JP2006161431A - Water breaking structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase reflected wave reduction performance while maintaining overflow wave stopping performance. <P>SOLUTION: This wave breaking structure comprises a body part 12 having, on its offshore side wall surface 18, an extension part 20 extended to an offshore and a wave dissipating/passing wall 14 forming a retarding chamber 30 in the clearance thereof from the offshore side wall surface 18 of the body part 12. The upper end part of the wave dissipating/passing wall 14 is formed to be separated from the extension part 20 and positioned under the offshore side end part 20b where it is not projected from the offshore side end part 20b of the extension part 20 to the offshore side. The upper end part of the wave dissipating/passing wall 14 is formed at a position lower than a sea level where overflow wave causes problems and higher than a sea level where the reflected wave causes problems. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a breakwater installed in a harbor or the like and a breakwater structure for revetment.

  Conventionally, as shown in FIG. 9, as a breakwater or a breakwater structure for revetment installed in a port or the like, a low-end (low revetment height) It is known that the amount of waves exceeding the revetment (overflow flow rate) can be greatly reduced. This type of breakwater structure is called a flare revetment here.

  When this flare revetment is installed in a relatively shallow sea area, a structure having a footing part (overhang) that usually protrudes to the offshore side is used, and when it is installed in a relatively deep sea area, As shown in FIG. 9, a structure (upper flare revetment) having a structure in which the lower part stands upright and the protruding part 60 is provided only at the upper part is used.

On the other hand, a structure in which a wave-dissipating structure is provided as a wave-proof structure is known. For example, Patent Documents 1 and 2 below disclose a wave-dissipating structure in which a water-reserving chamber is formed between a front wall having a slit and a rear wall that is disposed apart from the front wall. Thus, it is known that the wave-dissipating performance can be exhibited by forming a slit on the front surface and providing a water reserving chamber.
JP-A-6-272225 JP 2002-146746 A

  However, although the flare revetment is very excellent in the overtopping prevention performance, the wave reflectivity, that is, the ratio of the wave height of the reflected wave to the wave height of the incident wave is about 0.7 to 0.9, which is much less than that of a normal upright revetment. There is a problem that the performance of quenching a wave having a wave height of about 1 m, which has a problem of reflectivity, is inferior.

  On the other hand, in the structure disclosed in the patent document, although the reflected wave reduction performance can be exhibited, when a wave that causes overtopping arrives, the wave goes back in front of the front wall, so overtopping tends to occur. End up. That is, in this structure, although the reflected wave can be reduced by the front wall, there arises a problem that overtopping is induced.

  Therefore, the present invention has been made in view of such points, and an object thereof is to improve reflected wave reduction performance while maintaining overtopping prevention performance.

  For example, when applying a wave-absorbing structure to the flare revetment, as shown in FIG. 10, the front end of the projecting portion 60 and the front end of the footing portion 62 are connected by a slit-like structure 64 made of a vertical wall. It is possible. However, even in such a structure, when a wave in which overtopping becomes a problem arrives, the wave goes back to the front surface of the slit-like structure 64, and thus the slit-like structure 64 induces overtopping.

  Therefore, the present inventor has paid attention to the fact that the tide level in which overtopping is a problem is higher than the tide level in which reflected waves are a problem. Generally, the wave reflected by the wave-breaking structure becomes a problem when the fishing boat or the like can leave the port, for example, when the wave height is about 1 m or less. On the other hand, overtopping becomes a problem when the tide level rises or when the wave height exceeds 1.5 m, for example, compared to when reflected waves are a problem. For example, in the case of a typhoon or the like, the tide level is increased and the wave height is increased and the wavelength is increased as compared with the case where the reflected wave becomes a problem due to the low atmospheric pressure.

  Therefore, the present invention is characterized in that the upper end portion of the wave-dissipating transmission wall that exhibits the reflected wave reduction performance is disconnected from the protruding portion located on the upper end portion.

  Specifically, on the premise of a wave-proof structure standing facing offshore, the present invention is provided with at least part of the offshore side wall surface having a protruding portion that projects toward the offshore as it goes upward. A wave-dissipating wall that forms a water chamber between the main body part and the offshore wall surface of the main-body part, and an upper end portion of the wave-dissipating wall is spaced apart from the protruding part and the compressing wall. It is provided so as to be located below the offshore side end at a position that does not protrude offshore from the offshore side end of the outlet.

