Fish reef and fish reef installation method

Abstract

To provide a fish reef which can be installed on a water bottom in a stable state.SOLUTION: A fish reef 1 installed on a water bottom comprises a frame body 10 having a frame body lower end part 50. The frame body lower end part includes: a side wall part 51 for defining an internal space IS which can receive sand on the water bottom from a lower side; an upper wall part 52 arranged above the internal space so as to press the sand which has flowed into the internal space; and a water outflow part 56 for communicating the internal space with an external space OS of the internal space, so as to allow water existing in the internal space to flow to the outside of the internal space.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a fish reef and a method for installing the fish reef.

Background Art

[0002] Conventionally, a fish reef that is installed on the bottom of the sea or the like and forms an environment suitable for aquatic organisms to inhabit is known. For example, Patent Document 1 discloses a fish reef including four columnar bodies that contact the bottom of the sea, a beam-like body stretched between the four columnar bodies, and a top surface portion, and having an internal space surrounded by these members. A plurality of woods are accommodated in this internal space, and the gaps between the woods form an environment suitable for the habitation of aquatic organisms.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the technique described in Patent Document 1, there is a possibility that the fish reef is installed on the bottom of the sea (bottom of the water) in an unstable state. Specifically, in the technique according to Patent Document 1, the stability of the fish reef depends on the insertion depth of the four columnar bodies into the bottom of the sea. That is, the stability of the fish reef is determined by how deep the four columnar bodies penetrate into the bottom of the sea. Therefore, for example, when each of the columnar bodies is shallowly inserted into the bottom of the sea, the fish reef is installed in an unstable state.

[0005] The present invention has been made in view of the above problems, and an object thereof is to provide a fish reef that can be installed on the bottom of the water in a stable state.

Means for Solving the Problems

[0006] The fish reef according to one aspect of the present invention is a fish reef installed on the seabed, and includes a frame body having a lower end portion of the frame body. The lower end portion of the frame body includes a side wall portion that defines an internal space capable of receiving the sediment on the seabed from below, an upper wall portion disposed above the internal space so as to hold down the sediment that has flowed into the internal space, and a water outflow portion that communicates the internal space with the outside of the internal space so that the water existing in the internal space can flow out to the outside of the internal space.

[0007] According to this configuration, it is possible to form a base with sediment and support the fish reef with the base, so that the stability of the fish reef is improved. Specifically, in the above fish reef, since the internal space capable of receiving the sediment on the seabed from below is formed by the side wall portion and the upper wall portion, when the fish reef is installed on the seabed and sinks into the sediment on the seabed due to its own weight, the sediment on the seabed flows into the internal space. Here, since the fish reef has a water outflow portion that communicates the internal space with the outside of the internal space (hereinafter referred to as the external space), as sediment flows into the internal space, the water existing in the internal space flows out to the external space through the water outflow portion. As a result, the sediment existing in the internal space solidifies, and a base made of sediment is formed in the internal space. Since the fish reef is supported by this base, the stability of the fish reef is enhanced. As a result, it becomes possible to install the fish reef on the seabed in a stable state.

[0008] In the above fish reef, the lower end portion of the frame body may include a plurality of pipe members arranged in the horizontal direction, and the upper wall portion may be constituted by the lower surface portions of the plurality of pipe members.

[0009] According to this configuration, since the cross-sectional shape of the lower surface of the upper wall portion (hereinafter referred to as the lower surface of the upper wall) is wavy, it is possible to ensure a larger contact area between the lower surface of the upper wall and the sediment existing in the internal space compared to the case where the upper wall portion is configured such that the cross-sectional shape of the lower surface of the upper wall is, for example, a horizontal planar shape. That is, according to the above configuration, it is possible to ensure a larger contact area between the lower surface of the upper wall and the upper surface of the base made of sediment. As a result, relative movement (sliding) of the lower surface of the upper wall with respect to the upper surface of the base is suppressed, so that the stability of the fish reef is further improved.

[0010] In the above artificial reef, at least one end in the axial direction of at least one of the plurality of pipe members may be open.

[0011] According to this configuration, it becomes possible to inhabit aquatic organisms inside the pipe member. That is, it becomes possible to use the space inside the pipe member as part of the artificial reef.

[0012] In the above artificial reef, each of the plurality of pipe members may be constituted by a used oil well pipe.

[0013] According to the above configuration, it becomes possible to reuse the used oil well pipe. As this used oil well pipe, for example, an oil well pipe generated as waste material when an oil well (submarine oil well) used for extracting oil or the like from a submarine oil field is disassembled may be used.

[0014] In the above artificial reef, holes penetrating the wall portion are formed in the wall portion of the plurality of pipe members, and the water outflow portion may be constituted by the holes.

