six directions of arrows. is set up. The wave-dissipating structure 1 includes three rows of upright walls 4a, 4b, and 4C arranged at regular intervals on the base 3. Between the first upright wall 4a and the middle upright wall 4b, and between the middle upright wall 4b and the last upright wall 4c,
Water retarding portions 5a and 5b are formed, respectively. The leading upright wall 4a and the middle upright wall 4b are composed of columns 6.6, .
... are arranged in a row, so that each vertical wall 4
a and 4b have a transparent structure. A rectangular hole 7 (opening) is formed between the columns 6.6.

In the wave-dissipating structure 1, the distance between the leading upright wall 4a and the rearmost upright wall 4C is 0.2 to 0 of the wavelength of the incoming wave.
．． It is formed to have a magnification of 25 times. The leading upright wall 4a has an opening ratio (the area of the opening 7 below the water surface 2 divided by the area of the upright wall 4 below the water surface 2) of 0.3 to 0°4. Further, the intermediate upright wall 4b has a 1 m opening ratio of 0.1 to 0.2.
It is formed so that it is within the range of . A water retarding portion 5 is formed between the leading and intermediate upright walls 4a and 4b.
The wall spacing at a is the middle and rearmost upright walls 4b,
It is formed to be approximately equal to the wall surface spacing in the water retarding portion 5b formed between the water retarding portions 4c and 4c.

After this Uranami structure 1 is manufactured on land, it is floated in the sea using a float or the like with the leading upright wall 4a facing upward, and then towed to a predetermined position in the sea by a towing boat or the like. After pointing downward, the base 3 is placed on the seabed 18,
Fixed and installed.

In the wave-dissipating structure 1 configured as described above, waves attacking from the six directions of the arrows are directed to the top and middle upright walls 4a,
When passing through 4b, the traveling direction of the wave is disturbed before and after the wave, thereby reducing its energy. Furthermore, in this wave-dissipating structure 1, upright walls 4a, 4b, 4
In the water retarding parts 5a, 5b between C, the waves emitted by the intermediate and rearmost upright walls 4b, 4c and the respective water retarding parts 5a, 5
The waves entering b cancel each other out due to their respective phase differences, thereby reducing the reflected waves from the wave-dissipating structure 1. In particular, when the wave wavelength is short, the water retarding section 5a between the leading and intermediate upright walls 4a and 4b is formed, and when the wave wavelength is long, the water retarding sections 5a and 5b are integrated into the water retarding section. The waves within 5a and 5b cancel each other out. Therefore,
The structural conditions of this wave-dissipating structure 1, namely the distance between the leading upright wall 4a and the rearmost upright wall 4C, the frontage ratio of the upright walls 4a and 4b of each transmission structure, and each retarding section 5a.

By limiting the ratio of the wall spacing in 5b to an appropriate value, it is possible to realize a wave-dampening structure 1 that can be expected to have a good wave-dampening effect on waves with a wide range of periods.

The optimal range of the structural conditions is determined by the following theory and experimental results. First, as shown in FIGS. 2 and 3, the first,
A case will be considered in which an incident wave acts obliquely on the N-fold transmission wall type wave-dissipating structure 1 configured by installing the second, . . . , N-th transmission walls 21, 21, . In the case of a two-set transmission wall type wave-absorbing structure taken up in the present invention, it is sufficient to set N=2 in the following expansion formula. Here, the wave 22 with wavelength L travels in the direction of arrow A. Further, the first or leading transparent wall 21 is provided with an origin O at a location where it touches the sea surface 2, and the X axis is provided on the sea surface 2 from this origin O in a direction perpendicular to the normal line of the structure. At the same time, the Y-axis is provided on the sea surface 2 from this origin O along the normal line of the structure, and the Z-axis is provided perpendicularly above the sea surface 2 from this origin. X! J's-1 place f5t(s
=1.2. −.

No. S of wall thickness bs installed at N madashi J' 0-0)
The transparent wall 21 has an open portion where -dz S≦2≦-dzs 1, and has an impermeable structure in other portions. Furthermore, it is assumed that an impermeable wall is installed at the position of X=J'H. Here, in the following theory, the wall thickness of each transparent wall 21 is theoretically assumed to be sufficiently thin, and therefore, the shadow W range of discontinuity of water flow due to each transparent wall 21 is very large compared to the wavelength. Assume it is small.

