Submerged breakwater block

Abstract

The submerged breakwater block 1 comprises a lower frame body 10 having a first opening 11 and a frame body having second openings 21 and 24, which are shaped like the upper part of a cone cut out and are provided above the lower frame body 10, and an upper frame body 20 which shares at least one side with the lower frame body 10 at the boundary. Multiple small openings 31, which have a smaller opening area than the second openings 21 and 24, are arranged in a row in the second openings 21 and 24, and crossbars 32 are provided between adjacent small openings 31.

Description

Technical Field

[0001] The present disclosure relates to submerged breakwater blocks.

Background Art

[0002] Due to the "bleaching" of corals caused by the rising seawater temperature associated with global warming, and environmental degradation caused by the inflow of silt and nutrients from land areas, the degradation of coral reefs is occurring worldwide. Global warming also causes sea-level rise, and corals living in shallow waters cannot keep up with the speed of sea-level rise due to the above environmental degradation, further accelerating their degradation. The degradation of coral reefs results in a decrease in the biodiversity of coastal ecosystems, adverse effects on fishery resources and tourism resources, and degradation of the natural breakwater function of coral reefs, that is, the wave-dissipating function. Furthermore, corals are a source of sand for forming land, and their decrease and the like have become a very serious problem in terms of coastal protection (national land protection). To solve these problems, it is necessary to improve the environment of coral reefs, but the current coral reef restoration technology alone cannot solve the problems up to coastal protection.

[0003] Conventionally, for the purpose of dissipating and attenuating waves reaching the sandy beach in the offing, there is a "submerged breakwater (artificial reef)" formed by stacking and expanding wave-dissipating blocks such as natural stones and tetra pods imitating natural coral reefs. The structure of the submerged breakwater is usually for the purpose of wave-dissipating action, including the single block, and no environmental affinity function including a biological environment or the like is added. Also, from the viewpoint of the wave-dissipating function, in normal construction of conventional submerged breakwaters, it is common to prioritize workability and stack the blocks randomly, but in that case, the porosity that affects the wave-dissipating function becomes non-uniform, resulting in variations in the wave-dissipating function.

[0004] Also, although a conventional submerged breakwater is expected to have a fish reef effect, the conventional submerged breakwater has only a function such that the mound-shaped structure has a fish-aggregating effect only as a result.

[0005] A wave-dissipating fish reef having a wave-dissipating function and also usable as a fish reef for fishermen is disclosed in Patent Document [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Utility Model Registration No. 3221119 Gazette [Overview of the project] [Problems that the invention aims to solve]

[0007] However, while the artificial reef described in Patent Document 1 is said to create an environment that is conducive to the gathering of marine organisms such as fish and seaweed, it was not sufficient for the habitation of coral. During the process of coral larvae settling, the presence of small algae or soil particles (especially fine particles such as silt and clay) on the substrate where they settle can hinder settlement. Therefore, coral settlement could not be expected on the artificial reef described in Patent Document 1.

[0008] The problem addressed by this disclosure is to provide a submerged breakwater that is suitable for coral habitation and also has wave-dissipating properties. [Means for solving the problem]

[0009] This disclosure solves the aforementioned problems by the following solutions. For ease of understanding, the embodiments of this disclosure will be described using corresponding reference numerals, but are not limited thereto.

[0010] The first disclosure is a submerged breakwater block (1, 1B, 1C), for example, as shown in Figures 1, 5, 6, etc., comprising: a lower frame (10) having a first opening (11) and a frame having a second opening (21, 24, 50) in the shape of a cone with the upper part cut out, provided on the upper side of the lower frame (10), and an upper frame (20) sharing at least one side at the boundary with the lower frame (10), wherein a plurality of small openings (31, 51) with a smaller opening area than the second opening (21, 24, 50) are arranged in a row in the second opening (21, 24, 50), and crossbars (32, 52) are provided between adjacent small openings (31, 51).

[0011] The second disclosure is a submerged breakwater block (1, 1B, 1C) described in the first disclosure, characterized in that, for example, as shown in Figures 1, 5, 6, etc., the planar shape of the upper frame (20) formed by the base of the cone in the upper frame (20) is the same as the planar shape of the polygon in the lower frame (10).

[0012] The third disclosure is a submerged breakwater block (1, 1B) described in the first or second disclosure, characterized in that, for example, as shown in Figures 1 and 5, the small opening (31) and the crossbar (32) in the second opening (21, 24) are composed of a mesh member (30) attached to the upper frame (20).

