Method for installing a tension-moored floating structure and installation structure for a tension-moored floating structure

Abstract

To provide an installation method for a tension mooring floating body and an installation structure for the tension mooring floating body capable of surely securing reaction force with a simple structure and capable of being installed at a low cost.SOLUTION: A frame body 3 is suspended below a float body 2, and the float body 2 and the frame body 3 are towed to a place of installation. Then, after suspending the frame body 3 to a sea bottom 1, the float body 2 is evaded from above the frame body 3 in a state with the frame body 3 and a wire 5 coupled, and a weight body such as a concrete sinker is installed from above to the frame body 3. Later, the float body 2 is tension moored to the frame body 3 by applying tensile force to the wire 5, and installation of an installation structure of the tension mooring floating body is completed.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a method for installing a tension moored floating body and an installation structure for a tension moored floating body.

Background Art

[0002] Conventionally, in waters where the water depth is deeper than about 50 m, some floating type offshore wind power generation facilities have been put into practical use. In semi-submersible and spar types, which are typical types of floating offshore wind power generation, catenary mooring is basic, but in the tension leg platform (TLP) type, vertical tension mooring has been proposed. This is a method of maintaining restoring force by fixing the mooring means to the seabed and applying tension. Patent Document 1 describes a method in which a sinker and a floating body connected by a mooring means are moved to a predetermined position, then water is injected into the sinker to cause it to sink and the floating body is floated, and when the sinker touches the seabed, the mooring means is tensioned.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in catenary mooring, since the mooring means is arranged in a wide range near the floating body, the influence on ship navigation and fishing is large. In tension mooring, since the mooring means is arranged vertically, the influence on ships etc. is small, and the pitching oscillation of the floating body, which is a factor for automatic stop of the windmill, can also be suppressed, but cost reduction is an issue. For example, in the method of Patent Document 1, it is necessary to manufacture a large-scale sinker in order to inject water into the sinker and secure the reaction force at the seabed.

[0005] This invention has been made in view of the aforementioned problems, and its objective is to provide a method for installing a tension-mooring float and a structure for installing a tension-mooring float that is simple in structure, can reliably secure reaction force, and can be installed at low cost. [Means for solving the problem]

[0006] To achieve the aforementioned objective, the first invention is a method for installing a tension-mooring floating body, comprising the steps of towing the floating body to the installation site with a frame suspended below it, and lowering the frame to the seabed. And then, A method for installing a tension-moored float is characterized by comprising the steps of: moving the float aside while it is connected to the frame by a wire, and installing a weight on the frame from above; and applying tension to the wire to tension-moor the float to the frame.

[0007] In the first invention, the floating body is moved aside while connected to the frame suspended from the seabed by wires, and then the weight is installed on the frame from above. Therefore, the floating body and wires do not interfere with the work of installing the weight on the frame. In addition, the frame itself does not require weight to constitute the gravity foundation, so it is lightweight and easy to handle. According to the first invention, a gravity anchor with a simple structure that can reliably secure the reaction force from the seabed can be installed at low cost, and the floating body can be tensioned and moored.

[0008] It is desirable that one end of the wire is connected to a winding device, at least a portion of the wire is hung on a pulley located near the frame, and the other end is connected to the floating body, and that the frame is lowered to the seabed by feeding out the wire with the winding device, and that tension is applied to the wire by winding it up with the winding device. Alternatively, if water is poured into the floating body to sink the floating body, the wire is wound up or unwound by the winding device to make the wire a predetermined length, and then the water is drained from inside the floating body to raise the floating body and obtain a predetermined tension, the capacity of the winding device can be minimized. By connecting one end of the wire to a winding device, the length and tension of the wire can be easily adjusted. Furthermore, by using a pulley, the tension of two wires can be applied to a single wire.

[0009] The wire, which is suspended on the pulley, may have one side tensioned substantially vertically to the floating body with respect to the pulley, and the other side tensioned diagonally to the floating body with respect to the pulley. This allows the diagonally tensioned wires to function as braces.

[0010] The frame may be divided into multiple parts, and each of the frame parts may be connected to the floating body by the wires. This ensures that the frame can be securely attached to the seabed, even if there are uneven areas on the seabed.

[0011] When the frame is divided into multiple parts, a suspension beam is provided in the frame, and the suspension beam and the frame are connected by a connecting member. Before the weight is placed in the frame, the suspension beam is moved to the side of the frame, and it is desirable to have a connecting member retraction structure so that the connecting member does not overlap the upper part of the frame when the suspension beam is moved. This allows the weight to be installed onto the frame from above without interfering with the connecting members or the suspension beam.

