JPH11350448A - Seawall structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a seawall structure provided with necessary overtopping surpassing performance even by a low crown height. SOLUTION: This seawall structure is provided with a curved face part 11 protruding toward the offshore side on the upper part of an offshore side wall 10. In order to have necessary and sufficient overtopping surpassing performance in the installed sea territory of the seawall structure, the expression (I) indicating the crown height (hc) of the wall 10 on the offshore side capable of theoretically obstructing overtopping wave, against the installed water depth (h) of the seawall structure, the estimated maximum wave height Ho and wave length Lo is set in relation with a parameter X. The expression (I): X=2.83-1.39 h/B-15.6 Ho/Lo-0.84 Ho/B+12.6 S/(HoLo)-0.50 D/B, where B is height of a wall on the offshore side, D is length in the horizontal direction of the above- mentioned curved face part, and S is the sectional area of the territory sandwiched between the wall on the offshore side and a still water level in view from the width direction of the seawall structure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a breakwater and a breakwater structure for revetment installed in a harbor or the like.

[0002]

2. Description of the Related Art Conventionally, an upright caisson 50 having a rectangular parallelepiped shape as shown in FIG. 17 has been generally used as a breakwater or a seawall for seawalls installed in a harbor or the like. Such a breakwater structure is first grounded by digging the sea floor where the breakwater structure is to be installed and replacing it with sand 41, and forming a foundation 40 by providing a rubble mound 42 thereon, It is constructed by placing an upright caisson 50 serving as the main body of the wave-proof structure thereon. Such a foundation 40 supports the upright caisson (wavebreak structure main body) 50, increases the frictional resistance at the bottom surface of the upright caisson 50, and slides the upright caisson 50 when subjected to waves or seismic force. This is provided in order to prevent this.

In such a breakwater structure, in order to protect a ship or a building located on the land side of the breakwater structure from overtopping (a phenomenon in which the wave passes over the main body of the breaking structure), the overtopping is carried out. The height of the top (the height from the still water surface to the top surface of the breakwater structure) is set high enough to prevent it.

[0004] However, if the height of the top of the breakwater structure is increased in order to prevent wave overtopping, there arises a problem that the landscape is significantly impaired.

[0005] Furthermore, when the height of the top is increased, the cross-sectional area of the main body of the wave-proofing structure is increased and the weight is increased. Therefore, the foundation necessary for supporting the main body, especially the area requiring ground improvement is increased. As a result, there arises a problem that the cost and labor required for the construction of the breakwater structure are increased.

[0006] Therefore, it is required that the height of the top of the breakwater structure be kept as low as possible.

[0007] Under such demands, a curved surface portion is provided above the offshore wall surface so as to incline so as to approach the offshore surface, and a wave running up the offshore wall surface is bounced offshore. A breakwater structure having excellent non-overtopping characteristics capable of exhibiting high overtopping performance at a low top end height has been proposed (Kaigan Kogaku shushu Vol. 43, 1996, p776-p780).

[0008]

By the way, the overtopping performance required for such a breakwater structure differs depending on the purpose of use of the shore where the breakwater structure is installed. In other words, for example, a nuclear power plant, especially in coastal areas where facilities important for security are provided, in order to make the overtopping amount as close to zero as possible, very high overtopping prevention performance is required, while if it is a beach park, etc., Since it is not used during a typhoon or the like where high waves are likely to occur, it is sufficient to have a certain degree of overtopping performance. Furthermore, in such seaside parks, since it is required to make the height of the top end as low as possible and to provide a hydrophilic seawall without hindering the scenery, it is rather desirable to provide an overtopping wave blocking performance that is more than necessary. Absent.

[0009] Therefore, it is required that such a wave-preventing structure be provided with a necessary and sufficient overtopping prevention function according to the installation purpose and the like, while keeping the height of the top end as low as possible.

[0010] However, the above-described wave-breaking structure having the curved surface portion is superior in non-overtopping characteristics as compared with a wave-breaking structure composed of an upright-type caisson that has been generally used in the past. It is known that the shape conditions such as the inclination angle and area of the curved surface, the environmental conditions of the installation location such as the water depth and the assumed maximum wave height in the area where the breakwater is installed, and the overtopping The quantitative relationship with the inhibition performance was not clear.

Therefore, in the wavebreak structure having such a curved surface portion, the top height required for obtaining the required overtopping performance is not clear, so that the required overtopping performance can be reliably obtained. In addition, it is necessary to provide an unnecessarily high top height, and as a result, it is impossible to make use of the excellent non-overtopping characteristics of the wave-breaking structure having such a curved surface portion. Could not be kept low enough.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has been made in consideration of the above-mentioned problems. It is an object of the present invention to provide a wavebreak structure having a required overtopping performance while having a low top end height by clarifying the shape conditions quantitatively.

[0013]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention relates to a wave-breaking structure erected facing offshore, wherein at least the upper part of the offshore wall surface is protruded offshore. And an appropriate range of the top height hc of the curved surface is set using a parameter X defined by the following equation.

[0014]

(Equation 2)

Here, Ho is the maximum offshore wave height, Lo is the offshore wave wavelength, h is the installation depth of the structure, B is the height of the offshore wall, D is the horizontal length of the curved surface portion, and S is the offshore wall surface. It is sectional area seen from the width direction of the breakwater structure in the field sandwiched between the still water surfaces.