[0013] The fourth disclosure is a submerged breakwater block (1, 1B, 1C) described in any one of the first to third disclosures, characterized in that the planar shape of the lower frame (10) is hexagonal, for example, as shown in Figures 1, 5, and 6.

[0014] The fifth disclosure is a submerged breakwater block (1, 1B, 1C) described in any one of the first to third disclosures, characterized in that the area surrounded by the planar shape on the upper end side of the lower frame body (10) is different from the area surrounded by the planar shape on the lower end side of the lower frame body (10).

[0015] The sixth disclosure is a submerged breakwater block (1, 1B, 1C) described in any one of the first to third disclosures, characterized in that, for example, as shown in FIG. 6, a plurality of the first openings (11) are arranged on one surface of the lower frame body (10).

Advantages of the Invention

[0016] According to the present disclosure, it is possible to provide a submerged breakwater that is easy for corals to inhabit and has wave dissipation.

Brief Description of the Drawings

[0017] [Figure 1] It is a perspective view showing a first embodiment of a submerged breakwater block according to the present disclosure. [Figure 2] It is an exploded perspective view showing the state where the net member 30 is removed from the submerged breakwater block 1. [Figure 3] It is a view seen from above of the state where a large number of submerged breakwater blocks 1 are arranged on the bottom of the water. [Figure 4] It is a view seen from the side of the state where a large number of submerged breakwater blocks 1 are arranged on the bottom of the water. [Figure 5] It is a perspective view showing a second embodiment of a submerged breakwater block according to the present disclosure. [Figure 6] It is a perspective view showing a third embodiment of a submerged breakwater block according to the present disclosure.

Modes for Carrying Out the Invention

[0018] Hereinafter, an embodiment for implementing the present disclosure will be described with reference to the drawings and the like.

[0019] (First Embodiment) FIG. 1 is a perspective view showing a first embodiment of a submerged breakwater block according to the present disclosure. FIG. 2 is an exploded perspective view showing a state in which the net member 30 is removed from the submerged breakwater block 1. Note that each of the figures shown below, including FIG. 1, is a schematically shown figure, and the size and shape of each part are exaggerated or omitted as appropriate for easy understanding. In the following description, specific numerical values, shapes, materials, etc. are shown for the description, but these can be changed as appropriate. In the following description, words indicating the vertical directions such as "upward" and "downward" are used, but this represents the front side as "up" and the bottom side as "down" when the submerged breakwater intended by the present disclosure is installed in water in the correct orientation.

[0020] The submerged breakwater block 1 of the present embodiment is a structure that is installed in a state where a large number of them are arranged on the seabed, creates an environment suitable for the growth of coral, and also has a wave dissipation function. The submerged breakwater block 1 of the present embodiment includes a lower side frame body 10, an upper side frame body 20, a net member 30, and a fastening member 40.

[0021] The lower side frame body 10 is a frame body that forms a polygonal prism with a polygonal planar shape and has a first opening 11. The lower side frame body 10 of the present embodiment forms a regular hexagonal prism with a regular hexagonal planar shape. The bottom surface of the lower side frame body 10 of the present embodiment is a plate-like flat surface without holes, but it may be in a form with holes in the bottom surface. Also, since the inside of the lower side frame body 10 is a cavity, it can be said that the lower side frame body 10 forms a hexagonal cylinder with a hexagonal planar shape. The first openings 11 are provided on the six side surfaces 12 of the lower side frame body 10. No member corresponding to the net member 30 described later is attached to these first openings 11, and relatively large through-holes are left open as they are. The length of one side of the polygonal shape in the planar shape of the lower side frame body 10 can be exemplified as, for example, 1000 mm or more and 5000 mm or less.

[0022] The upper frame 20 is located above the lower frame 10 and is provided integrally with the lower frame 10. The upper frame 20 is a frame constructed in the shape of a pyramidal shape with the top cut out. The interior of the upper frame 20 is hollow. In this embodiment, the upper frame 20 is constructed in the shape of a regular hexagonal pyramid with the top cut out, and is provided with six pyramidal faces 22 and an upper surface 23. Each of the six pyramidal faces 22 is provided with a second opening 21, and the upper surface 23 is provided with a second opening 24. The planar shape of the upper frame 20, formed by the bases of the pyramidal shapes that constitute the upper frame 20, is the same as the planar shape of the polygon in the lower frame 10, that is, a regular hexagon in this embodiment. In this embodiment, the upper frame 20 shares all sides at the boundary with the lower frame 10, but the upper frame 20 may also share at least one side at the boundary with the lower frame 10.

