Platform Structure

Abstract

To provide a platform structure that can reduce the risk that floor plates on a platform of an oceanic structure are lost by waves.SOLUTION: A platform structure is constructed on a leg part of an oceanic structure, the platform structure provided with: a frame constructed so as to protrude in a side direction above a sea level from the outer peripheral surface of the leg part; a plate-like grating placed and laid on the frame; and a cable body connecting the grating and the frame. The displacement width of the grating in an upward floating direction above the frame is regulated by the cable body within a width corresponding to a length of the cable body.SELECTED DRAWING: Figure 3

Description

[Technical field]

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

[0002] Conventionally, an offshore wind turbine generator as described in the following Patent Document 1 has been known. In this type of offshore structure, an external platform is provided at the legs of the offshore structure for the purpose of providing an access route for workers from ships at sea, and for the purpose of carrying in, carrying out, and temporarily storing materials. For example, a davit crane for materials is installed on the external platform. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5993756 Summary of the Invention [Problem to be solved by the invention]

[0004] Such an external platform is provided so as to protrude laterally above the sea surface from the legs of the offshore structure. Due to this structure, waves running up from the sea surface along the outer periphery of the legs may collide with the external platform from below, exerting a force that pushes the floor plate of the external platform up from below. If the force acting from such running-up waves is strong, there is a risk that the floor plate will be blown off and lost, for example by falling into the sea.

[0005] The present invention aims to provide a platform structure that reduces the possibility of the decking of an external platform of an offshore structure being lost due to waves. [Means for solving the problem]

[0006] The platform structure of the present invention is a platform structure provided on the leg of an offshore structure, and comprises a frame constructed to protrude laterally above sea level from the outer circumferential surface of the leg, a plate-shaped grating placed and laid on the frame, and a rope connecting the grating to the frame, and the displacement width of the grating in the direction of floating upward from the frame is restricted by the rope to a width corresponding to the length of the rope.

[0007] The platform structure of the present invention is a platform structure provided on the leg of an offshore structure, and comprises a frame constructed to extend laterally above sea level from the outer circumferential surface of the leg, a plate-shaped grating placed and laid on the frame, and a hinge joint portion which hinges the grating to the frame and serves as the center of rotation of the grating in the direction of floating upward from the frame.

[0008] The platform structure of the present invention may further include a rope connecting the grating and the frame at another location of the hinge joint, and the rotation range of the grating in the direction of floating upward from the frame may be restricted by the rope to a rotation range corresponding to the length of the rope.

[0009] The platform structure of the present invention may further comprise a frangible bolt that fastens the grating to the frame and has a frangible portion that breaks when a predetermined upward force is applied to the grating. Effect of the Invention

[0010] According to the present invention, it is possible to provide a platform structure that reduces the possibility that the floor plate of an external platform of an offshore structure will be lost due to waves. [Brief description of the drawings]

[0011] [Figure 1] 1 is a front view of a wind power generator to which the platform structure of this embodiment is applied. [Diagram 2]FIG. 2 is an enlarged perspective view showing the vicinity of the platform of the wind power generator. [Diagram 3] FIG. 13 is a cross-sectional view showing the passageway of the external platform. [Figure 4] FIG. 4 is a plan view of the external platform of FIG. 3. [Diagram 5] 1A is an exploded perspective view of a bolt fastening portion in a passage portion, and FIG. 1B is a side view of a bolt used in the bolt fastening portion. [Figure 6] 11 is a perspective view showing the vicinity of a wire connection portion in the passage portion as viewed from below. FIG. [Figure 7] 1A is a cross-sectional view showing the grating of the passage section of this embodiment when it is subjected to run-up waves, FIG. 1B is a cross-sectional view showing the grating of the passage section of a modified example when it is subjected to run-up waves, and FIG. 1C is a cross-sectional view showing the grating of the passage section of another modified example when it is subjected to run-up waves. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of a platform structure according to the present invention will be described in detail with reference to the drawings. In the following description, the same or corresponding elements are given the same reference numerals in the drawings, and duplicated descriptions will be omitted as appropriate. In addition, the drawings may be simplified or exaggerated for ease of understanding, and the dimensional ratios and the like are not limited to those shown in the drawings.