The maximum offshore wave height Ho is set in order to assume the largest wave reaching the breakwater structure when designing a breakwater structure or the like. Considering the service life of the structure, etc., it refers to the maximum wave height of a wave that is expected to occur during this service life.

Here, the offshore wave means a wave in a region where the wave is not affected by the sea floor, a wave reaching the coastal area where the breakwater is installed passes, and a water depth is deeper than half the wavelength. (Toru Sawaragi and Ichiro Deguchi, "New Ocean Engineering" Kyoritsu Shuppan 19
Published in 1996, page 14).

In addition, the service life of such a breakwater structure is often assumed to be 50 years in civil engineering facilities (“Example of Design Calculation of Harbors and Offshore Structures”, Civil Engineering Special Edition, 1987.1, January 2001). VOL.28, NO.2, page 5).

Therefore, in the present invention, in consideration of the above circumstances, the maximum offshore wave height Ho refers to the maximum wave height of waves generated in the past 50 years from the time of construction in the sea area where the breakwater structure is installed. Shall be.

However, if there is no investigation data for the past 50 years from the time of construction, the above-mentioned document “Example of Design Calculation of Harbors and Offshore Structures”, page 54, “3.1.4 Calculation of Design Wave Height” is described. Based on the method of estimating the stochastic wave height, the probability is calculated from the obtained survey data with a reproducibility period of 50 years.
The calculated maximum wave height is defined as the maximum offshore wave height Ho.

The offshore wave wavelength Lo refers to the wavelength of the wave having the maximum offshore wave height Ho.

The installation water depth h of the structure is the height from the sea bottom to the still water surface.

Further, the hydrostatic surface is defined as an average height over one year of the highest tide surface and the lowest tide surface of each month observed within 5 days from the day of the new moon (Shuo) and the full moon (Nozomi). Based on the average high tide surface (H.W.L), which is the sea level, based on observations made during the past year from this reference date, with a date within one year from the construction of the breakwater as the reference date. Shall be set.

The parameter X calculated based on the introductions defined as described above has a curved surface portion which is inclined so as to approach the offshore side, as will be described in detail later. In the breakwater structure, the top height hc of the breakwater structure where the overtopping amount is theoretically 0 (to be precise,
It is a value that serves as an index of the top end height hc and the dimensionless dimension of the maximum offshore wave height Ho).

Therefore, for this parameter X,
If the top height hc of the curved surface portion is set, the required overtopping performance can be obtained, and the top height hc as low as possible can be realized while obtaining the required overtopping performance.

Specifically, according to the present invention, the height hc of the curved surface portion is made dimensionless by the maximum offshore wave height Ho.
c / Ho, for this parameter X, 0.5X or more,
And it is set within the range of 1.5X or less (claim 1).

The dimensionless amount hc / Ho of the top height is equal to 0.
When set to 5X, even during high waves, the amount of medium overtopping corresponding to the overtopping prevention performance required in a coastal area distant from a densely populated area such as a house or a general road is suppressed.
Therefore, the dimensionless amount hc / Ho of the top end height is 0.5X.
With the above setting, it is possible to satisfy the overtopping rejection performance in the coastal area where the medium overtopping is allowed.

On the other hand, as will be described later, in order to reduce the amount of overtopping to zero in an upright type breakwater structure, at least 1.5 times the wavebreak structure having a curved surface according to the present invention. More than double the top height is required. Therefore,
By setting the non-dimensional amount hc / Ho of the top height to 1.5X or less, it is possible to realize a top height that is lower than that of a conventional upright type breakwater structure.

Furthermore, the dimensionless amount hc /
If Ho is set to 1.2X or less (claim 2), it is possible to realize a sufficiently low top end height as compared with the conventional upright type breakwater structure.

The dimensionless amount hc / Ho of the height of the top is
Is set to 0.8X, even during high storms and the like, a small amount of overtopping corresponding to the overtopping prevention performance required in the coastal area adjacent to the coastal airport or the like that is not used during a storm or the like is suppressed. Therefore, the dimensionless dimension h of the top height is
If c / Ho is set to 0.8X or more (claim 3), it is possible to satisfy the overtopping prevention performance in the coastal area where this small amount of overtopping is allowed.

The dimensionless amount hc / Ho of the height of the top is
Is set to 1.0X, as described above, overtopping does not occur even at high waves as long as it is based on the theoretical value estimated from the experimental model. However, in practice, a very small amount of overtopping occurs at the time of a high wave or the like due to an error accompanying the calculation of the theoretical value. This very small amount of overtopping means that
Even when public facilities and general roads are dense,
This is the allowable overtopping amount. Therefore, if the dimensionless amount hc / Ho of the height of the top is set to 1.0X or more (claim 4), it is possible to satisfy the overtopping rejection performance in the coastal area where this very small amount of overtopping is allowed. Can be.

