Floating body structure

Abstract

To suppress fatigue in a floating body due to fluid force acting on a sacrificial anode.SOLUTION: A sacrificial anode 26 is stored in a storage unit 24 which is a recess indented from a bottom surface 211 of a floating body 21 toward inside of the floating body 21 below a water line, and is connected to a corrosion protection unit. The sacrificial anode 26 has greater ionization tendency than the corrosion protection unit. A cover unit 25 is arranged in a lower opening 244 of the storage unit 24 on the bottom surface 211 of the floating body 21 and closes the lower opening 244. Two communication ports (that is a first communication port 251 and a second communication port 252) communicating the storage space 240 with an outside space 90 are provided on a boundary surface between the storage space 240 formed by the storage unit 24 and the cover unit 25 and the outside space 90 which is a space surrounding the floating body 21. Thus, fatigue of the floating body 21 due to fluid force acting on the sacrificial anode 26 can be suppressed.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a floating structure. [Background technology]

[0002] Conventionally, in marine structures, coastal piers, river bridge piers, etc., cathodic protection is carried out to prevent corrosion of the steel material by attaching a sacrificial anode made of a metal that has a greater ionization tendency than the steel material to be protected to the surface of the steel material.

[0003] For example, the corrosion-resistant structure of Patent Document 1 discloses a technique for bonding a rectangular parallelepiped magnesium plate to a steel surface with a conductive adhesive. This corrosion-resistant structure proposes covering the surface of the magnesium plate and the surrounding steel surface with a gauze-like polyester fiber cloth impregnated with magnesium hydroxide, and further covering the gauze-like fiber cloth with a waterproof cover, thereby bringing gel-like magnesium hydroxide into contact with the steel surface around the magnesium plate and forming an environment in which the passivity of iron can be maintained. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-55147 Summary of the Invention [Problem to be solved by the invention]

[0005] Meanwhile, marine structures such as buoys and floating fish reefs that are moored offshore are subject to relatively large hydrodynamic forces due to waves, tides, and the like. These hydrodynamic forces also act on the sacrificial anodes fixed to the surface of the marine structures, and bending stresses and the like are continuously generated in the sacrificial anodes and in the parts of the marine structures near the sacrificial anodes. In addition, Karman vortices are generated by the water currents around the sacrificial anodes, and excitation forces due to these Karman vortices may be generated in the parts of the marine structures near the sacrificial anodes. As a result, the sacrificial anodes may fall off the marine structures, or damage such as cracks due to fatigue may occur in the parts of the marine structures near the sacrificial anodes.

[0006] The present invention has been made in consideration of the above problems, and has as its main object to suppress fatigue of the floating body caused by hydrodynamic forces acting on the sacrificial anodes. [Means for solving the problem]

[0007] A first aspect of the present invention is a floating structure comprising a floating body, a sacrificial anode accommodated in a storage section which is a recess recessed from the outer surface of the floating body toward the inside of the floating body below the waterline and connected to a part to be protected from corrosion and having a higher ionization tendency than the part to be protected from corrosion, and a cover section which is disposed at an opening of the storage section on the outer surface of the floating body and closes the opening. Two communication ports which communicate the storage space with the external space are provided at the boundary surface between a storage space formed by the storage section and the cover section and an external space which is the space around the floating body.

[0008] A second aspect of the present invention is the floating structure of the first aspect, wherein the two communication ports include a first communication port and a second communication port having an area larger than that of the first communication port.

[0009] A third aspect of the present invention is the floating structure of the second aspect, wherein the first communication port is located upstream of the second communication port with respect to a steady water flow in the installation water area.

[0010] A fourth aspect of the present invention is a floating structure of the second aspect (which may be either the second or third aspect), further comprising a straightening convex portion protruding from the cover portion toward the opposite side to the accommodation space and surrounding the second communication port.

[0011] A fifth aspect of the present invention is the floating structure of any one of the first to fourth aspects, wherein the shape of the storage section as viewed along a direction perpendicular to the cover section is long in one direction, and the two communication ports are disposed at both ends in the one direction.

[0012] A sixth aspect of the present invention is a floating structure of any one of aspects 1 to 4 (or any one of aspects 1 to 5), wherein the surface of the cover portion opposite the storage space is positioned on the same plane as the outer surface of the floating body surrounding the storage portion.

[0013] Aspect 7 of the present invention is a floating structure of any one of aspects 1 to 4 (or any one of aspects 1 to 6), wherein the outer surface of the floating body on which the accommodation section is provided is the bottom surface of the floating body.

[0014] Aspect 8 of the present invention is the floating structure of aspect 7, further comprising a plurality of sacrificial anodes including the sacrificial anode, and a plurality of cover parts including the cover part. The floating body is columnar about a central axis extending in the vertical direction. A plurality of accommodation parts including the accommodation part are provided on the bottom surface of the floating body. Each of the plurality of accommodation parts is groove-shaped extending in a radial direction about the central axis. The plurality of sacrificial anodes are respectively accommodated in the plurality of accommodation parts. Each of the plurality of cover parts is disposed in an opening of the plurality of accommodation parts on the bottom surface of the floating body to close the opening of the plurality of accommodation parts. Two communication ports communicating each of the accommodation spaces with the external space are provided on the boundary surface between each accommodation space formed by each accommodation part and each cover part and the external space.

[0015] A ninth aspect of the present invention is a floating structure according to any one of aspects 1 to 4 (or any one of aspects 1 to 6), wherein the outer surface of the floating body on which the accommodation section is provided is a side surface of the floating body. The accommodation section is a groove portion extending upward from the bottom surface of the floating body. One of the two communication ports is an opening of the groove portion in the bottom surface of the floating body.

[0016] A tenth aspect of the present invention is the floating structure of the ninth aspect, further comprising a plurality of sacrificial anodes including the sacrificial anode, and a plurality of cover parts including the cover part. The floating body is columnar about a central axis extending in the vertical direction. A plurality of accommodation parts including the accommodation part are provided on the side surface of the floating body. Each of the plurality of accommodation parts is a groove part extending upward from the bottom surface of the floating body. The plurality of sacrificial anodes are respectively accommodated in the plurality of accommodation parts. Each of the plurality of cover parts is disposed at an opening of the plurality of accommodation parts on the side surface of the floating body to close the opening of the plurality of accommodation parts. Two communication ports communicating each of the accommodation spaces with the external space are provided on the boundary surface between each accommodation space formed by each accommodation part and each cover part and the external space. One of the two communication ports of each accommodation space is an opening of each accommodation part on the bottom surface of the floating body. Effect of the Invention

[0017] In the present invention, fatigue of the floating body caused by hydrodynamic forces acting on the sacrificial anode can be suppressed. [Brief description of the drawings]

[0018] [Figure 1] FIG. 1 is a side view showing a configuration of a mooring system equipped with a floating structure according to a first embodiment. [Diagram 2] FIG. [Diagram 3] FIG. 2 is a bottom view showing a portion of the floating structure. [Figure 4] FIG. 2 is a vertical cross-sectional view showing a part of the floating structure. [Diagram 5] FIG. 2 is a bottom view showing a portion of the floating structure. [Figure 6] FIG. 2 is a vertical cross-sectional view showing a part of the floating structure. [Figure 7] FIG. 2 is a bottom view showing a portion of the floating structure. [Figure 8] FIG. 2 is a bottom view showing a portion of the floating structure. [Figure 9] FIG. 11 is a side view showing a part of a floating structure according to a second embodiment. [Figure 10] FIG. 2 is a bottom view showing a portion of the floating structure. [Figure 11] FIG. 2 is a side view showing a part of the floating structure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] 1 is a side view showing the configuration of a mooring system 1 including a floating structure 2 according to a first embodiment of the present invention. The mooring system 1 includes a floating structure 2, a mooring base 3, and a mooring line 4. The mooring system 1 is a system for mooring the floating structure 2, which floats on a water surface 91, to the water bottom 92 by the mooring line 4.