[0013] Fig. 1 is a front view showing a wind turbine generator 1 as an example of an offshore structure to which the platform structure of this embodiment is applied. As shown in the figure, the wind turbine generator 1 is installed, for example, on the seabed B, and performs offshore wind power generation. However, the wind turbine generator 1 is not limited to being installed on the ocean, and may be installed, for example, in a lake or a river. The wind turbine generator 1 includes legs 41 that extend vertically protruding from the seabed B above the seawater surface, and a generator body 42 attached to the upper end of the legs 41.

[0014] The generator body 42 includes a nacelle 5 and blades 6 attached to the nacelle 5. A generator, a speed increaser, and the like are housed inside the nacelle 5, and for example, a rotor shaft protrudes from the speed increaser to the outside of the nacelle 5. The blades 6 are fixed to the rotor shaft of the nacelle 5. The wind power generator 1 includes, for example, three blades 6. When the blades 6 rotate in response to the wind, this rotation is increased to a certain rotation speed by an amplifier inside the nacelle 5, and this rotational motion is converted into electric power by the generator inside the nacelle 5. For example, the nacelle 5 includes a wind vane and anemometer, and efficient power generation is performed by controlling the orientation of the rotor and the angle of the blades 6 in response to the wind speed and wind direction.

[0015] The leg 41 comprises a foundation 2 which is a monopile driven into the seabed B, a transition piece 3 connected above the foundation 2, and a tower 4 connected further above the transition piece 3. The main bodies of the foundation 2, the transition piece 3, and the tower 4 each have a roughly circular cross section and are arranged coaxially in the vertical direction. Note that the foundation 2 may comprise a tripile-type offshore wind power foundation or a jacket-type offshore wind power foundation instead of a monopile foundation type, and the type of foundation is not particularly limited.

[0016] The upper end of the foundation 2 is located below sea level and has a tapered shape. The lower end of the transition piece 3 has a conical inner surface corresponding to the tapered shape of the upper end of the foundation 2, and the transition piece 3 is installed on the foundation 2 so that the lower end is covered by the upper end of the foundation 2. During construction, the verticality of the transition piece 3 is adjusted on the foundation 2, and grout is filled between the lower end of the transition piece 3 and the upper end of the foundation 2. The foundation 2 and the transition piece 3 are joined (grout jointed) via this grout, and the verticality of the transition piece 3 is ensured, and thus the verticality of the wind turbine 1 is also ensured. The tower 4 is, for example, a vertical column made of concrete or steel, and is bolted to the upper end of the transition piece 3.

[0017] FIG. 2 is an enlarged perspective view of the vicinity of the bolted joint between the transition piece 3 and the tower 4. As shown in FIG. 2, inside the transition piece 3, a multi-layered internal platform 9 for operating and managing the wind power generator 1 is provided. An operator can move between the internal platforms 9 via a ladder or the like. Furthermore, at the upper end of the transition piece 3, an external platform 10 is provided that extends horizontally outward from the outer peripheral surface 3a. Furthermore, at the lower end of the tower 4 that is bolted to the transition piece 3, an entrance / exit 11 for entering and exiting the inside of the tower 4 is provided. An operator who operates and manages the wind power generator 1 moves to the external platform 10 via a ladder from a ship moored at the landing 51 (FIG. 1) near the sea surface. Then, the operator opens the door of the entrance / exit 11 to enter the inside of the tower 4, and can further access the internal platform 9 via an internal ladder or the like. The external platform 10 is used not only as an access route for workers as described above, but also for purposes such as carrying in and out materials and temporarily storing them. For example, a davit crane (not shown) is installed on the external platform 10.

[0018] Next, the external platform 10 will be described in more detail. As described above, the external platform 10 is provided so as to protrude laterally above the seawater level W from the outer peripheral surface 3a of the transition piece 3 of the offshore wind turbine 1. Note that the "seawater level W" here means the mean seawater level. A flat grating (lattice plate) is used as the floor plate of the external platform 10 to improve drainage and prevent the formation of puddles, and most of the underside of the grating is directly exposed to the seawater level W. The floor of the external platform 10 is formed by laying multiple such gratings closely together with no gaps.