The dimensionless amount hc / Ho of the height of the top is
Is set to 1.1X, overtopping does not occur theoretically even in the case of high waves, and overtopping can be completely prevented even in consideration of the error associated with the calculation of the theoretical value. . Therefore, the dimensionless dimension hc / Ho of the height of the top is
Is set to 1.1X or more (claim 5), it is possible to satisfy the extremely high overtopping performance required in a coastal area where facilities particularly important for security such as a nuclear power plant are installed.

Also, in order to receive as much of the waves as possible from the offshore at the curved surface portion and to bounce upward off the offshore side, the curved surface portion must have a hydrostatic surface height in order to more fully exhibit the overtopping wave preventing action. It is desirable to provide it in a region including the position (claim 6).

Further, the angle of the curved surface portion is increased from the lower part to the upper part in order to smoothly change the motion direction of the wave colliding with the offshore wall surface as a water mass and to rebound upward from the offshore side. (Claim 7).

Further, from the viewpoint of increasing the ground contact area of the main body of the breakwater structure to enhance its stability, the lower part of the offshore wall (the part below the curved surface) is formed to be substantially vertical. Is desirable (claim 8).

If the lower part of the offshore wall surface is formed as a substantially vertical plane as described above, this part can be easily manufactured in a planar shape.

Further, from the viewpoint of increasing the ground contact area of the breakwater structure, it is more desirable to configure the lower portion of the offshore wall surface so that the lower portion protrudes toward the offshore side. .

As described above, if the lower portion of the offshore wall surface is configured as a surface where the lower portion protrudes toward the offshore side, the wave pressure acting on the lower portion of the offshore wall surface has a downward component component. Therefore, the wave pressure acting on the offshore wall surface can be applied as a force for pressing the breakwater structure body downward, thereby increasing the frictional force on the lower surface of the breakwater structure body, This can contribute to prevention of sliding of the object body.

In such a breakwater structure,
In order to rebound the water mass going up along the curved surface to the offshore sea surface and obtain even higher overtopping performance, a top plate that protrudes almost horizontally toward the offshore above the curved surface Preferably, it is provided (claim 10).

Further, in such a breakwater structure,
In order to prevent even a small amount of water coming off the main stream of waves that have bounced offshore by the curved surface and flowing down on the top end surface from reaching the land side of the breakwater structure, and to obtain even higher overtopping performance It is preferable to provide, on the top end surface, a wave-reversing structure for damping water flowing to the top end surface.
1).

[0041]

FIG. 1 is a sectional view showing a first embodiment of a wave-proof structure according to the present invention. Similar to the conventional breakwater structure shown in FIG. 17, this breakwater structure is improved in ground by digging the sea floor and replacing it with sand, and a rubble mound is provided thereon to form a foundation 40. The wave-breaking structure main body 50 is installed on the upper part of the foundation 40.

As shown in FIG. 1, this wave-breaking structure is formed as a curved surface portion 11 having an arcuate surface in which the offshore wall surface 10 has a concave shape as a whole toward the offshore.

Since the curved surface 11 receives waves arriving from the offshore side and suppresses overtopping, it is desirable that all the arriving waves be received by the curved surface portion 11. However, the curved surface 11 according to this embodiment is preferred. The part 11 is always formed in an area including the water surface height position 91 including when the tide is at a low tide and when the tide is at a high tide when installed on the coast. further,
The curved surface portion 11 is located at the top of the offshore wall surface 10 from the lower side than the water surface height position 92 when the wave W having the maximum offshore wave height reaches the breakwater structure (top height position). It is formed over.

Accordingly, a wave having a lower wave height than the wave W having the maximum offshore wave height reaching the breakwater structure collides with the curved surface portion 11 from the offshore side as a water mass. In this way, this wave-breaking structure prevents the overtopping by changing the direction of movement of the water mass colliding with the curved surface portion 11 to an obliquely upward direction on the offshore side (inclination direction of the curved surface portion 11) and rebounding offshore. It has become.

FIG. 2 is a sectional view showing a second embodiment of the wavebreak structure according to the present invention. 2 to 11 showing the following embodiments, components similar to those in FIG. 1 are denoted by the same reference numerals as those in FIG.

The curved surface portion 11 of the breakwater structure according to the second embodiment has a smaller curvature than that of the breakwater structure of the first embodiment, that is, the protrusion amount to the offshore side is smaller. However, similarly to the first embodiment, since the curved surface portion 11 is formed in an area including the height position 91 of the still water surface L, the wave is prevented from overtopping by splashing the wave offshore. Has an action.

As described above, the offshore wall surface 10 of the breakwater structure according to the present invention has a simple configuration in which the entire surface is formed as one curved surface portion 11 formed by an arc surface (FIGS. 1 and 2). Even in the case of, the amount of protrusion to the offshore side with respect to the height of the offshore wall surface can be variously set, and qualitatively, regardless of the setting, the arriving wave is formed along the curved surface portion 11. It has an overtopping effect by bouncing offshore.

Therefore, next, the shape condition of the curved surface portion 11 of the wave-proof structure against external conditions such as various water depths and wave conditions in the sea area where such a wave-proof structure is installed, and the wave-proof structure Consider the quantitative relationship with the overtopping performance provided by an object, and in order to satisfy the overtopping performance required for such a breakwater structure, the shape conditions that such a breakwater structure should have, especially Consider the edge height.