[0015] According to this configuration, since the holes formed in the pipe member function as the water outflow portion, it becomes possible to more surely let the water existing in the internal space flow out to the external space.

[0016] An artificial reef installation method according to another aspect of the present invention is to sink an artificial reef having an internal space formed at the lower end portion to the bottom of the water to allow the sediment at the bottom of the water to flow into the internal space, and at least a part of the water in the internal space is allowed to flow out to the outside of the internal space through a water outflow portion that allows the internal space and the outside of the internal space to communicate with each other so that a base is formed by the sediment in the internal space.

[0017] According to this method, a base made of earth and sand can be formed in the internal space. And since the fish reef installed on the seabed is supported by the base, it becomes possible to install the fish reef on the seabed in a stable state.

Effects of the Invention

[0018] According to the present invention, it becomes possible to install the fish reef on the seabed in a stable state.

Brief Description of the Drawings

[0019]

Figure 1

Figure 2

Figure 3A

Figure 3B

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Mode for Carrying Out the Invention

[0020] Hereinafter, a fish reef 1 according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing a schematic configuration of a fish reef 1 according to an embodiment of the present invention.

[0021] [Overall Configuration of Fish Reef 1] The fish reef 1 is installed on the seabed 2 (FIG. 3A) to form an environment suitable for the habitation of marine organisms. In particular, the fish reef 1 according to this embodiment forms an environment suitable for the habitation of squid. However, the fish reef 1 may form an environment suitable for the habitation of marine organisms other than squid, and the fish reef 1 may also be installed on the bottom of a pond, lake, river, etc. As shown in FIG. 1, the fish reef 1 includes a frame body 10. The frame body 10 is a structure having a rectangular parallelepiped outer shape. The frame body 10 includes a support column portion 20, an upper end portion 30 of the frame body, a middle portion 40 of the frame body, and a lower end portion 50 of the frame body.

[0022] [Configuration of the support column portion 20] The support column portion 20 has a plurality (four in this example) of support column members 21 each extending along the vertical direction. The support column members 21 are arranged at intervals so that the virtual lines connecting the support column members 21 form a square shape when viewed from above. Specifically, the support column members 21 are arranged apart from each other in a first direction (FIG. 1) orthogonal to the vertical direction (FIG. 1), or in a second direction (FIG. 1) orthogonal to the vertical direction and the first direction.

[0023] [Configuration of the upper end portion 30 of the frame body] The upper end portion 30 of the frame body is connected to the upper end portion of the support column portion 20 by a method such as welding. The upper end portion 30 of the frame body includes an upper end horizontal bone portion 31, a top wall portion 32, a top wall connecting portion 33, an upper end peripheral portion 34, and an upper end peripheral connecting portion 35.

[0024] The upper end horizontal bone portion 31 includes a first pair of upper end horizontal bone members 311 connected to each other and a second pair of upper end horizontal bone members 312, and has a square outer shape with an opening in the center. The first pair of upper end horizontal bone members 311 each extend along the first direction so as to connect the support column members 21 arranged along the first direction, and face each other in the second direction. The second pair of upper end horizontal bone members 312 extend along the second direction in a state of facing each other in the first direction so as to connect the support column members 21 arranged along the second direction and connect the first pair of upper end horizontal bone members 311 to each other.

[0025] The top wall portion 32 has a plurality of top wall pipe members 320 that each extend along the second direction and are closely arranged side by side in the first direction, and constitutes the top surface of the fish reef 1.

[0026] The top wall connecting portion 33 is disposed between the upper end horizontal rib portion 31 and the top wall portion 32 in the vertical direction and connects the upper end horizontal rib portion 31 and the top wall portion 32. Specifically, the top wall connecting portion 33 has a plurality of top wall connecting members 330. Each of the plurality of top wall connecting members 330 includes a top wall connecting base portion 331 fixed to the upper surface of the first pair of upper end horizontal rib members 311, and a top wall support portion 332 that extends from the upper surface of the top wall connecting base portion 331 to the inside of the frame body 10 so as to be able to support the top wall portion 32 and is connected to the lower end portion of the top wall pipe member 320 of the top wall portion 32.

[0027] The upper end peripheral portion 34 is disposed so as to surround the upper end horizontal rib portion 31. The upper end peripheral portion 34 according to the present embodiment has a plurality of upper end peripheral pipe members 340 that extend along the axial direction (the first direction or the second direction).