[0020] The floating structure 2 is a structure that floats on a water surface 91 while being spaced above a water bottom 92. When the floating structure 2 is installed on the sea, the water surface 91 and the water bottom 92 are the sea surface and the sea bottom, respectively. The floating structure 2 is, for example, an observation buoy that is moored in a specified installation water area (i.e., installation sea area) and observes waves, tsunamis, etc. using a GPS (Global Positioning System). The floating structure 2 is, for example, a substantially cylindrical or cylindrical structure that is substantially circular in a plan view.

[0021] The mooring base 3 is, for example, a sinker (i.e., a weight) or an anchor (i.e., an anchor having holding power) sunk in the water bottom 92. Alternatively, the mooring base 3 may be a fixed structure that is installed in advance on the water bottom 92. The mooring base 3 does not necessarily have to be directly fixed to the water bottom 92, and may be, for example, an object that is indirectly fixed to the water bottom 92 in the water via another structure fixed to the water bottom 92.

[0022] The mooring line 4 is a substantially linear member that connects the floating structure 2 and the mooring base 3. The mooring line 4 is, for example, a mooring rope, a mooring chain, or a mooring chain and a mooring rope connected together. The mooring rope is, for example, a rope made of synthetic fiber or a metal including wire. In FIG. 1, the mooring line 4 is shown as a line for convenience of illustration.

[0023] In the example shown in Fig. 1, the floating structure 2 is moored at one point to the mooring base 3 by one mooring line 4. The floating structure 2 may be moored at multiple points. In the example shown in Fig. 1, the mooring point to which the upper end of the mooring line 4 is connected on the floating structure 2 is located underwater (i.e., below the water surface 91). The mooring point may be located at approximately the same position in the vertical direction as the water surface 91, or above the water surface 91 (i.e., in the air).

[0024] The floating structure 2 includes a floating body 21, a substructure 22 provided at the bottom of the floating body 21, and a superstructure 23 provided at the top of the floating body 21. The floating body 21 is the main body of the floating structure 2, and floats on the water surface 91 and penetrates the water surface 91. The floating body 21 is, for example, a substantially columnar or cylindrical structure centered on a central axis J1 extending in the vertical direction. In the example shown in FIG. 1, the floating body 21 is a substantially cylindrical part centered on the central axis J1. The water surface 91 is, for example, located at substantially the center of the floating body 21 in the vertical direction. In other words, the waterline of the floating structure 2 is, for example, located at substantially the center of the floating body 21 in the vertical direction.

[0025] The floating body main body 21 is a structure including metal members formed from metal. The metal is one or more of elemental metals, alloys, and metal compounds having electrical conductivity such as metal oxides. The floating body main body 21 is, for example, a steel structure whose main members are made of steel materials (i.e., iron and steel materials). The above-mentioned metal members included in the floating body main body 21 are parts to be protected from corrosion, in which corrosion is prevented or suppressed by cathodic protection using a sacrificial anode (also called a galvanic anode or cathodic anode) described later. In this embodiment, substantially the entire floating body main body 21 is made of steel materials, and the steel materials are the parts to be protected from corrosion.

[0026] The lower structure 22 is a structure extending downward from the center of the bottom surface 211, which is a part of the outer surface of the floating body main body 21. The lower structure 22 is, for example, a substantially cylindrical part centered on the central axis J1. The entire lower structure 22 is located below the water surface 91 (i.e., underwater). The lower structure 22 is formed, for example, from the metal described above, and is a part of the above-mentioned corrosion-protected part. In this embodiment, the lower structure 22 is also substantially entirely formed from steel. The above-mentioned mooring line 4 is connected to the lower end of the lower structure 22. Note that, in the floating structure 2, the part to which the mooring line 4 is connected may be changed in various ways.

[0027] The superstructure 23 is various devices and equipment etc. that are provided according to the purpose of use of the floating structure 2. As described above, when the floating structure 2 is used as an observation buoy for observing waves etc., the superstructure 23 includes, for example, a GPS receiver for acquiring three-dimensional movements of the floating structure 2. Based on the movements of the floating structure 2 acquired by the GPS receiver, fluctuations in the water surface 91 (for example, waves, tides, tsunamis etc.) are obtained. The superstructure 23 may include, for example, a solar panel for supplying power to the GPS receiver etc.

[0028] In the example shown in Fig. 1, the bottom surface 211 of the floating body main body 21 is an inclined surface that slopes upward as it moves outward in a radial direction (hereinafter simply referred to as "radial direction") about the central axis J1. In other words, the bottom surface 211 of the floating body main body 21 protrudes downward as it moves radially inward from the lower end of the substantially cylindrical side surface 212 of the floating body main body 21. The bottom surface 211 of the floating body main body 21 is located below the water surface 91 (i.e., underwater) over substantially the entire surface.

[0029] FIG. 2 is a bottom view of the floating structure 2. FIG. 3 is an enlarged view of a portion of the bottom surface of the floating structure 2. FIG. 4 is an enlarged longitudinal sectional view of a portion of the floating structure 2. In the floating structure 2, a plurality of accommodation sections 24 are provided on the bottom surface 211 of the floating body main body 21. Each of the plurality of accommodation sections 24 is a recess recessed upward from the bottom surface 211 of the floating body main body 21 (i.e., toward the inside of the floating body main body 21). In the example shown in FIG. 2, three accommodation sections 24 are arranged at approximately equal angular intervals in the circumferential direction (hereinafter, simply referred to as the "circumferential direction") about the central axis J1. The three accommodation sections 24 are arranged radially outwardly spaced from the lower structure 22. The radial positions of the three accommodation sections 24 are approximately the same.

[0030] The shapes of the plurality of storage sections 24 are substantially the same as each other. In the example shown in FIG. 2 to FIG. 4, each storage section 24 is a substantially groove-shaped recess (i.e., a groove) extending along the radial direction. The shape of the storage section 24 in the bottom view is a substantially rectangular strip shape that is long in the radial direction and short in the circumferential direction. The radial length of the storage section 24 in the bottom view is, for example, 1% to 20% of the diameter of the bottom surface 211 of the floating body main body 21 in the bottom view, and preferably 3% to 10%. The radial length of the storage section 24 in the bottom view is, for example, 2 to 10 times, and preferably 4 to 7 times, the circumferential width of the storage section 24 in the bottom view. The vertical height of the storage section 24 is, for example, substantially the same as the circumferential width of the storage section 24 in the bottom view.

