JP2018016966A - Breakwater structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a breakwater structure that can reduce the flow rate of an overtopping wave climbing over the entire breakwater structure and reaching the land side of the breakwater structure while securing a good prospect over the breakwater structure.SOLUTION: A breakwater structure 1 comprises a lower breakwater wall 4 erected on a seacoast, an upper breakwater wall 14 installed on the lower breakwater wall 4, having a shape of coming forward offshore more toward the upper side and for receiving waves, a frame 12 that is projected to the land side from the upper breakwater wall 14 while being installed integrally with the upper breakwater wall 14 and that is fixed to the lower breakwater wall 4, and a land-side wall 3 that has a drainage space 24 opening upward installed with the upper breakwater wall 14 so as to receive inflow of water climbing over the upper breakwater wall 14 and that is installed in a position on the land side of the upper breakwater wall 14.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a wave preventing structure.

  Conventionally, a wave-breaking structure having a wave return function installed on a coast is known. Patent Document 1 below shows an example of such a wave preventing structure.

  The wave-breaking structure disclosed in Patent Document 1 below is a caisson that is erected on the seabed or the like facing offshore and has a height that protrudes upward from the hydrostatic surface, and the top of the caisson on the top end surface of the caisson. And a parapet provided so as to protrude upward from the end face. The parapet has a return surface facing the offshore side. This wave return surface is a curved surface whose gradient changes continuously. The region from the vicinity of the lower end of the wave return surface to the intermediate position in the vertical direction recedes to the land side as it goes upward, and the region from the intermediate position to the vicinity of the upper end of the wave return surface goes offshore as it goes upward from the intermediate position. It is approaching. The waves that hit the wave-breaking structure from the offshore side and cross the caisson hit the parapet's return surface, reverse along the return surface, and return to the offshore side.

JP 2011-252335 A

  However, in the wave-breaking structure disclosed in Patent Document 1, when the wave that strikes is large, the wave may exceed the parapet. As countermeasures, for example, it may be possible to reduce the overtopping flow to the land side by installing a parapet with a larger height, but the view over the wavebreak structure may be hindered by the increase in the height. There is.

  An object of the present invention is to provide a wave-breaking structure capable of reducing the overtopping flow rate over the wave-breaking structure to the land side while ensuring a good view over the wave-breaking structure. Is to provide things.

  In order to achieve the above object, a wavebreak structure according to the present invention is a wavebreak structure installed along the coast, and includes a lower wavebreak wall standing on the coast and the lower wavebreak wall. It is installed and has a shape that protrudes to the offshore as it goes upward, and is provided integrally with the upper breakwater that receives waves, and protrudes from the upper breakwater to the land side, and projects to the lower side. An upper drainage space is opened between the frame fixed to the wave breaker and the upper wave breaker so as to allow inflow of water of waves over the upper wave breaker. A land side wall provided at a position on the land side of the wave wall.

  In this breakwater structure, a drainage space opened upward is provided between the upper breakwater and the land side wall provided on the land side of the upper breakwater. Even when over the wall, the wave water can flow into the drainage space. For this reason, it is possible to reduce the overtopping flow rate, which is the flow rate of wave water that travels from the offshore side over the entire wavebreaking structure and reaches the landside region with respect to the wavebreaking structure. And in this wave-breaking structure, since the overtopping flow rate can be reduced by the function of the drainage space, it is not necessary to increase the height of the wavebreaking structure more than necessary in order to suppress the overtopping flow rate. For this reason, according to this wave-breaking structure, it is possible to reduce the overtopping flow rate over the entire wave-breaking structure and reaching the land side of the wave-breaking structure while ensuring a good view over the wave-breaking structure. Moreover, in this wave-breaking structure, since the drainage space is formed in the land side area of the upper wave-breaking wall that does not contribute to wave return among the wave-breaking structures, the wave-return function of the wave-breaking structure is provided. The overtopping flow rate can be reduced while maintaining.

  The wave-breaking structure further includes a rear structure that covers the lower wave-breaking wall of the upper wave-breaking wall and the frame to support the upper wave-breaking wall and the frame from the land-side on the lower wave-breaking wall, The drainage space may be a space between a land side surface of the rear structure and an offshore surface of the land side wall.

  The wave-breaking structure is integrally formed with the land side wall on the lower wave-breaking wall, covers the land-side surface of the upper wave-breaking wall and the frame, and the upper wave-breaking wall and the frame. The drainage space may be a space surrounded by a structure in which the land side wall and the back structure are integrated.

  According to these structures, the strength of the upper wave barrier against the waves received by the upper wave breaker is increased by the back structure, and drainage is performed using the land side area of the upper wave breaker in the wave breakage structure. A space can be provided.

  It is preferable that the wave-breaking structure further includes a drain pipe that guides water flowing into the drainage space to a sea-side space of the wave-breaking structure.

  According to this structure, the water of the wave which flowed into drainage space can be drained to the sea side space of a wave-proof structure through a drainage pipe. For this reason, it is possible to prevent water from being accumulated and overflowing in the drainage space.

  In this case, the wave-breaking structure allows water to flow from the drainage space through the drain pipe to the sea-side space of the wave-breaking structure, while the sea-side space of the wave-breaking structure. It is preferable to further include a backflow prevention valve provided in the drain pipe so as to prevent water from flowing into the drain space through the drain pipe.

  According to this configuration, the water that flows into the drainage space can be drained through the drainage pipe to the seaside space of the wavebreaking structure, while large waves hit the wavebreaking structure, and the tide level changes the height of the drainage pipe. When it exceeds, seawater can be prevented from flowing into the drainage space through the drainage pipe from the seaside space of the wave-breaking structure.