[0012] It is desirable to have a directional restricting structure that controls the orientation of the suspension beam and the frame in water to a constant level, and to be able to restrict the direction in which the suspension beam is retracted relative to the frame when the suspension beam is retracted to the side of the frame. This allows the suspension beam to be positioned and retracted in the desired direction, regardless of the direction of water currents near the seabed.

[0013] The aforementioned weight is, for example, a concrete block having a hook. By using concrete blocks, the durability and weight of the weight can be ensured. In addition, by providing hooks, the installation and removal of the weight from the frame becomes easier. Since the removal of the cone and the frame is also easy, it becomes easy to leave nothing on the seabed when repairing the floating structure or removing it when it is no longer in service.

[0014] The second invention is a tension-mooring floating structure, comprising: a floating body; a frame positioned on the seabed below the floating body; a plurality of wires connecting the floating body and the frame; and a weight positioned on the frame. The aforementioned cone has a shape in which at least one side of a rectangular parallelepiped is cut off to form an inclined surface. This is an installation structure for a tensioned mooring float, characterized in that tension is applied to the aforementioned wire.

[0015] In the second invention, a weight is placed on a frame positioned on the seabed, and the floating body is tension-moored to the frame. Therefore, not only steel wires but also synthetic fiber ropes, which are high-strength, lightweight, and inexpensive but are considered to be weak against friction, can be used as wire materials, as the wire material is not dragged along the seabed. According to the second invention, the floating body can be tension-moored by reliably securing the reaction force from the seabed with a gravity-type anchor of a simple configuration.

[0018] The third invention is a tension-mooring floating structure, comprising a floating body, a frame positioned on the seabed below the floating body, a plurality of wires connecting the floating body and the frame, and a weight positioned on the frame, wherein tension is applied to the wires. The frame is divided into multiple sections, and each section of the frame is connected to the floating body by the wires. The tension mooring float installation structure is characterized in that a suspension beam is provided on the frame, the suspension beam and the frame are connected by a connecting member, and the suspension beam and the connecting member, and the frame and the connecting member are all joined by hinges. The fourth invention is a tension-mooring float installation structure comprising: a float; a frame disposed on the seabed below the float; a plurality of wires connecting the float and the frame; and a weight disposed on the frame, wherein tension is applied to the wires; the frame is divided into a plurality of parts, each of which is connected to the float by the wires; a suspension beam is provided on the frame; the suspension beam and the frame are connected by a connecting member; and the structure has a directional restricting structure that can control the orientation of the suspension beam and the frame in the water to a constant degree, and restrict the direction in which the suspension beam is retracted relative to the frame when the suspension beam is retracted to the side of the frame. According to the third and fourth inventions, Even if there are uneven areas on the seabed, the frame can be securely anchored to the seabed. [Effects of the Invention]

[0019] According to the present invention, it is possible to provide a method for installing a tension-mooring float and a structure for installing a tension-mooring float that are simple in structure, can reliably secure reaction force, and can be installed at low cost. [Brief explanation of the drawing]

[0020] [Figure 1](a) shows the state where the floating body 2 and the frame body 3 are connected; (b) shows the state where the frame body 3 is being moved below the floating body 2; (c) shows the state where the frame body 3 is suspended below the floating body 2. [Figure 2] (a) shows the state where the windmill 7 is mounted on the floating body 2; (b) shows the state where the floating body 2 with the suspended frame body 3 is being towed to the laying location; (c) shows the state where the frame body 3 is suspended to the seabed 1. [Figure 3] (a) shows the state where the concrete sinker 10 is installed on the frame body 3; (b) shows the state where the floating body 2 is tension moored to the frame body 3. [Figure 4] (a) shows the concrete sinker 10; (b) shows the method of installing the concrete sinker 10 on the frame body 3. [Figure 5] Figure showing another suspension jig 9a. [Figure 6] (a) shows the state where the filter unit 10b is installed on the frame body 3; (b) shows the state where the filter unit 10b is installed on the frame body 3. [Figure 7] (a) shows an example of arranging the wire 5a using the pulley 13; (b) shows an example of arranging the wire 5 without using the pulley. [Figure 8] (a) shows the state where the floating body 2 is located above the frame body 3; (b) shows the state where the floating body 2 is retracted from above the frame body 3. [Figure 9] (a) and (b) show an example where the wire 5 and the wire 5b are mixed; (c) shows an example where the wire 5 and the wire 5d are mixed; (d) shows an example where the wire 5 and the wire 5e are mixed. [Figure 10] (a) shows the state where the floating body 2 with the suspended frame body 3a is being towed to the laying location; (b) shows the state where the frame body 3a is lowered to the seabed 1; (c) shows the state where the concrete sinker 10 is installed on the frame body 3a. [Figure 11] (a) is an enlarged view of the range G shown in Fig. 10(a), showing the state where the suspension balance 16 is not retracted; (b) is an enlarged view of the range G2 shown in Fig. 10(c), showing the state where the suspension balance 16 is retracted. [Figure 12](a) is a diagram showing the state in which the suspension beam 16a is not retracted, and (b) is a diagram showing the state in which the suspension beam 16a is retracted. [Modes for carrying out the invention]