[0031] The accommodation section 24 is formed by a pair of side walls 241 extending approximately parallel to the radial direction, a pair of side walls 242 extending approximately parallel to the circumferential direction, and an upper surface 243 covering and closing the upper side of the space surrounded by the pair of side walls 241 and the pair of side walls 242. The side walls 241 and the side walls 242 are, for example, approximately flat plate-shaped members that are approximately perpendicular to the bottom surface 211 of the floating body main body 21. The upper surface 243 is, for example, an approximately flat plate-shaped member that is approximately parallel to the bottom surface 211 of the floating body main body 21, and is joined to the upper edges of the pair of side walls 241 and the pair of side walls 242. That is, the accommodation section 24 forms a space that is approximately rectangular parallelepiped-shaped. Each side wall 241, each side wall 242, and the upper surface 243 of the accommodation section 24 are formed of the above-mentioned metal and have electrical conductivity. Each side wall 241, each side wall 242 and the upper surface 243 of the accommodation section 24 are formed, for example, from the same steel material as the bottom surface 211 of the floating body main body 21. The shape of the accommodation section 24 may be changed in various ways. For example, the shape of the accommodation section 24 in the bottom view is not necessarily limited to a substantially rectangular shape, and may be, for example, a substantially circular or substantially elliptical shape. In this case, the space formed by the accommodation section 24 is, for example, a substantially cylindrical or substantially elliptical cylindrical shape.

[0032] The accommodation section 24 opens downward. An opening at the lower end of the accommodation section 24 (hereinafter, also referred to as a "lower opening 244") is formed at approximately the same position in the up-down direction as the bottom surface 211 of the floating body body 21 by connecting the lower end edges of the pair of side walls 241 and the pair of side walls 242 to the bottom surface 211 of the floating body body 21. In the example shown in FIG. 4, the lower opening 244 is an inclined opening that faces upward as it faces radially outward. Since the accommodation section 24 is located underwater (i.e., below the waterline of the floating structure 2), seawater around the floating structure 2 flows into the interior of the accommodation section 24 through the lower opening 244. Note that since the accommodation section 24 is fixed to the bottom surface 211 of the floating body body 21 in a watertight manner, seawater filling the interior of the accommodation section 24 does not flow into the space inside the accommodation section 24 of the floating body body 21.

[0033] A plurality of sacrificial anodes 26 used for cathodic protection of the floating body 21 are accommodated in the plurality of accommodation sections 24, respectively. In the example shown in FIG. 2, three sacrificial anodes 26 having substantially the same shape are arranged in the three accommodation sections 24, respectively. The sacrificial anodes 26 are, for example, substantially rectangular parallelepiped (i.e., substantially block-shaped) members. The sacrificial anodes 26 are fixed to the upper surface 243 of the accommodation section 24, and do not protrude downward from the lower opening 244. In other words, the entire sacrificial anodes 26 are accommodated in the accommodation section 24. The sacrificial anodes 26 are fixed, for example, by bolting to a conductive pedestal or the like provided on the upper surface 243 of the accommodation section 24. Alternatively, the sacrificial anodes 26 may be directly fixed to the upper surface 243 of the accommodation section 24. The sacrificial anodes 26 are electrically connected to substantially the entire floating body 21, which is the above-mentioned part to be protected from corrosion, via the upper surface 243 of the accommodation section 24.

[0034] The electric protection of the float body 21 using the sacrificial anode 26 is performed by a cathodic protection method using a galvanic anode method that does not use an external power source. The sacrificial anode 26 is formed of a metal having a higher ionization tendency than the above-mentioned part to be protected from corrosion (i.e., the metal member of the float body 21). As described above, the metal forming the sacrificial anode 26 is one or more of a simple metal, an alloy, and a metal compound having electrical conductivity such as a metal oxide. When the part to be protected from corrosion of the float body 21 is formed of a plurality of types of metals, it is preferable that the ionization tendency of the sacrificial anode 26 is higher than the ionization tendency of the metal most commonly used in the part to be protected from corrosion (i.e., the metal that is the main material of the float body 21). It is even more preferable that the sacrificial anode 26 has a higher ionization tendency than the metal having the highest ionization tendency among the plurality of types of metals that constitute the part to be protected from corrosion of the float body 21.

[0035] In this embodiment, as described above, substantially the entire float body 21 is a part to be protected from corrosion, which is made of steel, and the sacrificial anode 26 is made of a metal (e.g., an aluminum alloy) that has a higher ionization tendency than steel. As described above, the sacrificial anode 26 is electrically connected in water to the float body 21, which is a part to be protected from corrosion. Since the sacrificial anode 26 has a lower electric potential than the float body 21, it ionizes and dissolves in water. At this time, electrons are supplied from the sacrificial anode 26 to the float body 21, and a reduction reaction occurs in the float body 21, thereby preventing corrosion of the float body 21 (i.e., the part to be protected from corrosion).

[0036] The lower opening 244 of each accommodation section 24 on the bottom surface 211 of the floating body main body 21 is closed by a cover section 25. The cover section 25 is, for example, a substantially flat plate-shaped member. The three cover sections 25 illustrated in FIG. 2 have substantially the same shape. The cover section 25 is disposed at the lower opening 244 of the accommodation section 24 and fixed to a portion around the accommodation section 24 on the bottom surface 211 of the floating body main body 21. The cover section 25 may be detachably attached to the floating body main body 21 by bolting or the like, or may be fixed by welding or the like. The cover section 25 may be formed of, for example, the above-mentioned metal, or may be formed of a material other than metal, such as glass fiber.

[0037] The above-mentioned sacrificial anode 26 is disposed in the accommodation space 240 formed by the accommodation section 24 and the cover section 25. The accommodation space 240 is a space inside the accommodation section 24 with the lower opening 244 covered by the cover section 25. In other words, the accommodation space 240 is a space surrounded by a pair of side walls 241, a pair of side walls 242 and an upper surface 243 of the accommodation section 24, and the cover section 25 that closes the lower opening 244 of the accommodation section 24. The entire sacrificial anode 26 is disposed in the accommodation space 240. The lower surface 253, which is the outer surface of the cover section 25 (i.e., the surface of the cover section 25 opposite to the accommodation space 240), is located on approximately the same plane as the outer surface of the floating body main body 21 around the accommodation section 24 (i.e., the bottom surface 211). In other words, the lower surface 253 of the cover section 25 is approximately flush with the bottom surface 211 of the floating body main body 21 around the accommodation section 24. Furthermore, even if there are some unevenness on the underside 253 of the cover portion 25, so long as the underside 253 of the cover portion 25 and the bottom surface 211 of the floating body main body 21 around the storage portion 24 form a single smoothly continuous surface, it can be said that the underside 253 of the cover portion 25 and the bottom surface 211 of the floating body main body 21 are located on approximately the same plane.