[0028] The upper end peripheral connecting portion 35 is disposed between the upper end horizontal rib portion 31 and the upper end peripheral portion 34 and connects the two. The upper end peripheral connecting portion 35 has a plurality of upper end peripheral connecting members 350. Each of the plurality of upper end peripheral connecting members 350 includes an upper end peripheral connecting base portion 351 fixed to the outer surface of the first pair of upper end horizontal rib members 311 or the outer surface of the second pair of upper end horizontal rib members 312, and an upper end peripheral support portion 352 that extends from the outer surface of the upper end peripheral connecting base portion 351 in the first direction or the second direction so as to be able to support the upper end peripheral pipe member 340 of the upper end peripheral portion 34 and is connected to the inner surface of the upper end peripheral pipe member 340.

[0029] [Configuration of the middle portion 40 of the frame body] The middle portion 40 of the frame body is connected to the middle portion between the upper end portion and the lower end portion of the support column portion 20 by a method such as welding. The middle portion 40 of the frame body has a middle horizontal rib portion 41, a middle wall portion 42, a middle wall connecting portion 43, a middle peripheral portion 44, and a middle peripheral connecting portion 45.

[0030] The intermediate horizontal bone part 41 includes a first pair of intermediate horizontal bone members 411 and a second pair of intermediate horizontal bone members 412 that are connected to each other, and has a rectangular outer shape with an opening in the center. The first pair of intermediate horizontal bone members 411 each extend along the first direction so as to connect the column members 21 arranged along the first direction, and face each other in the second direction. The second pair of intermediate horizontal bone members 412 each extend along the second direction in a state of facing each other in the first direction so as to connect the column members 21 arranged along the second direction and to connect the first pair of intermediate horizontal bone members 411 to each other.

[0031] The intermediate wall part 42 has a plurality of intermediate wall pipe members 420 that each extend along the first direction and are closely arranged side by side in the second direction. By providing such an intermediate wall part 42 on the artificial reef 1, it is possible to form an environment more suitable for marine organisms such as squids that have the habit of laying eggs on the back surface (lower surface) of an object.

[0032] The intermediate wall connecting part 43 is disposed between the intermediate horizontal bone part 41 and the intermediate wall part 42 in the vertical direction and connects the intermediate horizontal bone part 41 and the intermediate wall part 42. Specifically, the intermediate wall connecting part 43 has a plurality of intermediate wall connecting members 430. Each of the plurality of intermediate wall connecting members 430 includes an intermediate wall connecting base part 431 fixed to the upper surface of the second pair of intermediate horizontal bone members 412, and an intermediate wall support part 432 that extends from the upper surface of the intermediate wall connecting base part 431 to the inside of the frame body 10 so as to be able to support the intermediate wall part 42 and is connected to the lower end part of the intermediate wall pipe member 420.

[0033] The intermediate peripheral part 44 is arranged so as to surround the intermediate horizontal bone part 41. The intermediate peripheral part 44 according to the present embodiment has a plurality of intermediate peripheral pipe members 440 that extend along the axial direction (the first direction or the second direction). The length dimension in the axial direction of each intermediate peripheral pipe member 440 is set to be larger than the length dimension in the axial direction of each of the above-mentioned upper end peripheral pipe members 340.

[0034] The intermediate peripheral connecting portion 45 is disposed between the intermediate horizontal rib portion 41 and the intermediate peripheral portion 44 and connects the two. The intermediate peripheral connecting portion 45 has a plurality of intermediate peripheral connecting members 450. Each of the plurality of intermediate peripheral connecting members 450 includes an intermediate peripheral connecting base portion 451 fixed to the outer surface of the column portion 20, and an intermediate peripheral support portion 452 extending from the outer surface of the intermediate peripheral connecting base portion 451 in the first direction or the second direction so as to be able to support the intermediate peripheral portion 44 and connected to the inner surface of the intermediate peripheral pipe member 440.

[0035] [Configuration of the lower end portion 50 of the frame body] The lower end portion 50 of the frame body is connected to the lower end portion of the column portion 20 by a method such as welding. The lower end portion 50 of the frame body has a side wall portion 51, an upper wall portion 52, an upper wall connecting portion 53, a lower end peripheral portion 54, a lower end peripheral connecting portion 55, and a water outflow portion 56.

[0036] The side wall portion 51 is open downward so as to be able to receive the sediment of the seabed 2, and defines an internal space IS (FIG. 3A) for accommodating the sediment. In this specification, the "sediment" refers to a mixture containing at least one of mud (particles with a particle size of less than 1 / 16 mm), sand (particles with a particle size of 2 mm or less and 1 / 16 mm or more), and gravel (objects with a particle size larger than 2 mm). Specifically, the side wall portion 51 has a first pair of side wall members 511 and a second pair of side wall members 512 that are connected to each other. The first pair of side wall members 511 each extend along the first direction so as to connect the column members 21 arranged along the first direction, and face each other in the second direction. The second pair of side wall members 512 extend along the second direction in a state of facing each other in the first direction so as to connect the column members 21 arranged along the second direction and connect the first pair of side wall members 511 to each other. The space located inside each pair of these side wall members 511, 512 is the internal space IS. That is, the side wall portion 51 constitutes four inner surfaces of the internal space IS. In FIG. 3A, an example in which an internal space IS having a substantially T shape is formed is shown, but this is merely an example, and the shape of the internal space IS can be appropriately changed.