[0023] The lower frame 10 and the upper frame 20 can be integrally formed from concrete, for example, in which case they can be easily manufactured in large quantities at low cost.

[0024] The net member 30 is a net-like member attached to the upper frame 20 so as to cover the second openings 21 and 24. The net member 30 has multiple small openings 31 arranged in a row, each with a smaller opening area than the second openings 21 and 24, and a crossbar 32 is provided between adjacent small openings 31. The size of the small openings 31 can be, for example, 10 mm to 50 mm. The width of the crossbar 32 can be, for example, 1 mm to 20 mm. The net member 30 may be, for example, a highly flexible net made by weaving rope (including ropes and cords), or a member made by opening multiple small openings 31 in a metal plate. In this embodiment, although an example was given in which an independent net member 30 is prepared for each of the second openings 21 and 24, i.e., seven net members 30 are prepared, some of these may be combined, or all of them may be combined. Furthermore, as the net member 30, a coral net (registered trademark), which is known to be effective for coral cultivation, can be suitably used.

[0025] The fastening member 40 is a member for fixing the mesh member 30 to the upper frame 20, and examples include bolts and screws. Note that other fixing methods, such as adhesive, may be used to fix the mesh member 30 to the upper frame 20.

[0026] Figure 3 is a view from above of a large number of submerged breakwater blocks 1 arranged on the seabed. Although Figure 3 shows a single layer of submerged breakwater blocks 1, the blocks may be stacked in two or more layers, as shown in Figure 4 below. Figure 4 is a view from the side of a large number of submerged breakwater blocks 1 arranged on the seabed. Although Figure 4 shows an example with two layers of submerged breakwater blocks 1, they may be stacked in three or more layers. In Figure 4, the symbol G represents the seabed, and the symbol W represents waves.

[0027] Wave dissipation occurs due to wave breaking caused by decreasing water depth and energy consumption due to the roughness of the seabed. Therefore, multiple submerged breakwater blocks 1 are stacked with appropriate height and width to construct a submerged breakwater as a whole. In this embodiment, the planar shape of the lower side frame 10 of the submerged breakwater block 1 is configured as a regular hexagon. As shown in Figure 3, the submerged breakwater blocks 1 can be arranged side by side without gaps. Similar to a honeycomb structure, external forces acting from the side on one submerged breakwater block 1 can be supported by multiple adjacent submerged breakwater blocks 1, resulting in a very strong structure as a whole. Therefore, even when subjected to wave forces, the interlocking structure makes it difficult for each block to be swept away, the planar arrangement is less likely to collapse, and stability can be maintained. Furthermore, conventionally, when stacking multiple blocks, random stacking was common for general wave-dissipating blocks such as tetrapods. However, in this embodiment, by installing the submerged breakwater blocks 1 in an orderly manner as shown in Figure 3, the wave-dissipating effect due to the gaps in the submerged breakwater blocks 1 and the overall shape can be achieved as designed. In other words, as shown in Figure 3, by arranging the submerged breakwater blocks 1 as a group, a submerged breakwater that is substantially larger when viewed as a whole can be constructed, thereby stabilizing the entire structure against waves and increasing the wave-dissipating effect through wave breaking.

[0028] Furthermore, as exemplified earlier, the size of submerged breakwater block 1 is arbitrary and can be determined according to the manufacturing location, transportation, and installation equipment. Similarly, the installation and stacking methods for submerged breakwater block 1 are arbitrary and can be determined according to the site. For example, submerged breakwater block 1 can be divided into two main sizes. Firstly, it can be a size that can be manufactured and installed by local stakeholders (such as fishermen and divers) without the use of heavy machinery (hereinafter referred to as small submerged breakwater block). Secondly, it can be a size used by specialized construction companies for coastal civil engineering work using heavy machinery vessels, etc. (hereinafter referred to as large submerged breakwater block). For example, a small submerged breakwater block could be approximately 1m high, 1.5m wide, and weigh around 100kg in the air. This small submerged breakwater block can be manufactured on a beach or similar location using a simple dedicated formwork, and then installed by placing balloons inside the internal space of the block and using buoyancy to move it around the sea. On the other hand, the large submerged breakwater block can be 2m to 3m high, 3m to 4.5m wide, and have an aerial weight of several tons to tens of tons. This large submerged breakwater block can be manufactured at a port near the installation site, transported by barge, and installed by crane.

[0029] Furthermore, the submerged breakwater block 1 of this embodiment has a first opening 11 and second openings 21 and 24 on each surface. These first openings 11 and second openings 21 and 24 generate vortices in response to the flow caused by waves, efficiently dissipating wave energy and attenuating wave height.

