Floating type platform, anchor container, floating body, and installation method for installing floating type platform on water

Abstract

To provide a floating type platform capable of reducing the manufacturing cost and installation work cost, as well and an installation method for installing the floating type platform on water.SOLUTION: A floating type platform (2) includes: a floating body (3) that is composed to support a tower (1) and is installed on water by taut mooring; an anchor container (4) provided with a plurality of containers (17); and a plurality of tethers (5) connecting the floating body (3) and the anchor container (4). Each of the plurality of containers (17) is fixed to at least one of the plurality of tethers (5) and is installed at water bottom. Each of the plurality of containers (17) includes a bottom, a container outer wall provided to surround the outer periphery of the bottom, and a container inner wall provided to face the container outer wall. Storage space is formed by the bottom, the container outer wall, and the container inner wall. Heavy material including at least one of soil, sand, gravel, crushed stone, or concrete pieces is stored in the storage space.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a floating platform, an anchor vessel body, a float, and an installation method for installing a floating platform on water. [Background technology]

[0002] A tension mooring method is known in which a float floating on the water surface is tethered to a pile driven into the water bottom down to the bedrock below, or to a heavy object placed on the water bottom, with a tether such as a chain, wire or rope, and the float is pulled underwater with a force stronger than the weight of the tether itself, thereby suppressing the motion of the float.

[0003] For floating platforms that support tall towers, low sway is an important quality of the floating platform. For example, when a tower for offshore wind power generation is installed, it greatly affects the power generation efficiency and stable operation of the facility. In this respect, tension mooring is an ideal mooring method. In addition, minimizing the area occupied by the entire floating platform, including not only the water surface where the float is located but also the bottom and underwater where the mooring device is installed, is also important in minimizing the impact on local fishing that originally used the same water area. Tension mooring, in which mooring devices such as chains are placed only directly under the float and do not deploy widely on the seabed or underwater, is a very effective mooring method in this respect as well. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5565803 [Non-patent literature]

[0005] [Non-Patent Document 1] “TLP concept of FOWT suitable for characteristics of Japan”,7th July 2022 MODEC Inc. [Non-Patent Document 2] GICON-SOF,“A modular and cost competitive TLP Solution”,GICON Summary of the Invention [Problem to be solved by the invention]

[0006] In tension mooring, it is necessary to install a strong foundation on the seabed that can not only support the initial tension applied to the tether but also withstand the buoyancy and drifting forces generated by waves, swells, tsunamis, etc. Conventionally, as described in Non-Patent Document 1, a method was used in which multiple piles were driven deeper into the ground from the seabed to form a foundation, but the construction of driving piles into the seabed in the deep sea is difficult and large-scale, and high construction costs were a problem. To solve this problem, gravity tension mooring devices described in Patent Document 1 and Non-Patent Document 2 were devised. However, these gravity tension mooring devices are heavy and huge concrete structures, and the manufacturing and installation costs are high. In particular, the load that needs to be most considered when installing a tower for offshore wind power generation is the horizontal wind pressure applied to the top of the tower during a typhoon, etc., and in order to support this, it is necessary to install a huge concrete structure on the seabed to withstand a large overturning moment. The costs of manufacturing and installing this huge concrete structure are an issue, and therefore the gravity-type tension mooring devices disclosed in Patent Document 1 and Non-Patent Document 2 have not been put to practical use.

[0007] An object of the present invention is to provide a floating platform and an installation method for installing a floating platform on water that can reduce manufacturing costs and installation construction costs. [Means for solving the problem]

[0008] A floating platform (2) according to one aspect of the present invention includes a float (3) configured to support a tower (1) and arranged on the water by tension mooring, an anchor vessel body (4) having a plurality of containers (17), and a plurality of tethers (5) connecting the float (3) and the anchor vessel body (4). Each of the plurality of containers (17) is fixed to at least one of the plurality of tethers (5) and is installed on the bottom of the water. Each of the plurality of containers (17) includes a bottom (19), a container outer wall (20) provided to surround the outer periphery of the bottom (19), and a container inner wall (21) provided to face the container outer wall (20). The bottom (19), the container outer wall (20), and the container inner wall (21) form a storage space (S). The storage space (S) stores a heavy object including at least one of soil, sand, gravel, crushed stone, and concrete pieces.

[0009] The bottom (19) may have an opening (190). The container inner wall (21) may be provided to surround the inner periphery of the bottom (19). Each of the plurality of containers (17) may further include a tether support member (22) formed on the container inner wall (21) and fixed to the at least one tether (5).

[0010] The container inner wall (21) may also have a cavity (36) that communicates with the opening and is open at the top.

[0011] In addition, an inner surface (26) of the container inner wall (21) facing the container outer wall may be inclined with respect to the height direction of the container (17). The distance between the container inner wall and the container outer wall in a horizontal direction perpendicular to the height direction may gradually decrease toward the bottom.

[0012] The tether support member (22) may also include a first tether support member (22a) formed on the inner wall of the container and fixed to one of the multiple tethers (5), and a second tether support member (22b) formed on the inner wall of the container and fixed to another one of the multiple tethers (5).

[0013] The floating body (3) may include a central pillar (12) configured to support the tower (1), a plurality of arms (6) extending radially from the central pillar (12) or near the central pillar (12), a stage (7) fixed to the central pillar (12), a plurality of first braces (13) each connected to a corresponding one of the plurality of arms and the stage (7) or the central pillar, a plurality of second braces (14) each connected to two adjacent arms of the plurality of arms, a plurality of tether fixing devices (8) configured to fix a corresponding one of the plurality of tethers, and a plurality of tether winches (9) configured to wind up a corresponding one of the plurality of tethers.

[0014] The floating body (3) may further include a plurality of grips (15) each connected to an end of one of the plurality of arms, the axial direction of each of the plurality of grips being substantially perpendicular to the axial direction of the corresponding arm, and a plurality of guides (16) each disposed on a corresponding one of the plurality of grips (15), each configured to come into contact with a corresponding one of the plurality of tethers and change the extending direction of the corresponding one tether. The tether fixing device (8) and the tether hoist (9) may be disposed on the stage.

[0015] A nacelle and blades may also be attached to the tower 1. The floating platform may be an offshore wind power platform.