  In this wave-breaking structure, the upper end of the wave-dissipating transmission wall is separated from the protruding part, so that when the tide level is high, waves coming from offshore are not blocked by the wave-dissipating transmitting wall and are not blocked by the absorbing part. By reaching directly, overtopping can be effectively prevented. On the other hand, when the tide level is low, the energy of waves arriving from offshore can be dissipated by the wave-dissipating transmission wall, and the reflected waves can be reduced.

  Here, the wave-dissipating transmission wall may be joined to a connection part protruding from the off-shore wall surface behind the off-wall side. In this case, it is possible to dispose the wave-dissipating wall only near the water surface, so the wave-dissipating wall is more compact than the structure in which the wave-dissipating wall is erected at the bottom of the wave-proof structure. can do. For this reason, it is particularly effective when installing a wave-breaking structure at a deep water depth.

  On the other hand, the main body may be provided with a footing portion that protrudes to the offshore side at the lowest part of the offshore wall surface, and the wave-absorbing transmission wall may be erected on the footing portion. In this case, it is possible to avoid an increase in the size of the wave-dissipating transmission wall in the wave-breaking structure installed at a shallow water depth, and furthermore, the wave-dissipating transmission wall can be provided using the footing portion. The wave-dissipating transmission wall can be easily provided so as to be separated from the protruding portion while preventing the structure of the wave-proof structure from becoming complicated.

  The wave-dissipating transmission wall may be configured to be inclined so as to recede from the offing as at least the upper part of the front wall facing the offing goes upward. In other words, if the front wall of the wave-dissipating transmission wall is configured as a vertical surface, even if the wave-dissipating transmission wall is below the water surface, a part of the wave to be overtopped hits the wave-dissipating transmission wall and is directly above it. However, if the front wall is inclined as in this configuration, even if a part of the water surface that hits the wave-dissipating wall is scattered upward, Can be easily received inside the protruding portion. As a result, the overtopping prevention performance can be improved.

  In addition, the wave-dissipating transmission wall may be disposed at a position retracted from the offshore side than the offshore side end portion of the protruding portion. In this configuration, even if the wave to be wave-dissipated hitting the wave-dissipating transmission wall is scattered right above, it can be received inside the protruding portion, so that the overtopping prevention performance can be effectively exhibited.

  And, if the upper end of the wave-dissipating transmission wall is provided below the tide level where overtopping is a problem, the wave that has arrived at the tide level where overtopping is a problem is surely pushed out. Therefore, overtopping prevention performance can be effectively exhibited. As the tide level where overtopping is a problem here, for example, the highest recorded tide level that represents the highest tide level in the statistics for the past several decades is applicable.

  Further, if the upper end portion of the wave-dissipating transmission wall is provided above the tide level at which the reflected wave is a problem, the wave that has arrived at the tide level at which the reflected wave is a problem can be surely extinguished. Since the wave transmission wall can be reached, the wave can be quenched by the wave transmission wall. As a result, the reflected wave reduction performance can be effectively exhibited. In addition, as a tide level where the reflected wave here becomes a problem, the highest tide level in one year corresponds, for example. Moreover, as a tide level in which this reflected wave becomes a problem, a tide level between the highest tide level and the lowest tide level within one year corresponds, for example.

  The wave-dissipating wall has a gap of 0.1 times or more and 0.3 times or less of the wavelength of the wave to be wave-dissipated between the offshore wall surface located behind the wave-dissipating wall. It is preferable that the wave-dissipating wall is arranged so that the aperture ratio is 15% or more and 40% or less, and the wave-dissipating wall has a problem of reflected waves. The height above the hydrostatic surface at the tide level is preferably 0.5 times or more and 2.0 times or less than the wave height of the wave to be extinguished. It is preferable that the height to the still water surface at the tide level where is a problem is configured to be at least three times the wave height of the wave to be quenched. By so doing, the reflectance can be reduced, so that the reflected wave reduction performance can be effectively exhibited while maintaining the overtopping prevention performance.

  The edge part of the opening part provided in the said quenching transmission wall may be comprised in the inclined form so that an opening area may expand toward the offing. In this configuration, since the wave can be smoothly introduced into the water reserving chamber through the wave-dissipating transmission wall, the reflected wave can be more effectively extinguished.

  As described above, according to the present invention, when a wave arrives when the tide level is high, it is possible to prevent the wave from going back through the wave-absorbing transmission wall, so that the overtopping prevention performance can be maintained. Furthermore, since the wave that arrives when the tide level is low can be quenched by the quenching transmission wall, the reflected wave reduction performance can be improved.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings. Here, after first describing the embodiment of the wave preventing structure, the overtopping blocking function and the reflected wave reducing function of the wave preventing structure are verified by a hydraulic experiment using a reduced model of the wave preventing structure.