For this consideration, a series of experiments were performed using a scale model of the two wave-breaking structures and a two-dimensional wave-making water tank, and a numerical analysis was performed based on the results of the experiments. Theoretical formula showing the quantitative relation between the shape condition and external condition of various wavebreaking structures and the overtopping performance was derived. In the following description, the breakwater structure according to the present embodiment will be referred to as a “flare type”.

FIG. 12 shows a two-dimensional wave-making water tank used in this series of experiments. In this experiment, an impervious slope with a 1/20 gradient imitating the seabed gradient was installed in this two-dimensional wave-making water tank (length 30 m, height 1.2 m, width 0.6 m). A scale model of the breakwater structure was installed on the transmission slope, and various waves generated by the wave maker were made to collide with this scale model. The water depth of the horizontal floor offshore was always set to ho = 85 cm.

FIG. 13 shows the shapes and dimensions of the two scale models I and II used in this experiment. Both of these model heights were B = 37.2 cm.

Table 1 shows the results of this series of experiments.

[0053]

[Table 1]

Table 1 shows the experimental conditions and results for each row, and in each experiment, the model shown in the second column of each row was obtained by comparing the model shown in the fourth column on the impermeable slope with the water depth h shown in the fourth column. At the position, the offshore wave height Ho was variously changed while the waveform gradient Ho / Lo was fixed to the shape shown in the eighth column, and the maximum offshore wave height Ho without overtopping was measured. The maximum offshore wave height Ho where this overtopping does not occur is shown in the fifth column.

Specifically, Experiment No. 1 shown at the top of Table 1
Taking the experiment of FIG. 13 as an example, this experiment corresponds to N of FIG.
o. The model I was placed at a position of water depth h = 22.5 cm, and the waveform gradient Ho / Lo was 0.03 for this model.
While fixing at 6, the waves of various offshore wave heights Ho were collided to check for the presence of overtopping.
It is shown that no overtopping occurred for the wave having the offshore wave height Ho = 18.5 cm shown in the column, but overtopping occurred for the wave exceeding 18.5 cm.

The presence / absence of this overtopping is determined by measuring the overtopping flow rate q (cm 3 / cm · sec) per unit width of the breakwater structure.
A dimensionless value q / √ (2 · g · H) of the overtopping flow q
o ³ ) is 0.0001 or less when no overtopping occurs. g is the gravitational acceleration.

Further, “Cross-sectional area S /
The "cross-sectional area S" in the "wave volume HoLo" is shown in FIG.
(A) and (b) are cross-sectional areas of the region sandwiched between the offshore wall surface and the still water surface as viewed from the width direction of the breakwater structure, as indicated by oblique lines in (b).

Next, based on the experimental results shown in Table 1, among the shape conditions and wave conditions of the breakwater structure, factors which greatly affect the overtopping performance of the breakwater structure will be considered.

FIG. 14 shows the difference in the top height hc at which the overtopping can be prevented in each flare type model shape.

In this figure, the horizontal axis represents the relative installation water depth h / Ho obtained by making the installation water depth h dimensionless at the offshore wave height Ho, and the horizontal axis direction shows various water depth conditions.

The vertical axis is the relative top height hc / Ho obtained by dimensioning the top height hc with the offshore wave height Ho. The relative top height hc / Ho indicates the minimum top height required to prevent overtopping, and the smaller this value, that is, the lower the top of the figure, the higher the overtopping performance. Is shown.

Further, in this figure, in addition to the flare-type wavebreak structure, the relative top height hc / Ho of the upright type wavebreak structure is also shown. This upright type breakwater structure is an upright breakwater seawall that has been widely used as an actual seawall, and is constructed by laminating tetrapods from the sea floor to the height of the top in front of the offshore wall surface, The figure shows the relative top height hc / Ho extracted from the known wave overtopping amount estimation diagram for the upright breakwater revetment.

As compared with the data of the upright type breakwater structure, the data of the flare type breakwater structure are all located on the lower side of FIG. It can be seen that the shape is very unlikely to cause overtopping. Specifically, the flare-type wave-proof structure has a relative top height hc / approximately about 1/3 to 2/3 of a conventionally known upright-type wave-proof structure.
It can be seen that it is possible to prevent overtopping with Ho.
In other words, in order to obtain the same overtopping prevention performance as that of the flare type, the upright type breakwater structure needs to be about 1.5 to 1.5 times of the flare type.
It can be seen that the top height hc is required to be tripled.

From this figure, it can be seen that, of the various shapes of the flare type wave-proof structure, the shape II is superior in wave overtopping performance.

Based on the results, the respective flared shapes shown in FIGS. 13A and 13B show that the region sandwiched between the offshore wall surface and the still water surface, that is, the above-described cross-sectional area S
Is the size of the structure on the still water surface
It is presumed that this has a great influence on the overtopping performance.

Next, the relationship between the waveform gradient Ho / Lo indicating the wave condition and the relative top height hc / Ho will be considered.

FIG. 15 shows two types of waveform gradients Ho / Lo = 0.
The relative top height hc / Ho with respect to 012 and 0.036 is shown.

Also in this figure, the horizontal axis represents the relative installation water depth h / Ho representing various water depth conditions, and the vertical axis represents the relative top height hc / Ho representing the overtopping performance. Therefore, the lower side of the figure indicates that the overtopping rejection performance is higher.