[0037] The upper wall portion 52 is disposed above the internal space IS and defines the upper end (upper surface) of the internal space IS. The upper wall portion 52 is constituted by the lower surface portions of a plurality of upper wall pipe members 520 (an example of a plurality of pipe members) included in the lower end portion 50 of the frame body. The plurality of upper wall pipe members 520 each extend along the second direction and are arranged closely side by side in the first direction (an example of the horizontal direction). As shown in FIG. 1, both ends of all the upper wall pipe members 520 according to the present embodiment in the axial direction (the second direction in this example) are open. Further, a plurality of wall holes penetrating the wall portion 520W (FIG. 3B) of at least one of the plurality of upper wall pipe members 520 according to the present embodiment are formed in the wall portion 520W. The plurality of wall holes include, for example, a first hole portion 521H (FIG. 3B) that communicates the internal space IS with the inside of the upper wall pipe member 520, and a second hole portion 522H (FIG. 3B) that communicates the inside of the upper wall pipe member 520 with the space above the upper wall portion 52. Note that the plurality of wall holes may further include a third hole (not shown) that communicates the inside of the upper wall pipe member 520 with the space on the side of the upper wall portion 52.

[0038] The upper wall connecting portion 53 is disposed between the side wall portion 51 and the upper wall portion 52 in the vertical direction and connects the side wall portion 51 and the upper wall portion 52. Specifically, the upper wall connecting portion 53 has a plurality of upper wall connecting members 530. Since the configuration of the plurality of upper wall connecting members 530 is the same as the configuration of the plurality of top wall connecting members 330 described above, the description thereof is omitted.

[0039] The lower end peripheral portion 54 is disposed so as to surround the side wall portion 51. The lower end peripheral portion 54 according to the present embodiment has a plurality of lower end peripheral pipe members 540 extending along the first direction or the second direction. The length dimension of each lower end peripheral pipe member 540 in the axial direction (the first direction or the second direction) is set to be equal to the length dimension of each of the intermediate peripheral pipe members 440 in the axial direction (the first direction or the second direction).

[0040] Since the configuration of the lower end peripheral connecting portion 55 is the same as the configuration of the intermediate peripheral connecting portion 45, the description thereof is omitted.

[0041] The water outflow part 56 communicates the internal space IS with the external space OS (hereinafter referred to as the external space OS) so that the water existing in the internal space IS can flow out to the outside of the internal space IS. The water outflow part 56 according to the present embodiment includes a first outflow part 561, a second outflow part 562, and a third outflow part 563 (FIG. 3B).

[0042] The first outflow part 561 is a plurality of gaps formed between the first pair of side wall parts 51, a plurality of upper wall pipe members 520, and a plurality of upper wall connecting members 530.

[0043] The second outflow part 562 is two gaps formed between the second pair of side wall parts 51, both upper wall pipe members 520 arranged on the outermost side among the plurality of upper wall pipe members 520, and the ends of the first pair of side wall parts 51 in the first direction. In FIG. 1, only one of the second outflow parts 562 is shown, and the other of the second outflow parts 562 is not shown.

[0044] The third outflow part 563 is a first hole part 521H (FIG. 3B) formed in the wall part 520W of the upper wall pipe member 520. By changing the shape or diameter of the first hole part 521H, the drainage property of the third outflow part 563 can be adjusted. Note that the third outflow part 563 is not an essential component of the fish reef 1.

[0045] [Details of Each Member] In the present embodiment, each support member 21 included in the support part 20 is made of an angle material having an L-shaped cross-sectional shape. The same applies to each cross member constituting the first pair of upper end cross members 311 and the second pair of upper end cross members 312, each cross member constituting the first pair of intermediate cross members 411 and the second pair of intermediate cross members 412, and each side wall member constituting the first pair of side wall members 511 and the second pair of side wall members 512. However, the configuration of each member is not limited to this, and instead of the angle material, a square columnar member, an H-shaped steel, an I-shaped steel, or the like may be used.