[0016] An anchor vessel body (4) according to one aspect of the present invention is configured to support a tower (1) and is connected to a floating body (3) arranged on the water by tension mooring via a plurality of tethers (5). The anchor vessel body (4) includes a plurality of vessels (17). Each of the plurality of vessels (17) is fixed to at least one of the plurality of tethers (5) and is installed on the bottom of the water. Each of the plurality of vessels (17) includes a bottom (19), a vessel outer wall (20) provided to surround the outer periphery of the bottom (19), and a vessel inner wall (21) provided to face the vessel outer wall (20). The bottom (19), the vessel outer wall (20), and the vessel inner wall (21) form a storage space (S). The storage space (S) stores a heavy object including at least one of soil, sand, gravel, crushed stone, and concrete pieces.

[0017] A float (3) according to one embodiment of the present invention is placed on water by tension mooring and is configured to support a tower (1). The float (3) includes a central pillar (12) configured to support the tower (1), a plurality of arms (6) extending radially from the central pillar (12) or near the central pillar (12), a plurality of grips (15) each connected to an end of one of the plurality of arms, the axial direction of each of the plurality of grips being approximately perpendicular to the axial direction of the corresponding arm, a stage (7) fixed to the central pillar (12), a plurality of first braces (13) each connected to a corresponding one of the plurality of arms and the stage (7) or the central pillar, a plurality of second braces (14) each connected to two adjacent arms of the plurality of arms, and a plurality of tether fixing devices (8) configured to fix a corresponding one of the plurality of tethers.

[0018] According to one aspect of the present invention, a method for installing the floating platform (2) on water by tension mooring includes the steps of: disposing the anchor vessel body (4) having the plurality of vessels (17) directly below the float (3) and towing the float (3) to a planned installation location while the float (3) is floating at a first waterline (28); placing the plurality of vessels (17) on the water bottom by paying out the plurality of tethers (5) into the water at the planned installation location; and, The method includes the steps of: pouring the heavy load, which includes at least one of soil, sand, gravel, crushed stone, and concrete pieces, into the storage space of each of the plurality of containers (17); winding up the plurality of tethers (5); sinking the float (3) to a second waterline (27) deeper than the first waterline (28); adjusting the tension of the plurality of tethers (5) so that the tension of the plurality of tethers (5) becomes a predetermined value; and fixing each of the plurality of tethers (5) to the float (3). Effect of the Invention

[0019] According to the present invention, it is possible to provide a floating platform and an installation method for installing a floating platform on water, which can reduce manufacturing costs and installation work costs. [Brief description of the drawings]

[0020] [Figure 1] FIG. 1 is an overall view of a floating platform supporting a tower according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a perspective view of the floating platform according to the present embodiment. [Diagram 3] FIG. 2 is a perspective view of an anchor container body according to the embodiment. [Figure 4] FIG. [Diagram 5] 1A is a plan view of the container, FIG. 1B is a cross-sectional view of the container taken along line AA, and FIG. 1C is a cross-sectional view of the container taken along line BB. [Figure 6] FIG. 13 is a diagram for explaining the propagation of a load inside a container. [Figure 7] FIG. 13 is a diagram for explaining the fishing reef effect of the container. [Figure 8] FIG. [Figure 9] FIG. 2 is a perspective view showing a main part of the float. [Figure 10] This figure shows the storage position of the anchor vessel body when launched and towed. [Figure 11] FIG. 2 is a diagram for explaining a method for installing the floating platform according to the present embodiment. [Figure 12] FIG. 2 is a diagram showing an example of a heavy object injection device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] Hereinafter, the floating platform according to this embodiment will be described with reference to the drawings.

[0022] 1 is an overall view of a floating platform 2 supporting a tower 1 according to this embodiment. In this embodiment, the floating platform 2 supports a large offshore wind turbine and floats on the water surface at a second waterline 27. A nacelle 42 and blades 40 may be attached to the tower 1.

[0023] FIG. 2 is a perspective view of a floating platform 2 supporting a tower 1. The floating platform 2 includes a float 3 configured to support the tower 1, an anchor vessel body 4 equipped with a plurality of containers 17 (four containers 17 in this example), and a plurality of tethers 5 connecting the float 3 and the anchor vessel body 4. In this embodiment, each of the four containers 17 is connected to the float 3 via two tethers 5. The method of mooring the floating platform 2 is a gravity tension mooring method in which the float 3 and the anchor vessel body 4 in which heavy objects such as soil and sand are placed in the containers 17 are tied together with a plurality of tethers 5, and the tethers 5 are applied with initial tension to pull the lower part of the float 3 into the sea for mooring. In this way, the float 3 is placed on the water in a state moored by the tension mooring method. Here, the heavy objects include at least one of soil, sand, gravel, crushed stone, and concrete pieces. The conventional gravity-type tension mooring devices described in Patent Document 1 and Non-Patent Document 2 are heavy and huge concrete structures, and the cost of producing the concrete structure itself is expensive, including the cost of materials such as the concrete and the reinforcing bars that support it, the cost of producing and installing the formwork for pouring the concrete, and the cost of pouring the concrete. On the other hand, the unit price of heavy materials such as soil and sand is generally a fraction of that of concrete, so the method of securing weight by pouring soil and sand into the container 17 of the anchor container body 4 installed on the seabed is effective in reducing production costs.

[0024] The tether 5 may be a rope, a wire, or a chain depending on the maximum tension that can be generated.

[0025] (Anchor vessel body 4) Next, the structure of the anchor vessel body 4 will be described below with reference to FIG. 3. FIG. 3 is a perspective view of the anchor vessel body 4. As shown in FIG. 3, the anchor vessel body 4 is connected to the floating body 3 via a tether 5 and installed on the seabed. The anchor vessel body 4 includes four vessels 17. Heavy objects including at least one of soil, sand, gravel, crushed stone, and concrete pieces are placed in each vessel 17. The vessels 17 are connected to each other by a connecting rope 18. The role of the connecting rope 18 is to suppress deviation of the relative positions of the four vessels 17. When the anchor vessel body 4 is lowered to the seabed and installed, first, a tugboat with the same number as the vessels 17 is prepared, and the tugboat and the vessels 17 are tied together by a rope or the like and pulled outward from the center of the anchor vessel body 4 to apply tension to the connecting rope 18 while the vessels 17 are lowered into the sea, whereby the vessels 17 can be installed on the seabed while maintaining the relative positions of the vessels 17.