Referring to this figure, the relative top height hc / c in the case where the waveform gradient Ho / Lo is large in the sea area where the breakwater is installed.
Ho is small, that is, it tends to be able to block the overtopping at a low top height. Therefore, the top height hc required to prevent the overtopping also depends on the waveform gradient Ho / Lo. It is inferred.

Further, considering the results shown in Table 1, the top height hc required to prevent overtopping is determined by the magnitude of the offshore wave height Ho itself, the water depth h, the height of the offshore wall surface, and the horizontal direction of the curved surface portion. It is presumed that it also depends on the ratio D / B of the length D.

As described above, the top height hc of the offshore wall surface
Depends on the maximum offshore wave height Ho, the offshore wave wavelength Lo, the installation water depth h, the offshore wall surface height B, the curved surface horizontal length D, the cross-sectional area S in the width direction of the region between the offshore wall surface and the still water surface, and the like. It is presumed that it has changed.

Therefore, based on all the data shown in Table 1, the relative top height hc / Ho is used as an objective variable, the ratio h / B of the installation water depth to the wall height, the waveform gradient Ho / Lo, the offshore wall surface The ratio of the height to the wave height Ho / B, the ratio of the cross-sectional area of the area between the offshore wall surface and the still water surface to the wave area S / (HoLo), and the ratio of the horizontal length of the protruding slope to the wall height D /
B was used as an explanatory variable and multiple regression analysis was performed.
From the two explanatory variables, the target variable, the relative top height hc /
An estimation formula for estimating Ho was obtained. This estimation formula (1) is as follows.

[0073]

(Equation 3)

According to this estimation equation (1), if the wavebreak structure has a relative top height hc / Ho corresponding to a value calculated from the above five explanatory variables by the right side of the equation,
In theory, it can be said that overtopping can be prevented. Hereinafter, the theoretical value of the relative top height hc / Ho required to prevent overtopping, calculated by the estimation formula (1), is represented by a parameter X.

Next, the accuracy of the estimation formula (1) will be verified.

FIG. 16 shows the relationship between the relative top height (parameter X) calculated from the estimation formula (1) and the relative top height hc / Ho actually detected by the water tank experiment. That is, in this figure, the horizontal axis represents the parameter X calculated by the estimation formula (1), and the vertical axis represents the relative top height hc / Ho actually detected by the water tank experiment.

According to this figure, each plot is on a straight line having a slope of 1 passing substantially through the origin, and the parameter X according to the estimation formula (1) and the relative top height hc /
It can be seen that Ho almost coincides, and the accuracy of the estimation formula (1) is high. Further, when the correlation coefficient between the two is obtained from the plot data of FIG. 15, the correlation coefficient is extremely high at 0.987, which also indicates that the estimation formula (1) has very good accuracy.

However, there is some variation between the relative top height hc / Ho calculated from the theoretical formula as the parameter X and the relative top height hc / Ho obtained from the experiment. . Therefore, based on the variation between the theoretical value and the experimental result, the relative top height hc / Ho that can completely reduce the overtopping amount to zero is obtained.

Therefore, in the figure, considering a straight line that looks at all plots on the left side, a straight line of hc / Ho = 1.1X can be drawn.

From this, under the wave conditions such as an arbitrary maximum offshore wave height Ho, etc., if an offshore wall surface having a relative crest height hc / Ho corresponding to 1.1X is set, this condition is obtained. Head height h required to prevent wave overtopping
According to the experimental results, c / Ho is lower than the straight line of 1.1X on the left side of the figure, that is, lower than the relative top height hc / Ho corresponding to 1.1X, so that it is possible to surely prevent the overtopping. .

On the other hand, in an actual revetment, the required overtopping performance depends on the purpose of use of the coastal area and the like, and it is not always necessary to reliably prevent the overtopping.

For example, in the case of a seawall adjacent to a seaside park installed in a coastal area distant from a densely populated area such as a house or a general road, when it is expected that a large wave will occur in a typhoon or the like, in principle, Since it is not used, rather than being able to prevent overtopping against waves having the maximum offshore wave height that can occur during a typhoon, etc. It is required that the top height hc be reduced to provide a hydrophilic revetment that prevents the landscape from being hindered.

Further, even if the seawall is located adjacent to an airport located in the coastal area, since the airport is closed during a typhoon or the like, the overtopping of the wave having the maximum offshore wave height Ho is completely prevented. It is not required to be able to do so. Instead of allowing a small amount of overtopping of such waves, it is required to make the top height hc as low as possible so as not to obstruct the view of the pilot.

Further, if the revetment is adjacent to an area where people, public facilities, and general roads are dense, slight overtopping can be tolerated. Rather than a high top-level seawall that prevents overtopping, a lower top-level seawall that requires only a small amount of overtopping but does not disturb the landscape is required.

Further, if it is a revetment along the coast where the most important facilities for security such as a nuclear power plant are installed, it is required to surely prevent overtopping even at the assumed maximum offshore wave height Ho.