  It is preferable that the wave-breaking structure further includes a grating lid that allows the water to pass through the drainage space while covering the opening at the upper end of the drainage space.

  According to this configuration, on the grating lid that covers the opening of the drainage space while maintaining the effect of reducing the overtopping flow to the land side of the wavebreaking structure while ensuring a good view over the wavebreaking structure. While human traffic is possible, wave water that passes over the upper barrier can pass through the grating lid and flow into the drainage space. Further, since the grating lid does not transmit foreign matters having a size exceeding the interval between the lattices, according to the configuration, such foreign matters can be prevented from falling into the drainage space.

  It is preferable that the said wave-proof structure has a parapet which protrudes above the opening of the upper end of the said drainage space.

  According to this structure, the progress to the land side of the wave over the upper wave barrier can be suppressed by the parapet. For this reason, it is possible to further reduce the overtopping flow rate over the entire wave-proof structure and reaching the land side.

  In this case, it is preferable that the parapet is arranged at a position on the land side with respect to the opening at the upper end of the drainage space.

  According to this configuration, even when the water of the wave that has passed over the upper breakwater passes over the opening of the drainage space to the land side, the water of the wave is caused by the parapet. It is possible to suppress the traveling to the land side and to change the direction of the traveling of the wave water so that the water of the wave flows into the drainage space. For this reason, the drainage effect by drainage space can be promoted.

  As described above, according to the present invention, it is possible to reduce the overtopping flow rate over the entire wavebreaking structure and reaching the landside of the wavebreaking structure while ensuring a good view over the wavebreaking structure. Possible wave-breaking structures can be provided.

It is a longitudinal cross-sectional view in the direction orthogonal to the wave-proof surface of the wave-proof structure by 1st Embodiment of this invention, and its peripheral area | region. It is a figure for demonstrating the construction method of the wave-proof structure by 1st Embodiment. It is a figure for demonstrating the construction method of the wave-proof structure by 1st Embodiment. It is a figure for demonstrating the construction method of the wave-proof structure by 1st Embodiment. It is a figure for demonstrating the construction method of the wave-proof structure by 1st Embodiment. It is a longitudinal cross-sectional view in the direction orthogonal to the wave-proof surface of the wave-proof structure by 2nd Embodiment of this invention, and its peripheral area | region. It is a figure for demonstrating the construction method of the wave-proof structure by 2nd Embodiment. It is a figure for demonstrating the construction method of the wave-proof structure by 2nd Embodiment. It is a figure for demonstrating the construction method of the wave-proof structure by 2nd Embodiment. It is a figure for demonstrating the construction method of the wave-proof structure by 2nd Embodiment. It is a longitudinal cross-sectional view in the direction orthogonal to the wave-proof surface of the wave-proof structure by 3rd Embodiment of this invention, and its peripheral area | region. It is a longitudinal cross-sectional view in the direction orthogonal to the wave-proof surface of the wave-proof structure by 4th Embodiment of this invention, and its peripheral area | region. It is a figure which shows the result of the hydraulic experiment which investigated the reduction effect of the overtopping flow rate by drainage space and a parapet.

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

(First embodiment)
FIG. 1 shows a longitudinal section of a wave-proof structure 1 according to the first embodiment of the present invention and its surrounding area. The wave-breaking structure 1 according to the first embodiment is installed along the coast and prevents the wave from traveling to the land side. The wave preventing structure 1 includes a back wall 2, a lower wave preventing wall 4, a plurality of wave preventing blocks 6, a back structure 8, a plurality of drain pipes 20, a plurality of backflow prevention valves 21, and a plurality of And a grating lid 26.

  The rear wall 2 is a wall body standing along the coast, and occupies a range of a predetermined thickness from the land-side end of the wave-breaking structure 1 toward the offshore side of the sea. The back wall 2 is in contact with the ground of the land. Further, the rear wall 2 includes a land side wall 3 provided at a position on the land side of the upper breakwater wall 14 to be described later, more specifically, a land side wall 3 provided at a land side position of the rear structure 8 to be described later, and a land side wall of the back wall 2. 3, that is, a base portion 5 that is a portion of the back wall 2 below the land side wall 3.

  A portion of the land side wall 3 below a predetermined intermediate position in the vertical direction and the base 5 are composed of the existing revetment 100 originally installed along the coast. That is, the wavebreak structure 1 is produced using the existing revetment 100. The existing revetment 100 is made of reinforced concrete, and has a foundation 101 installed on the coastal ground and a wall body 102 standing on the foundation 101.

  The portion of the land side wall 3 below the intermediate position is formed by the upper part of the wall body 102 of the existing revetment 100. And the part above the said intermediate position of the land side wall 3 is formed of the raising part 10 provided on the wall body 102. As shown in FIG. The raised portion 10 is made of concrete, is provided on the top surface 103 at the upper end of the wall body 102, and is integrated with the wall body 102. The raised portion 10 protrudes upward from the top surface 103 of the wall body 102. The raised portion 10 covers the top surface 103 of the wall body 102 so as to extend along the coast.

  The lower breakwater wall 4 is erected on the offshore side of the rear wall 2 on the coast and receives waves. The lower wave barrier 4 is constructed in a form that can transmit the load received from the waves to the back wall 2. Specifically, the lower wave barrier 4 is formed of reinforced concrete so as to cover the surface of the rear wall 2 on the offshore side of the base 5 and to be integrated with the base 5. The lower part of the lower break wall 4 is buried in the ground at a position adjacent to the offshore side of the foundation 101.