[0038] The cover part 25 is provided with a first communication port 251 and a second communication port 252. The first communication port 251 and the second communication port 252 are through holes that penetrate the cover part 25 in the up-down direction. The above-mentioned accommodation space 240 communicates with the external space 90, which is the space around the floating body main body 21, through the first communication port 251 and the second communication port 252. In other words, the first communication port 251 and the second communication port 252 are openings formed on the boundary surface between the accommodation space 240 and the external space 90. The external space 90 means the entire space spreading around the floating structure 2. The external space 90 does not include a space partitioned by the configuration of the floating body structure 2, such as the inside of the floating body main body 21, nor does it include the above-mentioned accommodation space 240. Below the water surface 91, seawater is present in the external space 90, and seawater can move between the external space 90 and the storage space 240 via the first communication port 251 and the second communication port 252.

[0039] The first communication port 251 and the second communication port 252 overlap with both ends of the accommodation section 24 extending in the radial direction in a bottom view. In other words, the shape of the accommodation section 24 seen along a direction perpendicular to the cover section 25 is long in one direction, and the first communication port 251 and the second communication port 252 are disposed at both ends in the one direction (hereinafter also referred to as the "longitudinal direction"). In the example shown in Figs. 3 and 4, no communication port other than the first communication port 251 and the second communication port 252 is provided on the boundary surface between the accommodation space 240 and the external space 90, and seawater does not move between the external space 90 and the accommodation space 240 via communication ports other than the first communication port 251 and the second communication port 252.

[0040] 3, the first communication opening 251 and the second communication opening 252 each have a substantially rectangular shape in bottom view. The first communication opening 251 and the second communication opening 252 are each provided across substantially the entire width of the storage section 24 in a direction perpendicular to the longitudinal direction in FIG. 3 (hereinafter also referred to as the "width direction"). The width of the first communication opening 251 in the width direction is substantially the same as the width of the second communication opening 252 in the width direction. Note that the shapes of the first communication opening 251 and the second communication opening 252 in bottom view are not limited to a substantially rectangular shape and may be modified in various ways.

[0041] When viewed in a direction perpendicular to the cover portion 25, the area of ​​the second communication port 252 is larger than the area of ​​the first communication port 251. The area of ​​the second communication port 252 when viewed in a direction perpendicular to the cover portion 25 (hereinafter also simply referred to as "area") is, for example, 1.5 times or more, and preferably 2 times or more, the area of ​​the first communication port 251. Furthermore, the area of ​​the second communication port 252 is, for example, 10 times or less, and preferably 5 times or less, the area of ​​the first communication port 251.

[0042] The floating structure 2 swings up and down due to the influence of waves and the like. During this vertical swing, when the floating structure 2 moves downward relative to the water surface 91, a water current from below to above acts on the bottom surface 211 of the floating body 21. As described above, the area of ​​the first communication port 251 is smaller than the area of ​​the second communication port 252, and the accommodation space 240 is filled with seawater at approximately the same pressure as the external space 90. Therefore, according to Bernoulli's theorem, the flow velocity of seawater passing through the first communication port 251 is greater than the flow velocity of seawater passing through the second communication port 252.

[0043] Therefore, the water flowing from below toward the bottom surface 211 of the floating body main body 21 flows from the external space 90 into the accommodation space 240 through the first communication port 251, and flows out from the accommodation space 240 to the external space 90 through the second communication port 252. This generates a flow of seawater from the first communication port 251 to the second communication port 252 in the accommodation space 240, promoting the exchange of seawater in the accommodation space 240. Note that the flow of seawater from the first communication port 251 to the second communication port 252 in the accommodation space 240 is also generated by fluctuations in water pressure in the vicinity of the cover part 25 due to waves and the like, and promotes the exchange of seawater in the accommodation space 240 in a manner substantially similar to that described above.

[0044] In this way, by promoting the exchange of seawater in the accommodation space 240, the concentration of metal ions eluted from the sacrificial anode 26 into the seawater is prevented from increasing excessively in the accommodation space 240 (i.e., in the vicinity of the sacrificial anode 26), and the inhibition of the elution of metal ions from the sacrificial anode 26 due to the increase in concentration is also prevented. As a result, cathodic protection of the floating body main body 21 is performed favorably.

[0045] In the cover part 25 illustrated in FIG. 3 and FIG. 4, the first communication port 251 is disposed near the left end (i.e., the outer end in the radial direction) of the accommodation part 24, and the second communication port 252 is disposed near the right end (i.e., the inner end in the radial direction) of the accommodation part 24. In the example illustrated in FIG. 1, the steady water flow (e.g., the tidal current in the installation sea area) in the installation water area of ​​the floating structure 2 is from the left side to the right side in the figure, so that the first communication port 251 in FIG. 3 and FIG. 4 is located upstream of the second communication port 252 with respect to the steady water flow. Therefore, the steady water flow is more likely to flow into the first communication port 251 than into the second communication port 252, and the flow of seawater from the first communication port 251 to the second communication port 252 in the accommodation space 240 described above is increased. As a result, the exchange of seawater in the accommodation space 240 is further promoted, and the cathodic protection of the floating body main body 21 is more suitably performed.

[0046] As described above, the floating structure 2 includes the floating body 21, the sacrificial anode 26, and the cover portion 25. The sacrificial anode 26 is accommodated in the accommodation portion 24, which is a recess that is recessed from the outer surface of the floating body 21 (in the above example, the bottom surface 211) toward the inside of the floating body 21 below the waterline, and is connected to the part to be protected from corrosion (in the above example, substantially the entire floating body 21). The sacrificial anode 26 has a higher ionization tendency than the part to be protected from corrosion. The cover portion 25 is disposed at an opening (in the above example, the lower opening 244) of the accommodation portion 24 on the outer surface of the floating body 21 to close the opening. Two communication ports (i.e., a first communication port 251 and a second communication port 252) are provided at the boundary surface between the storage space 240 formed by the storage section 24 and the cover section 25 and the external space 90, which is the space surrounding the floating body main body 21, connecting the storage space 240 and the external space 90.

[0047] In this way, by accommodating the sacrificial anode 26 in the accommodation space 240, it is possible to suppress fatigue of the floating body main body 21 caused by fluid forces acting on the sacrificial anode 26 (for example, bending stress and excitation forces due to Karman vortices). As a result, it is possible to suppress damage to the floating body main body 21. In addition, by providing two communication ports at the boundary surface between the accommodation space 240 and the external space 90 (in the above example, the cover part 25), as described above, it is possible to promote the exchange of seawater within the accommodation space 240 and suitably perform cathodic protection of the floating body main body 21.

[0048] As described above, in the floating structure 2, it is preferable that no communication openings other than the above two communication openings are provided on the boundary surface between the accommodation space 240 and the external space 90. This makes it possible to reduce the fluid force acting on the cover part 25 from the seawater flowing along the lower surface 253 of the cover part 25. As a result, it is possible to reduce fatigue of the cover part 25 and the floating body main body 21.