[0086] In view of the above, different relative overtopping heights hc / Ho satisfying the overtopping performance in the coastal area where such a wavebreaking structure is installed.
In order to obtain the above value, in the above-described water tank experiment, the amount of overtopping at a relative top height hc / Ho equal to or less than the parameter X corresponding to the relative top height that can theoretically prevent overtopping was measured. .

According to this experiment, when the height of the top end is set to about half (1 / 2X) of the parameter X, a moderate overtopping amount allowed in the seaside park or the like is measured. When a top height of about 0.8 times (0.8X) was set, a small amount of overtopping allowed at the airport or the like was measured.

Therefore, considering that the precision of the theoretical equation (1) is sufficiently high, 0.5
With a relative top height hc / Ho of X or more, the overtopping amount can be suppressed to a medium level or less, and with a relative top height hc / Ho of 0.8X or more, the overtopping amount can be suppressed to a small amount. It is speculated that this can be done.

That is, if the coastal area allows a moderate amount of overtopping for the wave having the maximum offshore wave height Ho in accordance with the overtopping prevention performance required in the coastal area where the above-mentioned breakwater structure is installed. , Relative top height hc of the breakwater structure
/ Ho is set to 0.5X or more with respect to the above parameter X, and if the coastal area allows a small amount of overtopping, the relative top height hc / Ho of the breakwater structure is set to 0.8X or more. By doing so, the required overtopping rejection performance can be satisfied, and the highest possible top height required from the viewpoint of the landscape and the like can be realized.

The flare type breakwater structure having the simplest form in which the curved surface portion 11 formed of a circular arc is formed on the entire offshore wall surface 10 shown in FIGS. 1 and 2 has been described. The wave preventing structure according to the present invention is not limited to such a form, and may be configured, for example, as in the following third to eleventh embodiments (FIGS. 3 to 11). By applying the above-mentioned theoretical expression (1) also to the form of the wave-breaking structure, it is possible to obtain a low top height while sufficiently and sufficiently satisfying the overtopping-prevention performance required for the wave-breaking structure.

Third Embodiment (FIG. 3) In this embodiment, the curved surface portion 11 of the offshore wall surface 10 is formed only on the upper portion of the offshore wall surface 10, and the lower portion of the offshore wall surface 10 is formed as a vertical surface 12. It is.

According to this structure, the lower portion of the offshore wall surface 10 is a substantially flat portion, so that it is easy to manufacture.
Compared with the first and second embodiments (FIGS. 1 and 2), the ground area of the lower surface of the wavebreak structure main body 50 is increased, so that high stability can be obtained.

Fourth and Fifth Embodiments (FIGS. 4 and 5) In these embodiments, the lower surface of the offshore wall surface 10 is formed as a surface portion 121 which is inclined so as to approach the offshore side.

According to this structure, since the wave pressure applied to the surface portion 121 has a component component (downward vertical wave force) that presses the breakwater structure main body 50 downward, the lower part of the offshore wall surface 10 is formed. The wave pressure applied to the
It can act as a downward force that increases the frictional force of the lower surface.

Further, the lower part of the offshore wall surface 10 is substantially vertical surface 12
As compared with the third embodiment (FIG. 3) configured as
Since the ground contact area on the lower surface of the wavebreak structure main body 50 can be further increased, the stability can be particularly improved.

Further, as in the fifth embodiment (FIG. 5),
If the lower portion of the offshore wall surface 10 approaching the offshore side is configured as a curved surface having a continuously changing curvature with the upper curved portion 11 of the offshore wall surface 10, it will collide with the offshore wall surface 10 as a water mass. Since the waves can smoothly move along the offshore wall surface 10, the waves can be more smoothly bounced offshore to obtain excellent non-overtopping characteristics.

Sixth Embodiment (FIG. 6) In this embodiment, the lower part of the offshore wall surface 10 is
And a surface portion 121 whose lower side is inclined so as to approach the offshore side.

With this configuration, the curved surface portion 11 and the surface portion 12 and the surface portion 1 are different from those of the fourth embodiment (FIG. 4).
Since the angle of opening at the joint between the surface 2 and the surface portion 121 can be increased, the stress concentration that tends to occur due to a change in the inclination angle of the offshore wall surface 10 at these joints can be reduced.

Further, according to this structure, since the wave pressure applied to the flat portion 12 has a component component (downward vertical wave force) for pressing the wave-breaking structure body 50 downward, the offshore wall surface The wave pressure applied to the lower part of 10 can act as a downward force that increases the frictional force on the lower surface of the wavebreak structure main body 50.

Further, the lower part of the offshore wall surface 10 is substantially vertical surface 1
In comparison with the case where only two are provided (the first embodiment, etc.),
Since the ground contact area on the lower surface of the wavebreak structure main body 50 can be further increased, the stability can be particularly improved.

Seventh Embodiment (FIG. 7) In this embodiment, a top plate 21 is provided above a curved surface portion 11 and on a top surface 20 so as to extend in a substantially horizontal direction toward the offshore side. The top plate 21 is configured by attaching a plate-shaped member formed of, for example, a steel plate or a steel / concrete composite structure to the top surface 20.

Since such a top end plate 21 can be formed by a simple plate-like member, it can be easily manufactured and installed without a significant increase in cost. In addition, such a top plate 21 is provided on the offshore side wall surface 1.
It may be integrally formed as a part of the wave-breaking structure main body 50 where 0 is formed.