  The lower breakwater wall 4 has a lower breakwater surface 4 a that is a surface that receives waves toward the offshore side of the sea, and a top surface 4 b that is located at the upper end of the lower breakwater wall 4. The lower wave-breaking surface 4a is a flat surface inclined toward the land side as it goes upward. The top surface 4b is a substantially horizontal plane, and is one level lower than the top surface 103 of the wall body 102 of the existing revetment 100.

  The plurality of wave blocking blocks 6 are installed on the top surface 4b of the lower wave blocking wall 4 so as to be adjacent to each other along the coast. Each wave-breaking block 6 has a concrete upper wave-breaking wall 14 and a steel frame 12.

  The upper wave barrier 14 is installed on the top surface 4b of the lower wave barrier 4 and has a wave return function for receiving waves and returning the received waves to the offshore side. Specifically, the upper wave barrier 14 has a shape that protrudes to the offshore side as it goes upward. The upper breakwater wall 14 has an upper wavebreak surface 14a that is a surface that faces the offshore side and receives waves, and has a curved surface shape (concave shape) that smoothly protrudes toward the offshore side as the upper wavebreak surface 14a moves upward. Make. The shape of the upper wave preventing surface 14a provides the wave return function of the upper wave preventing wall 24.

  The upper breakwater walls 14 of the plurality of breakwater blocks 6 are arranged side by side along the coast, and the upper breakwater surfaces 14a are continuous along the coast. Further, the upper wave-breaking surface 14a and the lower wave-breaking surface 4a of the lower wave-breaking wall 4 are continuous. A surface for receiving a wave of 1 is formed. The wave that hits the wave preventing surface 1a rises along the wave preventing surface 1a, reverses along the upper wave preventing surface 14a, and returns to the offshore side.

  The frame 12 is provided integrally with the upper wave barrier 14 and protrudes from the upper wave barrier 14 to the land side. Specifically, the frame 12 includes a curved plate portion (not shown) and a protruding portion 13.

  The curved plate portion is a steel plate having a curved shape along the upper wave preventing surface 14 a and is embedded in the upper wave preventing wall 14. In other words, the concrete upper wave preventing wall 14 is formed so as to cover the curved plate portion, and the upper wave preventing surface 14a is formed along the curved shape of the curved plate portion.

  The protruding portion 13 extends from the curved plate portion to the land side, and protrudes from the upper wave barrier 14 to the land side. The bottom of the protrusion 13 is fixed to the upper end of the upper wave barrier 14 by an anchor 18. The upper end portion of the protruding portion 13 is at a height position that is relatively close to the upper end portion of the upper wave barrier 14.

  As described above, the wave-blocking block 6 is composed of a composite of the concrete upper wave-breaking wall 14 and the steel frame 12, so that the wave-blocking block 6 has high tenacity against external force. For this reason, even when the wave preventing block 6 receives a large external force such as a tsunami wave force, the wave breaking block 6 can be prevented from brittle fracture.

  The back structure 8 supports each wave-blocking block 6 from the back, that is, from the land side with respect to the sea. The rear structure 8 is made of concrete, is provided on the top surface 4b of the lower wave barrier 4 on the land side of the upper wave barrier 14 and extends along the coast. The rear structure 8 covers the land side surface of the upper wave barrier 14 of each wave block 6 and the entire protrusion 13 of the frame 12 of each wave block 6 so that the upper wave barrier 14 and the frame 12 are landed. Support from. In other words, the back structure 8 is integrated with each wave blocking block 6, and the protruding portion 13 of each wave blocking block 6 is buried in the back structure 8. The back structure 8 enters between the top surface 4b of the lower wave barrier 4 and the bottom of the protrusion 13 of the frame 12 to connect the lower wave barrier 4 and the protrusion 13 to each other. The top surface of the back structure 8 is substantially flush with the top surface of the upper wave barrier 14. The top surface of the back structure 8 and the top surface of the upper wave barrier 14 and the top surface of the land side wall 3 are substantially at the same height.

  The rear structure 8 is provided at a position on the offshore side of the land side wall 3 with a drainage space 24 between the rear structure 8 and the land side wall 3. That is, the land side wall 3 is provided at a position on the land side with a drainage space 24 between the rear structure 8 and, in other words, the upper wave barrier 14. The drainage space 24 is a space for draining wave water that has passed over the upper wave barrier 14 and the back structure 8 from the offshore side to the land side. The drainage space 24 has a groove shape extending along the coast, and is open upward so as to allow inflow of wave water over the upper wave barrier 14 and the back structure 8 from the offshore side.

  The end on the offshore side of the drainage space 24 is defined by the land side surface of the rear structure 8, and the end on the landside of the drainage space 24 is defined by the offshore surface of the land wall 3. That is, the drainage space 24 is a space between the land side surface of the back structure 8 and the offshore side surface of the land side wall 3. The land-side surface of the back structure 8 that defines the offshore end of the drainage space 24 is inclined so as to be directed toward the land side as it goes downward. An opening on the upper end of the drainage space 24 is defined by the edge on the land side at the upper end of the rear structure 8 and the edge on the offshore side at the upper end of the land side wall 3 (lifting portion 10). Wave water flows into the drainage space 24 from this opening.

  The plurality of drain pipes 20 guides the water flowing into the drain space 24 to the space on the offshore side of the wave-breaking structure 1. Each drain pipe 20 is embedded in the lower wave barrier 4. The plurality of drain pipes 20 are installed at certain intervals in the direction in which the drain space 24 extends, that is, the direction along the coast. One end of each drain pipe 20 is provided in a region located between the land side surface of the back structure 8 and the offshore side surface of the land side wall 3 in the upper end portion of the lower breakwater wall 4. An opening at one end of each drainage pipe 20 is connected to the bottom of the drainage space 24. Further, the other end of each drain pipe 20 is installed in the vicinity of the lower wave-breaking surface 4 a on the upper part of the lower wave-breaking wall 4. The opening at the other end of each drain pipe 20 is open to the space on the offshore side of the lower wave-breaking surface 4a.