The fluid region delimited by the permeable walls 21, 21,...
In the order in which the wave 22 advances: (1), (2), ..., (N+
It is named 1>. The depth of this fluid region is −
hl, -h2,..., -11N++.

The wave-dissipating structure 1 having the above structure has a frequency σ(−2π
Let us consider the case where a wave having the period 22) is incident at an angle of θ with the X axis. The movement of this wave 22 is
It is assumed to be a small amplitude wave in a perfect fluid, and the velocity potential Φr (X, y, Z; t
)−φr (x, y, z)eI(rtJ(r =
1, 2. .

C;=l, Z, -----, N-1-1-1 (do)-
-----(,3) Here, the distance between each transparent wall 21.21 1s=,1'S
J' S−+ −bs (s wl, 2. ・=
, N), A is the incident wave, B is the reflected wave, and 0(j
ゝ, E(j), H are standing waves, Cn, F n”, G
n'', I n are complex constants representing scattered waves in each fluid region. Also, k and kn are given as the characteristic ff+ of the following equation, where 0 is the gravitational acceleration.

Considering that the width of the opening in the transmission wall is extremely small relative to the incident wavelength, the flow velocity component US (Z) (S-1, 2, ·, N> in the X-axis direction is dominant in this opening). Therefore, the flow velocity component US in the X-axis direction
(Z) and each velocity potential φS are related by the following equation from the continuity of flow rate, assuming that the aperture ratio of each permeable wall 21 is εS (S=1.2...,N). It will be done.

By substituting equations (1) to (3) into equation (5), the following equation is obtained.

-------('7) Function system cos Kcr) (z+hr) and cos-(r) kn (z+hr) (r -1, 2, -, N+ 1
> forms a completely orthogonal system in 2-a to -h, so it can be rearranged by multiplying the formula % (+hr), and Z=-d2s-+ to -d
Taking into account that the submolecule Us (z)-0(s = 1.2°..., N> other than 2s), if we perform a definite integral in the interval (-hr, o), we obtain equation (1 ) to (3) are given by the following equations.

However, n-1, 2, -, j-1, 2, -, N-1, and MO"', Mn" (r = 1-2, =
・.

N+1) is defined by the following equation.

Therefore, as shown in equations (7) to (14) above, each undetermined complex constant is determined by determining the flow velocity component Us(z) in the X-axis direction at the opening of the transmission wall 21 by appropriate means,
As a result, the velocity potential φS of each fluid region is determined.

Next, the equation of motion of the flow around the S-th permeable wall 21 is expressed as the flow velocity component US (Z) (s = 1.2°...
, N), the following equation is obtained.

Here, Ps and PS++ are the fluid pressures before and after the permeable wall 21, ρ is the density of the fluid, Cs*, and LSI is the orifice length of 10 lapses and 10 times of observation If). The above formula (17
) is obtained by replacing the nonlinear resistance ring in this equation with a linear resistance term in which the energy consumption of the fluid during one cycle of the wave 22 is equal to Can be rewritten.

Here, by substituting equations (1) to (3) into equation (18), the following equation is obtained.

Furthermore, formulas (8) to (15) are added to formulas (20) to (22) above.
By substituting and rearranging, the formula (23) is finally the following formula % formula %
m) It is a simultaneous integral equation and is almost impossible to solve analytically except for special problems. Therefore, after numerically integrating equation (23) and converting it into simultaneous equations, the unknown function Us(
It is necessary to find z). Here, to the complex constant representing the incident wave, the incident wave η in the fluid region (1) is expressed as cos(ic”)(z cosθ−+7siJ
)cnl, then A=-+; given by Q/2σ.

Here, the value of y in the above equation may be any value.

In addition, in the actual calculation, (Jso in equation (19) is also not known, so it is necessary to confirm its convergence by substituting the initial value as appropriate and repeating the calculation. Then, Us(z) is calculated, the reflectance KR is obtained from equation (8).
-I can calculate B/A I.

Here, a case will be described in which partition walls extending in a direction parallel to the X-axis are provided at intervals of yo in the water retarding section.