[0030] Furthermore, each side of the lower frame 10 near the bottom is provided with first openings 11 to which members corresponding to the net members 30 are not attached. This makes it easier to draw wave energy into the submerged breakwater block 1, and when it escapes upward, the water force is attenuated by the net members 30, thereby enhancing the wave-dissipating effect. In addition, the presence of first openings 11 to which members corresponding to the net members 30 are not attached makes it easier for marine organisms (fish, seaweed, crustaceans) to enter the submerged breakwater block 1, providing them with a habitat and thus exhibiting an effect as an artificial reef. As coral grows in the submerged breakwater block 1, and as it has many first openings 11 and second openings 21, 24, the first openings 11 and second openings 21, 24 provide hiding places and spawning grounds for fish, including juvenile fish, thus exhibiting a very strong effect as an artificial reef.

[0031] Furthermore, by making the upper frame 20 of the submerged breakwater block 1 a cone and narrowing its shape in the water depth direction toward the water surface, the area subjected to wave force is reduced, and the center of gravity of the submerged breakwater block 1 is located towards the bottom, thus making it more stable. This is a very effective configuration for stabilizing the submerged breakwater block 1 in its installed state, given that wave force is greater closer to the water surface.

[0032] The net member 30 has a rib section 32, making it very suitable for coral cultivation. Specifically, it has been shown, for example, in Japanese Patent Publication No. 2018-191615, that coral larvae first attach to the underside of the rib section 32. Furthermore, the performance of CoralNet (registered trademark) as a coral attachment and cultivation base has been demonstrated in many field applications. In the submerged breakwater block 1 of this embodiment, coral first attaches to the underside of the rib section 32, and as it grows, it expands to the outside of the submerged breakwater block 1, until finally the submerged breakwater block 1 is covered with coral on both the front and back surfaces of the net member 30.

[0033] The submerged breakwater block 1 of this embodiment has a configuration that combines the function of a base for coral attachment and growth with a wave-dissipating function. Therefore, while conventional methods involved manually fixing each coral net (registered trademark) to the seabed or blocks, using the submerged breakwater block 1 of this embodiment simplifies the installation process to simply arranging the submerged breakwater blocks 1, allowing for the installation of many blocks in a short time and potentially leading to a significant expansion of the coral regeneration area. Moreover, since the submerged breakwater block 1 combines the function of a base for coral attachment and growth with a wave-dissipating function, these multiple effects can be obtained at once. Furthermore, the net members 30 can be attached to the submerged breakwater block 1 afterwards, and can be easily replaced with net members 30 on which coral has taken root.

[0034] In a submerged breakwater (a collection of submerged breakwater blocks 1) constructed on the seabed by arranging multiple submerged breakwater blocks 1 as described above, the expansion of coral communities can further enhance the wave-dissipating effect and enable it to function as an artificial reef. As various types of coral grow in the submerged breakwater (a collection of submerged breakwater blocks 1), it is expected that it will develop into a coral reef equivalent to a natural one in the future, and that it will also grow in line with the gradual rise in sea level that will occur in the future, thus realizing a sustainable coral reef.

[0035] (Second Embodiment) Figure 5 is a perspective view showing a second embodiment of the submerged breakwater block according to this disclosure. The submerged breakwater block 1B of the second embodiment is the same as the submerged breakwater block 1 of the first embodiment, except that the lower frame 10 is longer in the vertical direction and a plurality of first openings 11 are arranged on one side surface 12 of the lower frame 10. Therefore, parts that perform the same functions as those of the first embodiment described above are denoted by the same reference numerals, and redundant explanations are omitted as appropriate.

[0036] As shown in Figure 5, in the second embodiment, the submerged breakwater block 1B has two first openings 11 arranged vertically on one side 12 of the lower frame 10. This allows for increased water flow in the lower frame 10 while maintaining the strength of the submerged breakwater block 1B. It also allows for an increased height for each submerged breakwater block 1B.

[0037] Of the two first openings 11 arranged vertically side by side on the side surface 12 of the lower frame 10, it is desirable to leave the lower first opening 11 as a large opening to allow fish to easily enter the submerged breakwater block 1B and to facilitate the introduction of water flow. On the other hand, a member equivalent to the net member 30 may be attached to the upper first opening 11.