  FIG.1 and FIG.2 is schematic which shows 1st Embodiment of the wave-proof structure 10 which concerns on this invention. As shown in FIG. 1, the wave-breaking structure 10 is erected facing offshore, and includes a main body 12 and a wave-dissipating transmission wall 14.

  The main body portion 12 includes a base portion 16 having a substantially constant thickness in the wave traveling direction. On the upper side of the base portion 16, an offshore side wall surface 18 that faces the offshore urges forward toward the offshore. 20 is formed. The protruding portion 20 is formed on the upper side of the main body portion 12, and the upper end surface (top end surface) of the protruding portion 20 constitutes the upper end surface of the main body portion 12. The upper end surface of the protruding portion 20 is configured to be flat, while the lower surface 20a is formed in a convex curved shape.

  The upper end portion of the protruding portion 20 is formed at a position higher than the previous highest tide level (H.H.W.L). The past high tide level represents the highest tide level in statistics over the past several decades.

  The main body portion 12 is integrally provided with a connection portion 22 that protrudes forward from the offshore side wall surface 18 of the base portion 16 toward the offshore. The connecting portion 22 is composed of a plurality of flat plate portions 22a arranged at intervals. Each of the flat plate portions 22a has a rectangular flat plate shape and is arranged in a vertical posture so as to follow the wave traveling direction.

  The wave-absorbing transmission wall 14 is joined to the front end of the connecting portion 22. The wave-dissipating transmission wall 14 is disposed in front of the base portion 16 (offshore side) and at a position corresponding to the intermediate height of the main body portion 12. The wave-dissipating transmission wall 14 is composed of a plate-like wall body arranged so that the normal direction of the front wall surface 14a facing the offing matches the traveling direction of the waves.

  In this embodiment, the wave-dissipating transmission wall 14 is disposed in such a posture that the front wall surface 14a is a vertical surface, and the front wall surface 14a is disposed directly below the offshore side end portion 20b of the protruding portion 20. Yes.

  The wave-absorbing transmission wall 14 is formed so that the upper end portion thereof is substantially equal to the lower end portion of the protruding portion 20. The upper end portion of the wave-dissipating transmission wall 14 is disposed at a position lower than the highest peak tide level, and is disposed at a position higher than the highest tide level (HWL). This high tide represents the highest tide in one year. Note that the upper end of the wave-dissipating transmission wall 14 can be arranged at a position higher than the tide level set between the highest tide level (H.W.L) and the lowest tide level (L.W.L). . The lowest tide level represents the lowest tide level in one year.

  There is a high possibility that overtopping will be a problem at the highest tide level. For this reason, the wave-dissipating transmission wall 14 is formed so that the upper end portion thereof is lower than the highest peak tide level so that the wave-dissipating transmission wall 14 is submerged at the tide level WL1 where the tide level is high and overtopping is a problem. Is going to increase. On the other hand, when the tide level is below the maximum tide level, reflected waves are likely to be a problem. For this reason, by forming the upper end portion of the wave-dissipating transmission wall 14 to be higher than the maximum tide level, the wave-dissipating transmission wall 14 protrudes above the water surface and is transmitted through the wave-dissipation when the reflected wave is at the tide level WL2. The wall 14 is often subjected to waves.

  A plurality of slits 26 as openings are formed in the wave-dissipating transmission wall 14. Each of the slits 26 has a vertically elongated shape formed from the upper end to the lower end of the wave-dissipating transmission wall 14, and is formed between the joint portions with the flat plate portions 22a. As a result, the wave-dissipating transmission wall 14 is divided into a number of wall body constituent portions 14b corresponding to the respective flat plate portions 22a. In other words, in front of the base portion 16, a plurality of wall body constituent portions 14b are arranged in parallel at intervals. The wall constituting portion 14b and the flat plate portion 22a are joined in a T shape as viewed from above.

  A gap between the offshore wall surface 18 of the main body portion 12 and the wave-dissipating transmission wall 14 is formed as a water reserving chamber 30. The water chamber 30 is partitioned into a plurality of small rooms by the flat plate portions 22 a, and the partitioned small rooms are connected to the offshore side of the wave-dissipating transmission wall 14 through slits 26.