[0026] (Container 17) Next, the structure of the container 17 will be described below with reference to Figs. 4 and 5. Fig. 4 is a perspective view of the container 17. Fig. 5(a) is a plan view of the container 17. Fig. 5(b) is an AA cross-sectional view of the container 17. Fig. 5(c) is a B-B cross-sectional view of the container 17. In the container 17, the outer circumference of the bottom 19 is surrounded by the container outer wall 20, and the top is open, so that heavy objects such as soil and sand can be put in from the top. Note that Fig. 5 shows XYZ axes set for the container 17. One of the X-axis, Y-axis, and Z-axis is perpendicular to the other axis. The Z-axis direction corresponds to the height direction of the container 17. The horizontal direction perpendicular to the Z-axis corresponding to the height direction of the container 17 is parallel to the X-axis and Y-axis.

[0027] As shown in FIG. 4 and FIG. 5, the container 17 includes a bottom 19, a container outer wall 20, a container inner wall 21, and a pair of tether support members 22. The bottom 19 has a circular opening 190. The container outer wall 20 is provided so as to surround the outer periphery of the bottom 19. The container inner wall 21 is provided so as to surround the inner periphery of the bottom 19 (in other words, the outer periphery of the opening 190) and to face the container outer wall 20. The pair of tether support members 22 are formed on the container inner wall 21. At least one tether 5 (one tether 5 in this example) is fixed to the tether support member 22. The bottom 19, the container outer wall 20, and the container inner wall 21 form a storage space S. The storage space S stores a heavy object including at least one of soil, sand, gravel, crushed stone, and concrete pieces.

[0028] (Container inner wall 21) The container inner wall 21 communicates with the opening 190 of the bottom 19 and has a cavity 36 with an open top. The cavity 36 is a place where small fish can take refuge from strong currents, and is also expected to be effective as a fishing reef. The inner surface 26 of the container inner wall 21 facing the container outer wall 20 is inclined with respect to the Z-axis direction (height direction) of the container 17 (see FIG. 5(a)). The distance between the container inner wall 21 and the container outer wall 20 in the horizontal direction (XY direction) perpendicular to the Z-axis direction gradually decreases as the container approaches the bottom 19. Here, as the position in the Z-axis direction approaches the bottom 19, the diameter of the container inner wall 21 gradually increases, and therefore the distance between the container inner wall 21 and the container outer wall 20, which corresponds to the difference between the radius of the container outer wall 20 and the radius of the container inner wall 21, also gradually decreases (see FIG. 5(a) and FIG. 5(b)).

[0029] If the container 17 does not have an inner wall, the bottom 19 will be far from the side wall near the center, and will need to be supported from below by a large strength member. Therefore, by providing the container inner wall 21 forming the side of a cylinder, rectangular column, cone, pyramid, truncated cone, or truncated pyramid near the center, the container inner wall 21 itself will become a strong strength member, and at the same time, the bone 25 supporting the bottom 19 from below can be made short and thin, leading to a reduction in the weight of the bone 25. Note that if the maximum value of the tension applied to the tethers 5 connected to the container 17 differs for each tether 5, shifting the position of the container inner wall 21 toward the tether 5 with a relatively weak tension is effective in reducing the required amount of heavy materials such as soil and sand.

[0030] (Tether support member 22) One of the pair of tether support members 22, tether support member 22a (an example of a first tether support member) and the other tether support member 22b (an example of a second tether support member), are provided on the inner surface 26 of the container inner wall 21, and face each other through a cavity 36 formed in the container inner wall 21. The number of tether support members 22 provided in the container 17 is not particularly limited. By providing the tether support members 22 on the container inner wall 21, a strong mooring force can be transmitted to the container 17. A tether fixing portion 23 for fixing the tether 5 is provided on the upper surface of the tether support member 22. When a heavy load such as sand and soil is dumped from a ship 32 into the container 17 installed on the seabed using a heavy load dumping hose 30, the tether 5 extending straight from the container 17 to the floating body 3 on the water surface may be an obstacle (see FIG. 12, etc.). By providing the tether support member 22 having the tether fastening part 23 for pulling in the float 3 on the container inner wall 21 instead of the container outer wall 20, when dumping heavy objects such as soil and sand, the heavy object dumping hose 30 and the like can be disposed on the outside of the container inner wall 21, reducing the possibility of the heavy object dumping hose 30 and the tether 5 coming into contact with each other. In addition, by locating the place for dumping heavy objects such as soil and sand on the outside of the tether fastening part 23, the volume for dumping the required amount of heavy objects such as soil and sand can be easily adjusted by changing the diameter of the container outer wall 20 at the design stage, regardless of the shape of the float 3 or the attachment position and number of the tethers 5.

[0031] (Effectiveness of Strength of Tether Support Member 22) Next, the effectiveness of the strength of the tether support member 22 will be described below with reference to FIG. 6. FIG. 6 is a diagram for explaining how the load resulting from the tension of the tether 5 propagates through the container 17. The large tension applied to the tether 5 is transmitted to the tether support member 22 by the tether fixing portion 23, and then to the bone 25 via the container inner wall 21, and must become a force that supports heavy objects such as soil and sand from below through the bottom 19. The strength required is such that the large load can be supported over the entire series of paths, enough to lift heavy objects such as soil and sand that are poured into the container 17. It is possible to support the load of the tether 5 with the entire tether support member 22 by making the surrounding portion of the tether fixing portion 23 in the tether support member 22 a large casting, but since most of the container 17 is made of steel plate, it is necessary to prevent damage to the container 17 by distributing and transmitting the load over the entire series of paths described above.

[0032] In this embodiment, the tether support member 22 is connected to the vessel inner wall 21 having a truncated cone-shaped side surface via a long weld line 24. The vertical tension of the tether 5 is directly transmitted to the tether support member 22 as a vertical force, but this force is dispersed over the entire area of ​​the long weld line 24. Moreover, this force can be considered by decomposing it into an in-plane component and an out-of-plane component of the vessel inner wall 21. Since a plate is generally very strong against in-plane forces, the in-plane component of the force can be ignored in terms of strength design. On the other hand, with regard to the out-of-plane component of the force, when the vessel inner wall 21 has a curved surface or a bent edge, the buckling strength is significantly improved compared to a simple flat surface, so the reinforcing material can be reduced.

[0033] Next, the force transmitted to the container inner wall 21 is transmitted to the bone 25. In this case, since the bone 25 is connected to the container inner wall 21 as a cantilever beam, it is necessary to provide a bracket 29 on the inside of the container inner wall 21. The bone 25 is disposed between the container inner wall 21 and the container outer wall 20, and compared to a case in which the container inner wall 21 is not present and the container outer wall 20 is connected to the opposite side of the container outer wall 20, the length of the bone 25 can be significantly shortened, and the size of the bone 25 can be reduced, thereby reducing the amount of steel used. Finally, the bone 25 supports heavy loads such as soil and sand from below via the bottom 19.

