JP2006161402A - Construction method for improving water breaking structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a construction method for improving a water breaking structure requiring less construction period, eliminating environmental problems, and having excellent overflow wave stopping performance. <P>SOLUTION: This construction method comprises a cutting step for cutting off the upper side portion 32 of an existing bulkhead 3 constructed along a shore, a manufacturing step for manufacturing, in a plant, the blocks 40, 40, ... of a newly constructed bulkhead 4 formed such that their extended amounts to an offshore side are larger than the extended amount of the cut upper side portion 32, and a joining step for placing the manufactured blocks 40, 40, ... of the newly constructed bulkhead 4 on the lower side portion 31 of the existing bulkhead 3 in place of the upper side portion 32 cut off in the cutting step and joining to its lower side portion 31 with reinforcements 6 for anchoring. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an improved construction method of a breakwater structure for a seawall such as a breakwater or a quay wall that protects a ship, land life, buildings and the like from wave overtopping waves and wave power in a harbor and a coastal coastal area.

  In the existing revetment, when the wave height increases due to changes in the seabed ground and harbor structures, the overtopping flow increases, the design tide level and wave conditions (design wave height, etc.) themselves change, and the overtopping flow increases. Or when the utilization situation of a bank revetment changes and it becomes necessary to reduce the overtopping flow rate, it is necessary to reduce the overtopping flow rate and improve the overtopping prevention performance. Conventionally, the following methods are known as methods for improving the overtopping prevention performance.

  That is, as shown in FIG. 4, the overtopping flow rate is reduced by increasing the height of the revetment top by attaching a new revetment 52 to the sea 2 side of the existing revetment 51 installed on the foundation ground 1. .

Further, as shown in FIG. 5, wave energy is dissipated by laminating a wave-dissipating work 53 such as a tetrapod (product name) on the sea 2 side of the existing revetment 51 installed on the foundation ground 1. The result is a method of reducing overtopping flow. For example, in patent document 1, the wave-dissipating block is laminated | stacked from the base ground 1 to the caisson upper part which has a retreating parapet.
JP 2000-204528 A

  In the method shown in FIG. 4, the new revetment 52 is usually made of the same RC (steel reinforced concrete) structure as the existing revetment 51 and is manufactured locally. That is, a formwork is installed on the sea 2 side of the existing revetment 51, and a reinforcing bar is laid in the formwork, and then concrete is poured and hardened. For this reason, there was a problem that the production period was long and the construction was affected by the weather due to the local construction. Therefore, it is difficult to cope with the newly constructed revetment 52 having a complicated shape that further increases the production period.

  In addition, since concrete construction work is carried out at sea, there is a risk that concrete components may flow out into the sea, which is also an environmental problem. In addition, by increasing the height of the revetment top (the height of the revetment from the still water surface), the landscape from the land side could be damaged.

  In the method shown in FIG. 5, since the wave-dissipating work 53 is laminated on the sea 2 side, the coastline is crushed and there is a problem in terms of the environment. In other words, in Patent Document 1, the coastline may be crushed by the wave-dissipating block.

  The present invention has been made in view of the above circumstances, and its object is to provide an improved construction method for a wave-breaking structure that requires a short construction period, has no environmental problems, and has excellent overtopping prevention performance. It is to be.

  The present invention is a method for improving an existing wave-breaking structure installed along a shore, a cutting step for cutting an upper portion of the wave-breaking structure, and an upper portion of the cut-off upper portion. A wavebreaker manufacturing process for manufacturing a wavebreaker having a shape with a large projecting amount to the offshore side, and the wavebreaker manufactured in place of the wavebreaker in place of the upper part cut out in the cutting process. A wave-protecting body joining step of installing on a structure and joining the wave-proof structure.

  Here, the specific shape of the protruding portion of the wave preventing body is not limited, but if this portion simply protrudes linearly in the horizontal direction, a large vertical wave is generated in the protruding portion when there is a wave. Force is easy to act. On the other hand, as in the invention according to claim 2, in the improved construction method of the wave preventing structure according to claim 1, in the wave preventing body manufacturing process, a smooth curved surface is pushed toward the offshore side. It is preferable to manufacture a wave-proof body having a wave-proof surface.