[0046] In addition, in the present embodiment, each ceiling wall pipe member 320 of the ceiling wall portion 32, each upper end peripheral pipe member 340 of the upper end peripheral portion 34, each intermediate wall pipe member 420 of the intermediate wall portion 42, each intermediate peripheral pipe member 440 of the intermediate peripheral portion 44, each upper wall pipe member 520 of the upper wall portion 52, and each lower end peripheral pipe member 540 of the lower end peripheral portion 54 are each made from a used oil well pipe processed to a predetermined length. Note that, for example, used oil well pipes generated as waste materials when disassembling an oil well (subsea oil well) constructed for extracting oil or the like from a subsea oil field may be used. However, the configuration of each of these pipe members is not limited to used oil well pipes, and for example, pipe members newly manufactured at a factory or the like for manufacturing the artificial reef 1 according to the present embodiment may also be used.

[0047] [Installation method of artificial reef 1] Next, the installation method of the artificial reef 1 will be described. FIG. 2 is a flowchart showing the installation method of the artificial reef 1. The installation method includes a throwing step, a flowing-in step, and a water outflow step. FIG. 3A is a view showing the state where the artificial reef 1 is installed on the seabed 2 in the throwing step. Note that FIG. 3A shows a cross-section of the artificial reef 1 as viewed along the cutting plane shown by the line IIIA-IIIA in FIG. 1. FIG. 3B is an enlarged view of the region IIIB in FIG. 3A. FIG. 4 is a view showing the state where the artificial reef 1 sinks to the seabed 2. Similar to FIG. 3A, FIG. 4 shows a cross-section of the artificial reef 1 as viewed along the cutting plane shown by the line III-III in FIG. 1. Note that FIG. 4 shows the artificial reef 1 after a predetermined time (for example, several months) has elapsed since the start of sinking.

[0048] Referring to FIG. 2, first, the throwing step (step S1) is performed. Specifically, in the throwing step, the artificial reef 1 having the internal space IS is thrown into the sea, and as shown in FIG. 3A, the artificial reef 1 is landed on the seabed 2.

[0049] Next, the process proceeds to the inflow step (step S2). In the inflow step, the fish reef 1 that has landed on the seabed 2 sinks into the ground due to its own weight (initially sinks). As described above, the side wall portion 51 at the lower end of the frame body of the fish reef 1 according to the present embodiment opens downward so as to be able to receive the sediment of the seabed 2 (opening). Therefore, as the fish reef 1 sinks into the seabed 2, the sediment of the seabed 2 flows into the internal space IS from below the side wall portion 51. As shown in FIG. 4, the sediment that has flowed into the internal space IS is pressed by the upper wall lower surface 52a of the upper wall portion 52 disposed above the internal space IS. As a result, an aggregate of sediment in the shape of a rectangular parallelepiped is formed.

[0050] Next, the process proceeds to the water outflow step (step S3). In the water outflow step, at least a part of the water present in the internal space IS flows out to the external space OS through the water outflow portion 56. That is, in the water outflow step, the water present in the internal space IS is pushed out to the external space OS by the sediment that has flowed into the internal space IS and is pressed by the upper wall lower surface 52a of the upper wall portion 52. Specifically, in the water outflow step, the water in the internal space IS is pushed out to the external space OS through at least one of the first outflow portion 561, the second outflow portion 562, and the third outflow portion 563. When water flows out through the first outflow portion 561, the water flows out to the external space OS in a flow as shown by the arrow A1 in FIG. 1, for example. When water flows out through the second outflow portion 562, the water flows out to the external space OS in a flow as shown by the arrow A2 in FIG. 1, for example. When water flows out through the third outflow portion 563 (the first hole portion 521H), the water flows out to the external space OS in a flow as shown by the arrow A3 in FIG. 3B, for example. That is, the water that has flowed into the inside of the upper wall pipe member 520 (a part of the external space OS) from the internal space IS through the first hole portion 521H flows out above the upper wall pipe member 520 through the second hole portion 522H. However, the outflow path of the water through the first hole portion 521H is not limited to this. For example, the water that has flowed into the inside of the upper wall pipe member 520 through the first hole portion 521H may flow out from the opening at the axial end of the upper wall pipe member 520. Thus, by draining water from the internal space IS in the water outflow step, the sediment accommodated in the internal space IS can be solidified. Thereby, a base 100 (FIG. 4) made of sediment is formed in the internal space IS.

[0051] From the perspective of making the earth and sand contained in the internal space IS stronger, while allowing water to flow out from the internal space IS, it is preferable to suppress the outflow of earth and sand from the internal space IS. Also, from the perspective of more surely allowing water to flow out from the internal space IS, qualitatively, it is preferable that the diameter (opening area) of the first outflow portion 561, the second outflow portion 562, or the third outflow portion 563 is set large. For this reason, in the present embodiment, the size of the diameter (opening area) of the first outflow portion 561, the second outflow portion 562, or the third outflow portion 563 is adjusted according to the particle size of the earth and sand. That is, when installing the fish reef 1 in a region of the seabed 2 containing a large amount of sand, such as a sandy area, the diameter of the first outflow portion 561, the second outflow portion 562, or the third outflow portion 563 is set relatively small. Thereby, compared with the case where the diameter of each outflow portion 561, 562, 563 is set large, it is possible to more surely suppress the outflow of earth and sand together with water from each outflow portion 561, 562, 563. Also, when installing the fish reef 1 in a region of the seabed 2 containing a large amount of gravel, such as a rocky reef area, the diameter of the first outflow portion 561, the second outflow portion 562, or the third outflow portion 563 is set relatively large. Thereby, compared with the case where the diameter of each outflow portion 561, 562, 563 is set small, it is possible to more surely allow the water in the internal space IS to flow out to the external space OS.