  In the wave-breaking structure 10 configured as described above, as shown in FIG. 2, when the tide level is high and overtopping becomes a problem, the wave-dissipating transmission wall 14 is submerged under the water surface. The overtopping target wave that arrives at this time has a high wave length and a long wavelength. Since the upper end portion of the wave-dissipating transmission wall 14 is spaced downward from the protruding portion 20, when the wave overcoming wave arrives at the wave preventing structure 10, the wave overcoming target wave is almost blocked by the wave-dissipating transmission wall 14. The urging section 20 is reached directly without being pushed. For this reason, the wave to be overtopped is rebounded offshore by the urging unit 20, thereby effectively preventing overtopping.

  On the other hand, when the tide level is low and the reflected wave becomes a problem, the wave-dissipating transmission wall 14 protrudes on the water surface. The wave to be wave-dissipated at this time has a wave height as low as about 1 m and a short wavelength. When the wave to be wave-dissipated arrives at the wave-breaking structure 10, the wave to be wave-dissipated first reaches the wave-dissipating transmission wall 14, and a part of the wave is introduced into the water reserving chamber 30 through the slit 26. At this time, the energy of the wave is reduced by disturbing the wave by the slit 26 and generating a vortex, and further, the wave energy is dissipated and dissipated in the water reserving chamber 30 by the multiple reflection. it can.

  Therefore, when a wave in which overtopping is a problem has arrived, it is possible to prevent the wave from going back through the wave-dissipating transmission wall 14, so that the overtopping blocking performance can be maintained, and the reflected wave becomes a problem. Even if a wave arrives, the wave can be extinguished by the quenching transmission wall 14, so that the reflected wave reduction performance can be improved.

  In addition, in the present embodiment, since the wave-absorbing transmission wall 14 is joined to the connecting portion 22 projecting from the main body portion 12, the wave-absorbing transmission wall 14 can be disposed only near the water surface. Compared to a configuration in which the wave-dissipating wall 14 is erected at the lowermost part of the wave structure 10, the wave-dissipating wall 14 can be configured more compactly. For this reason, it becomes effective especially when installing the wave-proof structure 10 in the place where water depth is deep.

  Next, another embodiment will be described. In the following embodiments, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  FIG. 3 shows a second embodiment of the wave-breaking structure 10 according to the present invention. The wave-breaking structure 10 is configured such that the wave-dissipating transmission wall 14 is inclined.

  Specifically, unlike the first embodiment, the connection portion 22 is configured in a trapezoidal shape whose upper side is shorter than the lower side when viewed from the side. The wave-dissipating transmission wall 14 is configured to be inclined so as to recede from offshore as it goes up as a whole including the front wall surface 14a. And the upper end part in the front wall surface 14a of the wave-dissipating transmission wall 14 is arrange | positioned directly under the offshore side edge part 20b of the protrusion part 20. FIG. The installation height of the wave-dissipating transmission wall 14 is the same as that in the first embodiment.

  According to the second embodiment, when a wave to be overtopped has arrived, even if a part of the wave below the water surface hitting the wave-dissipating transmission wall 14 scatters upward, it is reflected on the lower surface 20a ( It can be easily received on the inside. As a result, the overtopping prevention performance can be improved.

  The entire wave-dissipating wall 14 may be disposed at a position retracted from the offshore side than the offshore side end portion 20 b of the protruding portion 20, or the lower end portion is the offshore side end portion of the protruding portion 20. You may protrude in the offing side rather than 20b. Further, the upper end portion of the wave-dissipating transmission wall 14 may be disposed at a position retreated from the offing compared to the offshore side end 20 b of the protruding portion 20.

  Further, in the second embodiment, the connecting portion 22 may be formed in a rectangular shape as in the first embodiment, and the thickness of the wave-absorbing transmission wall 14 may be changed up and down. In this case, the rear wall surface of the wave-dissipating wall 14 extends in the vertical direction, while the front wall surface 14a is inclined so as to recede from the offshore as it goes upward.

  FIG. 4 shows a third embodiment of the wave-breaking structure 10 according to the present invention. Unlike the second embodiment, the wave preventing structure 10 has only an upper portion 14c of the front wall surface 14a of the wave-dissipating transmission wall 14 inclined.

  Specifically, the connection part 22 is configured in an inclined shape so that only the upper part at the tip part to which the wave-dissipating transmission wall 14 is joined retreats from offshore. And only the upper part of the wave-dissipating transmission wall 14 is inclined correspondingly. As a result, the wave-absorbing transmission wall 14 has an inclined shape in which the upper part 14c of the front wall surface 14a facing the offing recedes from the offing toward the upper side.