  Further, as in the invention according to claim 3, in the improved construction method of the wave preventing structure according to claim 2, in the wave preventing body manufacturing step, the tangential direction at the lower end of the wave preventing surface is the upper side in the cutting step. It is preferable to manufacture a wave-blocking body having a shape that substantially matches the tangential direction at the upper end of the wave-blocking surface of the wave-breaking structure from which a portion has been cut.

  According to this invention, the upper part of the existing wave-breaking structure installed along the shore is excised. A wave breaker having a shape that protrudes more offshore than the excised upper portion is manufactured at the factory. The manufactured wave-proof body is installed on the wave-proof structure instead of the cut upper portion, and is joined to the wave-proof structure. When a wave is applied to the wave-breaking structure after the improvement work is performed, the wave can be returned to the offshore side by the wave-blocking body that has largely pushed toward the sea. Accordingly, the overtopping flow rate can be reduced and the overtopping prevention performance can be improved without increasing the revetment top height.

  In addition, since the superstructure (wavebreaker) manufactured in advance at the factory is only installed locally, even if the wavebreaker has a relatively complex shape that has largely protruded to the sea, the construction period , Can reduce costs. In addition, in the case of a steel / concrete composite structure, the wave breaker can be reduced in weight to the extent that it can resist vertical wave force, and the construction period and cost are greatly reduced compared to the RC structure and concrete structure. be able to.

  In addition, since there is no concrete placement work at sea, there is no risk of the concrete components flowing out into the sea, and there are no environmental problems. In addition, since the height of the revetment top does not increase, the landscape from the land side is not impaired. Moreover, since the wave-dissipating work is not laminated on the sea side as in the conventional example, the coastline is not crushed, and there is no environmental problem.

  According to invention of Claim 2, even if a wave hits the wave-proof body joined to the wave-proof structure, the wave is smoothly guided along the wave-proof surface that approaches the smooth curved surface. Since it is returned to the side, a large vertical wave force is unlikely to act on the wave breaker, which is advantageous in terms of strength.

  According to the invention described in claim 3, a smooth and continuous wave-breaking surface is obtained between the wave-breaking surface of the wave-breaking structure whose upper portion is cut off and the wave-breaking surface of the wave-breaking body, and the wave hits. Sometimes the waves are guided more smoothly along the smooth continuous wavefront and returned to the offshore side.

  FIG. 1 is a perspective view showing the overall structure of a revetment after improvement work according to an embodiment of the present invention. As shown in FIG. 1, in this revetment (wave-breaking structure) after the improvement work, the upper portion 32 (see FIG. 2A described later) of the existing revetment 3 installed on the foundation ground 1 is prevented. It replaces each block 40, 40, ... of the newly constructed revetment 4 as a wave body. 5 is a back lining stone or earth and sand (back lining stone etc.).

  The foundation ground 1 is composed of a sand layer 11 excavated and backfilled from the seabed ground, and a rubble mound 12 stacked on the sand layer 11, and is formed along the shore. In addition, in the figure, it is wide on the sea 2 side, but this is designed to be compatible with future layering of wave breakers.

  The existing revetment 3 is originally an RC structure integrally formed on the foundation ground 1, but here, only the lower part 31 having a rectangular cross section having a wave-breaking surface 33 forming a vertical wall on the sea 2 side is provided. It's being used.

  The new revetment 4 is formed as RC blocks 40, 40,... Divided into an appropriate number (in FIG. 1, an example divided into three in the direction along the shore) is shown. 40,... Are installed on the lower portion 31 of the existing revetment 3, and are fixed to the lower portion 31 by fixing means (not shown).