[0052] [Operational Effects] As described above, in the fish reef 1 according to the present embodiment, a base 100 made of sediment is formed, and the fish reef 1 can be supported by the base 100, so that the stability of the fish reef 1 is improved. Specifically, in the fish reef 1 described above, an internal space IS capable of receiving the sediment of the seabed 2 from below is formed by the side wall portion 51 and the upper wall portion 52. Therefore, when the fish reef 1 is installed on the seabed 2 and sinks into the sediment of the seabed 2 due to its own weight, the sediment of the seabed 2 flows into the internal space IS. Here, since the fish reef 1 has a water outflow portion 56 that communicates the internal space IS and the external space OS, as the sediment flows into the internal space IS, the water existing in the internal space IS flows out to the external space OS through the water outflow portion 56. As a result, the sediment existing in the internal space IS hardens, and a base 100 made of sediment is formed. Since the fish reef 1 is supported by this base 100, the stability of the fish reef 1 is enhanced. As a result, it becomes possible to install the fish reef 1 on the seabed 2 in a stable state.

[0053] Furthermore, in the present embodiment, the base 100 restricts the sinking of the fish reef 1. Specifically, the upper surface 100a of the base 100 supports the lower surface 52a of the upper wall of the upper wall portion 52 so as to prevent the fish reef 1 from sinking. In this way, in the present embodiment, the fish reef 1 that has sunk due to initial sinking is restricted by the base 100 from sinking deeper into the seabed 2. As a result, it is possible to suppress the fish reef 1 from being buried in the sediment of the seabed 2 and losing its function as a fish reef.

[0054] Furthermore, according to the configuration of the present embodiment, it is possible to suppress the displacement of the installation position of the fish reef 1. For example, when a force that pushes the fish reef 1 from the side, such as a sea current, acts on the fish reef 1, the fish reef 1 may move relative to the seabed 2, and as a result, the installation position of the fish reef 1 on the seabed 2 may deviate from the position intended by the installer. On the other hand, according to the configuration of the present embodiment, even if a force that pushes the fish reef 1 from the side acts on the fish reef 1, the support portion 20 and the side wall portion 51 are caught by the base 100, and the relative movement of the fish reef 1 with respect to the seabed 2 is restricted. Thereby, it is possible to suppress the displacement of the installation position of the fish reef 1. Further, even if a force that causes the fish reef 1 to topple, such as a sea current, is applied to the fish reef 1, the toppling of the fish reef 1 can be suppressed by the same action as described above.

[0055] In addition, in the present embodiment, since the upper wall portion 52 is composed of a plurality of upper wall pipe members 520, as shown in FIG. 3B, the cross-sectional shape of the lower surface 52a of the upper wall of the upper wall portion 52 has a wave shape. In this way, it is possible to ensure a larger contact area between the lower surface 52a of the upper wall and the sediment existing in the internal space IS, compared with the case where the upper wall portion 52 is configured such that the cross-sectional shape of the lower surface 52a of the upper wall has, for example, a horizontal planar shape. That is, it is possible to ensure a larger contact area between the lower surface 52a of the upper wall and the upper surface 100a of the base 100. As a result, the relative movement (sliding) of the lower surface 52a of the upper wall with respect to the upper surface 100a of the base is suppressed. As a result, the stability of the fish reef 1 is further improved. In particular, as shown in FIG. 3B, in the present embodiment, each arc portion of the lower surface 52a of the upper wall is in close contact with the sediment, and the base 100 and the lower end portion 50 of the frame body are in a state of being meshed with each other in a comb shape, so that the displacement and toppling of the fish reef 1 are more reliably suppressed.

[0056] In addition, in the present embodiment, since at least one end of at least one of the plurality of upper wall pipe members 520 in the axial direction (here, the second direction) is open, it is possible to allow marine organisms to inhabit the inside of the upper wall pipe member 520. That is, it is possible to use the space inside the upper wall pipe member 520 as a part of the fish reef 1.