[0021] [First Embodiment] Hereinafter, a first embodiment of the present invention will be described in detail with reference to the drawings. Figures 1 to 3 show the installation method of the tension-mooring floating structure, and Figure 4 shows the frame 3 and concrete sinker 10. In the first embodiment, the installation method and installation structure of the tension-mooring floating structure that moors the floating body 2 equipped with a wind turbine 7 to the seabed 1 will be described.

[0022] To install a tension-moored floating structure, first, as shown in Figure 1(a), the floating structure 2 and the frame 3 are connected by wire 5 near the quay. The floating structure 2 is designed to accommodate a wind turbine 7 (Figure 2) of an offshore wind power generation facility. The frame 3 is, for example, a steel truss structure, and corrosion resistance is ensured by heavy corrosion protection or by providing a corrosion allowance. The frame 3 may also be constructed using reinforced concrete slabs or PC slabs. The frame 3 has, for example, a bottom 31 and side 32, and floats on the water surface by attaching multiple floats 4. The wire 5 is, for example, a chain, a rope such as a fiber braided wire, or a wire such as a coated steel strand. One end of the wire 5 is connected to a winding device (winding machine 6) installed on the floating structure 2, and the other end is connected to the frame 3. It is desirable that the wire 5 is locked by the locking mechanism of the winding machine 6 and simultaneously held at a locking point (not shown) provided on the floating structure 2 near the winding machine 6. The wires 5 are positioned one at each of the four corners of the floating body 2 and frame 3, which are rectangular in plan view.

[0023] After connecting the floating body 2 and the frame body 3, the floats 4 are sequentially removed from the frame body 3 as shown in Figure 1(b), and the frame body 3 is lowered below the floating body 2. At this time, a tugboat may be used to support the movement of the frame body 3. Then, the frame body 3 is suspended below the floating body 2 as shown in Figure 1(c). The floating body 2 is designed to float on the water surface with the frame body 3 suspended from it. The wire 5 is adjusted in length by the winding machine 6 to suspend the frame body 3 in the appropriate position underwater.

[0024] Once the frame 3 is suspended from the floating body 2, the wind turbine 7 is mounted onto the floating body 2 using a crane from the land side, as shown in Figure 2(a). Then, the floating body 2 with the frame 3 suspended and the wind turbine 7 mounted is towed to the laying site using a towboat (not shown), as shown in Figure 2(b). Next, the wire 5 is fed out by the winding machine 6, and the frame 3 is lowered to the seabed 1 and settled, as shown in Figure 2(c).

[0025] Once the frame 3 is settled on the seabed 1, the wire 5 connecting the frame 3 and the floating body 2 is further fed out by the winding machine 6, while the floating body 2 is moved away from above the frame 3 by a towboat (not shown) as shown in Figure 3(a). Then, a lifting jig 9 with a concrete block (concrete sinker 10) suspended from it is lowered into the water by a crane barge 8 or the like, and the concrete sinker 10 is installed on the frame 3 from above. The concrete sinker 10 is, for example, a rectangular prism, and positional displacement can be prevented by installing multiple units at once. When installing the concrete sinker 10, it is desirable to monitor the position of the lifting jig 9 and the concrete sinker 10 in real time using the camera of a remotely operated underwater vehicle (ROV27) and guide them onto the frame 3. Note that the monitoring method is not limited to the ROV27's camera; sonar images may be used, or the position may be detected by underwater GPS with a transmitter attached to the lifting jig 9.