  In the third embodiment, as in the second embodiment, even if a part of the wave to be overtopped is scattered upward, it can be easily received by the lower surface 20a of the urging portion 20.

  In the third embodiment, the connecting portion 22 may be formed in a rectangular shape as in the first embodiment, and only the front wall surface 14a in the upper part of the wave-dissipating transmission wall 14 may be formed in an inclined shape.

  FIG. 5 shows a fourth embodiment of the wave preventing structure 10 according to the present invention. The wave-dissipating transmission wall 14 of the wave-breaking structure 10 is formed in a trapezoidal cross-section when each wall body component 14b is viewed from above. In other words, the edge 26a of the slit 26 is formed in an inclined shape so that the opening area increases toward the front (offshore).

  According to the fourth embodiment, since the wave that has reached the wave-dissipating transmission wall 14 is likely to smoothly flow into the water reserving chamber 30 through the slit 26, the reflected wave can be more effectively extinguished.

  In the fourth embodiment, the wave-dissipating transmission wall 14 may be configured so that at least the front wall surface 14a of the upper portion 14c is inclined as in the second and third embodiments.

  FIG. 6 shows a fifth embodiment of the wave preventing structure 10 according to the present invention. In the wave-breaking structure 10, the front wall surface 14 a of the wave-dissipating transmission wall 14 is disposed at a position where the front wall surface 14 a recedes from the offshore side than the offshore side end portion 20 b of the protruding portion 20. The front wall surface 14a is parallel to the vertical surface.

  When a wave in which overtopping is a problem is reached, a part of the wave below the water surface may hit the wave-dissipating transmission wall 14 and scatter upward. In the fifth embodiment, the front wall surface 14a of the wave-dissipating transmission wall 14 Since it is retreating from the offshore side end 20 b of the urging portion 20, it is possible to easily receive the scattered wave to be overtopped inside the urging portion 20.

  FIG. 7 shows a sixth embodiment of the wave preventing structure 10 according to the present invention. In the wave preventing structure 10, the lower surface 20a of the protruding portion 20 is configured by a flat inclined surface. The front wall surface 14 a of the wave-dissipating transmission wall 14 is located immediately below the offshore side end portion 20 b of the protruding portion 20.

  Even if the lower surface 20a of the protruding portion 20 is planar as in the present embodiment, the same effects as those of the first embodiment can be achieved.

  FIG. 8 shows a seventh embodiment of the wave-breaking structure 10 according to the present invention. In the seventh embodiment, unlike the first to sixth embodiments, the wave-dissipating transmission wall 14 is erected on the footing portion 34.

  Specifically, a footing portion 34 that protrudes from the base portion 16 in the same direction as the protruding portion 20 is provided at the lowermost portion of the main body portion 12 of the wave preventing structure 10. The distal end of the footing part 34 is located directly below the offshore side end 20 b of the protruding part 20, and the wave-dissipating transmission wall 14 is erected at the distal end of the footing part 34. Note that the footing part 34 may protrude further to the offshore side than the projecting part 20, and the wave-absorbing transmission wall 14 may be erected at an intermediate part of the footing part 34. Further, even when the wave-dissipating transmission wall 14 is erected on the footing portion 34, the wave-dissipating transmission wall 14 may be configured to be inclined as in the above-described embodiment, and the protruding portion 20 It may be provided at a position retracted rearward than the offshore side end 20b.

  Although not shown, a slit is formed in the wave-absorbing transmission wall 14, and a region between the base portion 16, the footing portion 34, and the wave-dissipating transmission wall 14 is formed as a water reserving chamber 30.

  According to the seventh embodiment, in the wave-breaking structure 10 installed at a shallow depth, it is possible to avoid an increase in the size of the wave-dissipating transmission wall 14, and the wave-extinguishing using the footing unit 34. Since the transmission wall 14 can be provided, the wave-dissipating transmission wall 14 can be easily provided so as to be separated from the protruding portion 20 while preventing the structure of the wave preventing structure 10 from becoming complicated.

  In addition, in the said 1st-6th embodiment, it is good also as a structure by which the footing part is provided in the lowest part of the main-body part 12. FIG.

  Subsequently, the overtopping prevention performance and the reflected wave reduction performance of the wave breaker structure 10 configured as described above will be verified by a hydraulic experiment using a reduced model.