  Each of the blocks 40, 40,... Has a curved wave-proof surface 41 that smoothly protrudes toward the offshore side, and the tangential direction at the lower end of the wave-proof surface 41 is the lower portion 31 of the existing revetment 3. Is formed so as to substantially coincide with the tangential direction at the upper end of the wave preventing surface 33. As a result, a smoothly continuous wave-breaking surface is obtained between the wave-breaking surface 33 of the lower part 31 of the existing revetment 3 and the wave-breaking surface 41 of each block 40, 40,. Become. Therefore, when a wave hits, the wave is smoothly guided along the smoothly continuous wave-breaking surface and returned to the offshore side, so that a large vertical wave force is unlikely to act on the newly constructed revetment 4 and is strong. Is advantageous.

  The rear shape of each block 40, 40,... Has a downwardly inclined surface, and a horizontal projecting portion 43 is provided at the lowermost portion, and the rear end of the projecting portion 43 is located on the land side of the existing revetment 3. Match with the vertical wall. Thereby, each block 40,40, ... is stably installed and fixed on the lower part 31 of the existing revetment 3. Then, a back stone 5 or the like is placed on the protruding portion 43.

  FIG. 2 is an explanatory view showing an improved construction method for revetment that characterizes the present invention. In FIG. 2, one of the blocks constituting the newly constructed revetment is shown.

  In this method, an excavation process for excising the existing revetment 3, a manufacturing process for manufacturing the new revetment 4 at the factory (wavebreaker manufacturing process), and a new revetment 4 placed on the existing revetment 3 after excision. And a joining step (a wave-protecting body joining step) for joining together. Hereinafter, each step will be described in detail with reference to FIGS.

  FIG. 2A shows the state of the existing revetment 3 before improvement work. That is, the existing revetment 3 is installed on the foundation ground 1 so as to extend in a direction perpendicular to the paper surface, and is composed of a sea-side vertical wall (wave-proof surface) 33, a land-side vertical wall 34, a ceiling surface 35, and a bottom surface 36. It has a rectangular cross section. An upper parapet 37 for avoiding waves is formed on the sea 2 side of the ceiling surface 35.

Excision process:
In this step, the upper portion 32 of the existing revetment 3 is cut at a stretch with a concrete cutter (not shown). This excision position (indicated by a broken line in FIG. 2A) is preferably set slightly above the still water surface at high tide in consideration of the safety and ease of construction.

  And as shown in FIG.2 (b), the existing revetment 3 from which the upper part 32 was excised will be in the state in which only the lower part 31 was left. After leveling by an appropriate method so that the upper surface 38 of the lower portion 31 is horizontal, the anchor reinforcing bars 6 are implanted upwards at appropriate locations on the upper surface 38.

Manufacturing process:
In this process, the newly constructed revetment 4 is manufactured in units of blocks at a factory not shown. Each block 40, 40,... Is formed by laying a reinforcing bar in a predetermined formwork, placing concrete, and curing for a predetermined period, as in a normal RC structure. Here, the new revetment 4 is preferably made as large as possible so that the number of blocks is reduced in order to reduce site construction. In order to allow the newly constructed revetment 4 to counter the vertical wave force, it is preferable to make the block weight as heavy as possible. On the other hand, there are certain limitations in consideration of transportation of each block 40, 40,... From the factory to the site, suspension work during assembly at the site, and the like. Therefore, each block 40, 40,... Is set to have an appropriate size and weight in consideration of the design, transportation, wave conditions, and the like. In addition, illustration of a hanging piece etc. is omitted.

  As shown in FIG. 2 (b), each block 40, 40,... After molding has a sea-side bent wall (wave-proof surface) 41, a land-side vertical wall 45, a stepped ceiling surface 46, and a bottom surface 47. And has a deformed cross section. The shape of the sea-side bent wall 41 is a vertical surface in the vicinity of the upper end in order to ensure strength, but has an arc shape (or a parabolic shape or the like) that protrudes offshore from just below to the lower end.

  Further, on the bottom surface 47 of each block 40, 40,..., A joining vertical hole 42 having a predetermined depth so as to correspond to the anchor reinforcing bar 6 planted in the lower portion 31 of the existing revetment 3 after the molding. Is formed. The blocks 40, 40,... Of the newly constructed revetment 4 thus manufactured are transported through the land or sea to the site where the existing revetment 3 is installed.