[0026] After installing the concrete sinker 10 into the frame 3, the floating body 2 is returned to its upper position above the frame 3 as shown in Figure 3(b) while winding the wire 5 with the winding machine 6. Then, water is poured into the floating body 2 to allow it to sink to an appropriate depth, and the wire 5 is wound up with the winding machine 6 until there is no slack. After that, water is drained from the floating body 2, and buoyancy is generated in the direction of arrow A on the floating body 2, thereby applying tension to the wire 5 in the direction of arrow B, and the floating body 2 is tension-moored to the frame 3, completing the tension-moored floating body installation structure 30.

[0027] As described above, the tension-mooring floating structure 30 installed in the first embodiment uses a gravity-type anchor, which is a frame 3 placed on the seabed 1 below the floating body 2 with a concrete sinker 10 on top. Tension is applied to multiple wires 5 connecting the floating body 2 and the frame 3, thereby tension-mooring the floating body 2. Therefore, the wires 5 are not dragged on the seabed 1, and inexpensive synthetic fiber ropes can be used as wires 5. In addition, by connecting one end of the wires 5 to a winding machine 6, the tension of each wire 5 can be easily adjusted while the tension-mooring floating structure 30 is in use.

[0028] In the first embodiment, when installing the tension-mooring floating structure 30, the floating body 2 is moved away from above the frame 3 while connected to the frame 3 suspended from the seabed 1 by wires 5, and the concrete sinker 10 is installed on the frame 3 from above. Therefore, the floating body 2 and wires 5 do not interfere with the work of installing the concrete sinker 10 on the frame 3. According to the first embodiment, a gravity-type anchor with a simple structure that can reliably secure the reaction force of the seabed 1 can be constructed at low cost, and the floating body 2 can be tension-moored.

[0029] In the first embodiment, one wire 5 was placed near each of the four corners of the rectangular floating body 2 and frame 3 in a plan view, but the number of wires 5 should be determined so as to ensure the necessary tension force. Also, the dimensions and quantity of the concrete sinkers 10 should be determined so as to ensure the reaction force due to the underwater weight required in the design.

[0030] In the first embodiment, water was added to the floating body 2 when it was tensioned and moored to the frame 3, but this operation is not essential. The tension can be adjusted and the floating body 2 tensioned and moored simply by winding the wire 5 with the winding machine 6.

[0031] Furthermore, the shape and installation method of the concrete sinker 10 are not limited to those described above. As shown in Figure 4(a), one side of the bottom surface of the rectangular parallelepiped may be cut to form an inclined surface 12a, and one side of the top surface may be cut to form an inclined surface 12b parallel to the inclined surface 12a.

[0032] When using concrete sinkers 10a, a tapered guide 33 is provided at the upper end of the side portion 32 of one side of the frame 3, as shown in Figure 4(b). When installing the concrete sinkers 10a on the frame 3, the inclined surface 12a is slid along the tapered guide 33 or the inclined surface 12b of the previously installed concrete sinker 10a as shown by arrow C, and then the side portion 12 is slid along the side portion 32 or the side portion 12 of the previously installed concrete sinker 10a as shown by arrow D. This allows the concrete sinkers 10a to be brought into close contact with the frame 3 or the previously installed concrete sinkers 10a and aligned.

[0033] Furthermore, it is desirable that the concrete sinkers 10 and 10a be provided with hooks 11 on their upper surfaces for suspension from the lifting jig 9, as shown in Figure 4(a). Providing hooks 11 makes it easier to lift and remove the concrete sinkers after the wind power generation period of approximately 20 to 25 years has ended.

[0034] The lifting jig 9 is not limited to the one shown in Figure 3. Figure 5 shows another lifting jig 9a. The lifting jig 9a has a rotation control device 19 and a thruster 20. The rotation control device 19 can arbitrarily control the horizontal orientation of the lifting jig 9a, and the thruster 20 can finely adjust the position and orientation of the lifting jig 9a. By remotely controlling the position and orientation of the lifting jig 9a, the concrete sinker 10 can be positioned in the desired orientation even in areas with tidal currents, improving workability.

[0035] The weight is not limited to concrete sinker 10. Figure 6 shows an example in which filter unit 10b is used as the weight. The filter unit 10b is made of crushed stone placed in a mesh bag of synthetic fibers. When using filter unit 10b as the weight, as shown in Figure 6(a), the suspension jig 9 from which the filter unit 10b is suspended is lowered into the water, and the filter unit 10b is installed on the frame 3 from above. The filter units 10b may also be stacked on top of the frame 3 as shown in Figure 6(b).