[0019] In the following, the structure of a passage section 10A (FIG. 2) which is relatively narrow among the external platform 10 will be described as an example. FIG. 3 is a cross-sectional view showing the passage section 10A, in which the radial direction of the transition piece 3 is the left-right direction in the figure, and the circumferential direction is the direction perpendicular to the plane of the figure. FIG. 4 is a plan view of the passage section 10A. In the following, when the terms "radial direction" and "circumferential direction" are simply used, they will mean the radial direction and circumferential direction of the transition piece 3.

[0020] The passage section 10A of the external platform 10 includes a frame 55 constructed so as to protrude laterally above the seawater surface from the outer peripheral surface 3a, and a plurality of plate-shaped gratings 57 placed and laid on the frame 55. In this embodiment, a GRP grating made of GRP (glass fiber reinforced plastic) is used as the grating 57 to prevent corrosion in a marine environment. The frame 55 includes two beams 59, 61 extending circumferentially concentrically with the transition piece 3 on the outer peripheral side of the outer peripheral surface 3a, a handrail 63 attached to the outer peripheral surface of the beam 61 and rising upward, and a plurality of beams 65 extending radially to connect the beams 59 and 61. The beams 59, 61, 65 are made of square steel pipes. Support beams 67 for supporting the frame 55 from below are provided so as to extend radially at intervals in the circumferential direction from the outer peripheral surface 3a of the transition piece 3. The frame 55 is supported by the transition piece 3 with the lower surface of the beam 59 abutting against the upper surface of the support beam 67. The support beam 67 and the beam 59 are connected to each other using a predetermined bolt or the like.

[0021] The upper surfaces of the beams 59, 61, and 65 are formed flush, and the grating 57 is placed so as to abut against these upper surfaces. The grating 57 is fan-shaped in plan view, and the radial width of the grating 57 is approximately the same as the width of the passage section 10A. The grating 57 is laid almost without gaps in the circumferential direction to form the floor of the passage section 10A. The grating 57 is sandwiched radially between the outer peripheral surface 3a and the handrail 63, so that radial displacement is restricted. The beams 59 and 61 are disposed at intervals in the radial direction, and the beams 65 are disposed at intervals in the circumferential direction. The lower surface of the grating 57 is exposed vertically downward to the seawater surface W side through the gaps between these beams.

[0022] As shown in Fig. 4, the passage portion 10A is provided with bolt fastening portions 77 that bolt-fasten the grating 57 to the frame 55. One grating 57 is fixed to the frame 55 by five bolt fastening portions 77. Four of the bolt fastening portions 77 are arranged so as to straddle the boundary between two gratings 57 adjacent in the circumferential direction, and are involved in fastening the two gratings 57. The other bolt fastening portion 77 is provided on the beam 59 at the circumferential center of the grating 57.

[0023] As shown in FIG. 5(a), the bolt fastening portion 77 at the circumferential center has a bolt receiving portion 77e welded to the upper surface of the beam 59, a fastening plate 77b installed on the upper surface of the grating 57, and a bolt 77a that penetrates the fastening plate 77b and the grating 57 and is screwed into the bolt receiving portion 77e. The upper surface of the grating 57 is provided with a recess 77c for embedding the fastening plate 77b and a through hole 77d for inserting the bolt receiving portion 77e. The head of the bolt 77a has the configuration of a conical head of a countersunk bolt, and a conical counterbore hole into which the head of the bolt 77a is embedded is formed on the upper surface of the fastening plate 77b. With these configurations, the fastening plate 77b and the bolt 77a do not protrude from the surface of the grating 57 in the bolt fastening portion 77.