[0034] (Holding power by bone 25) Reinforcing ribs 25 are arranged radially on the underside of the bottom 19, and these ribs 25 also serve as spikes protruding into the seabed and are effective in resisting the horizontal force applied to the anchor vessel body 4 from the tether 5. In this way, by providing reinforcing members such as the ribs 25 on the outer surface of the vessel 17 and eliminating protrusions on the inner surface of the vessel 17 surrounded by the vessel outer wall 20, the vessel inner wall 21 and the bottom 19, it becomes easier to recover heavy objects such as soil and sand that have been thrown into the vessel 17, which must be performed when the floating platform 2 supporting the tower 1 is removed from the installation sea area.

[0035] (Fishing reef effect) FIG. 7 is a diagram for explaining the fishing reef effect of the container 17. It is known that oysters, seaweed, etc. attach to the floating body 3 during operation and play a role as a fishing reef. In addition, in the case of the container 17 that is installed on the seabed, not only does the surface of the heavy object such as sand and soil that is poured into the container 17 eventually become roughly the same as the seabed and become a habitat for benthic organisms, but also the water quality of the cavity 36 in the container inner wall 21 is maintained by effectively exchanging seawater with the cavity 36 through the opening of the cavity 36. In this way, the cavity 36 becomes a valuable space where various fish, including small fish, can take refuge from storms and strong water currents.

[0036] (Main part of floating body 3) Next, the structure of the float 3 will be described below with reference to Figures 8 and 9. Figure 8 is a side view of the float 3. Figure 9 is a perspective view showing the main parts of the float 3. For convenience of explanation, the arms 6, the first brace 13, the second brace 14, and the grip 15 extending perpendicular to the paper surface are omitted in Figure 8.

[0037] As shown in Figures 8 and 9, the float 3 is placed on the ocean while being moored by a tension mooring method, and is configured to support the tower 1. The float 3 includes a central pillar 12, a base 11, a plurality of arms 6, a plurality of grips 15, a plurality of guides 16, a stage 7, a plurality of first braces 13, a plurality of second braces 14, a plurality of tether fixing devices 8, and a plurality of tether hoists 9.

[0038] The central pillar 12 is configured to support the tower 1. The tower 1 is fixed to the upper surface of the central pillar 12 by fastening means such as bolts and nuts. The central pillar 12 is disposed on a base 11. A tether storage space 10 for storing a tether 5 is also mounted on the base 11. A plurality of arms 6 (four in this example) extend radially from the base 11. In this regard, if the base 11 is not provided on the float 3, the four arms 6 may extend radially from the central pillar 12. Each arm 6 may extend parallel to a horizontal direction perpendicular to the height direction of the float 3 (extension direction of the tower 1). As shown in FIG. 8, the upper surface of each arm 6 may be flush.

[0039] Each of the multiple (four in this example) grips 15 is connected to the tip of a corresponding one of the four arms 6. The axial direction A2 of each grip 15 is approximately perpendicular or perpendicular to the axial direction A1 of the corresponding arm 6 and the axial direction of the central pillar 12 (see FIG. 8). Similarly, the axial direction A1 of each arm 6 is approximately perpendicular or perpendicular to the axial direction of the central pillar 12. Each of the multiple (eight in this example) guides 16 is disposed on a corresponding one of the four grips 15. As shown in FIG. 2, in this example, two guides 16 are disposed on each grip 15. Each guide 16 is configured to contact a corresponding one of the multiple tethers 5 and to change the extension direction of the corresponding one tether 5. Each tether 5 is bent by the guide 16.

[0040] The stage 7 is fixed to the central pillar 12. In particular, the stage 7 is disposed between the tower 1 and the base 11 in the height direction of the floating body 3. The stage 7 is fixed to the central pillar 12 with the central pillar 12 inserted into a through hole 72 formed in the stage 7. A plurality of first braces 13 (four in this example) are connected to corresponding ones of the four arms 6 and the stage 7. The first braces 13 may be connected to corresponding ones of the four arms 6 and the central pillar 12. Each first brace 13 extends obliquely with respect to the height direction of the floating body 3.

[0041] Each of the multiple (four in this example) second braces 14 is disposed between two adjacent arms 6. One end of each second brace 14 is connected to one of the two adjacent arms 6, and the other end of each second brace 14 is connected to the other of the two adjacent arms 6. Each second brace 14 may extend parallel to the horizontal direction of the floating body 3.

[0042] A plurality of (eight in this example) tether fixing devices 8 are disposed on the stage 7 (see FIG. 2). Each tether fixing device 8 is configured to fix a corresponding one of the eight tethers 5. A plurality of (eight in this example) tether winding machines 9 are disposed on the stage 7 (see FIG. 2). Each tether winding machine 9 is configured to wind up and unwind a corresponding one of the eight tethers 5.

[0043] (Design points of floating body 3) In order to reduce the manufacturing cost of the floating body 3, the following points must be considered. 1) Reduce the maximum tension applied to tether 5 during operation. 2) The amount of ballast water carried during operation is reduced, thereby reducing the weight of the steel material of the floater 3.

[0044] (Reduces the maximum tension applied to the tether during operation) When there is no wind, waves or swell and the float 3 is floating at the second waterline 27, part of the buoyancy can be cancelled by loading ballast water, and the tension applied to the tether 5 can be adjusted to the initial tension assumed at the time of design. On the other hand, when a strong wind blows and a tower 1 for wind power generation is loaded, a strong horizontal force is applied to the top of the tower 1 due to the wind pressure. This force generates a large moment on the float 3 floating on the water surface according to the following formula. Note that L is the distance from the float 3 to the top of the tower 1, and Fn is the wind pressure. M = L × Fn Here, M is the moment. L is the distance from the fulcrum to the force point. Fn is the component of the force perpendicular to the line joining the fulcrum and the force point.

[0045] This moment needs to be supported by the tension generated in the tether 5. In this case, when the above formula is applied, L can be read as the distance between the tethers 5, and Fn as the tension applied to the tether 5, and therefore it can be seen that in order to reduce the tension Fn, it is effective to increase the distance L between the tethers 5. For this reason, in this embodiment, the arms 6 are extended as long as their strength allows.