[0049] As described above, the two communication ports preferably include the first communication port 251 and the second communication port 252 having a larger area than the first communication port 251. This makes it possible to easily form a flow of seawater from the first communication port 251 to the second communication port 252 in the accommodation space 240 by utilizing the vertical rocking of the floating structure 2, etc. As a result, the exchange of seawater in the accommodation space 240 can be further promoted, and cathodic protection of the floating body 21 can be more suitably performed.

[0050] As described above, it is preferable that the first communication port 251 is located upstream of the second communication port 252 with respect to the steady water flow in the installation water area. This makes it possible to favorably form a flow of seawater from the first communication port 251 to the second communication port 252 in the accommodation space 240. As a result, the exchange of seawater in the accommodation space 240 can be further promoted.

[0051] As described above, the shape of the storage section 24 when viewed along a direction perpendicular to the cover section 25 is long in one direction, and the above-mentioned two communication ports (i.e., the first communication port 251 and the second communication port 252) are disposed at both ends in the one direction. This makes it possible to prevent seawater from accumulating at the end of the storage space 240 in the one direction. As a result, it is possible to further promote the exchange of seawater within the storage space 240.

[0052] As described above, the surface of the cover part 25 opposite to the accommodation space 240 (the lower surface 253 in the above example) is located on the same plane as the outer surface of the floating body main body 21 around the accommodation part 24 (the bottom surface 211 in the above example). This makes it possible to reduce the fluid force acting on the cover part 25 from seawater flowing along the lower surface 253 of the cover part 25. As a result, it is possible to suppress fatigue of the cover part 25 and the floating body main body 21 caused by the fluid force.

[0053] As described above, the outer surface of the floating body 21 on which the accommodation section 24 is provided is preferably the bottom surface 211 of the floating body 21. This makes it almost unnecessary to consider positional interference between the accommodation section 24 and mooring-related equipment in the floating structure 2, and therefore improves the degree of freedom in arranging the accommodation section 24.

[0054] As described above, the floating structure 2 preferably further includes a plurality of sacrificial anodes 26 including the above-mentioned sacrificial anode 26, and a plurality of cover parts 25 including the above-mentioned cover part 25. The floating body body 21 is columnar about a central axis J1 extending in the vertical direction. In addition, a plurality of accommodation parts 24 including the above-mentioned accommodation part 24 are provided on the bottom surface 211 of the floating body body 21. Each of the plurality of accommodation parts 24 is groove-shaped extending in a radial direction about the central axis J1. The plurality of sacrificial anodes 26 are respectively accommodated in the plurality of accommodation parts 24. Each of the plurality of cover parts 25 is disposed in the openings (i.e., the lower openings 244) of the plurality of accommodation parts 24 on the bottom surface 211 of the floating body body 21 to close the openings of the plurality of accommodation parts 24. Two communication ports (i.e., a first communication port 251 and a second communication port 252) are provided at the boundary surface between each storage space 240 formed by each storage section 24 and each cover section 25 and the external space 90, connecting each storage space 240 to the external space 90.

[0055] In this way, by accommodating the multiple sacrificial anodes 26 in the multiple accommodation spaces 240, respectively, and providing two communication ports at each of the boundary surfaces, it is possible to suppress fatigue of the floating body body 21 caused by the fluid force acting on each sacrificial anode 26, and to suitably perform cathodic protection of the floating body body 21. Furthermore, by making each accommodation section 24 into a groove shape extending in the radial direction, each accommodation section 24 functions as a groove rib (also called a rib groove) provided on the bottom surface 211 of the floating body body 21. As a result, the strength of the bottom surface 211 of the floating body body 21 can be increased.

[0056] As described above, it is preferable that the multiple storage sections 24 are arranged at equal angular intervals in the circumferential direction at the same radial position, thereby making it possible to further increase the strength of the bottom surface 211 of the floating body main body 21.

[0057] In the floating structure 2, each of the plurality of accommodation sections 24 is preferably formed as a groove extending in a direction perpendicular to the radial direction (i.e., approximately in the circumferential direction) on the bottom surface 211 of the floating body main body 21. In this case, each accommodation section 24 functions as a groove rib, so that the strength of the bottom surface 211 of the floating body main body 21 can be increased.

[0058] In the floating structure 2, an additional structure for promoting the flow of seawater from the first communication port 251 to the second communication port 252 in the accommodation space 240 may be provided. For example, as shown in Figs. 5 and 6, a flow straightening protrusion 254 surrounding the periphery of the second communication port 252 may be provided. The flow straightening protrusion 254 is provided on the lower surface 253 of the cover part 25 and is a protrusion protruding downward from the cover part 25 (i.e., the opposite side to the accommodation space 240). In the example shown in Fig. 5, the flow straightening protrusion 254 surrounds the entire periphery of the second communication port 252. The height of the flow straightening protrusion 254 (i.e., the amount of protrusion from the lower surface 253 of the cover part 25) is, for example, 1 mm to 15 mm.

[0059] In this way, by further providing the straightening convex portion 254 to the floating structure 2, the seawater in the external space 90 is suppressed from flowing into the accommodation space 240 through the second communication port 252. In addition, the flow of seawater flowing out from the accommodation space 240 to the external space 90 through the second communication port 252 is straightened, so that the outflow of seawater from the accommodation space 240 through the second communication port 252 is promoted. As a result, the flow of seawater from the first communication port 251 to the second communication port 252 in the accommodation space 240 can be promoted.

[0060] Furthermore, in the floating structure 2, a straightening protrusion substantially similar to the straightening protrusion 254 may be provided on the upper surface of the cover part 25 (i.e., the surface facing the accommodation space 240) so as to surround the periphery of the first communication port 251. This promotes the inflow of seawater into the accommodation space 240 via the first communication port 251. As a result, the flow of seawater from the first communication port 251 to the second communication port 252 in the accommodation space 240 can be promoted.

[0061] Alternatively, the edge of the first communication port 251 may be tapered so as to approach the center of the first communication port 251 as it extends upward. This makes the area of ​​the first communication port 251 on the lower surface 253 of the cover part 25 larger than the area of ​​the first communication port 251 on the upper surface of the cover part 25. As a result, the inflow of seawater into the accommodation space 240 via the first communication port 251 is promoted, and the flow of seawater from the first communication port 251 to the second communication port 252 in the accommodation space 240 can be promoted.

[0062] In the floating structure 2, each of the first communication opening 251 and the second communication opening 252 may be divided into two or more regions. For example, in the example shown in FIG. 7, the second communication opening 252 is divided into two regions 255 by a partition part 256 having a substantially rectangular strip shape extending in the left-right direction in the figure. The partition part 256 is a part of the cover part 25 and is a substantially flat plate-shaped part. The region overlapping with the two regions 255 in the bottom view in the accommodation space 240 is continuous via the region overlapping with the partition part 256 in the bottom view in the accommodation space 240. In the example shown in FIG. 7, the area of ​​the second communication opening 252 is the sum of the areas of the two regions 255 and is larger than the area of ​​the first communication opening 251.