  Each drain pipe 20 generally inclines so as to go downward as it goes from one end to the other end, and the slope of the inclination changes at a plurality of locations between the both ends. Due to the inclination of each drainage pipe 20, the water flowing into the drainage pipe 20 from the drainage space 24 through the opening at one end of each drainage pipe 20 flows to the other end of each drainage pipe 20. It is discharged to the space off the wave-proof surface 4a.

  Each drain pipe 20 is provided with a backflow prevention valve 21. Specifically, the backflow prevention valve 21 is provided in the vicinity of the other end of each drain pipe 20, that is, in the vicinity of the outlet of each drain pipe 20. The backflow prevention valve 21 allows the flow of water from the position on the drainage space 24 side to the space on the offshore side of the lower wave preventing surface 4a with respect to the backflow prevention valve 21 in the drain pipe 20, while the backflow prevention valve 21 is concerned. The flow of water from the offshore position toward the drainage space 24 through the drainage pipe 20 is blocked. That is, the backflow prevention valve 21 allows water to flow from the drainage space 24 through the drainage pipe 20 to the seaside space of the wavebreaking structure 1, while from the seaside space of the wavebreaking structure 1. The drain pipe 20 is provided so as to prevent water from flowing into the drain space 24 through the drain pipe 20. Since the backflow prevention valve 21 is provided in each drainage pipe 20, water flowing into the drainage space 24 is drained from the drainage space 24 to the sea through each drainage pipe 20, while a large wave is generated on the wave-preventing surface 1a. The seawater is prevented from flowing into the drainage space 24 through the drainage pipes 20 from the sea side space of the wave-breaking structure 1 when the tide level is approached or when the tide level exceeds the height position of each drainage pipe 20.

  The grating lid 26 is a grid-like lid that covers the opening at the upper end of the drainage space 24. The plurality of grating lids 26 are arranged side by side in the direction in which the drainage space 24 extends, that is, in the direction along the coast, and offshore at the edge on the land side at the upper end of the back structure 8 and the upper end of the land side wall 3 (lifting portion 10). It is fitted between the side edges. The grating lid 26 allows water to permeate into the drainage space 24, while preventing foreign matters larger than the interval between the lattices from falling into the drainage space 24. Further, the grating lid 26 has a strength that allows a person to pass through the grating lid 26.

  Next, the construction method of the wave-breaking structure 1 according to the first embodiment will be described.

  As shown in FIG. 2, an existing revetment 100 used as a part of the wavebreak structure 1 is installed on the coast.

  The ground adjacent to the offshore side of the foundation 101 of the existing revetment 100 is excavated and removed. And in the space which removed the ground, a formwork is installed at intervals from the existing revetment 100 to the offshore side. Then, reinforcement is performed in the space between the installed formwork and the surface on the offshore side of the existing revetment 100, and a plurality of reinforcing bars are installed on the existing revetment 100. Each incision bar is installed on the existing revetment 100 so as to protrude from the surface on the offshore side of the existing revetment 100. After that, by placing concrete in the space between the formwork and the offshore side of the existing revetment 100, the lower breakwater wall 4 (see FIG. 3) covering the offshore side of the existing revetment 100 is constructed. . Before placing the concrete on the lower breakwater 4, the backflow flows into the area where the upper part of the lower breakwater 4 is formed in the space between the mold and the offshore surface of the existing revetment 100. A plurality of drain pipes 20 with prevention valves 21 are arranged at positions and postures that the drain pipes 20 should take. Thereby, the several drainage pipe 20 is embedded and installed in the upper part of the lower wave barrier 4 constructed by placing concrete as mentioned above. After the construction of the lower wave barrier 4, the space not occupied by the lower wave barrier 4 is refilled among the spaces formed by removing the ground as described above.

  On the other hand, a plurality of wave blocking blocks 6 are prepared at the site where the wave blocking structure 1 is constructed. These wave-breaking blocks 6 are manufactured in a factory, for example, and the manufactured wave-breaking blocks 6 are transported to the site.

  Next, as shown in FIG. 4, a plurality of wave blocking blocks 6 are installed on the top surface 4 b of the lower wave blocking wall 4. At this time, the wave blocking blocks 6 are installed on the top surface 4b so that the plurality of wave blocking blocks 6 are arranged along the coast. A plurality of anchors 18 are attached to the lower wave barrier 4 so as to protrude from the top surface 4 b of the lower wave barrier 4, and the bottom of the protruding portion 13 of the frame 12 of the wave blocking block 6 is coupled to the anchor 18. Let As a result, the frame 12 is fixed to the lower wave barrier 4 via the anchor 18.

  After that, the raised portion 10 is constructed on the top surface 103 of the wall body 102 of the existing revetment 100 to form the land side wall 3, and the rear structure 8 is replaced with the upper wave barrier on the top surface 4 b of the lower wave barrier 4. Construction is carried out so as to leave a drainage space 24 between the land side wall 3 at the position 14 on the land side (see FIG. 5).

  Specifically, as a formwork for constructing the raised portion 10, a land-side formwork projecting upward from the top surface 103 of the wall body 102 along the land-side surface of the upper end portion of the wall body 102. And an offshore mold that protrudes above the top surface 103 of the wall 102 along the offshore surface of the upper end of the wall 102. Further, the formwork for constructing the rear structure 8 is separated from the land side edge of the protruding portion 13 of each wave blocking block 6 on the top surface 4 b of the lower wave blocking wall 4, and the wall body 102. Install away from the sea. The raised portion 10 is formed by placing concrete in a space between the land-side formwork for construction of the raised portion 10 and the offshore-side formwork. Further, the back structure 8 is formed by placing concrete in a space between the formwork for the construction of the back structure 8 and the land side surface of the upper wave barrier 14 of each wave block 6. . A drainage space 24 is formed between the land wall 3 formed from the raised portion 10 and the upper portion of the wall body 102 formed as described above, and the rear structure 8 formed as described above.