[0046] In this embodiment, one container 17 is designed to be pulled by two tethers 5, so by arranging guides 16 corresponding to each tether 5 at the same distance from the center of base 11, it is possible to withstand tension up to the upper limit of the strength of the two tethers 5. In order to accommodate this, grips 15 are provided at the tips of arms 6 to install two guides 16.

[0047] On the other hand, the tension applied to the tether 5 also increases due to an increase in buoyancy caused by a temporary rise in the water level due to waves or swells. Therefore, in order to suppress the maximum value of the tension of the tether 5, it is important to minimize the horizontal cross-sectional area (hereinafter referred to as the waterline area) of the float 3 at the height of the second waterline 27 and suppress the increase in buoyancy caused by the rise in the water level. In this embodiment, it is necessary to minimize the diameter of the central pillar 12 and the first brace 13 within the range possible in terms of strength. The first brace 13 is installed diagonally toward the central pillar 12 and is gathered near the central pillar 12 around the second waterline 27, so that it is possible to suppress oscillations such as pitching (vertical oscillation) and rolling (lateral oscillation) that occur in the float 3 due to waves and swells.

[0048] (Reducing the amount of ballast water carried during operation and reducing the weight of steel materials on Float 3) If the amount of ballast water can be reduced, the weight of the steel materials used to construct the tanks that carry it can be reduced, which contributes to lower manufacturing costs. Even if the outer walls of the compartments carrying ballast water are removed during operation to make them areas outside the float 3, this does not affect the buoyancy generated in the float 3, so it is desirable to reduce the compartments carrying ballast water as much as possible. Note that when reducing the amount of ballast water, it is desirable to consider the following two points. 1) When towing, floating at the first waterline 28, it must float stably without ballast water. 2) Minimize the displacement between the first waterline 28 and the second waterline 27.

[0049] (Consider how to float stably without ballast water while towing) "Floating without ballast water" means that the weight and buoyancy of the float 3 are equal at the first waterline 28. In a steel float 3, the weight of the float 3 is roughly the same as the weight of the steel, so it is necessary to adjust the dimensions of each part of the float 3 so that the buoyancy is the same as the weight estimated in advance. For this reason, the volume (displacement) of the float 3 below the first waterline 28 is restricted.

[0050] Moreover, "floating stably" means that the float 3 has sufficient stability even when it is subjected to rocking caused by waves and swells during towing, and to an overturning moment caused by wind. For this purpose, it is necessary to secure a waterline area at a position away from the central pillar 12 by extending the arms 6 as far as possible and arranging the grips 15 at their tips. Extending the arms 6 as far as possible while being restricted by the volume below the first waterline 28 of the float 3, i.e., the buoyancy, means that the arms 6 have a shape like a thin and long rod. As a result, the arms 6 are insufficiently strong, and therefore a first brace 13 that supports the arms 6 in the vertical direction and a second brace 14 that supports them in the horizontal direction are required. However, since the second brace 14 is also included in the above-mentioned buoyancy restriction, it is preferable to make it as thin as possible.

[0051] Also, it is preferable that the first brace 13 is as thin as possible due to the requirement of "minimizing the displacement between the first waterline 28 and the second waterline 27." However, when the arm 6, the first brace 13, and the second brace 14 are thinned, it is preferable to evaluate their strength and confirm that they have sufficient strength to prevent damage during towing and operation. In addition, "floating stably without ballast water while towing" means that it is possible to independently tow the floating platform 2 to the installation area using only multiple tugboats without using a large support ship, which is effective in reducing the installation cost of the floating platform 2.

[0052] (Effect of towing vessel 17 on stability) As shown in FIG. 10, the container 17 during towing is fixed directly below the arm 6 and the grip 15. If the float 3 tilts significantly during towing, the grip 15 may come completely above the water surface, and at the same time, the grip 15 on the opposite side of the central pillar 12 may become completely submerged. In such a case, a part of the container 17, which is usually completely submerged, will come above the water surface. At this time, the upper surface of the container 17 has a water line area, and if the float 3 is tilted further to lift the container 17, a large restoring force proportional to the water line area of ​​the container 17 is generated, so the container 17 side hardly lifts up. For this reason, in order to tilt the float 3 further, it is necessary to sink the part with a large water line area, such as the base 11 below the central pillar 12, so the float 3 is less likely to tilt. In other words, if the float 3 tilts significantly due to motion caused by waves or swells during towing, the container 17 can be expected to generate a restoring force larger than usual and prevent the float 3 from capsizing.

[0053] (Axisymmetrical nature of floating body 3) In the process of sinking the float 3 from the first waterline 28 to the second waterline 27, the horizontal position of the center of gravity of the increased displacement must be aligned with the horizontal position of the center of gravity when floating at the first waterline 28. If the two do not match, it will be necessary to load ballast water to correct the difference. In this embodiment, the central pillar 12 and base 11 are disposed directly below the tower 1. The axes of the central pillar 12 and base 11 may coincide with the axis of the tower 1. In addition, some of the members constituting the float 3 may be disposed so as to be symmetrical with respect to the axis of the tower 1.

[0054] (Minimize the displacement from the first waterline 28 to the second waterline 27) Since the float 3 floats at the first waterline 28 without ballast water, in order to sink it to the second waterline 27, it is necessary to load ballast water with a weight equivalent to at least the increase in displacement during that period minus the initial tension applied to the tether 5. Specifically, the following relationship holds. (Weight of ballast water)=(Displacement from the first waterline 28 to the second waterline 27)+(Weight of the anchor vessel body 4)-(Total initial tension of the tethers 5)

[0055] From the above formula, it is clear that it is important to minimize the "displacement from the first waterline 28 to the second waterline 27." Specifically, the following components need to be reviewed. However, as mentioned above, the review must be limited to the extent that sufficient strength is maintained.

[0056] 1) Freeboard of base 11: In order to ensure that the base 11 has enough stability to quickly rise to the surface even if it is submerged for a short time due to waves or rolling during towing, it is necessary to ensure that the volume is up to a certain height above the water surface. This height is called the freeboard.

[0057] 2) Diameter of central pillar 12: The upper part of the central pillar 12 must in principle have the same strength as the bottom end of the tower 1 in order to withstand the large bending moment that it receives from the tower 1, but there is almost no bending moment at the bottom end of the central pillar 12. For that reason, it is possible for the central pillar 12 to have a triangular pyramid shape that is thick at the top and thin at the bottom. However, this is more difficult to manufacture than a cylindrical shape, so care must be taken when evaluating the manufacturing costs.