Joining process:
In this step, as shown in FIG. 2 (b), each block 40, 40,... Of the newly constructed revetment 4 transported from the factory is suspended by, for example, a marine crane, and the lower part of the existing revetment 3 Install in a row on top of 31. At that time, as shown in FIG. 2C, the blocks 40, 40,... Are positioned so that the distal ends of the anchor reinforcing bars 6 enter the joining vertical holes.

  Then, each block 40, 40,... And the lower portion 31 of the existing revetment 3 are joined by injecting mortar or the like into the gap between the joining vertical hole 42 and the tip of the anchor reinforcing bar 6. Moreover, between each block 40,40, ... and between each block 40,40, ... and the lower part 31 of the existing revetment 3, the water-stopping material, such as rubber | gum, is filled suitably. . The revetment after the improvement work is as shown in FIG.

  By the way, in FIG. 1, a case where a sea-side vertical wall is provided as the wave-preventing surface 33 of the lower part 31 of the existing revetment 3 is shown, but the wave-preventing surface 33 is not necessarily a vertical wall. Further, it is not necessary to make the block shape behind the newly constructed revetment 4 coincide with the land-side vertical wall of the existing revetment 3. For example, as shown in FIG. 3 (a), the wave-breaking surface 33 in the lower part of the existing revetment 3a is an upward inclined surface toward the land, and the shape behind each block 40, 40,. You may provide the horizontal protrusion part 43 as an inclined surface and the lowest part.

  Even in that case, as long as the breakwater surface 33 of the existing revetment 3a and the breakwater surface 41 of each block 40, 40,... The wave rising from the wave surface 33 can be returned to the offshore side by the curved wave-proof surface 41 protruded from each block 40, 40,... Of the newly constructed revetment 4a, and the overtopping flow rate can be reduced.

  In FIG. 3 (a), the rear shape of each block 40, 40,... Of the newly constructed revetment 4a is inclined to the land side and a horizontal projecting portion 43 is provided. There is no. For example, in FIG. 3 (b), the back shape of each block 40, 40,... Of the newly constructed revetment 4b is a stepped vertical wall and a horizontal protruding portion 43 is provided, and in FIG. The entire shape of each block 40, 40,... Of the revetment 4c protrudes from the existing revetment 3a.

  As for these, as long as the breakwater surface 33 of the existing revetment 3a and the breakwater surfaces 41 of the respective blocks 40, 40,... The wave rising from the breakwater surface 33 can be returned to the offshore side by the curved curved wavebreak surface 41 of each block 40, 40,... Of the newly constructed revetments 4b, 4c, and the overtopping flow rate can be reduced. .

  Further, FIGS. 3D to 3F show the case where the upper parapet 44 is provided in each of FIGS. 3A to 3C. However, the upper parapet 43 can further reduce the overtopping flow rate. it can.

  Next, hydraulic experiments conducted on the above-mentioned improved revetment and the existing revetment before the improved construction will be described.

  This revetment has a cross-sectional structure as shown in FIG. 3 (d), and the amount of the block 40, 40,... The top end of the arc of the wave-breaking surface 41 is about 1.5 m above the sea level (sea floor +3.2 m) (sea floor +4.7 m). Furthermore, there is an upper end of the upper parapet 44 above 0.6 m (the seabed + 5.3 m), which matches the height of the top of the existing revetment 3 before this improvement work.

Here, an overtopping flow rate experiment was conducted using an irregular wave having an offshore wave height H _o ′ = 2.0 m, a period T _o = 4.5 sec, and a wavelength L = 32 m, converted in accordance with the local specifications.

As a result, the height of the top of the existing revetment and the main revetment is 5.30 m, but the overtopping flow rate is 8.65 × 10 ⁻³ m ³ / m / sec. This revetment was 1.20 × 10 ⁻³ m ³ / m / sec, about 1/7, and it was found that the overtopping flow rate can be greatly reduced.