  Finally, a plurality of grating lids 26 (see FIG. 1) are arranged on the upper end of the rear structure 8 that defines the opening at the upper end of the drainage space 24 so that the grating lids 26 are aligned in the longitudinal direction of the drainage space 24. It fits between the edge part of the side and the edge part of the offshore side of the upper end of the land side wall 3 (lifting part 10).

  As described above, the wave preventing structure 1 according to the first embodiment is constructed.

  In the wave-breaking structure 1 according to the first embodiment, the drainage space 24 opened upward between the upper wave-breaking wall 14 and the land-side wall 3 provided at the land-side position of the upper wave-breaking wall 14 is provided. Since it is provided, even when a large wave climbs over the upper end of the upper wave barrier 14 from the offshore side, the water of the wave can flow into the drainage space 24. For this reason, it is possible to reduce the overtopping flow rate, which is the flow rate of wave water that travels from the offshore side over the entire wavebreaking structure 1 to the land side region of the wavebreaking structure 1. Moreover, since the overtopping flow rate can be reduced by the function of the drainage space 24, it is not necessary to increase the height of the wave preventing structure 1 more than necessary in order to suppress the overtopping flow rate. For this reason, it is possible to reduce the overtopping flow rate of the wavebreaking structure 1 to the land side while ensuring a good view over the wavebreaking structure 1.

  Moreover, in the said 1st Embodiment, the drainage space 24 is provided in the land side area | region of the upper wave-breaking wall 14 which does not contribute to a wave return among the wave-breaking structures 1. FIG. For this reason, the overtopping flow rate to the land side of the wave preventing structure 1 can be reduced while ensuring the wave return function of the wave preventing structure 1.

  Moreover, in the said 1st Embodiment, since the back structure 8 which covers the land side surface of the upper wave-breaking wall 14 and the protrusion part 13 whole of the flame | frame 12 and supports the upper wave-breaking wall 14 from the land side is provided. The rear structure 8 can reinforce the strength of the upper wave barrier 14 against waves. In addition, in the first embodiment, the offshore end of the drainage space 24 is defined by the land side surface of the back structure 8. That is, in the first embodiment, the back structure 8 can be used as a structure for defining the drainage space 24 while strengthening the strength of the upper wave barrier 14 with the back structure 8.

  Moreover, since the wave-breaking structure 1 according to the first embodiment includes the drain pipe 20 that guides the water that has flowed into the drainage space 24 to the space on the offshore side of the lower wave-breaking surface 4a, the wave that has flowed into the drainage space 24 is provided. Water can be discharged to the sea through the drain pipe 20. For this reason, it is possible to prevent water from being accumulated in the drainage space 24 and overflowing.

  Further, since the drain pipe 20 is provided with the backflow prevention valve 21, the water in the drain space 24 can be drained to the sea through the drain pipe 20, while the tide level is when the big wave hits the wave preventing surface 1a. When the height position of 20 is exceeded, seawater can be prevented from flowing from the space on the wave-breaking surface 1a to the drainage space 24 through the drainage pipe 20.

  In the wave-breaking structure 1 according to the first embodiment, the grating lid 26 covers the opening at the upper end of the drainage space 24. For this reason, it is possible to allow a person on the grating lid 26 to pass while maintaining the effect of reducing the overtopping flow rate to the land side of the wavebreaking structure 1 while ensuring a good view over the wavebreaking structure 1. On the other hand, wave water that has passed over the upper wave barrier 14 can pass through the grating lid 26 and flow into the drainage space 24. Further, since the grating lid 26 does not allow the foreign matter having a size exceeding the interval between the lattices to pass therethrough, the foreign matter can be prevented from falling into the drainage space 24.

(Second Embodiment)
FIG. 6 shows a longitudinal section of the wave-breaking structure 1 according to the second embodiment of the present invention and its surrounding area. In the wave breaker structure 1 according to the second embodiment, the rear structure 8 is placed on the land wall 3 on the lower wave breaker 4 and the wall 102 of the existing revetment 100 after the upper portion 102a is removed as described later. The drainage space 24 is a space surrounded by a structure 30 in which the land side wall 3 and the back structure 8 are integrated. Hereinafter, the configuration of the wave preventing structure 1 according to the second embodiment will be specifically described.

  The wave-breaking structure 1 according to the second embodiment is common to the wave-breaking structure 1 according to the first embodiment in that it is manufactured using the existing revetment 100. However, the breakwater structure 1 according to the second embodiment is manufactured using the existing revetment 100 after the upper part 102a of the wall body 102 of the existing revetment 100 is removed and the upper part 102a is removed.

  The top surface 103a of the wall body 102 after the upper part 102a is removed and the top surface 4b of the lower wave barrier 4 are provided at substantially the same height. The structure 30 is provided on the top surface 103 a of the wall body 102 and the top surface 4 b of the lower wave barrier 4 on the land side of the upper wave barrier 14. The rear structure 8 included in the structure 30 covers the land surface of the upper wave barrier 14 and the entire protrusion 13 of the frame 12 to support the upper wave barrier 14 and the frame 12 from the land side.