[0058] 3) Arm 6 diameter: Because the arms 6 are long, simply narrowing them a little will significantly reduce the displacement and the waterline area at the first waterline 28. In addition, since there is a possibility that a large compressive force will be applied by the tether 5 and the first brace 13 during operation, it is necessary to determine the diameter of the arms 6 after evaluating their buckling strength.

[0059] 4) Diameter of first brace 13: Since there is a risk of buckling when compressive force is applied, it is necessary to determine the diameter of the first brace 13 after a sufficient strength evaluation. If ballast water is loaded into the grip 15 during operation to offset buoyancy, the possibility of compressive force being applied to the first brace 13 can be significantly reduced.

[0060] 5) Diameter of second brace 14: Most of the second brace 14 is already submerged at the first waterline 28, and when changing the diameter of the second brace 14, it is necessary to pay attention to changes in the first waterline 28. The forces acting on the second brace 14 are due to wind pressure as well as drift forces caused by currents, waves, and swells, and the load is not large compared to that on the first brace 13.

[0061] 6) Grip 15 Diameter: Since the grip 15 is important for ensuring stability at the first waterline 28, when reducing the diameter of the grip 15, the effect on stability must be considered.

[0062] Up to this point, we have discussed the points to be considered regarding the overall configuration of the floating body 3. Next, we will describe matters specific to each individual member that constitutes the floating body 3 as necessary.

[0063] (Base 11) The base 11 secures buoyancy to support most of the weight of the tower 1 and the central pillar 12 at the first waterline 28, and also has a tether storage space 10 installed in its upper part. In addition, having the arms 6, which are subject to a strong force, penetrate inside the base 11 is advantageous in terms of strength design, since it makes it possible to offset part of the force between the two arms 6 arranged in opposing positions, and is effective in reducing the weight of steel materials.

[0064] (Arm 6) In this embodiment, four arms 6 extend in all directions from the base 11. A grip 15 is disposed at the end of each arm 6. When the extension direction of the tension acting on the tether 5 during operation is changed by a guide 16 provided on the grip 15, a force compressing the arm 6 is generated, and at the same time, a force pushing the tip of the arm 6 downward is also generated. This downward force is transmitted to the first brace 13 that supports the arm 6 in the vertical direction, thereby supporting the arm 6. Furthermore, at this time, a bending moment is generated at the connection part between the arm 6 and the first brace 13. Since this bending moment is generated repeatedly due to fluctuations in wind pressure, etc., fatigue cracks are likely to occur on the upper surface of the connection part between the arm 6 and the first brace 13, so it is preferable to consider the fatigue strength at the design stage. In addition, depending on the circumstances, the plate thickness of the arm 6 and the connection position between the arm 6 and the first brace 13 may be reviewed. In principle, the same consideration is also required for the connection position between the arm 6 and the second brace 14. It is also possible to make a part or the whole of the arm 6 a void section, thereby canceling part of the force pushing the tip of the arm 6 downward.

[0065] (Grip 15) In this embodiment, the grip 15 is attached to the tip of the arm 6. A guide 16 for bending the tether 5 is installed on the grip 15. As described above, the grip 15 can ensure the stability when the float 3 floats at the first waterline 28 during towing. On the other hand, when the float 3 floats at the second waterline 27 during operation, if the entire volume of the grip 15 itself becomes buoyant, the downward force generated by bending the tether 5 will be greatly exceeded, and an excessive load will be applied to the arm 6 and the first brace 13. Therefore, when the float 3 floats at the second waterline 27 during operation, it is advantageous in terms of strength design of the float 3 to load ballast water on the grip 15 to use it as a ballast tank, and this is effective in reducing the weight of the steel material of the float 3.

[0066] (Guide 16) In this embodiment, a tether fixing device 8 that fixes the tether 5 is installed on a stage 7 provided on the central pillar 12. The extension direction of the tether 5, which extends straight from the tether fixing part 23 of the container 17, is changed by the guide 16, and it extends diagonally upward toward the tether fixing device 8 arranged on the stage 7. As the extension direction of the tether 5 changes, the guide 16 receives horizontal and vertical forces proportional to the tension. When the floating body 3 is subjected to wind pressure, a lateral force may also act on the tether 5, and the guide 16 receives this lateral force as well. The guide 16 may be provided with a mechanism to prevent the tether 5 from coming off the guide 16.

[0067] (Stage 7) The stage 7 is firmly fixed to the central pillar 12 at a position above the arm 6 and higher than the second waterline 27. In order to reduce the number of times that the stage 7 is exposed to green waves during a severe storm, it is effective to install the stage 7 at a high position. On the other hand, when the wind power generation tower 1 is mounted on the central pillar 12, the position of the stage 7 can be determined from the viewpoint of ensuring a clearance between the tip of the blade 40 and the stage 7. It is preferable to design the stage 7 on the premise that it will be exposed to green waves. For example, when a deep beam is provided on the stage 7, it is preferable to form a light hole as large as possible in the stage 7. It is preferable to minimize the area on which the deck of the stage 7 is laid. Also, when it is unavoidable to lay a deck, a water-permeable structure such as a grating may be provided on the stage 7.

[0068] (Tether Fixing Device 8) The tether fixing device 8 is installed on the stage 7 at a position adjacent to the tether winding machine 9. The tether fixing device 8 receives tension acting on the tether 5. For this reason, the tether fixing device 8 may be firmly fixed to the stage 7. Since the stage 7 is attached to the central pillar 12, if the tether fixing device 8 is installed at a position away from the central pillar 12, a large moment will be generated at the fixed position between the stage 7 and the central pillar 12, so it is preferable that the tether fixing device 8 is installed at a position as close to the central pillar 12 as possible. The distance between two adjacent tether fixing devices 8 arranged on the stage 7 may be shorter than the distance between two adjacent guides 16. In this case, the two tethers 5 extending from one grip 15 to the stage 7 do not have to be parallel to each other.

[0069] (Tether winch 9) A tether winch 9 is installed on the stage 7. The tether winch 9 enables the payout of the tether 5 when the anchor vessel body 4 is lowered to the seabed, the adjustment of the initial tension of the tether 5 during operation, and the winding up of the tether 5 when the floating platform 2 supporting the tower 1 is removed. When adjusting the initial tension of the tether 5, the tether 5 may be slightly wound up using the tether winch 9 in order to release the load applied to the tether fixing device 8.