[0063] In the floating structure 2, the first communication opening 251 and the second communication opening 252 do not necessarily have to be through holes formed in the cover portion 25. For example, a notch may be provided in the outer edge of the cover portion 25 near the side wall 241 or the side wall 242 of the accommodation portion 24, and the area surrounded by the notch and the lower edge of the side wall 241 or the side wall 242 may be the first communication opening 251 or the second communication opening 252.

[0064] Alternatively, as shown in FIG. 8, instead of the cover part 25 illustrated in FIG. 3, a flat plate-like member having a length in the left-right direction (i.e., radial direction) shorter than that of the storage part 24 and having no through-holes may be attached to the lower opening 244 at the center of the left-right direction of the storage part 24 as the cover part 25a. In this case, the center of the lower opening 244 in the left-right direction is closed by the cover part 25a, and both ends of the lower opening 244 in the left-right direction are not closed and open downward. The opening provided at the left end of the lower opening 244 becomes the first communication opening 251a, and the opening provided at the right end of the lower opening 244 becomes the second communication opening 252a having an area larger than that of the first communication opening 251a. In this case, since it is not necessary to provide through-holes or the like serving as the first communication opening 251a and the second communication opening 252a in the cover part 25, the manufacturing of the floating structure 2 can be simplified.

[0065] Next, a floating structure 2b according to a second embodiment of the present invention will be described with reference to Figs. 9 and 10. Fig. 9 is a side view showing a part of the floating structure 2b. Fig. 10 is a bottom view of the floating structure 2b. In the floating structure 2b, a storage section 24b and a cover section 25b, which are different in structure from the storage section 24 and the cover section 25 shown in Figs. 2 to 4, are arranged at a position different from that of the storage section 24 and the cover section 25. The other configurations of the floating structure 2b are substantially similar to those of the floating structure 2 described above, and in the following description, the same reference numerals will be used to designate corresponding configurations. Note that Fig. 9 shows a cross section of the lower left portion of the figure.

[0066] In the floating structure 2b, the multiple accommodating sections 24b are provided on the side surface 212 of the floating body main body 21. In other words, the outer surface of the floating body main body 21 on which the multiple accommodating sections 24b are provided is the side surface 212 of the floating body main body 21. In the example shown in Fig. 10, the four accommodating sections 24b are arranged at approximately equal angular intervals in the circumferential direction around the central axis J1. The multiple accommodating sections 24b have approximately the same shape.

[0067] Each of the accommodating sections 24b is a recess recessed from the side surface 212 of the floating body main body 21 toward the inside of the floating body main body 21 (i.e., toward the radially inward direction). The accommodating sections 24b are generally groove-shaped recesses (i.e., grooves) extending generally parallel to the vertical direction and opening radially outward. The accommodating sections 24b extend from the bottom surface 211 of the floating body main body 21 to near the vertical center of the floating body main body 21. The upper end of the accommodating section 24b is located below the water surface 91 (i.e., below the waterline of the floating structure 2b). The vertical length of the accommodating section 24b is, for example, 10% to 70% of the vertical height of the floating body main body 21.

[0068] An opening of the accommodation section 24b in the side surface 212 of the floating body main body 21 (hereinafter, also referred to as "side opening 244b") is covered by the cover section 25b. The space inside the accommodation section 24b with the side opening 244b covered by the cover section 25b becomes an accommodation space 240b in which the sacrificial anode 26 is accommodated. The sacrificial anode 26 is fixed, for example, to a radially inner side surface of the accommodation section 24b. The outer surface of the cover section 25b (i.e., the surface of the cover section 25b opposite to the accommodation space 240b) is located on approximately the same plane as the outer surface of the floating body main body 21 around the accommodation section 24b (i.e., the side surface 212).

[0069] 9 and 10, the lower end of the accommodation section 24b opens on the bottom surface 211 of the floating body main body 21, and this opening serves as a first communication port 251b that communicates the accommodation space 240b with the above-mentioned external space 90. In addition, the upper edge of the cover section 25b is located lower than the upper end of the accommodation section 24b. On the side surface 212 of the floating body main body 21, the region between the upper end of the accommodation section 24b and the upper edge of the cover section 25b is an opening, and this opening serves as a second communication port 252b that communicates the accommodation space 240b with the external space 90.

[0070] The shape of the first communication port 251b in a bottom view and the shape of the second communication port 252b when viewed along a radial direction substantially perpendicular to the second communication port 252b are, for example, substantially rectangular. These shapes are not necessarily limited to being substantially rectangular and may be modified in various ways. The area of ​​the first communication port 251b in a bottom view and the area of ​​the second communication port 252b when viewed along a radial direction substantially perpendicular to the second communication port 252b may be the same, or one of them may be larger.

[0071] The entire first communication port 251b and the entire second communication port 252b are located below the water surface 91 (i.e., underwater). The floating structure 2b swings up and down due to the influence of waves and the like. During the vertical swing, when the floating structure 2b moves downward relative to the water surface 91, seawater flows from the external space 90 into the accommodation space 240b through the first communication port 251b, and the seawater in the accommodation space 240b flows out to the external space 90 through the second communication port 252b. When the floating structure 2b moves upward relative to the water surface 91, seawater flows from the external space 90 into the accommodation space 240b through the second communication port 252b, and the seawater in the accommodation space 240b flows out to the external space 90 through the first communication port 251b. This promotes the exchange of seawater in the accommodation space 240b.

[0072] As described above, the floating structure 2b includes the floating body 21, the sacrificial anode 26, and the cover portion 25b. The sacrificial anode 26 is accommodated in the accommodation portion 24b, which is a recess that is recessed from the outer surface of the floating body 21 (in the above example, the side surface 212) toward the inside of the floating body 21 below the waterline, and is connected to the part to be protected from corrosion (in the above example, substantially the entire floating body 21). The sacrificial anode 26 has a higher ionization tendency than the part to be protected from corrosion. The cover portion 25b is disposed at an opening (in the above example, the side opening 244b) of the accommodation portion 24b on the outer surface of the floating body 21 to close the opening. Two communication ports (i.e., a first communication port 251b and a second communication port 252b) are provided at the boundary surface between the storage space 240b formed by the storage portion 24b and the cover portion 25b and the external space 90, which is the space surrounding the floating body main body 21, connecting the storage space 240b and the external space 90.

[0073] In this way, by accommodating the sacrificial anode 26 in the accommodation space 240b, it is possible to suppress fatigue of the floating body main body 21 caused by fluid forces acting on the sacrificial anode 26, in substantially the same manner as the floating structure 2. As a result, it is possible to suppress damage to the floating body main body 21. In addition, by providing two communication ports at the boundary surface between the accommodation space 240b and the external space 90, it is possible to promote exchange of seawater within the accommodation space 240b and to suitably perform cathodic protection of the floating body main body 21.