[0036] Hereinafter, another example of the present invention will be described as the second to fourth embodiments. Each embodiment will be described in terms of how it differs from the embodiments described so far, and similar components will be denoted by the same reference numerals in the figures, etc., and their descriptions will be omitted. Furthermore, the components described in each embodiment, including the first embodiment, can be combined as needed.

[0037] [Second Embodiment] Figure 7(a) shows an example in which the wire 5a is positioned using the pulley 13. The second embodiment differs from the first embodiment mainly in that the wire 5a is connected to the winding machine 6 and the floating body 2.

[0038] As shown in Figure 7(a), the wire 5a is hung on a pulley 13 located near a corner of the frame 3. One end of the wire 5a is connected to the winding machine 6 with respect to the pulley 13, and the other end is connected to the floating body 2 by a fixing part 14.

[0039] In the example shown in Figure 7(a), similar to the first embodiment, the winding machine 6 feeds out the wire 5a to lower the frame 3 to the seabed 1 or to move the floating body 2 away from above the frame 3. The winding machine 6 also winds up the wire 5a to return the floating body 2 to above the frame 3 or to apply tension to the wire 5a. When tensioning and mooring the floating body 2 to the frame 3, the wire 5a is tensioned approximately vertically to the floating body 2 between the pulley 13 and the winding machine 6 and between the pulley 13 and the fixing part 14.

[0040] In the second embodiment, if the required tension cannot be secured with a single wire 5, the required tension can be secured by applying tension to a single wire 5a arranged using a pulley 13. For example, if four wires 5a are arranged using a pulley 13 as shown in Figure 7(a), the same tension can be secured as when eight wires 5 are arranged, with one end connected to the winding machine 6 and the other end connected to the frame 3 by a fixing part 15, as shown in Figure 7(b).

[0041] [Third Embodiment] Figure 8 shows an example in which wires 5b and 5c are arranged using pulley 13. The third embodiment differs from the second embodiment in that one side of the wires 5b and 5c is positioned diagonally to the floating body 2 with respect to pulley 13.

[0042] As shown in Figure 8(a), wires 5b and 5c are hung on pulleys 13 located near the corners of the frame 3. One end of wire 5b is connected to the winding machine 6 relative to the pulley 13, and the other end is connected to the side surface 21b of the floating body 2 by a fixing part 14. One end of wire 5c is connected to the winding machine 6 relative to the pulley 13, and the other end is connected to the side surface 21a of the floating body 2 by a fixing part 14a. The fixing part 14a consists of a main fixing part 29 located near the center of the side surface 21a and temporary fixing parts 28 located near both ends of the side surface 21a. Note that wires 5b connected to the two side surfaces 21b that are the back sides of the floating body 2 are not shown in Figure 8.

[0043] In the example shown in Figure 8, similar to the first embodiment, the winding machine 6 feeds out the wires 5b and 5c to lower the frame 3 to the seabed 1 or to move the floating body 2 away from above the frame 3. The winding machine 6 also winds up the wires 5b and 5c to return the floating body 2 to above the frame 3 or to apply tension to the wires 5b and 5c. When tensioning and mooring the floating body 2 to the frame 3, the wires 5b and 5c are tensioned approximately vertically to the floating body 2 between the pulley 13 and the winding machine 6, and diagonally to the floating body 2 between the pulley 13 and the fixing parts 14 and 14a.

[0044] The wire 5c is connected to the main fixing section 29 as shown in Figure 8(a) when lowering the frame 3 to the seabed or when tensioning and mooring the floating body 2 to the frame 3. When retracting the floating body 2, the wire 5c is connected to the temporary fixing section 28 as shown in Figure 8(b). By connecting the wire 5c to the temporary fixing section 28 and retracting the floating body 2 in the direction of arrow E, the weight can be installed on the frame 3 from above without interfering with the wire 5c.

[0045] In the third embodiment, if the required tension cannot be secured with a single wire 5, the required tension can be secured by applying tension to two wires 5b and 5c arranged using a pulley 13. Furthermore, by tensioning one side of the wires 5b and 5c approximately vertically with respect to the pulley 13 and the other side at an angle, the angled tensioned portion functions as a brace that resists the horizontal force caused by the water flow, thereby stabilizing the installation structure of the tensioned mooring float.