[0024] The bolt 77a is a fragile bolt that is intentionally manufactured to be easily broken, and the bolt 77a is provided with a fragile portion that is relatively easily broken by axial tensile force. Specifically, as shown in FIG. 5(b), the bolt 77a has a narrowed portion 78b between the head 78a and the threaded portion 78c, the narrowed portion 78b having a smaller diameter than the threaded portion 78c, formed as the fragile portion. When excessive tensile force acts on the bolt 77a in the axial direction, the narrowed portion 78b breaks and the bolt 77a loses its fastening force. Such a bolt 77a may be manufactured by forming the narrowed portion 78b by cutting a commercially available flat head bolt. According to this configuration, when a predetermined upward force acts on the grating 57, the bolt 77a breaks, and the fixation of the grating 57 at the bolt fastening portion 77 is released. Then, when the fixation of the five bolt fastening portions 77 is released, the grating 57 can be displaced upward against its own weight by the upward force.

[0025] Furthermore, in the passage 10A, a hinge joint 75 is provided that hinge-joins the grating 57 to the frame 55. As shown in Figures 3 and 4, the hinge joint 75 connects the outer peripheral edge of the grating 57 to the upper surface of the beam 61. The hinge axis of the hinge joint 75 extends horizontally and extends in the vertical direction in Figure 4 near the outer peripheral edge of the grating 57. If the bolt fastening part 77 did not exist, the grating 57 would be able to rotate around the hinge joint 75 in a direction floating upward from the frame 55 (counterclockwise in Figure 3).

[0026] Furthermore, in the passage 10A, the grating 57 and the frame 55 are connected by a cable. Specifically, as shown in FIG. 6, a wire connection portion 71 is provided that connects the grating 57 and the frame 55 with a wire 71c. The wire connection portion 71 is provided at four locations for one grating 57, and is disposed at a position away from the hinge axis of the hinge joint portion 75 described above. The wire connection portion 71 includes a perforated piece 71a attached to the lower surface of the grating 57 near the beam 65, a perforated piece 71b fixed to the side surface of the beam 65 by, for example, welding, and a wire 71c that connects the perforated pieces 71a and 71b together.

[0027] The wire 71c is longer than the distance between the perforated pieces 71a and 71b, and connects the perforated pieces 71a and 71b in a slack state. Therefore, if the bolt fastening portion 77 does not exist, the grating 57 can be displaced in a direction floating upward from the frame 55 at the position of the wire connection portion 71, with the height at which the wire 71c becomes taut as the upper limit. In other words, at the position of the wire connection portion 71, the displacement width of the grating 57 in the direction floating upward from the frame 55 is restricted to a width corresponding to the length of the wire 71c. The displacement width of the grating 57 is set, for example, so that the floating grating 57 does not exceed the height of the handrail 63. In the passage portion 10A, four wire connection portions 71 are provided for one grating 57 at positions away from the hinge axis of the hinge joint portion 75 described above.

[0028] The effects of the external platform 10 as described above will be described. As described above, the passage 10A of the external platform 10 protrudes laterally from the outer peripheral surface 3a, and most of the lower surface of the floor plate of the grating 57 is directly exposed to the seawater surface W. Due to this structure, waves running up from the seawater surface W along the outer peripheral surface 3a of the transition piece 3 may collide with the grating 57 from below, and in this case, a force that pushes the grating 57 up from below acts on it. If the force acting from such running-up waves is strong, there is a risk of problems occurring, such as damage to the grating 57, damage to the frame 55, or the grating 57 being blown off and falling into the sea and being lost.

[0029] In particular, in this type of external platform 10, a grating with a relatively small opening ratio may be adopted in order to prevent trouble such as objects falling through the lattice of the grating 57 to below the external platform 10. For example, in this embodiment, a GRP grating is adopted as described above, and therefore the opening ratio is relatively small compared to a metal grating. A large force from run-up waves is particularly likely to act on such a grating 57 with a small opening ratio.

[0030] In contrast, in the external platform 10 of this embodiment, when a force stronger than a predetermined value due to run-up waves acts on the grating 57, an excessive tensile force acts on the bolts 77a of the bolt fastening parts 77, causing the constricted parts 78b to break. When the bolts 77a break in all five bolt fastening parts 77, the fixation of the grating 57 by the bolt fastening parts 77 is released, as shown in Fig. 7(a). Then, the grating 57 rotates upward around the hinge joint part 75 within the rotation range allowed by the wire connection part 71 due to the force of the run-up waves so as to float up.