Assuming that the interval yo between the partition walls is sufficiently small relative to the wavelength of the incident wave, the fluid motion within the retarding section is considered to have only a component in the X-axis direction, independent of the angle of incidence of the incident wave. . Therefore, even when the partition wall is provided in the water retarding section as described above, the integral equation can be obtained using the same method as when the partition wall is not provided.

Now, in order to obtain US(Z), it is necessary to estimate the loss coefficient C3 of the transmission wall 21 and the apparent orifice length US. These are mutually related by the following equation using the drag force coefficient CD and the mass coefficient CM in the wave force calculation formula, which are calculated using the flow velocity at the opening of the transparent wall 21.

C"-CoCI- and) --- (24) Bi Mon + CH (
1- and)lεlb---(25) where ε is the aperture ratio of the transparent wall 21, and b is the wall thickness of the transparent wall 21. However, as stated in this theory, the transparent wall 21 is
For a wave-dissipating structure that is affected by Q and has an impermeable wall installed behind it, the CD and C of the above formula are
M has not been disclosed. Therefore, by directly measuring the wave force acting on the first and second transmitting walls 21621 for the double transmitting wall type wave-dissipating structure handled in the present invention,
Drag coefficient COs, CHs (s = 1
．． I decided to look for 2).

If the front wave force FTs (s-1, 2) acting on the transparent wall 21 is expressed as a linear combination of the drag force FDS and the mass force Fls, this total wave force FT5 can be written as the following equation. Ru.

Fvs(t)-do05(t) ″FI5(t,)”
(:03(t) Jtos(t>+C, Msrtrft
stt, > -------(?G) Here, US is the current velocity, τ is the height reached by the wave from the water surface at the permeable wall, and h is the water depth. Also, dAS and dV
s is a minute area and a minute volume, respectively, and if the width of the structure is ds, these are respectively expressed as in the following equations.

The drag coefficients CDS and CH3 in Equation (26) are each a function of time, but it is assumed that they take constant values in the water depth direction.

The flow rate us in equations (27) and (28) can be expressed as the following equation on the wall surface of each transmission wall 21 using a relational equation based on the repeated reflection of waves within the retarding section.

Here, t ft Ir? z rr+ C05 ``U method'' ◆h+hrb+ srnm However, σ is the wavelength of the incident wave, and γS and γtS (S-1°2) are the reflectance and transmittance of the single transmission wall 21, respectively.

Next, by substituting equations (27) to (30) into equation (26), L
9 Calculated wave power FTs and double transparent wall type wave dissipating structure 1
The measured wave force Fms acting on each transparent wall 21 matches,
Furthermore, if it is assumed that the drag coefficient CDs and the mass coefficient CHs do not change during a minute time Δ°C, both coefficients are given by the following equations.

Therefore, using the above equation, it is possible to calculate approximate values of the drag force coefficient and mass coefficient at any time t from the experimental results. Furthermore, the drag coefficient and mass coefficient obtained from this experimental result are formulated into an appropriate function system based on wave conditions and structural conditions, and the constants included in the formula are set so that the sum of the squares of the experimental value and the value from the estimated formula is the minimum. It was decided that The results are shown in the following equation: 1° where X is the embankment width. .

Therefore, the above formulas (24), (25) and (33)
, (34), it is possible to estimate the loss coefficient and apparent orifice length of the first and second transmission walls 21.21 in the double transmission wall type wave-dissipating structure 1.

Next, each numerical value of the structural conditions of the wave-dissipating structure 1 will be specifically examined based on the above theory.

FIG. 5 is a diagram showing the relationship between the reflectance KR (vertical axis) and the relative water depth h + /L (horizontal axis) of the -overlapping or double-transmitting wall type wave-dissipating structure. Here, each parameter is
-ta In the case of the permeable wall type, the water depth ratio h2/h+-1,0, the frontage ratio ε-0,3, and in the case of the double permeable wall type, the water depth ratio h
2/h+ =h3/h+ =1.0, idle water width ratio Jl/J
2=1.0.1) 110 ratio ε+ =0.3, ε2-0.
1, and the waveform gradient Hi /L==0.03,
The angle of incidence is θ-0°.

In Figure 5, the relative water depth h +
/ Under the condition of L≧0.1, when the relative water depth is changed, that is, when the period is changed under the condition that the water depth h + is fixed, - In the case of a heavy permeable wall type, the retarding section will generate waves of a specific period (in this case, the relative water depth h+/L-0, 2), and the reflectance KR increases for waves of other periods, whereas in the case of the double-transmitting wall type, Therefore, the change in the reflectance KR is small, and its absolute value is also small compared to the case of the single transmission wall type.