[0074] As described above, in the floating structure 2b, it is preferable that no communication openings other than the above two communication openings are provided on the boundary surface between the accommodation space 240b and the external space 90. In other words, it is preferable that no openings such as through holes are provided in the cover portion 25b. This makes it possible to reduce the fluid force acting on the cover portion 25b from the seawater flowing along the outer surface of the cover portion 25b. As a result, it is possible to reduce fatigue of the cover portion 25b and the floating body main body 21.

[0075] As described above, the outer surface of the floating body 21 on which the accommodation section 24b is provided is preferably the side surface 212 of the floating body 21. The accommodation section 24b is a groove extending upward from the bottom surface 211 of the floating body 21, and one of the two communication openings (i.e., the first communication opening 251b) is preferably an opening of the groove in the bottom surface 211 of the floating body 21. In this way, by providing the accommodation section 24b on the side surface 212 of the floating body 21, it is possible to facilitate access to the sacrificial anode 26 during maintenance of the floating structure 2b, etc. Furthermore, by making the opening of the accommodation section 24b in the bottom surface 211 of the floating body 21 the first communication opening 251b, it is not necessary to provide a through hole or the like serving as the first communication opening 251b in the cover section 25b, and therefore the manufacturing of the floating structure 2b can be simplified.

[0076] The shape of the storage section 24b when viewed along a direction perpendicular to the cover section 25b is elongated in the vertical direction, and the above-mentioned two communication ports (i.e., the first communication port 251b and the second communication port 252b) are disposed at both ends of the storage section 24b in the vertical direction. This makes it possible to prevent seawater from accumulating at the ends of the storage space 240b in the vertical direction. As a result, it is possible to further promote the exchange of seawater within the storage space 240b.

[0077] The surface of the cover part 25b opposite to the accommodation space 240b (i.e., the outer surface) is located on the same plane as the outer surface of the floating body 21 around the accommodation part 24b (the side surface 212 in the above example). This makes it possible to reduce the fluid force acting on the cover part 25b from seawater flowing along the outer surface of the cover part 25b. As a result, it is possible to suppress fatigue of the cover part 25b and the floating body 21 caused by the fluid force.

[0078] As described above, the floating structure 2b preferably further includes a plurality of sacrificial anodes 26 including the above-mentioned sacrificial anode 26, and a plurality of cover parts 25b including the above-mentioned cover part 25b. The floating body 21 is columnar about a central axis J1 extending in the vertical direction. In addition, a plurality of accommodation parts 24b including the above-mentioned accommodation part 24b are provided on a side surface 212 of the floating body 21. Each of the plurality of accommodation parts 24b is a groove part extending upward from a bottom surface 211 of the floating body 21. The plurality of sacrificial anodes 26 are respectively accommodated in the plurality of accommodation parts 24b. Each of the plurality of cover parts 25b is disposed in the openings (i.e., side openings 244b) of the plurality of accommodation parts 24b on the side surface 212 of the floating body 21 to close the openings of the plurality of accommodation parts 24b. Two communication ports (i.e., a first communication port 251b and a second communication port 252b) that communicate each storage space 240b with the external space 90 are provided at the boundary surface between each storage space 240b formed by each storage section 24b and each cover section 25b. One of the two communication ports of each storage space 240b (i.e., the first communication port 251b) is an opening of each storage section 24b in the bottom surface 211 of the floating body main body 21.

[0079] In this way, by accommodating the multiple sacrificial anodes 26 in the multiple accommodation spaces 240b, respectively, and providing two communication ports at each of the boundary surfaces, it is possible to suppress fatigue of the floating body main body 21 caused by the fluid force acting on each sacrificial anode 26, and to suitably perform cathodic protection of the floating body main body 21. Furthermore, by making each accommodation section 24b into a groove shape extending in the vertical direction, each accommodation section 24b functions as a groove rib (also called a rib groove) provided on the side surface 212 of the floating body main body 21. As a result, the strength of the side surface 212 of the floating body main body 21 can be increased.

[0080] It is preferable that the multiple storage sections 24b are arranged at equal angular intervals in the circumferential direction at the same radial position, whereby the strength of the side surface 212 of the floating body main body 21 can be further increased.

[0081] In the example shown in Fig. 9, the upper end of the accommodation portion 24b is located below the water surface 91, but is not limited thereto. For example, as shown in Fig. 11, a groove portion extending upward from the bottom surface 211 of the floating body main body 21 to the upper surface of the floating body main body 21 may be the accommodation portion 24b. In this case, an opening formed by the upper edge of the cover portion 25b and the accommodation portion 24b at the same height as the upper edge of the cover portion 25b (i.e., an upper opening of the accommodation space 240b) becomes the second communication port 252b.

[0082] In this case, as in the example shown in Fig. 9, when the floating structure 2b moves downward relative to the water surface 91 during the vertical rocking of the floating structure 2b, seawater flows from the external space 90 into the accommodation space 240b through the first communication port 251b, and the seawater in the accommodation space 240b flows out to the external space 90 through the second communication port 252b. When the floating structure 2b moves upward relative to the water surface 91, seawater flows from the external space 90 into the accommodation space 240b through the second communication port 252b, and the seawater in the accommodation space 240b flows out to the external space 90 through the first communication port 251b. This promotes the exchange of seawater in the accommodation space 240b.

[0083] 9 and 11, the second communication port 252b may be disposed above the waterline of the floating structure 2b. In this case, when the floating structure 2b sways up and down, the second communication port 252b is submerged below the water surface 91, and the exchange of seawater in the accommodation space 240b is promoted.

[0084] The floating structures 2 and 2b described above can be modified in various ways.

[0085] For example, in the floating structure 2, the flow straightening protrusion 254 does not necessarily have to surround the entire periphery of the second communication port 252, and may be provided so as to surround the periphery of the second communication port 252 partially.

[0086] In the floating structure 2, the sacrificial anode 26 does not necessarily have to be fixed to the upper surface 243 of the accommodation section 24, and may be fixed to the side wall 241 or the side wall 242 of the accommodation section 24. Alternatively, when the cover section 25 is conductive, the sacrificial anode 26 may be fixed to the upper surface of the cover section 25 (i.e., the surface facing the accommodation space 240). Similarly, in the floating structure 2b, the sacrificial anode 26 does not necessarily have to be fixed to the radially inner side surface of the accommodation section 24b, and may be fixed to another position within the accommodation space 240b.

[0087] The number of the accommodation sections 24 provided in the floating structure 2 may be one or more than one. Similarly, the number of the accommodation sections 24b provided in the floating structure 2b may be one or more than two. In the floating structure 2, in addition to the accommodation section 24, the accommodation section 24b may also be provided, and the sacrificial anode 26 may be accommodated in each of the accommodation sections 24 and the accommodation section 24b.

[0088] The accommodation section 24b does not necessarily need to extend substantially parallel to the vertical direction, and may extend in a direction inclined with respect to the vertical direction on the side surface 212 of the floating body main body 21. The accommodation sections 24, 24b do not necessarily need to be groove-shaped recesses, and may be recesses having various shapes.