  In this experiment, a reduced model was installed in a two-dimensional wave tank (not shown) (length 30 m, height 1.2 m, width 0.6 m, water depth 80 cm), and this reduced model was generated by a wave generator. This was done by colliding irregular waves. In the following description, structural dimensions and wave specifications are represented by local values.

  As the reduction model, a reduction model (Examples 1 to 4) of the wave-breaking structure 10 according to the present invention and a reduction model (Comparative Examples 1 to 2) of a conventional wave-breaking structure were used. Each reduction model is as follows.

  The model of Example 1 is a model of the first embodiment shown in FIGS. 1 and 2. In the reduced model of the first embodiment, the depth Bo of the base portion 16 with respect to the offshore side end portion 20b of the protruding portion 20 is 3.7 m, and the depth B1 of the base portion 16 with respect to the wave-dissipating transmission wall 14 is 3.7 m. Then, the height (height on the still water surface) h1 from the still water surface to the upper end portion of the wave-dissipating transmission wall 14 when the reflected wave is at the tide level WL2 in question is 1 m, and from the lower end portion of the wave-dissipating transmission wall 14 The height to the still water surface (height under the still water surface) h2 when the water is at the tide level WL2 is 3 m. Further, the aperture ratio ε of the wave-absorbing transmission wall 14 was set to 25%. Here, the aperture ratio ε represents the ratio of the area occupied by the slit 26 in the wave-dissipating transmission wall 14.

  The model of Example 2 is a model of the second embodiment shown in FIG. The dimensions of the model of the second embodiment are the same as the model of the first embodiment except for the wave-dissipating transmission wall 14. In this model, the wave-absorbing transmission wall 14 is inclined by 80 degrees (indicated by θ1 in FIG. 3) with respect to the water surface, and the front wall surface 14a at the tide level WL2 where the reflected wave becomes a problem is the offshore side end portion 20b of the protruding portion 20. It was located just below.

  The model of Example 3 is a model of the third embodiment shown in FIG. The dimensions of the model of Example 3 are the same as the model of Example 1 except for the upper part of the wave-dissipating transmission wall 14. In this model, a portion of 1 m from the upper end protruding above the tide level WL2 is inclined 45 degrees (indicated by θ2 in FIG. 4) on the wave-dissipating transmission wall 14 with respect to the water surface.

  The model of Example 4 is a model of the fourth embodiment shown in FIG. The dimensions of the model of Example 4 are the same as the model of Example 1 except for the slit 26. In this model, the edge 26a of the slit 26 was inclined 45 degrees (indicated by θ3 in FIG. 5B) with respect to the wave traveling direction.

  The model of the comparative example 1 models the wave-breaking structure (upper flare revetment) which does not have the wave-dissipating transmission wall shown in FIG. The dimensions of the model of Comparative Example 1 are the same as those of Example 1 except for the wave-dissipating transmission wall.

  The model of the comparative example 2 models the wave-proof structure shown in FIG. The aperture ratio of the slit-like structure 64 provided at the front end of the wave-proof structure was 25%, and the depth Bo from the slit-like structure 64 was 3.7 m.

The overtopping prevention performance was measured by an overtopping flow rate measurement experiment in which the overtopping target wave collides with each reduced model and the overtopping flow rate Q (m ³ / m / sec) at that time was measured. The overtopping target wave was a significant wave height of 4 m, a wavelength of 72 m, and a period of 6.8 sec, and the tide level WL1 when overtopping was a problem was +2.40 m (at H.H.W.L). At this time, the height at the top of the wave-breaking structure 10 (height of the wave-breaking structure 10 on the still water surface) hc was 3.3 m.

  For reflected wave reduction performance, the target wave to be waved collides with each reduced model, the wave height of the reflected wave at that time is measured, and the reflectance indicating the ratio of the wave height of the reflected wave to the wave height of the incident wave is obtained. A measurement experiment was conducted. The wave to be wave-dissipated was a significant wave height of 1 m, a wavelength of 21.4 m, and a period of 3.7 sec, and the tide level WL2 where the reflected wave was a problem was +0.90 m (at HWL). The top height hc of the wave preventing structure 10 at this time is 4.8 m (= 3.3 + 2.40-0.90).

  The results of the overtopping flow rate measurement experiment and the reflectance measurement experiment are shown in Table 1 below.