Similarly, FIG. 6 shows the reflectance KR (vertical axis) of the single- or double-transmissive wall type wave-absorbing structure and the waveform gradient Hi /L (
FIG. Here, each parameter is -ffi in the case of a permeable wall type, water depth Fi2/fi
+-1.0, opening ratio ε-0.3, and in the case of double permeable wall type, water depth ratio h2/h+=h3/h+・1. O, free water width ratio J+/ノ2=1゜0, opening ratio ε+ =0.3, ε2=
0.1, and the common relative water depth h 1/L=0.24
4. Embankment body width ratio (distance between the leading transparent wall and the trailing non-transparent wall) X/L = 0.25, and the incident angle θ = o'r.

In Figure 6, the waveform gradient 1 seen in the normal Fhi region
Under the condition of 1i/I-≦0.05, the change in waveform slope,
In other words, for a change in the wave wavelength and wave height (1), the reflectance KR of the double-transmitting wall type Uranami structure is better than that of the double-transmitting wall type. Both the change and absolute value are small.

Therefore, according to the experimental results shown in Figures 5 and 6, the double-permeable wall type wave-absorbing structure can withstand waves with a wider range of periods and wave heights than the double-permeable wall type wave-absorbing structure. It can be said that this is the wave-dampening M4 structure 1 that can provide a good wave-dampening effect. Therefore, in the following discussion, only the double transparent wall wave-dissipating structure will be considered.

As mentioned above, the reflectance KR of the double transmitting wall type wave-dissipating structure is:
Waveform gradient H; /L that defines wave conditions.

Two dimensionless parameters, relative water depth h + / L, and the embankment body width ratio X/L and water depth ratio h2/L that define the structural conditions.
h+, h3/III, free water width ratio) 1/J2, m10
Its value is determined by seven parameters: the ratios ε1, ε2, and the incident angle θ. Therefore, in the following discussion, the optimal range of each of the above parameters will be considered.

First, the embankment body width ratio X/L and the aperture ratio ε1 and ε of each permeable wall
Consider the optimal range of 2. Figures 7 to 9 show the reflectance KR (ill axis) and the embankment body width ratio X/L (horizontal axis).
FIG. 3 is a diagram showing the relationship between the aperture ratios εl and ε2 as parameters. Here, the other parameters are h+/L-0,244, Hi/L-0,03, hz/
h+-hs/h+ -1-0,! + /42 =1.0
, θ−〇°. Also, Figures 7 to 9
In the figure, FIG. 7 shows the aperture ratio ε2-0 of the intermediate transmission wall.
1, Figure 8 shows ε2-0.2. In FIG. 9, εz-0.3.

In FIGS. 7 to 9, in any case, the reflectance KR takes a minimum value within the range of the embankment body width ratio X/L-0.2 to 0.25. Therefore, for the wave IL of the incoming wave, the total width
If it is limited within the range of 5 f8, it is possible to realize the wave-dissipating structure 1 in which the reflectance KR is kept low. Conversely, in the wave-breaking structure 1 having a bank body width ratio X/L outside the above range, the reflectance KR cannot be made sufficiently small.

Next, the optimum range of the aperture ratio ε2 of the intermediate transmission wall will be examined. In Figures 7 to 9, the aperture ratio ε2
As becomes larger, the change in the reflectance KR with respect to the change in the embankment body width ratio X/L becomes larger. Therefore, in order to suppress the change in reflectance to a small value even if the period of the incoming waves changes, it is necessary to limit the aperture ratio ε2 within the range of 0.1 to 0.2. Conversely, in the wave-dissipating structure 1 having an aperture ratio ε2 outside the above range, changes in reflectance with respect to changes in wave period cannot be kept small.

Furthermore, based on the above conditions, the aperture ratio ε of the leading transparent wall is
Consider the optimal range for i.

In FIGS. 7 and 8, as the aperture ratio ε1 increases, the absolute value of the minimum reflectance KR decreases. Therefore, from this experimental result, it is considered desirable to set the opening ratio ε1 to a value as large as possible.