[0089] The cover part 25 does not necessarily have to be flush with the bottom surface 211 of the floating body main body 21, and may be convexly bulged downward from the bottom surface 211, or may be concave upward from the bottom surface 211. Similarly, the cover part 25b may be convexly bulged radially outward from the side surface 212 of the floating body main body 21, or may be concave radially inward from the side surface 212.

[0090] In the floating structure 2, the first communication port 251 and the second communication port 252 do not necessarily have to be provided at both ends in the longitudinal direction of the accommodation section 24, and may be provided at other positions. Similarly, in the floating structure 2b illustrated in Fig. 9, the first communication port 251b and the second communication port 252b do not necessarily have to be provided at both ends in the up-down direction of the accommodation section 24b, and may be provided at other positions.

[0091] 3, the first communication port 251 does not necessarily have to be located upstream of the second communication port 252 with respect to the steady water flow in the installation water area, and may be located downstream of the second communication port 252. In the floating structure 2, the area of ​​the first communication port 251 may be the same as the area of ​​the second communication port 252, or may be larger than the area of ​​the second communication port 252.

[0092] In the floating structure 2, in addition to the first communication port 251 and the second communication port 252, another communication port may be provided at the boundary surface between the accommodation space 240 and the external space 90. Similarly, in the floating structure 2b, in addition to the first communication port 251b and the second communication port 252b, another communication port may be provided at the boundary surface between the accommodation space 240b and the external space 90.

[0093] In the floating structure 2, the shapes and structures of the substructure 22 and the superstructure 23 may be modified in various ways. Also, the substructure 22 and / or the superstructure 23 may be omitted. The same applies to the floating structure 2b.

[0094] The shape of the floating body 21 is not limited to a substantially cylindrical shape centered on the central axis J1, and may be modified in various ways. For example, the floating body 21 may be a substantially polygonal prism shape centered on the central axis J1. Alternatively, the floating body 21 may be a ship-shaped, semi-submersible, or pontoon-shaped structure.

[0095] The accommodation sections 24, 24b may be provided at locations other than the bottom surface 211 and the side surface 212 of the floating body main body 21, so long as they are provided on the outer surface of the floating body main body 21 below the waterline of the floating structures 2, 2b.

[0096] The floating body 21 may contain a material other than the above-mentioned metals, and may be mainly made of the material other than the metal (e.g., concrete). For example, the floating structures 2, 2b may be caissons or the like, which are concrete structures whose surfaces are covered with steel plates. In this case, the steel plates are the above-mentioned corrosion-protected parts.

[0097] The structure of the floating structures 2, 2b may be applied to various structures other than the above-mentioned observation buoys for observing waves, etc. The floating structures 2, 2b may be, for example, buoys other than the above-mentioned observation buoys, floating fish reefs, floats for offshore wind power generation, caissons, etc.

[0098] The configurations in the above-described embodiment and each of the modified examples may be combined as appropriate as long as they are not mutually inconsistent. [Explanation of symbols]

[0099] 2,2b Floating structures 21 Floating body 24,24b Storage section 25, 25a, 25b Cover part 26 Sacrificial anode 90 Exterior Space 211 (of the floating body) bottom 212 (of the floating body) side 240,240b Containment space 244 (Lower opening of storage unit) 244b (container) side opening 251,251a,251b 1st communication port 252,252a,252b 2nd communication port 253 (Cover) Underside 254 Flow straightening protrusion J1 center axis

Claims

1. A floating structure, A floating body; a sacrificial anode that is accommodated in a receiving portion that is a recess that is recessed from the outer surface of the floating body toward the inside of the floating body below the waterline and is connected to a part to be protected from corrosion, and that has a higher ionization tendency than the part to be protected from corrosion; A cover portion is disposed at an opening of the accommodation portion on the outer surface of the floating body to close the opening; Equipped with A floating structure in which two communication ports are provided at the boundary surface between the storage space formed by the storage section and the cover section and the external space, which is the space surrounding the floating body, connecting the storage space and the external space.

2. The floating structure according to claim 1, The two communication ports are: A first communication port; A second communication port having an area larger than that of the first communication port; A floating structure comprising:

3. The floating structure according to claim 2, The first communication port is a floating structure located upstream of the second communication port with respect to the steady water flow in the installation water area.

4. The floating structure according to claim 2, The floating structure further includes a straightening protrusion protruding from the cover portion toward the opposite side to the storage space and surrounding the second communication port.

5. The floating structure according to any one of claims 1 to 4, The shape of the housing portion when viewed along a direction perpendicular to the cover portion is elongated in one direction, The two communication ports are disposed at both ends of the floating structure in the one direction.

6. The floating structure according to any one of claims 1 to 4, A floating structure in which the surface of the cover portion opposite the storage space is positioned on the same plane as the outer surface of the floating body surrounding the storage portion.

7. The floating structure according to any one of claims 1 to 4, A floating structure, wherein the outer surface of the floating body on which the accommodation section is provided is the bottom surface of the floating body.

8. The floating structure according to claim 7, A plurality of sacrificial anodes including the sacrificial anode; A plurality of cover parts including the cover part; Further equipped with The floating body is columnar about a central axis extending in the vertical direction, A plurality of accommodation sections including the accommodation section are provided on the bottom surface of the floating body, Each of the plurality of accommodating portions has a groove shape extending in a radial direction centered on the central axis, The plurality of sacrificial anodes are respectively accommodated in the plurality of accommodation portions, The plurality of cover parts are disposed at the openings of the plurality of accommodation parts on the bottom surface of the floating body body to close the openings of the plurality of accommodation parts, A floating structure in which two communication ports are provided at the boundary between each storage space formed by each storage section and each cover section and the external space, communicating each storage space with the external space.

9. The floating structure according to any one of claims 1 to 4, The outer surface of the floating body on which the accommodation section is provided is a side surface of the floating body, The accommodation portion is a groove portion extending upward from the bottom surface of the floating body, A floating structure, wherein one of the two communication ports is an opening of the groove portion in the bottom surface of the floating body.

10. The floating structure according to claim 9, A plurality of sacrificial anodes including the sacrificial anode; A plurality of cover parts including the cover part; Further equipped with The floating body is columnar about a central axis extending in the vertical direction, A plurality of accommodation sections including the accommodation section are provided on the side surface of the floating body, Each of the plurality of accommodation portions is a groove portion extending upward from the bottom surface of the floating body, The plurality of sacrificial anodes are respectively accommodated in the plurality of accommodation portions, The plurality of cover portions are disposed at the openings of the plurality of storage portions on the side surfaces of the floating body body to close the openings of the plurality of storage portions, Two communication ports are provided at boundaries between the external space and each of the storage spaces formed by the storage sections and the cover sections, the communication ports communicating the respective storage spaces with the external space; A floating structure, wherein one of the two communication openings of each of the storage spaces is an opening of each of the storage sections in the bottom surface of the floating body.

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