As shown in Table 1, in the upper flare revetment of Comparative Example 1, the overtopping flow rate Q is very small as 0.0034 (m ³ / m / sec), but the reflectance Kr is very large as 0.83. . That is, the upper flare revetment has high wave overtopping prevention performance, but has very low reflected wave reduction performance. On the other hand, in the comparative example 2, the reflectance Kr is as small as 0.35, but the overtopping flow rate Q is 0.042 (m ³ / m / sec), which is one digit larger than the others. This is because, in Comparative Example 2, the overtopping target wave goes back through the slit-like structure 64 at the front end and directly exceeds the wave-proof structure. In Comparative Example 2, it can be said that the reflected wave reduction performance is high, but the overtopping prevention performance is very low.

  On the other hand, in Examples 1 to 4, the overtopping flow rate Q is small and the reflectance Kr is also small. In particular, in Examples 2 and 3, both the overtopping flow rate Q and the reflectance Kr are improved as compared with Example 1. Therefore, it can be seen that by tilting the wave-dissipating transmission wall 14, not only the overtopping flow rate Q can be reduced, but also the wave-dissipating performance can be improved.

  Further, in Example 4, the overtopping flow rate Q is larger than those in Examples 2 and 3, but the reflectance Kr is smaller than those in Examples 2 and 3. Therefore, it can be seen that the wave extinction performance can be improved by inclining the edge 26a of the slit 26.

  Next, various dimensions such as the wave-dissipating transmission wall 14 were examined for the wave-proof structure 10 of the present invention shown in FIGS. 1 and 2.

(1) Study on depth B1 Various types of depth B1 of the base portion 16 with respect to the wave-absorbing transmission wall 14 were prepared, and the influence on the reflectance Kr due to the difference in the depth B1 was examined. This examination was performed by changing the ratio (B1 / L) of the depth B1 to the wavelength L of the wave to be quenched in the range of 0.05 to 0.4 and performing the same experiment as the reflectance measurement experiment. The result is shown in FIG. As shown in the figure, the reflectance (Kr) is 0.3 or less when the ratio (B1 / L) is in the range of 0.1 to 0.3. . In general, 0.3 to 0.4 is adopted as the reference value of the reflectance Kr, but in this study, the reference value of the reflectance Kr is set to 0.3 in order to evaluate more strictly.

  In the reflectance measurement experiment, in the model of Example 1, the depth B1 is 3.7 m and the wavelength L of the wave to be quenched is 21.4 m, so B1 / L is 0.17. Yes.

(2) Examination concerning the aperture ratio ε The aperture ratio ε of the wave transmission wall 14 was changed in the range of 10% to 50%, and the influence on the reflectance Kr due to the difference in the aperture ratio ε was examined. The examination results are shown in FIG. As shown in the figure, the reflectance Kr is 0.3 or less when the aperture ratio ε is in the range of 15% to 40%.

(3) Examination on height h1 on the still water surface Prepare various types of the height of the upper end portion of the wave-dissipating transmission wall 14 to the reflectance Kr due to the difference in the height h1 of the wave-dissipating transmission wall 14 The effect of was examined. The result is shown in FIG. In the figure, the horizontal axis represents the value (h1 / H) obtained by making the height h1 on the still water surface dimensionless with the wave height H of the wave to be quenched, and the vertical axis represents the reflectance Kr. As shown in the figure, in the range where the height h1 on the still water surface is smaller than the wave height H (h1 / H <1), the reflectance Kr increases as the height h1 on the still water surface decreases, and the wave-dissipating performance increases. On the other hand, in the range where the height h1 on the still water surface is larger than the wave height H (h1 / H> 1), the reverse tendency is seen. The reflectance (Kr) is about 0.3 or less when the value (h1 / H) is in the range of 0.5 to 2.0.

(4) Study on the height h2 below the still water surface Prepared with various changes in the height of the lower end portion of the wave-absorbing transmission wall 14 to the reflectance Kr due to the difference in the height h2 of the wave-absorbing transmission wall 14 The effect of was examined. The result is shown in FIG. In the figure, a value (h2 / H) obtained by making the static water surface height h2 dimensionless with the wave height H of the wave to be quenched is taken on the horizontal axis, and the reflectance Kr is taken on the vertical axis. As shown in the figure, as the value (h2 / H) increases, the reflectivity Kr gradually decreases, and when the value of the height h2 below the hydrostatic surface of the wave-absorbing transmission wall 14 increases, the wave-dissipating performance. Can be seen to improve. And when this value (h2 / H) is 3 or more, it turns out that the reflectance Kr becomes 0.3 or less, and good wave-dissipating performance is shown in this range.