However, considering the structural strength of the leading transparent wall,
Since there is a possibility that the permeable wall itself becomes brittle as the opening ratio ε1 increases, the opening ratio ε1 needs to be limited within the range of 0.3 to 0.4. Conversely, with the wave-breaking structure 1 having an aperture ratio ε1 below the above range, it is not possible to realize a wave-breaking structure with a low reflectance; With body 1, it is difficult to obtain enough strength to resist the incoming waves.

Next, the free water width ratio! Consider an optimal range of +/12. Figure 10 shows the reflectance KR (vertical axis) and the embankment body width ratio X/L.
(Horizontal axis) is a diagram showing the relationship with the free water width ratio J1/Jz as a parameter. Here, the other parameters are tl+/L-0,244, Hi/L=, respectively.
0.03, ε+ =0.3, ε2=0.1, Fiz/F
It = hz/h+ = 1.0 and θ = O°. In FIG. 10, at Jj, as the free water width ratio 1/j2 increases, the absolute value of the minimum reflectance KR decreases to 1. However, the range of change in reflectance rest tends to increase.

Therefore, in order to realize a wave-dissipating structure that exhibits a good wave-dissipating effect for waves with a wide range of periods, it is necessary to suppress both the minimum value and the variation width of the reflectance. It is necessary to limit the floating width ratio of body 1 to around 1.0 meters. Conversely, with a wave-breaking structure having a free water width ratio outside the above range, both the minimum value and the variation range of reflectance cannot be kept small.

Finally, we will examine the effects of installing a partition wall within the retarding section. Figures 11 and 12 show the reflectance KR (
FIG. 3 is a diagram showing the relationship between the vertical axis) and the embankment body width ratio X/L (horizontal axis) using the incident angle θ of the incident wave and the presence or absence of a partition wall as parameters. As shown in FIG. 12, when a partition wall is provided in the water retarding section, the reflectance K with respect to an increase in the incident angle is higher than when no partition wall is provided within the water retarding section, as shown in FIG. 11.
It becomes possible to suppress the increase in R to a small value. Therefore, by providing the partition in the water retarding section, it is possible to realize the J: ridge wave-dissipating structure 1 in which the reflectance does not increase even if waves are obliquely incident on the wave-dissipating structure 1.

As shown in the above experimental results, the wave structure 1 constructed according to the numerical ranges shown above reduces the energy of the waves passing through the top and middle upright walls 4a and 4b, and 5a and 5b act separately or together depending on the wavelength of the incoming wave, and the water retarding portion 5a,
The wave reflected within 5b and the wave transmitted through it are canceled out and reduced by their phase difference. Therefore, it is possible to realize a wave-dampening structure that can be expected to have a good wave-dampening effect on waves with a wide range of periods.

Moreover, since the wave-dissipating structure 1 is formed into a unit, less work is required on the sea, and therefore it can be constructed and installed in a short period of time. At the same time, this wave-dissipating structure 1 can be applied to places with severe wave conditions in deep water areas, and can also have the effect of an offshore breakwater or a fishing reef.

Next, FIG. 4 is a diagram showing a wave-dissipating structure according to a second embodiment of the present invention. In FIG. 4, the wave-dissipating M4 structure 1 is configured as a box-shaped so-called caisson. Similar to the first embodiment, this Uranami structure 1 has the following features:
Base 3 and three rows of upright walls 4a formed on this base 3
, 4b, and 4C. The Zarani Uranami structure 1 has side walls 10 and 1 at both ends and upper end thereof, respectively.
0 and a top plate 11 are provided, so that the wave-dissipating structure 1 is formed into a box shape as a whole.

Between the first upright wall 4a and the middle upright wall 4b, and between the middle upright wall 4b and the last upright wall 4c, there are first
Water retarding portions 5a and 5b are formed in the same manner as in the embodiment. Further, the leading upright wall 4a and the middle upright wall 4b are constructed by arranging a plurality of columns 6, 6, . has a transparent structure.

The wave-dissipating structure 1 is formed such that the distance between the leading upright wall 4a and the rearmost upright wall 4C is within the same range as the distance in the first embodiment. Further, the leading and middle uprights 94a and 4b are each l;11
The 0 ratio is formed to be within the same range as the aperture ratio in the first embodiment. Then, 63 GJ is applied to the water retarding portion 5a formed in the front and middle upright walls 4a and 4b.
As in the first embodiment, the wall spacing is approximately equal to the wall spacing between the water retarding portions 5b formed between the intermediate and rearmost upright walls 4b and 4C.