  The drainage space 24 is defined by being surrounded by the structure 30. Specifically, in the second embodiment, the dimension in the height direction of the protruding portion 13 of the frame 12 of each wave blocking block 6 is smaller than the dimension in the height direction of the protruding portion 13 in the first embodiment. Thereby, the area | region which does not interfere with the said protrusion part 13 is ensured above the protrusion part 13 among the said structures 30, and the drainage space 24 is provided in the area | region. That is, the drainage space 24 is provided directly above the projection 13 of the frame 12 so as not to interfere with the projection 13, and the depth of the drainage space 24 is smaller than the depth of the drainage space 24 in the first embodiment. ing.

  By configuring the drainage space 24 in this way, an area required when the drainage space 24 is provided on the land side of the protruding portion 13 as in the first embodiment is unnecessary. For this reason, the dimension of the structure 30 in the direction orthogonal to the coastline and the up-down direction can be reduced.

  The top surface of the structure 30, that is, the top surface of the back structure 8 and the top surface of the land side wall 3 are substantially at the same height as the top surface of the upper wave barrier 14. An opening at the upper end of the drainage space 24 is formed on the top surface of the structure 30. That is, the opening at the upper end of the drainage space 24 is formed between the upper end portion of the back structure 8 and the upper end portion of the land side wall 3.

  Further, in the second embodiment, the drain pipe 20 extends from the position adjacent to the offshore side of the bottom of the drainage space 24 toward the offshore side to the upper wave preventing surface 14a. That is, one end of the drain pipe 20 is provided at a site adjacent to the offshore side of the bottom of the drain space 24 in the back structure 8. The opening at one end of the drainage pipe 2 is connected to the bottom of the drainage space 24. The other end of the drain pipe 20 is installed at a position in the vicinity of the upper wave-breaking surface 14 a in the upper wave-breaking wall 14. The opening at the other end of the drain pipe 2 is opened to a space on the offshore side of the upper wave preventing surface 14a. The drain pipe 20 passes through the back structure 8 and the upper wave barrier 14. The drain pipe 20 is inclined so as to go downward as it goes from one end to the other end, that is, toward the offshore side. The slope of the drain pipe 20 is substantially constant throughout the drain pipe 20. The drain pipe 20 is disposed above the protrusion 13 of the frame 12.

  The rest of the configuration of the wave preventing structure 1 according to the second embodiment is the same as the structure of the wave preventing structure 1 according to the first embodiment.

  Next, the construction method of the wave-breaking structure 1 according to the second embodiment will be described.

  In the second embodiment, first, the upper portion 102a (see FIG. 7) of the wall body 102 of the existing revetment 100 is removed by an excavating machine or the like.

  Next, after excavating and removing the ground adjacent to the offshore side of the foundation 101 of the existing revetment 100, concrete is cast on the offshore side of the existing revetment 100 in the same manner as in the first embodiment. The lower breakwater wall 4 (see FIG. 8) that is integrated with the revetment 100 is constructed. The lower wave barrier 4 is constructed so that the top surface 4b thereof is substantially flush with the top surface 103a of the wall body 102 after the upper portion 102a is removed as described above.

  Further, a plurality of wave blocking blocks 6 are prepared at the site where the wave blocking structure 1 is constructed. In the second embodiment, a plurality of wave blocking blocks 6 with the drain pipes 20 attached are prepared at the site. For example, when each wave-blocking block 6 is manufactured in a factory, a drain pipe 20 is attached to the wave-blocking block 6, and the wave-blocking block 6 with the drain pipe 20 attached is transported to the site.

  Thereafter, as shown in FIG. 9, the plurality of wave blocking blocks 6 with the drain pipes 20 attached thereto are installed on the top surface 4 b of the lower wave blocking wall 4. The installation process of the wavebreak block 6 is the same as the installation process of the wavebreak block 6 in the first embodiment.

  Next, as shown in FIG. 10, the rear structure 8 and the land side wall 3 are integrated with the top surface 4 b of the lower break wall 4 and the top surface 103 a of the wall body 102 on the land side of the upper break wall 14. The structure 30 which has it is constructed. At this time, the structure 30 is constructed so as to leave the drainage space 4 between the rear structure 8 and the land wall 3.

  Specifically, a land-side formwork for forming a land-side side surface of the land wall 3 of the structure 30 is installed so as to protrude from the ground above the land-side side surface of the wall body 102. In addition, in the space between the installed land-side formwork and the land side surface of the upper wave barrier 14, a formwork for leaving the drainage space 24, that is, a drainage space formwork surrounding the drainage space 24 is installed. To do. The drainage space formwork is installed with an interval upward from the protruding portion 13 of the wave blocking block 6. In addition, when installing the drainage space formwork, the tip of the drainage pipe 20 extending from the upper wavebreak wall 14 of each wavebreak block 6 to the land side is on the offshore side of the bottom of the space surrounded by the drainage space formwork. The drain pipe 20 is set at an adjacent position, and the posture of the drain pipe 20 is set to an inclined posture that the drain pipe 20 should take.

  Thereafter, ready-mixed concrete is poured between the upper wave barrier 14 and the drainage space formwork and between the land-side formwork and the drainage space formwork. This ready-mixed concrete is also filled in the space below the drainage space mold between the upper wave barrier 14 and the land-side mold, covering the entire protrusion 13 of the frame 12 of each wave-block 6. It also enters between the bottom of the protrusion 13 and the top surface 4b of the lower wave barrier 4. When the concrete is solidified, a structure 30 is formed, and a drainage space 24 opened in the top surface of the structure 30 is formed in the structure 30.

  Finally, a plurality of grating lids 26 are fitted between the land-side edge at the upper end of the back structure 8 and the off-shore edge at the upper end of the land side wall 3 so as to cover the opening at the upper end of the drainage space 24. .