[0046] In the third embodiment, all the wires connecting the floating body 2 and the frame 3 are connected to the pulley 13, but only some of the wires may be connected to the pulley 13. Figure 9 shows an example of wire arrangement. The example shown in Figure 9(a) is suitable for the installation structure of a tension-moored floating body installed in a body of water where the direction indicated by arrow F1 is the main direction of the waves. The pulley 13 is provided near the two corners of the frame 3 that are located upstream of the water flow, and wires 5b are arranged on the two surfaces parallel to arrow F1 among the four surfaces sandwiched between the floating body 2 and the frame 3. Near the remaining two corners of the frame 3, wires 5 are connected that are tensioned approximately vertically. This makes it possible to stabilize the installation structure of the tension-moored floating body against the water flow in the direction indicated by arrow F1.

[0047] The example shown in Figure 9(b) is suitable for the installation structure of a tension-moored floating body installed in a body of water where the direction indicated by arrow F2 is the main wave direction. Two pulleys 13 are provided near one of the four corners of the frame 3 that is located on the upstream side of the water flow, and wires 5b are placed on two orthogonal surfaces on the upstream side of arrow F2, among the four surfaces sandwiched between the floating body 2 and the frame 3. Wires 5 that are tensioned approximately vertically are connected near the remaining three corners of the frame 3. This makes it possible to stabilize the installation structure of the tension-moored floating body against the water flow in the direction indicated by arrow F2.

[0048] The example shown in Figure 9(c) is suitable for the installation structure of a tension-moored floating body installed in a body of water where the direction indicated by arrow F3 is the main wave direction. A pulley 13 is provided near the diagonal corner of the frame 3 in the direction perpendicular to arrow F3. The wire 5d is hung on the pulley 13, with one end connected to the winding machine 6 and the other end connected to the floating body 2. One side of the wire 5d is tensioned approximately vertically to the pulley 13, and the other side is tensioned diagonally so as to cross the space between the floating body 2 and the frame 3. This makes it possible to stabilize the installation structure of the tension-moored floating body against the water flow in the direction indicated by arrow F3.

[0049] Note that the pulley 13 is not essential when tensioning the wire at an angle. As shown in Figure 9(d), it is also possible to provide the wire 5 that is tensioned approximately vertically and the wire 5e that is tensioned at an angle separately. One end of the wire 5e is connected to the winding machine 6 and the other end is connected to the frame 3 by the fixing part 15, and it functions as a brace that resists the horizontal force caused by the water flow.

[0050] [Fourth Embodiment] Figure 10 shows an example using a frame 3a divided into multiple parts, and Figure 11 shows details of the frame 3a. The fourth embodiment differs from the first embodiment mainly in that the frame 3a on which the weight is installed is divided into multiple parts.

[0051] As shown in Figure 10, the frame 3a is divided into multiple sections, and each frame 3a is connected to the floating body 2 by a single wire 5f and suspended from the floating body 2. The wire 5f and the frame 3a are positioned, for example, near the four corners of the floating body 2 and frame 3, which are rectangular in plan view. One end of the wire 5f is connected to a winding machine 6 installed on the floating body 2, and it is hung over the direction regulating structure 23, while the other end is connected to the floating body 2.

[0052] In the fourth embodiment, similar to the first embodiment, the frame 3a is suspended and the floating body 2 on which the wind turbine 7 is mounted is towed to the installation site, as shown in Figure 10(a). Next, the wire 5f is fed out by the winding machine 6, and the frame 3a is lowered, as shown in Figure 10(b), and both are brought to the bottom 1 of the seabed.

[0053] As shown in Figure 11(a), a suspension beam 16 is provided on the frame 3a, and the suspension beam 16 and the side portion 32a of the frame 3a are connected by four connecting members 17. The suspension beam 16 and the connecting members 17, and the side portion 32a and the connecting members 17 are all joined by hinges 18. The hinges 18 rotatably connect the connecting members 17 to the suspension beam 16 and the side portion 32a.

[0054] Furthermore, a directional restricting structure 23 is connected to the suspension beam 16 by four wires 24. The directional restricting structure 23 consists of a horizontal member 26 and pulleys 25 provided at both ends of the horizontal member 26, and is positioned so that the rotation axis of the pulleys 25 is parallel to the rotation axis of the hinge 18. By attaching the wires 5f to the two pulleys 25 of the directional restricting structure 23, when the frame 3a is lowered, the orientation of the suspension beam 16 and the frame 3a in the water can be constantly restricted to match the orientation of the frame 3a when it hits the seabed 1, which is determined considering the water flow, etc.