Similar to the first embodiment, this Uranami structure 1 is manufactured on land, then floated in the sea by a float or the like, and further towed to a predetermined position W in the sea by a towing boat or the like, and then placed on the seabed. Ail on 8, fixed! iQ is placed.

The action of this Uranami structure 1 to dissipate incoming waves is similar to the action of the wave dissipating structure of the first embodiment. Here, the wave dissipating structure 1! Since the 1lIl wall 10.10 corresponds to the partition wall in the above-mentioned theory and experimental results, even if waves are obliquely incident on this Uranami structure 1, the wave-damping effect is not weakened.

Note that the wave-dissipating structure of the present invention is not limited to the above embodiments. For example, the upright wall may have a piled structure. Furthermore, a plurality of the wave-dissipating structures according to J5 in the above-mentioned embodiment may be arranged in a row to constitute the Uranami structure as a whole.

"Effects of the Invention" As explained above, according to this invention, the distance between the leading M vertical wall and the rearmost vertical wall is 0.2 to 0.25 times the wavelength of the incoming wave. The value of the aperture ratio of the leading upright wall, which is the value obtained by dividing the area of the transparent part in the leading upright wall by the area of the entire leading upright wall, is within the range of 0.3 to 0.4, and the middle The value of the aperture ratio of the upright wall is 0.1 to 0.
Since the wave-dissipating structure was constructed such that the distance between the walls is within the range of 2 and the wall spacing in the retarding section between each upright wall is approximately equal, the incoming waves pass through the leading and middle upright walls. At this time, the traveling direction of the wave is disturbed before and after the wave, thereby reducing its energy. Furthermore, within the water retarding section, waves reflected from the upright wall and waves entering each of the retarding sections cancel each other out due to their respective phase differences, thereby reducing reflected waves from the wave-dissipating structure.

In particular, when the wave wavelength is short, the water retarding parts between the leading and middle straight walls are separated, and when the wave wavelength is long, each water retarding part is integrated. We perform the batting performance.

Therefore, it is possible to realize a wave-dissipating structure that can exhibit a dramatic wave-dissipating effect on waves of 1 μl in circumference over a wide range.

In addition, when the wave-dissipating structure is a box-shaped caisson, the wave-dissipating effect can be improved even if waves are obliquely incident on the wave-dissipating structure due to the reflection of waves on the side walls of the wave-dissipating structure. never fades.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a wave-dissipating structure which is a first embodiment of the present invention, FIG. 2 is a diagram explaining details of the invention, FIG. 3 is a diagram similar to FIG. 2, and FIG. is a perspective view showing a wave-dissipating structure according to a second embodiment of the present invention, FIG. 5 is a diagram showing an example of the relationship between relative water depth and reflectance of the wave-dissipating structure, and FIG. Figure 7 is a diagram showing an example of the relationship between the reflectance of the wave structure and the reflectance of the wave-dissipating structure. Figure 8 is a diagram similar to Figure 7. Figure 9 is a diagram similar to Figure 7, Figure 10 is a diagram similar to Figure 7, Figure 11 is a diagram similar to Figure 7, and Figure 12 is a diagram similar to Figure 7. be. 1... Wave structure, 4... Upright wall, 5...
... Retarding section, 6... Column body.

Claims (2)

[Claims] (1) A wave-dissipating structure comprising at least three rows of upright walls forming a plurality of water retarding sections therebetween, and at least the first and middle upright walls of the upright walls having a transparent structure consisting of columnar rows. and the distance between the first upright wall and the last upright wall is 0.2 to 0.2 of the wavelength of the incoming wave.
5 times, and the value of the aperture ratio of the leading upright wall, which is the value obtained by dividing the area of the transparent part in the leading upright wall by the area of the entire leading upright wall, is within the range of 0.3 to 0.4. , the value of the aperture ratio of the upright walls in the middle is within the range of 0.1 to 0.2, and the wall spacing in the water retarding part between the upright walls is formed to be approximately equal. wave-dissipating structure. (2) The wave-dissipating structure according to claim 1, wherein the wave-dissipating structure is a box-shaped caisson.