  The structure other than the above of the construction method of the wave preventing structure 1 according to the second embodiment is the same as the construction method of the wave preventing structure 1 according to the first embodiment.

  According to the second embodiment, the same effect as in the first embodiment can be obtained.

(Third embodiment)
FIG. 11 shows a longitudinal section of the wave-breaking structure 1 according to the third embodiment of the present invention and its surrounding area. The wave-breaking structure 1 according to the third embodiment basically has the same configuration as the wave-breaking structure 1 according to the first embodiment, and in addition to that, over the opening at the upper end of the drainage space 24. It has a parapet 40 for suppressing the water of the wave that has passed through to the land side.

  Specifically, the parapet 40 is provided adjacent to the land side of the upper end opening of the drainage space 24, and is located above the upper end opening of the drainage space 24, in other words, the top surface and the rear side of the upper breakwater wall 14. The top surface of the structure 8 and the top surface of the grating lid 26 protrude above the top surface. Specifically, the parapet 40 extends upward from the land wall 3. That is, the parapet 40 is formed by increasing the dimension in the height direction of the raised portion 10 of the land side wall 3 more than the dimension in the height direction of the raised portion 10 in the first embodiment. The parapet 40 extends in the direction along the coastline, that is, in the longitudinal direction of the land wall 3.

  The configuration other than the above-described configuration of the wave preventing structure 1 according to the third embodiment is the same as the structure of the wave preventing structure 1 according to the first embodiment.

  In the wave-breaking structure 1 according to the third embodiment, even when the wave water that has passed over the upper wave-breaking wall 14 tries to pass over the opening at the upper end of the drainage space 24 to the land side, the parapet 40 The wave water can be suppressed from traveling to the land side of the wave-breaking structure 1, and the direction of the wave water can be changed so that the wave water flows into the drainage space 24. . For this reason, the overtopping flow volume to the land side of the wave-proof structure 1 can be reduced more.

  The other effects obtained by the wave preventing structure 1 of the third embodiment are the same as the effects obtained by the wave preventing structure 1 of the first embodiment.

(Fourth embodiment)
FIG. 12 shows a longitudinal section of the wave-breaking structure 1 according to the fourth embodiment of the present invention and its surrounding area. The wave-breaking structure 1 according to the fourth embodiment basically has the same configuration as the wave-breaking structure 1 according to the second embodiment, and further includes a parapet 40. The parapet 40 has the same function as the parapet 40 in the third embodiment.

  Specifically, the parapet 40 is provided adjacent to the land side of the upper end opening of the drainage space 24, and is located above the upper end opening of the drainage space 24, in other words, the top surface and the rear side of the upper breakwater wall 14. The top surface of the structure 8 and the top surface of the grating lid 26 protrude above the top surface. Specifically, the parapet 40 is formed by extending the land side wall 3 of the structure 30 to a position higher than the land side wall 3 in the second embodiment. That is, the parapet 40 is formed integrally with the land wall 3 of the structure 30. Further, the parapet 40 extends in the direction along the coastline, that is, in the longitudinal direction of the land wall 3.

  Configurations other than the above-described configuration of the wave preventing structure 1 according to the fourth embodiment are the same as those of the wave preventing structure 1 according to the second embodiment.

  In the wave-breaking structure 1 according to the fourth embodiment, the wave water can be prevented from traveling to the land side of the wave-breaking structure 1 by the parapet 40 as in the wave-breaking structure 1 according to the third embodiment. At the same time, the direction of the water of the wave can be changed so that the water of the wave flows into the drainage space 24. For this reason, the overtopping flow volume to the land side of the wave-proof structure 1 can be reduced more.

  The other effects obtained by the wave preventing structure 1 of the fourth embodiment are the same as the effects obtained by the wave preventing structure 1 of the second embodiment.

(Demonstration experiment of reduction effect of overtopping flow rate by drainage space and parapet)
A hydraulic experiment was conducted to demonstrate the effect of reducing the overtopping flow rate by providing a drainage space in a wave-breaking structure and the effect of reducing the overtopping flow rate by providing a parapet in addition to the drainage space. The hydraulic experiment will be described below.

  In this hydraulic experiment, a plurality of simple models of the wave-breaking structure were produced, and the produced models were used for the experiment. The plurality of models used in the experiment are the first to third models having the characteristics of the wave-breaking structure according to the present invention and the comparison models to be compared with the first to third models.

  The first model has an upper wave barrier having the same characteristics as the upper wave barrier of the wave break structure in each of the above embodiments, and drainage opened upward at a position on the land side of the upper wave barrier. Have a space. In this first model, the horizontal distance from the offshore tip of the upper breakwater to the land end of the upper end opening of the drainage space is set to 2.0 m.

  The second model has the same configuration as the first model except that the horizontal distance from the offshore tip of the upper breakwater to the land end of the upper end of the drainage space is set to 3.0 m. Have

  The third model has the same configuration as the second model except that it has a parapet that protrudes upward adjacent to the land side of the opening at the upper end of the drainage space. That is, in this third model, the horizontal distance from the offshore tip of the upper wave barrier to the land end of the upper end opening of the drainage space is set to 3.0 m, and the parapet is provided. .

  The comparative model has the same configuration as the first model except that it does not have a drainage space. That is, in this comparative model, no drainage space is provided and no parapet is provided.

  About the above 1st-3rd models and comparative models, the hydraulic experiment which set the conditions of the bottom of the seabed of each model installation and the wave which hits the same was performed, respectively, and the overtopping flow generated by each model was measured. . FIG. 13 shows the horizontal distance and overtopping obtained from the measurement results of the first to third models and the comparative model from the offshore tip of the upper barrier to the land end of the upper end of the drainage space. The correlation with the flow rate ratio is shown.