According to this embodiment, the water mass that collides with the curved surface portion 11 consumes most of its kinetic energy as potential energy when it is lifted up along the slope of the curved surface portion 11, and thus the kinetic energy The weak water mass that has lost much collides with the top end plate 21. For this reason, the wave pressure acting on the top end plate 21 becomes small. The water mass that collides with the top end plate 21 is
As a result, the water mass is prevented from returning to the sea surface on the offshore side, so that the water mass is prevented from exceeding the top end surface 20, and excellent non-overtopping characteristics are obtained.

Eighth to Eleventh Embodiments (FIGS. 8 to 11) In the eighth embodiment, as shown in FIG. 8, a wave-turning surface 22 having a wave-turning surface 221 inclined on the top end surface 20 toward the offshore side. Is provided.

By providing such a wave-returning structure 22, even if only the offshore wall surface 10 causes overtopping, the water-returning structure 22 prevents the water flowing on the top end surface 20 from damming. Therefore, the non-overtopping characteristic as a wave-breaking structure can be further improved.

This is because, when the small amount of overtopping is observed in each of the above model experiments, the water that has passed the main body 50 of the seawater is not affected by the small amount of overtopping. Since a very small amount of water, which is considered to have been separated from the mainstream of the bounced waves, had flowed down onto the top end face 20, the wave-returning work 22 dammed this water and caused it to reach the land side of the top end face 20. Otherwise, overtopping can be prevented as a wavebreaking structure.

Therefore, the wave returning structure 22 does not directly receive the wave pressure of the wave arriving from the offshore, but separates the weak water flowing from the main flow of the bounced wave and flowing down to the top end face 20 from the wave-proof structure. Since it is only necessary to block the object so as not to reach the land side, a strong structure is not required, and the structure can be configured as a simple structure as compared with the offshore wall surface 10. In addition, since it is only necessary to block a small amount of water flowing down to the top end face 20, it is not necessary to increase the height in the height direction.
, The height of the top can be made sufficiently lower than that of a conventional upright type wave-proof structure (FIG. 17).

Further, if such a wave-returning structure 22 is provided on the wave-breaking structure having the top height hc set based on the theoretical formula (1), the relative top height hc / Ho is obtained. Can be further reduced, and particularly excellent non-overtopping characteristics can be provided.

It is to be noted that the wave-reversing structure 22 may be formed separately from the wave-breaking structure main body 50 and attached to the top end face 20, or may be integrally formed with the wave-breaking structure main body 50.

As shown in FIG. 9, as a structure having the same operation and effect as the surfacing 22, a surfacing 23 having a vertical surfacing surface 231 on the top end face 20.
(Ninth Embodiment) may be provided. Furthermore, a configuration may be provided in which a wave-returning surface is formed such that the wave-returning surface is inclined upward on the land side.

Further, as shown in FIG. 10, such a wave-return surface is formed at the forefront of the top end surface 20, that is, at the top of the offshore wall surface 10 as a vertical surface 241 continuous with the curved surface portion 11. (Tenth Embodiment) Even with such a configuration, the vertical surface 241 does not allow a small amount of water that has peeled off from the main flow of the repelled wave to reach the top end surface 20, not as a part of the curved surface portion 11 that repels the wave. Because it acts as a wave return surface for
There is no need to increase the height in the height direction, and there is no change in that the height of the top end can be sufficiently reduced as compared with the conventional upright type breakwater structure (FIG. 17).

In order to prevent the water flowing on the top end face 20 from reaching the land side of the main body 50 as described above, a drainage means may be provided on the top end face 20.

With such a configuration, the offshore wall surface 10
Even if only a small amount of overtopping occurs, water can be prevented from reaching the land side of the top end face 20 by the drainage means, so that non-overtopping characteristics are further improved. Can be.

Such a drainage means may be constituted by a groove formed on the top end face 20 (eleventh embodiment, FIG. 1).
1) Alternatively, it can be configured by forming the top end surface 20 so as to be inclined toward the offshore side.

Further, a wave breaker may be provided in front of the offshore wall surface of the breakwater structure according to each of the above-described embodiments, and according to this breakwater, the wave reaching the offshore wall surface of the breakwater structure may be provided. Therefore, the overtopping performance can be further improved and the height of the top end can be reduced.

[0116]

As described above, according to the present invention, since the curved portion is provided at least above the offshore surface, excellent non-overtopping characteristics can be obtained, and the shape condition of the offshore surface and Clarify the quantitative relationship between the external conditions such as the offshore wave height and the overtopping performance of the breakwater structure, and based on this relationship, determine the structure of the offshore wall surface of the breakwater structure, especially the height of the top. ,
The wave-prevention structure is set to meet the required wave-overtopping performance in the sea area as required and sufficient. A structure can be provided.

Therefore, while maintaining the view of the coastal area where the breakwater structure is installed, the body of the breakwater structure is reduced in weight, thereby reducing the required foundation and reducing the cost and labor required for ground improvement. Can be.

[Brief description of the drawings]

FIG. 1 is a cross-sectional configuration diagram showing a first embodiment of a wavebreak structure according to the present invention.