[0038] (Third embodiment) Figure 6 is a perspective view showing a third embodiment of the submerged breakwater block according to this disclosure. The submerged breakwater block 1C of the third embodiment differs from the first embodiment in that it does not use a mesh member 30, and the upper frame 20 has a second opening 50 with a small opening 51 and a crossbar 52 as part of the shape of the upper frame 20. Otherwise, it has the same form as the submerged breakwater block 1 of the first embodiment. Therefore, the same reference numerals are used for parts that perform the same functions as those of the first embodiment described above, and redundant explanations are omitted as appropriate.

[0039] The submerged breakwater block 1C of the third embodiment does not have a member equivalent to the mesh member 30 in the submerged breakwater block 1 of the first embodiment. Instead, the submerged breakwater block 1C of the third embodiment has a second opening 50 in the upper frame 20, which has a small opening 51 and a crossbar 52, and this opening is formed as part of the shape of the upper frame 20.

[0040] In the case where the second opening 50 having a small opening 51 and a crossbar 52 is configured as the shape of the upper frame 20, as in the submerged breakwater block 1C of the third embodiment, the size of the small opening 51 can be exemplified as 10 mm to 300 mm. The width of the crossbar 52 can be exemplified as 10 mm to 100 mm.

[0041] According to the third embodiment of the submerged breakwater block 1C, the upper frame 20 is configured with a second opening 50 having a small opening 51 and a crossbar 52, which makes the manufacturing of the submerged breakwater block 1C easier.

[0042] (Transformed form) The embodiments described above are not limited to those described above, and various modifications and changes are possible, which are also within the scope of this disclosure.

[0043] (Modified form 1) In each embodiment, an example was given in which the planar shape of the upper frame 20 formed by the base of the cone in the upper frame 20 is the same as the planar shape of the polygon in the lower frame 10. However, the invention is not limited to this, and for example, the planar shape of the upper frame formed by the base of the cone in the upper frame may be partially or completely different from the planar shape of the polygon in the lower frame.

[0044] (Modified form 2) In each embodiment, the lower frame 10 is described as having a substantially regular hexagonal prism shape, and the area enclosed by the planar shape on the upper end side of the lower frame 10 and the area enclosed by the planar shape on the lower end side are substantially the same. However, it is not limited to this, and for example, the area enclosed by the planar shape on the upper end side of the lower frame 10 and the area enclosed by the planar shape on the lower end side of the lower frame 10 may be different. In other words, the lower frame 10 may also be composed of a conical surface.

[0045] (Modified form 3) In each embodiment, the planar shape of the lower frame 10 was described as being approximately a regular hexagonal prism. However, it is not limited to this, and the planar shape of the lower frame 10 may be other polygonal shapes such as an octagon or a quadrilateral.

[0046] While each embodiment and its variations can be used in combination as appropriate, a detailed explanation is omitted. Furthermore, this disclosure is not limited to the embodiments described above. [Explanation of Symbols]

[0047] 1, 1B, 1C Submerged breakwater blocks 10 Lower frame 11. First opening 12 Side view 20 Upper frame 21. Second opening 22 Conical surface 23 Top side 24. Second opening 30 Net components 31 Small opening 32 Cross section 40 Fastening members 50 Second opening 51 Small opening 52 Cross section

Claims

1. The planar shape forms a polygonal prism, and the lower side frame has a first opening, A frame having a second opening in the shape of a cutout at the upper part of a cone provided on the upper side of the lower frame, and an upper frame sharing at least one side at the boundary with the lower frame, Equipped with, The second opening has a number of smaller openings arranged in a row, each having a smaller opening area than the second opening, and a crossbar is provided between adjacent smaller openings. A submerged breakwater block, wherein the width of the aforementioned crossbar is 10 mm or more and 100 mm or less.

2. In the submerged breakwater block according to claim 1, The planar shape of the upper frame, formed by the base of the cone in the upper frame, is the same as the planar shape of the polygon in the lower frame. A submerged breakwater block characterized by the following features.

3. In the submerged breakwater block according to claim 1 or claim 2, The small opening and the crossbar in the second opening are formed by a mesh member attached to the upper frame. A submerged breakwater block characterized by the following features.

4. In the submerged breakwater block according to claim 1 or claim 2, The planar shape of the lower frame is hexagonal. A submerged breakwater block characterized by the following features.

5. In the submerged breakwater block according to claim 1 or claim 2, The area enclosed by the planar shape of the upper end of the lower frame body is different from the area enclosed by the planar shape of the lower end of the lower frame body. A submerged breakwater block characterized by the following features.

6. In the submerged breakwater block according to claim 1 or claim 2, The lower frame body has multiple first openings arranged on one surface. A submerged breakwater block characterized by the following features.

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