[0070] (10 tether storage spaces) A tether storage space 10 is provided on the base 11. The tether 5 is stored in the tether storage space 10 when the float 3 is launched and towed. When the float 3 is in operation, the tether 5 is hardly stored in the tether storage space 10. Therefore, a water-permeable structure such as a lattice may be adopted for the side wall of the tether storage space 10. In this case, the drift force applied to the float 3 is reduced, and therefore it is possible to reduce the tension acting on the tether 5.

[0071] (Launching and Towing) Next, the storage position of the anchor vessel body 4 at the time of launching and towing will be described below with reference to FIG. 10. FIG. 10 is a diagram showing the storage position of the anchor vessel body 4 at the time of launching and towing. When the float 3 is assembled and launched at a shipyard or the like, the anchor vessel body 4 is hung by the tether 5 directly below the float 3, and the float 3 and the anchor vessel body 4 are launched in a state in which their relative positions are fixed so as not to move. At this time, the float 3 floats at the first waterline 28. Also, most of the tether 5 is stored in the tether storage space 10. When the float 3 floats at the first waterline 28, the second moment of area mainly due to the waterline plane of the arms 6 and the grips 15 is large, so that the float 3 can secure sufficient stability against the pitching during towing. Therefore, the float 3 can be towed by several tugboats without the need for a large barge or support ship, which is effective in reducing the installation cost of the floating platform 2.

[0072] Next, a method for installing the floating platform 2 according to this embodiment will be described below with reference to Fig. 11. Fig. 11 is a diagram for explaining a method for installing the floating platform 2 according to this embodiment. Fig. 11 shows the procedure from launching the floating platform 2 to installing the floating platform 2. In step S1, the anchor vessel body 4 equipped with a plurality of containers 17 is placed directly below the floating body 3, and the floating body 3 is towed to a planned installation site while floating at the first waterline 28.

[0073] (Step S2: Installing the anchor vessel) When the floating body 3 arrives at the planned installation location, the anchor vessel body 4 is lowered to the seabed by letting out multiple (eight in this example) tethers 5 into the sea. It is preferable to investigate the condition of the seabed in advance and determine the planned installation location of the anchor vessel body 4 so that the vessel 17 of the anchor vessel body 4 does not run aground on large rocks.

[0074] (Step S3: Inserting heavy objects) Heavy objects are thrown from a ship 32 into the storage space S of four containers 17 installed on the seabed using a heavy object throwing device 35. The heavy objects are, for example, soil, sand, gravel, crushed stone, concrete pieces, etc. Specifically, as shown in FIG. 12 , after a heavy object throwing hose 30 is lowered into the sea from the ship 32, the heavy object throwing hose 30 is guided to a predetermined position using three propulsion devices 31 attached to the heavy object throwing hose 30. Specifically, when the tip of the heavy object throwing hose 30 reaches the storage space S of the containers 17, the heavy object is thrown into the storage space S from the heavy object throwing hose 30.

[0075] (Step S4: Installation) After the heavy load has been placed into the vessel 17 of the anchor vessel body 4, the float 3 is submerged to the second waterline 27 by winding up the tether 5 with the tether winch 9. If tension greater than the planned initial tension occurs in the tether 5 at this time, ballast water is loaded onto the float 3 and the tension of the tether 5 is adjusted so that the tension of the tether 5 becomes a predetermined value. Then, each of the multiple tethers 5 is fixed to the float 3 using the multiple tether fixing devices 8. In this manner, the floating platform 2 is installed on the sea using the tension mooring method.

[0076] (Resiliency during installation) 8 shows a first waterline 28 and a second waterline 27 of the float 3. In the process of installing the float 3 by retracting the tether 5, when the arm 6 and the grip 15 of the float 3 are submerged under the water surface, the waterline area decreases suddenly and the float 3 loses its stability. On the other hand, in this state, the tension of the tether 5 is sufficiently large, so there is no risk of the float 3 capsizing. It is preferable not to load ballast water on the float 3 until the tension of the tether 5 is sufficiently large.

[0077] (Heavy load loading device 35) FIG. 12 shows a heavy load input device 35. In order to input heavy loads such as sand and soil to a specific position on the seabed, it is preferable to use a means for accurately moving the tip of the heavy load input hose 30 to the target position. In the midst of disturbances such as wind, waves, and currents, it is difficult to quickly guide the tip of the heavy load input hose 30 to the target position by simply controlling the position of the ship 32 as in the past. For this reason, by providing a propulsion device 31 at the tip of the heavy load input hose 30, it becomes possible to guide the tip of the heavy load input hose 30 to the target position. In addition, it is preferable to control the overall shape of the heavy load input hose 30 by providing multiple (three in this example) propulsion devices 31 on the heavy load input hose 30. In this case, it becomes possible to more reliably input heavy loads from the heavy load input hose 30 into the storage space S of the container 17.

[0078] (Removed) When the floating platform 2 supporting the tower 1 is to be removed from the installation sea area, the floating platform 2 can be removed without using a large support ship, as in the installation, by following the steps shown in Fig. 11 in reverse. In this case, it is necessary to recover the heavy objects such as sand and soil contained in the container 17 by sucking seawater using the heavy object injection hose 30. A water jet injection device or the like may be attached to the tip of the heavy object injection hose 30 in order to turn the surface of the heavy objects such as sand and soil deposited in the accommodation space S of the container 17 into a slurry.

[0079] As described above, the floating platform 2 supporting the tower 1 is a tension-moored floating platform including a float 3, an anchor vessel body 4, and a plurality of tethers 5 connecting the float 3 and the anchor vessel body 4. The anchor vessel body 4 is not a conventional large concrete structure, but is composed of a plurality of vessels 17 for storing heavy loads such as inexpensive soil and sand. The floating platform 2 can be towed by a tugboat without using a large dedicated ship or barge because it can stand on its own even during towing. In addition, the floating platform 2 can be installed without using a large support ship by lowering the anchor vessel body 4 into the sea by paying out the tether 5 using the tether winch 9 mounted on the float 3, and then loading heavy loads such as soil and sand into each vessel 17 from a ship 32 equipped with a heavy load loading device 35. In this way, it is possible to reduce the manufacturing cost and installation construction cost of the floating platform 2. In addition, it is possible to significantly suppress the motion of the float 3 by tension mooring during operation of the floating platform 2. Furthermore, the anchor vessel body 4, which is expected to have a fish reef effect, can provide a floating platform 2 that is also effective in revitalizing the fishing industry.