It is a perspective view showing the whole wave-proof structure object concerning a 1st embodiment of the present invention. It is the schematic which shows the said wave-proof structure seeing from the side. It is the FIG. 2 equivalent view of the wave-proof structure which concerns on 2nd Embodiment of this invention. It is the FIG. 2 equivalent view of the wave-proof structure which concerns on 3rd Embodiment of this invention. The wave-proof structure based on 4th Embodiment of this invention is shown, (a) is a FIG. 2 equivalent view, (b) is a top view of the wall body structure part joined to the flat plate part. It is the schematic which shows the wave-proof structure which concerns on 5th Embodiment of this invention seeing from a side. It is the schematic which shows the wave-proof structure which concerns on 6th Embodiment of this invention seeing from a side. It is the schematic which shows the wave-proof structure which concerns on 7th Embodiment of this invention seeing from a side. It is a perspective view which shows the whole structure of the conventional wave-breaking structure (upper flare revetment). It is a perspective view which shows the whole wave preventing structure which applied the slit-shaped structure to the conventional flare revetment. It is a characteristic view which shows the relationship between ratio (B1 / L) and reflectance Kr. It is a characteristic view which shows the relationship between aperture ratio (epsilon) and reflectance Kr. It is a characteristic view which shows the relationship between a value (h1 / H) and the reflectance Kr. It is a characteristic view which shows the relationship between a value (h2 / H) and the reflectance Kr.

Explanation of symbols

DESCRIPTION OF SYMBOLS 12 Main body part 14 Wave-dissipating transmission wall 14a Front wall 14c Upper part 18 Offshore wall surface 20 Extrusion part 20b Offshore side edge part 22 Connection part 30 Reservoir chamber 34 Footing part

Claims (12)

It is a wave-breaking structure that is erected facing offshore,
A main body provided with a protruding portion that protrudes toward the offshore as it goes upward, on at least a part of the offshore wall surface,
A wave-dissipating transmission wall that forms a water-retarding chamber with the offshore wall surface of the main body,
The upper end portion of the wave-dissipating transmission wall is provided so as to be separated from the projecting portion and located below the offshore end portion at a position that does not protrude from the offshore end portion of the projecting portion. A wave-proof structure characterized by being made.   The wave-breaking structure according to claim 1, wherein the wave-dissipating transmission wall is joined to a connection portion protruding from the off-shore wall surface behind the off-wall side. The main body is provided with a footing portion that protrudes to the offshore side at the bottom of the offshore wall surface,
The wave-breaking structure according to claim 1, wherein the wave-dissipating transmission wall is erected on the footing portion.   The said wave-dissipating transmission wall is comprised in the inclined shape which recedes from offshore as at least the upper part of the front wall surface which faces offshore goes upwards, The any one of Claim 1 to 3 characterized by the above-mentioned. Wave-proof structure.   The wave-breaking structure according to any one of claims 1 to 4, wherein the wave-dissipating transmission wall is disposed at a position retreated from the offshore side from the offshore side end portion of the protruding portion. .   The wave-breaking structure according to any one of claims 1 to 5, wherein an upper end portion of the wave-dissipating transmission wall is provided below a tide level where overtopping is a problem. .   The wave preventing structure according to any one of claims 1 to 6, wherein an upper end portion of the wave-dissipating transmission wall is provided so as to be positioned above a tide level at which a reflected wave is a problem. object.   The wave-dissipating wall has a gap of 0.1 times or more and 0.3 times or less of the wavelength of the wave to be wave-dissipated between the offshore wall surface located behind the wave-dissipating wall. The wave preventing structure according to any one of claims 1 to 7, wherein the wave preventing structure is arranged.   The wave-breaking structure according to any one of claims 1 to 8, wherein the wave-absorbing transmission wall has an aperture ratio of 15% or more and 40% or less.   The wave-dissipating wall is configured such that the height above the hydrostatic surface at the tide level where reflected waves are a problem is 0.5 times or more and 2.0 times or less the wave height of the wave to be wave-dissipated. The wave-proof structure of any one of Claim 1 to 9.   The wave-dissipating transmission wall is configured such that the height from the lower end of the wave-dissipating wall to the hydrostatic surface at the tide level where the reflected wave is a problem is more than three times the wave height of the wave to be wave-dissipated. 10. The wave preventing structure according to any one of 10 above.   The edge part of the opening part provided in the said quenching transmission wall is comprised in the inclined shape so that an opening area may expand toward the offing, In any one of Claim 1 to 11 characterized by the above-mentioned. The described wave barrier structure.

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