FIG. 2 is a cross-sectional configuration diagram illustrating a second embodiment of a wavebreak structure according to the present invention.

FIG. 3 is a cross-sectional configuration diagram illustrating a third embodiment of a wavebreak structure according to the present invention.

FIG. 4 is a cross-sectional configuration diagram illustrating a fourth embodiment of a wavebreak structure according to the present invention.

FIG. 5 is a cross-sectional configuration diagram showing a fifth embodiment of a wavebreak structure according to the present invention.

FIG. 6 is a cross-sectional configuration diagram showing a sixth embodiment of a wavebreak structure according to the present invention.

FIG. 7 is a cross-sectional configuration diagram illustrating a seventh embodiment of a wavebreak structure according to the present invention.

FIG. 8 is a sectional configuration view showing an eighth embodiment of a wavebreak structure according to the present invention.

FIG. 9 is a sectional configuration view showing a ninth embodiment of a wavebreak structure according to the present invention.

FIG. 10 is a cross-sectional configuration diagram showing a tenth embodiment of a wavebreak structure according to the present invention.

FIG. 11 is a sectional configuration view showing an eleventh embodiment of a wavebreak structure according to the present invention.

FIG. 12 is a cross-sectional view showing a two-dimensional wave-making water tank used in a series of water tank experiments.

FIG. 13 is a cross-sectional view showing scale models I and II used in an aquarium experiment.

FIG. 14 is a graph showing the difference in the top height hc at which the overtopping can be prevented in each of the flare-type scale models.

FIG. 15 is a graph showing relative top edge heights hc / Ho with respect to various waveform gradients Ho / Lo.

FIG. 16 is a graph showing a relationship between a relative top height (parameter X) calculated from the estimation formula (1) and a relative top height hc / Ho actually detected by a water tank experiment.

FIG. 17 is a cross-sectional configuration diagram showing a conventional wavebreak structure using an upright caisson.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Offshore wall surface 11 Curved surface part 12 Substantially vertical surface 20 Top end surface 21 Top end plate 22, 23 Wave return work 25 Drainage means (drainage ditch) 40 Foundation

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Tomokazu Nakagawa 1-5-5 Takatsukadai, Nishi-ku, Kobe City Inside Kobe Research Institute, Kobe Steel Ltd. (72) Inventor Takehiro Nakaoka Takatsukadai, Nishi-ku, Kobe-shi 1-5-5 Kobe Steel, Ltd.Kobe Research Institute (72) Inventor Kenichi Sugii 1-3-1-18 Wakihamacho, Chuo-ku, Kobe Kobe Steel Ltd.Kobe Head Office (72) Inventor Hamasaki Yoshihiro 1-3-18, Wakihama-cho, Chuo-ku, Kobe Kobe Steel, Ltd.Kobe headquarters (72) Inventor Naoto Takehana 1-3-18, Wakihama-cho, Chuo-ku, Kobe Kobe Steel, Kobe headquarters

Claims (11)

[Claims] 1. A wave-breaking structure erected facing offshore, wherein at least an upper portion of an offshore wall surface is provided with a curved portion inclined so as to approach offshore, and a top end of the curved portion is provided. The quantity hc / Ho obtained by dimensioning the height hc by the maximum offshore wave height Ho is set within the range of 0.5X or more and 1.5X or less with respect to the parameter X defined by the following equation. A breakwater structure characterized by the following. (Equation 1) However, Ho is the maximum offshore wave height, Lo is the offshore wave wavelength, h is the installation depth of the structure, B is the height of the offshore wall, D is the horizontal length of the curved surface portion, and S is the offshore wall surface and the still water surface. 4 is a cross-sectional area of a region sandwiched between the wave-breaking structures as viewed from the width direction. 2. The wavebreak structure according to claim 1, wherein a dimensionless amount hc / Ho of a top height hc of the curved surface portion is set to 1.2X or less with respect to the parameter X. 3. The wavebreak structure according to claim 1, wherein a dimensionless amount hc / Ho of a top height hc of the curved surface portion is set to 0.8X or more with respect to the parameter X. . 4. The wavebreak structure according to claim 1, wherein a dimensionless amount hc / Ho of a top height hc of the curved surface portion is set to 1.0X or more with respect to the parameter X. . 5. The waveproof structure according to claim 1, wherein a dimensionless amount hc / Ho of a top height hc of the curved surface portion is set to 1.1X or more with respect to the parameter X. . 6. The wavebreak structure according to claim 1, wherein said curved surface portion is provided in a region including a still water level position. 7. The breakwater according to claim 1, wherein an inclination angle of the curved surface portion is configured to increase from a lower portion to an upper portion of the offshore wall surface. Structure. 8. The breakwater structure according to claim 1, wherein a lower portion of the offshore wall surface is configured as a substantially vertical plane. 9. The wavebreak structure according to claim 1, wherein a lower portion of the offshore wall surface is configured such that a lower side protrudes toward the offshore side. . 10. The wavebreak structure according to claim 1, wherein a top plate that extends substantially horizontally toward the offshore side is provided above the curved surface portion. Stuff. 11. The protection according to claim 1, wherein a wave-returning structure is provided on a top end surface of the offshore wall surface to block water flowing to the top end surface. Wave structure.