[0055] Once the frame 3a is set afloat on the seabed 1, the floating body 2 is moved away from above the frame 3a while the wire 5f is further fed out by the winding machine 6, as shown in Figure 10(c). Also, the suspension beam 16 is moved to the side of the frame 3a, as shown in Figure 11(b). The direction of retraction of the floating body 2 is restricted by the pulley 25 of the direction restricting structure 23 in the direction of arrow H in Figure 11(b). Furthermore, the direction of retraction of the suspension beam 16 relative to the frame 3a is restricted so as to substantially coincide with the retraction direction of the floating body 2 by the rotation of the connecting member 17 by the hinge 18. The connecting member 17 can be tilted to the side so as not to interfere with the top of the frame 3a by the connecting member retraction structure, which connects the connecting member 17 to the suspension beam 16 and the frame 3a by the hinge 18.

[0056] After the suspension beam 16 is moved to the side of the frame 3a, the suspension jig 9, from which the concrete sinker 10 (which is the weight) is suspended, is lowered into the water using a crane barge 8 or the like, as shown in Figure 10(c), and the concrete sinker 10 is installed on the frame 3a from above. Then, as in the first embodiment, the floating body 2 is returned to the position above the frame 3a while the wire 5f is wound up with the winding machine 6, and tension is applied to the wire 5f by winding it up with the winding machine 6, thereby tensioning and mooring the floating body 2 to the frame 3a.

[0057] In the fourth embodiment as well, the wire 5f is not dragged on the seabed 1, and inexpensive ropes or the like, which are considered to be susceptible to friction, can be used as the wire 5f. In addition, since the floating body 2 and the suspension beam 16 are moved out of the way, they do not interfere with the work of installing the concrete sinker 10 on the frame 3a. Therefore, similar to the first embodiment, a gravity anchor with a simple structure that can reliably secure the reaction force of the seabed 1 can be constructed at low cost, and the floating body 2 can be tensioned and moored.

[0058] In the fourth embodiment, since the frame 3a is divided into multiple parts, even if there are uneven areas on the seabed 1 as shown in Figure 10, the frame 3a can be reliably brought to rest on the seabed 1 and a reaction force can be secured. Furthermore, by providing a retraction structure for the connecting member 17 and a direction regulating structure 23, the suspension beam 16 and the connecting member 17 can be retracted in a desired direction.

[0059] Note that the divided frame is not limited to those described above. Figure 12 shows the details of the frame 3b. As shown in Figure 12(a), the bottom 31a of the frame 3b and the suspension beam 16a provided above the frame 3b are trapezoidal in plan view. The suspension beam 16a and the side 32a of the frame 3b are connected by four connecting members 17a, which are made of wire. The connecting members 17a can be chains, wires, ropes, etc. In addition, a directional control structure 23 is connected above the suspension beam 16a. The directional control structure 23 is positioned so that the axis of rotation of the pulley 25 is parallel to the bottom 34 of the suspension beam 16a. By hanging the wire 5f on the directional control structure 23, the orientation of the suspension beam 16a and the frame 3b in the water can be controlled to be constant when the frame 3b is lowered.

[0060] Even when using the frame 3b, as shown in Figure 10(c), the floating body 2 is moved away from above the frame 3b while the wire 5f is further fed out by the winding machine 6. Also, as shown in Figure 12(b), the suspension beam 16a is moved to the side of the frame 3b. The direction of retraction of the floating body 2 is restricted by the pulley 25 of the direction restricting structure 23 in the direction of arrow J, that is, from the long side to the short side of the base 34 of the suspension beam 16a. Furthermore, the direction of retraction of the suspension beam 16a relative to the frame 3b is restricted to substantially coincide with the direction of retraction of the floating body 2 by connecting the frame 3b and the suspension beam 16a with four connecting members 17a. The connecting members 17a can be tilted to the side so as not to overlap the top of the frame 3b by the connecting member retraction structure which forms a trapezoid with the suspension beam 16a and the frame 3b.

[0061] The frame 3b may have a projection 22 on the lower surface of its bottom 31a, as shown in Figure 12(a). By providing the projection 22, when the frame 3b is lowered to the seabed 1, the projection 22 penetrates the seabed 1, as shown in Figure 12(b), preventing the frame 3b from shifting position due to water currents. This makes it possible to more reliably ensure that the connecting member retraction structure, which prevents the connecting member 17a from overlapping the upper part of the frame 3b when the suspension beam 16a is retracted, functions correctly.