  The overtopping flow ratio is the ratio of the overtopping flow rate for each of the first to third models to the overtopping flow rate for the comparative model, that is, the overtopping flow measured in each of the first to third models with the overtopping flow rate measured in the comparative model. It is a value obtained by dividing the flow rate. In addition, the overtopping flow rate ratio of the comparative model is shown in FIG. 13 as 1.0.

  As shown in FIG. 13, in the first model, the overtopping flow rate ratio is close to 0.5 and smaller than 1.0. Therefore, by providing a drainage space in the wave-breaking structure, the drainage space is reduced. It can be seen that the overtopping flow rate can be reduced compared to a wave-proof structure such as a comparative model without it.

  Moreover, the horizontal distance from the tip of the upper breakwater on the offshore side to the land-side end of the upper end of the drainage space is 3.0 m, and the overtopping flow rate ratio of the second model is 2.0 m. It is smaller than the overtopping flow rate ratio of the first model. From this, the overtopping flow rate is increased by increasing the horizontal distance from the offshore tip of the upper breakwater to the land end of the upper end opening of the drainage space, that is, by increasing the range of the opening of the drainage space. It can be seen that can be further reduced.

  In addition, when comparing the second model and the third model, where the horizontal distance from the offshore tip of the upper barrier wall to the land end of the upper end of the drainage space is 3.0 m, the overtopping of the third model It can be seen that the flow ratio is slightly smaller than the overtopping flow ratio of the second model. Therefore, it can be seen that the effect of reducing the overtopping flow rate can be improved by providing a parapet.

  The wave preventing structure according to the present invention is not necessarily limited to the above. For example, the following configuration can be adopted as the configuration of the wave-proof structure according to the present invention.

  The drainage space 24 may be filled with a filler that allows permeation of water that has flowed into the drainage space 24, such as crushed stone.

  Further, for the wave-breaking structure 1 in which the drain pipe 20 penetrates the upper wave barrier 14 of the wave-blocking block 6, the drain pipe 20 is not necessarily attached to the wave-blocking block 6 when the wave-breaking block 6 is manufactured. For example, after transporting the wave blocking block 6 to the site where the wave blocking structure 1 is to be constructed, the drain pipe 20 is attached to the wave blocking block 6 or the wave blocking block 6 is installed on the lower wave blocking wall 4. After that, the drain pipe 20 may be attached to the wave preventing block 6. In this case, a hole for passing the drain pipe 20 is formed in the upper wave barrier 14 at the time of manufacturing the wave breaker block 6, and the wave breaker block 6 is transported to the site and then formed in the upper wave breaker wall 14. After the drainage pipe 20 is inserted into the hole, the drainage pipe 20 is attached to the wavebreaker block 6 or the wavebreaker block 6 is installed on the lower wavebreaker wall 4 and then drained into the hole formed in the upper wavebreaker wall 14. The drain pipe 20 may be attached to the wave breaker block 6 by inserting the pipe 20.

  The position where the parapet is provided is not necessarily limited to the land side of the opening at the upper end of the drainage space 24. For example, a parapet may be provided on the offshore side of the upper end opening of the drainage space 24. In this case, the flow rate of the waves traveling to the land side at the position off the opening of the drainage space 24 can be reduced by the parapet. For this reason, also in this case, the overtopping flow rate to the land side of the wave preventing structure 1 can be reduced.

DESCRIPTION OF SYMBOLS 1 Wave breaker structure 3 Land side wall 4 Lower wave barrier 8 Back structure 12 Frame 14 Upper wave barrier 20 Drain pipe 21 Backflow prevention valve 24 Drain space 26 Grating lid 40 Parapet

Claims (8)

A wave-breaking structure installed along the coast,
A lower breakwater standing on the coast,
It is installed on the lower wave barrier, has a shape that protrudes to the offshore side toward the upper side, and an upper wave barrier that receives waves,
A frame that is provided integrally with the upper wave barrier and projects from the upper wave barrier to the land, and is fixed to the lower wave barrier;
A drainage space opened upward so as to allow inflow of wave water over the upper breakwater is provided between the upper breakwater and a position on the land side of the upper breakwater. A wave-breaking structure comprising a land wall. A back structure for supporting the upper wave barrier and the frame from the land side, covering the land side surface of the upper wave barrier and the frame on the lower wave barrier,
The wave-breaking structure according to claim 1, wherein the drainage space is a space between a land-side surface of the back structure and an off-shore surface of the land side wall. A rear structure formed integrally with the land side wall on the lower break wall, covering the land side surface of the upper break wall and the frame, and supporting the upper break wall and the frame from the land side. In addition,
The wave-breaking structure according to claim 1, wherein the drainage space is a space surrounded by a structure in which the land side wall and the rear structure are integrated.   The wavebreak structure according to any one of claims 1 to 3, further comprising a drain pipe that guides water that has flowed into the drainage space to a sea-side space of the wavebreak structure.   While allowing the water to flow from the drainage space through the drainage pipe to the seaside space of the wavebreak structure, the drainage space passes through the drainage pipe from the seaside space of the wavebreak structure. The wave preventing structure according to claim 4, further comprising a backflow prevention valve provided in the drain pipe so as to prevent water from flowing into the drainage pipe.   The wavebreak structure according to any one of claims 1 to 5, further comprising a grating lid that allows permeation of water into the drainage space while covering an opening at an upper end of the drainage space.   The wave-breaking structure according to any one of claims 1 to 6, further comprising a parapet that protrudes upward from an opening at an upper end of the drainage space.   The said parapet is a wave-proof structure of Claim 7 arrange | positioned in the position of the land side rather than the opening of the upper end of the said drainage space.

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