[0057] In addition, in the present embodiment, the used oil well pipe is reused as the upper wall pipe member 520. Further, in the present embodiment, used oil well pipes are also reused for the ceiling wall pipe member 320, the upper end peripheral pipe member 340, the intermediate wall pipe member 420, the intermediate peripheral pipe member 440, the upper wall pipe member 520, and the lower end peripheral pipe member 540. According to this configuration, it is possible to effectively utilize the used oil well pipes generated as waste materials when disassembling a subsea oil well or the like.

[0058] In addition, in the present embodiment, since the first hole portion 521H formed in the wall portion 520W of the upper wall pipe member 520 is used as a part of the water outflow portion 56, that is, the third outflow portion 563, the water existing in the internal space IS can be more reliably caused to flow out to the external space OS.

[0059] Furthermore, according to the configuration according to the present embodiment, it becomes possible to reuse a used oil well pipe in which holes are formed in the wall portion. Specifically, in the above-described subsea oil well, crude oil may ooze out from around the oil well pipe driven into the seabed. Therefore, in order to take in the oozed crude oil into the oil well pipe, a plurality of holes may be formed in the oil well pipe. Specifically, a plurality of holes for taking in crude oil while suppressing the intrusion of subsea sediment into the inside of the oil well pipe may be formed in the oil well pipe. And according to the configuration according to the present embodiment, since the oil well pipe in which such a plurality of holes are formed is reused as the upper wall pipe member 520, it is possible to effectively utilize the used oil well pipe in which a plurality of holes are formed.

[0060] Furthermore, according to the configuration according to the present embodiment, since the first hole portion 521H and the second hole portion 522H are formed in the wall portion 520W, when the fish reef 1 is thrown into the sea in the throwing step, the air in the internal space IS can be exhausted through these holes. That is, the air in the internal space IS can be released as bubbles. As a result, it is possible to suppress the displacement of the installation position of the fish reef 1 on the seabed due to the influence of the air existing in the internal space IS.

[0061] [Modification Example] The above describes the fish reef 1 according to an embodiment of the present invention. Note that the present invention is not limited to the above form. In the present invention, the following modified embodiments are possible.

[0062] (1) The present invention can also be applied to fish reefs for underwater organisms other than squids. Hereinafter, it will be described with reference to FIGS. 5 and 6. FIG. 5 is a perspective view showing an example of a schematic configuration of the fish reef according to this modification. FIG. 6 is a perspective view showing another example of a schematic configuration of the fish reef according to this modification. The present invention may be applied to, for example, a fish reef 101 as shown in FIG. 5. The fish reef 101 shown in FIG. 5 is for forming an environment suitable for the habitation of crustaceans such as lobsters and has a basket-like outer shape capable of accommodating a plurality of conglomerates inside. Alternatively, the present invention may be applied to a fish reef 201 as shown in FIG. 6. The fish reef 201 shown in FIG. 6 has a potted-plant-like outer shape so as to be able to form an environment suitable for the growth of seaweeds such as eelgrass. In addition, the present invention is applicable to fish reefs having various shapes.

[0063] (2) In the previous embodiment, an example in which the upper wall portion 52 is composed of a plurality of upper wall pipe members 520 has been described, but the configuration of the upper wall portion is not limited to this. Hereinafter, it will be described with reference to FIGS. 7 and 8. FIG. 7 is an enlarged cross-sectional view showing an example of the configuration of the upper wall portion according to this modification. FIG. 8 is an enlarged cross-sectional view showing another example of the configuration of the upper wall portion according to this modification. As shown in FIG. 7, the upper wall portion 52S according to this modification includes, for example, a horizontal planar lower surface 52s of the upper wall and is composed of a plate-like member fixed to each support member 21 by a method such as welding. When such an upper wall portion 52S is adopted, the water in the internal space IS flows out along the path shown by the arrow A4. From the viewpoint of ensuring a larger contact area between the lower surface of the upper wall portion and the upper surface 100a of the base, it is preferable that the cross-sectional shape of the lower surface has an uneven shape like the upper wall portion 52 according to the previous embodiment.

[0064] Also, as shown in FIG. 8, the upper wall portion 52T according to still another example includes a serrated lower surface 52t of the upper wall, and is constituted by a plate-like member fixed to each support member 21 by a method such as welding. When such an upper wall portion 52T is adopted, the water in the internal space IS flows out along the path shown by arrow A5. In addition, the configuration of the upper wall portion according to the present invention can be appropriately changed as long as it does not deviate from the gist of the present invention.

[0065] (3) In the previous embodiment, the example in which the upper wall portion 52 has a plurality of upper wall pipe members 520 arranged in close contact with each other in the first direction has been described. However, the arrangement mode of the plurality of upper wall pipe members 520 is not limited to this. For example, the plurality of upper wall pipe members 520 may be arranged at intervals in the first direction. In this way, a gap is formed between the plurality of upper wall pipe members 520. And the said gap may be utilized as the water outflow part 56. However, from the viewpoint of retaining the earth and sand in the internal space IS as much as possible, it is preferable that the plurality of upper wall pipe members 520 are arranged in close contact with each other as in the previous embodiment.