[0062] Preferred embodiments of the present invention have been described above with reference to the attached drawings, but the present invention is not limited to these examples. It will be obvious to those skilled in the art that various modifications or alterations can be conceived within the scope of the technical idea disclosed herein, and these will naturally also fall within the technical scope of the present invention. [Explanation of Symbols]

[0063] 1……Undersea 2………Floating body 3, 3a, 3b……frame body 4... Float 5, 5a, 5b, 5c, 5d, 5e, 5f……wire rod 6... Winding machine 7……Windmill 8... Crane barge 9, 9a... Lifting fixture 10, 10a... Concrete Shinka 10b… Filter Unit 11…Hook 12, 21a, 21b……side 12a, 12b……slanted surface 13... Pulley 14, 14a, 15...Fixed part 16, 16a... Hanging balance 17, 17a… Connecting members 18... Hinge 19... Rotation control device 20...Thrusters 22……protrusion 23……Direction regulation structure 24……Wire rod 25... Pulley 26……Horizontal material 27...ROV 28... Temporary fixing part 29……Main fixing part 30... Installation structure of tension mooring floats 31, 31a……bottom 32, 32a... Side 33...Tapered guide 34...Bottom

Claims

1. A method for installing a tension-moored floating structure, The process involves towing the floating structure to the installation site with the frame suspended below it, The process involves lowering the frame to the seabed, then retracting the floating body while it is connected to the frame by wire, and then installing the weight onto the frame from above. A step of applying tension to the wire to tension and moor the floating body to the frame, A method for installing a tension-moored floating body, characterized by comprising the following:

2. The aforementioned wire has one end connected to a winding device. At least a portion of the wire is hung on a pulley located near the frame, and the other end is connected to the floating body. The method for installing a tension-mooring floating body according to claim 1, characterized in that the frame is lowered to the seabed by feeding out the wire by the winding device, and tension is applied to the wire by winding up the wire by the winding device.

3. The method for installing a tensioned mooring float according to claim 2, characterized in that the wire material placed on the pulley is tensioned substantially vertically to the float on one side with respect to the pulley, and the other side is tensioned diagonally to the float on the pulley.

4. The method for installing a tension-moored floating body according to claim 1, characterized in that the frame is divided into multiple parts, and each of the frame parts is connected to the floating body by the wire.

5. A balance beam is provided on the frame, and the balance beam and the frame are connected by a connecting member. Before the weight is placed on the frame, the balance beam is moved to the side of the frame. The method for installing a tensioned mooring float according to claim 4, characterized in that it has a connecting member retraction structure so that the connecting member does not overlap the upper part of the frame when the suspension beam is retracted.

6. The suspension beam and the frame have a directional control structure that controls their orientation in water to be constant. The method for installing a tensioned mooring float according to claim 5, characterized in that it is possible to restrict the direction in which the suspension beam is retracted relative to the frame when the suspension beam is retracted to the side of the frame.

7. The method for installing a tension-mooring float according to claim 1, characterized in that the weight is a concrete block having a hook.

8. A tension-mooring floating structure, Floating body and, Below the floating body is a frame placed on the seabed, Multiple wires connecting the floating body and the frame, A weight placed in the frame, It is equipped with, The aforementioned cone has a shape in which at least one side of a rectangular parallelepiped is cut off to form an inclined surface. An installation structure for a tensioned mooring float, characterized in that tension is applied to the aforementioned wire.

9. Installation structure for a tensioned mooring float, Floating body and, Below the floating body is a frame placed on the seabed, Multiple wires connecting the floating body and the frame, A weight placed in the frame, It is equipped with, Tension is applied to the aforementioned wire, The aforementioned frame is divided into multiple parts, Each of the aforementioned frames is connected to the floating body by the aforementioned wires, A suspension beam is provided on the frame, and the suspension beam and the frame are connected by a connecting member. A tension-mooring float installation structure characterized in that the suspension beam and the connecting member, and the frame and the connecting member are all joined by hinges.

10. Installation structure for a tension-mooring floating body, Floating body and, Below the floating body is a frame placed on the seabed, Multiple wires connecting the floating body and the frame, A weight placed in the frame, It is equipped with, Tension is applied to the aforementioned wire, The aforementioned frame is divided into multiple parts, Each of the aforementioned frames is connected to the floating body by the aforementioned wires, A suspension beam is provided on the frame, and the suspension beam and the frame are connected by a connecting member. An installation structure for a tension-mooring float, characterized in that it has a directional restricting structure that can control the orientation of the suspension beam and the frame in water to a constant level, and restrict the direction in which the suspension beam is retracted relative to the frame when the suspension beam is retracted to the side of the frame.

Images