  As described above, according to the present embodiment, the upper portion 32 of the existing revetment 3 installed along the shore is excised. Each block 40, 40,... Of the newly constructed revetment 4 having a shape that has a larger amount of protrusion to the offshore side than the excised upper portion 32 is manufactured at the factory. Each block 40, 40,... Of the manufactured new revetment 4 is installed on the lower portion 31 instead of the removed upper portion 32 of the existing revetment 3. , 40,... And the lower portion 31 of the existing revetment 3 are joined by anchor reinforcing bars 6 or the like. When a wave is applied to the revetment after such improvement work is performed, the wave can be returned to the offshore side by the blocks 40, 40,... Accordingly, the overtopping flow rate can be reduced and the overtopping prevention performance can be improved without increasing the revetment top height.

  Moreover, since the blocks 40, 40,... Of the newly constructed revetment 4 manufactured in advance at the factory are only installed locally, even if each block 40, 40,. Even with a relatively complicated shape, the construction period and cost can be reduced. When the steel / concrete composite structure is adopted, each block 40, 40,... Of the newly built revetment 4 can be reduced in weight within the range that can counter the vertical wave force. Compared to a concrete structure, it can be greatly reduced.

  In addition, since there is no concrete placement work at sea, there is no risk of the concrete component flowing out into the sea, and there are no environmental problems. In addition, since the height of the revetment top does not increase, the landscape from the land side is not impaired. Moreover, since the wave-dissipating work is not laminated on the sea side as in the conventional example, the coastline is not crushed, and there is no environmental problem.

  In addition, in the said embodiment, the upper surface 38 of the lower part 31 of the existing revetment 3 is leveled, and the horizontal bottom face 47 contacts each block 40,40, ... of the new revetment 4 on it. In this case, the anchor rebar 6 alone is used to counter the wave force, so that there is a possibility that the stress becomes excessive. Therefore, in order to reduce the stress applied to the anchor reinforcing bars 6, the upper surface 38 of the lower portion 31 of the existing revetment 3 and the bottom surface 47 of each block 40, 40,. You may make it provide the part which an uneven surface meshes. The same applies to the blocks 40, 40,.

  Moreover, in the said embodiment, although each block 40,40, ... of the new revetment 4 is divided | segmented in the direction along a shore in FIG. 1, similarly, each block 40,40, ... of the new revetment 4 is divided. .. can also be divided vertically.

It is a perspective view which shows the whole bank protection structure in one Embodiment of this invention. It is explanatory drawing which shows the improvement construction method of this revetment. This is a modification of the revetment. It is explanatory drawing which shows an example of the improvement construction method of the conventional revetment. It is explanatory drawing which shows the other example of the conventional revetment improvement method.

Explanation of symbols

1 Foundation Ground 11 Sand Layer 12 Rubble Mound 2 Sea 3 Existing Revetment (Existing Wave Structure)
31 Lower part 32 Upper part 33 Wave breaker 4 New revetment (wave breaker)
40 Block 41 Wave-proof surface 42 Vertical hole for joining 43 Projecting part 44 Upper parapet 5 Backing stone, etc. 6 Reinforcing bar for anchor

Claims (3)

A method for improving an existing wave-breaking structure installed along the shore,
Excision step of excising the upper part of the wave-breaking structure;
A wave breaker manufacturing process for manufacturing a wave breaker having a shape with a large amount of protrusion to the offshore side than the excised upper part,
A wave-breaking body joining step of installing the wave-breaking body manufactured on the wave-breaking structure instead of the upper part cut out in the cutting step and bonding the wave-breaking structure to the wave-breaking structure. An improved construction method for wave-proof structures.   In the improvement construction method of the wave-proof structure according to claim 1, the wave-blocking body manufacturing process includes manufacturing a wave-blocking body having a wave-blocking surface that protrudes toward a smooth curved surface toward the offshore side. An improved construction method for wave-breaking structures.   The improved construction method for a wave preventing structure according to claim 2, wherein, in the wave preventing body manufacturing step, the wave tangent direction at the lower end of the wave preventing surface is the wave preventing surface of the wave preventing structure whose upper portion is cut away in the cutting step. An improved construction method for a wave-breaking structure, characterized in that a wave-breaking body having a shape substantially matching the tangential direction at the upper end of the wave-breaking structure is manufactured.

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