[0066] (4) In the previous embodiment, the example in which the water outflow part 56 includes the first outflow part 561, the second outflow part 562, and the third outflow part 563 (the first hole part 521H) has been described. However, the configuration of the water outflow part 56 can be appropriately changed. For example, the water outflow part 56 may not include the first outflow part 561 and the second outflow part 562. That is, the water outflow part 56 may be constituted by the third outflow part 563 (the first hole part 521H). Or the water outflow part 56 may be constituted by the first outflow part 561 and the second outflow part 562. Or the water outflow part 56 may be constituted by the first outflow part 561 or the second outflow part 562.

[0067] (5) In the previous embodiment, an example in which both ends of all the upper wall pipe members 520 among the plurality of upper wall pipe members 520 are open in the second direction has been described. However, the configuration of the plurality of upper wall pipe members 520 is not limited to this. For example, both ends of some of the plurality of upper wall pipe members 520 in the second direction may be open, and both ends of the remaining upper wall pipe members 520 among the plurality of upper wall pipe members 520 in the second direction may be closed. Alternatively, only one end of all the upper wall pipe members 520 in the second direction may be open, and the other end in the second direction may be closed.

[0068] (6) In the previous embodiment, the first hole 521H and the second hole 522H that penetrate the wall portion 520W of the upper wall pipe member 520 in the radial direction have been described. However, the configurations of the first hole 521H and the second hole 522H are not limited to this. For example, the first hole 521H and the second hole 522H may penetrate the wall portion 520W in a direction inclined with respect to the radial direction.

[0069] (7) The opening areas of the first outflow portion 561, the second outflow portion 562, and the third outflow portion 563 can be appropriately changed. For example, the opening area of the second outflow portion 562 can be adjusted by changing the number of upper wall pipe members 520 that make up the upper wall portion 52. This will be described below with reference to FIG. 9. FIG. 9 is a perspective view showing a schematic configuration of the fish reef 301 according to this modification. In the fish reef 301 shown in FIG. 9, compared with the fish reef 1 in FIG. 1, the number of upper wall pipe members 520 has increased by one. By doing so, the opening area of the second outflow portion 562 can be made smaller compared to the opening area of the second outflow portion 562 of the fish reef 1 in FIG. 1. Thereby, it is possible to more reliably suppress the outflow of sediment from the internal space IS.

Explanation of Reference Numerals

[0070] 1: Fish reef 2: Seabed (an example of the water bottom) 10: Frame body 50: Lower end portion of the frame body 51: Side wall portion 52: Upper wall portion 52a: Lower surface of the upper wall 56: Water outflow part 100: Pedestal 100a: Upper surface of the pedestal 511: First pair of side wall members 512: Second pair of side wall members 520: Upper wall pipe member (an example of a pipe member) 520W: Wall part 521H: First hole part (an example of a hole part) 522H: Second hole part 561: First outflow part 562: Second outflow part 563: Third outflow part IS: Internal space OS: External space

Claims

1. A fish reef installed on the seabed, comprising a frame body having a lower end portion of the frame body, wherein the lower end portion of the frame body has a side wall portion defining an internal space capable of receiving the sediment on the seabed from below, an upper wall portion disposed above the internal space so as to hold down the sediment flowing into the internal space, and a water outflow portion communicating the internal space with the outside of the internal space so as to allow the water existing in the internal space to flow out to the outside of the internal space, the fish reef.

2. The lower end portion of the frame body includes a plurality of pipe members arranged in the horizontal direction, and the upper wall portion is constituted by the lower surface portions of the plurality of pipe members. The fish reef according to Claim 1.

3. At least one end in the axial direction of at least one of the plurality of pipe members is open. The fish reef according to Claim 1 or 2.

4. Each of the plurality of pipe members is constituted by a used oil well pipe. The fish reef according to Claim 3.

5. Holes penetrating the wall portion are formed in the wall portion of the plurality of pipe members, and the water outflow portion is constituted by the holes. The fish reef according to Claim 4.

6. A method for installing a fish reef, wherein a fish reef having an internal space formed in the lower end portion is submerged on the seabed to allow the sediment on the seabed to flow into the internal space, and at least a part of the water in the internal space is allowed to flow out to the outside of the internal space through a water outflow portion that communicates the internal space with the outside of the internal space so as to allow the water existing in the internal space to flow out to the outside of the internal space, thereby forming a base by the sediment in the internal space. A method for installing a fish reef.

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