[0080] Although the embodiment of the present invention has been described above, the technical scope of the present invention should not be interpreted as being limited by the description of the embodiment. The embodiment is an example, and it is understood by those skilled in the art that various modifications of the embodiment are possible within the scope of the invention described in the claims. The technical scope of the present invention should be determined based on the scope of the invention described in the claims and its equivalents. [Explanation of symbols]

[0081] 1: Tower 2: Floating platform 3: Floating body 4: Anchor vessel body 5: Tether 6: Arms 7: Stage 8: Tether fixing device 9: Tether hoist 10: Tether storage space 11: Bass 12: Heart Pillar 13: First brace 14: 2nd brace 15: Grip 16: Guide 17: Container 18: Connecting rope 19: Bottom 20: Container outer wall 21: Container inner wall 22, 22a, 22b: Tether support member 23: Tether attachment part 24: Welding seam 25: Bones 26: Inner surface 27: Second Waterline 28: First Waterline 29: Bracket 30: Heavy load input hose 31: Propulsion device 32: Ship 35: Heavy load loading device 36: Cavity 40: Blade 42: Nasser 72:Through hole 190:Opening A1: Arm axis A2: Grip axial direction S: Containment space

Claims

1. a floating body (3) configured to support the tower (1) and arranged on the water by tension mooring; An anchor container body (4) having a plurality of containers (17); A plurality of tethers (5) connecting the floating body (3) and the anchor container body (4); A floating platform (2) comprising: Each of the plurality of containers (17) is fixed to at least one of the plurality of tethers (5) and is placed on the bottom of the water; Each of the plurality of containers (17) comprises: The bottom (19); A container outer wall (20) provided so as to surround the outer periphery of the bottom (19); A container inner wall (21) provided so as to face the container outer wall (20); Equipped with The bottom (19), the outer wall (20) and the inner wall (21) of the container form a storage space (S), The storage space (S) stores heavy objects including at least one of soil, sand, gravel, crushed stone, and concrete pieces. Floating platform (2).

2. The bottom (19) has an opening (190), The container inner wall (21) is provided to surround the inner periphery of the bottom (19), Each of the plurality of containers (17) further comprises a tether support member (22) formed on the container inner wall (21) and fixed to the at least one tether (5). A floating platform (2) according to claim 1.

3. The container inner wall (21) has a cavity (36) that communicates with the opening and is open at the top. A floating platform (2) according to claim 2.

4. An inner surface (26) of the container inner wall (21) facing the container outer wall is inclined with respect to the height direction of the container (17), A distance between the inner wall and the outer wall of the container in a horizontal direction perpendicular to the height direction gradually decreases toward the bottom. A floating platform (2) according to claim 1.

5. The tether support member (22) a first tether support member (22a) formed on the inner wall of the container and fixed to one of the plurality of tethers (5); a second tether support member (22b) formed on the inner wall of the container and fixed to another one of the plurality of tethers (5); having A floating platform (2) according to claim 3.

6. The floating body (3) is a central pillar (12) configured to support the tower (1); A plurality of arms (6) extending radially from the central pillar (12) or from the vicinity of the central pillar (12); A stage (7) fixed to the central pillar (12); a plurality of first braces (13), each connected to a corresponding one of the plurality of arms and to the stage (7) or the central pillar; a plurality of second braces (14), each connected to two adjacent arms of the plurality of arms; a plurality of tether locking devices (8) configured to lock a corresponding one of the plurality of tethers; a plurality of tether winches (9) configured to winch up corresponding ones of the plurality of tethers; Equipped with A floating platform (2) according to any one of claims 1 to 5.

7. The floating body (3) is a plurality of grips (15) each connected to a tip of one of the plurality of arms, the axial direction of each of the plurality of grips being substantially perpendicular to the axial direction of the corresponding arm; a plurality of guides (16), each of which is disposed on a corresponding one of the plurality of grips (15), each of which is configured to contact a corresponding one of the plurality of tethers and to change an extending direction of the corresponding one of the plurality of tethers; Further equipped with The tether fixing device (8) and the tether hoist (9) are disposed on the stage. A floating platform (2) according to claim 6.

8. The tower (1) is provided with a nacelle (42) and blades (40); The floating platform is an offshore wind power generation platform. A floating platform (2) according to any one of claims 1 to 5.

9. An anchor vessel body (4) configured to support a tower (1) and connected via a number of tethers (5) to a floating body (3) arranged on the water by tension mooring, The anchor container body (4) comprises a plurality of containers (17), Each of the plurality of containers (17) is fixed to at least one of the plurality of tethers (5) and is placed on the bottom of the water; Each of the plurality of containers (17) comprises: The bottom (19); A container outer wall (20) provided so as to surround the outer periphery of the bottom (19); A container inner wall (21) provided so as to face the container outer wall (20); Equipped with The bottom (19), the outer wall (20) and the inner wall (21) of the container form a storage space (S), The storage space (S) stores heavy objects including at least one of soil, sand, gravel, crushed stone, and concrete pieces. Anchor receptacle body (4).

10. A floating body (3) arranged to be placed on water by tension mooring and to support a tower (1), The floating body (3) is a central pillar (12) configured to support the tower (1); A plurality of arms (6) extending radially from the central pillar (12) or from the vicinity of the central pillar (12); a plurality of grips (15) each connected to a tip of one of the plurality of arms, the axial direction of each of the plurality of grips being substantially perpendicular to the axial direction of the corresponding arm; A stage (7) fixed to the central pillar (12); a plurality of first braces (13), each connected to a corresponding one of the plurality of arms and to the stage (7) or the central pillar; a plurality of second braces (14), each connected to two adjacent arms of the plurality of arms; a plurality of tether locking devices (8) configured to lock a corresponding one of the plurality of tethers; The float (3).

11. 13. A method for installing a floating platform (2) on water by tension mooring as claimed in claim 1, said method comprising the steps of: a step of towing the floating body (3) to a planned installation site while the anchor vessel body (4) including the plurality of vessels (17) is disposed directly below the floating body (3) and the floating body (3) is floating at a first waterline (28); placing the plurality of containers (17) on the bottom of the water at the intended installation location by letting out the plurality of tethers (5) into the water; A step of pouring the heavy object including at least one of soil, sand, gravel, crushed stone, and concrete pieces into each of the storage spaces of the plurality of containers (17) arranged on the bottom of the water; reeling in the plurality of tethers (5); Submerging the floating body (3) to a second waterline (27) that is deeper than the first waterline (28); adjusting tension of the plurality of tethers (5) so that the tension of the plurality of tethers (5) is a predetermined value; fastening each of the plurality of tethers (5) to the floating body (3); Including, installation methods.

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