[0031] As a result, the grating 57 receives run-up waves along the nearly vertical outer peripheral surface 3a in an inclined position. Also, the run-up waves are more likely to pass through the gaps between the grating 57 and the outer peripheral surface 3a and the gaps between the gratings 57. Therefore, the grating 57 can deflect the force of the run-up waves. By deflecting the force of the run-up waves in this way, damage to the grating 57 and damage to the frame 55 can be suppressed. Also, since the grating 57 is connected to the frame 55 at the hinge joint 75 and the wire connection 71, the possibility of the grating 57 being separated from the frame 55 is suppressed, and for example, the possibility of the grating 57 falling into the sea and being lost can be reduced.

[0032] In addition, due to the presence of the wire connection part 71, the rotation of the grating 57 about the hinge joint part 75 occurs within the range of the rotation width allowed for the wire connection part 71, so that the possibility of the grating 57 colliding with and damaging the handrail 63 or the like due to excessive rotation can be reduced. In addition, due to the presence of the bolt fastening part 77, when there are no strong run-up waves as described above, the grating 57 is stably fixed to the frame 55, and it is possible to prevent the grating 57 from moving inadvertently within the external platform 10. In this way, the breaking strength of the bolt 77a is designed within a range in which the bolt 77a does not break so that the grating 57 does not move inadvertently under normal circumstances, and the bolt 77a breaks when the grating 57 receives the force of the run-up waves that should be deflected.

[0033] Here, even if it is permissible for the grating 57, which has been lifted up by the run-up waves, to collide with the handrail 63, it is undesirable for the grating 57 to collide with the transition piece 3. In particular, in the bolted joint between the transition piece 3 and the tower 4 described above, the flange 3b at the upper end of the transition piece 3 is butted against the flange at the lower end of the tower 4 and bolted vertically. Therefore, a large number of bolts (not shown) related to the fixing of the tower 4 are fastened to the flange 3b, and the flange 3b is a particularly important part. It is particularly undesirable for the grating 57 to collide with such a flange 3b.

[0034] In contrast, in the external platform 10, the hinge joint 75 is provided on the outer peripheral edge of the grating 57. With this structure, as shown in Fig. 7(a), the grating 57 rotates upward around the outer peripheral edge. Even if this rotation causes the grating 57 to interfere with the handrail 63, it does not interfere with the transition piece 3, and in particular does not interfere with the flange 3b. Therefore, with the above structure, it is possible to prevent the grating 57 from colliding with the transition piece 3, and in particular with the flange 3b, due to run-up waves.

[0035] The bolt fastening portion 77 may be omitted from the external platform 10. In this case, the above-mentioned advantageous effect is achieved, that is, run-up waves are diverted by the hinge joint portion 75 and the wire connection portion 71 without going through the process of breaking the bolt 77a.

[0036] In addition, the hinge joint 75 may be omitted in the external platform 10. In this case, after the grating 57 receives a strong run-up wave and the bolt 77a breaks, the grating 57 floats upward within the range allowed by the wire connection part 71 (within the range corresponding to the length of the wire 71c) as shown in FIG. 7(b). This makes it easier for the run-up wave to pass through the gap between the grating 57 and the outer peripheral surface 3a and the gap between the gratings 57, so that the grating 57 can deflect the force of the run-up wave, and damage to the grating 57 and the frame 55 can be suppressed. In order to efficiently obtain such an effect, it is preferable that the wire connection part 71 is provided at three or more places for one grating 57. In addition, the possibility that the grating 57 will separate from the frame 55 is suppressed, and for example, the possibility that the grating 57 will fall into the sea and be lost can be reduced. In order to efficiently obtain this effect, the wire connection portion 71 (particularly the wire 71c) is designed to have a strength that will not break due to the force of the expected run-up waves. Furthermore, the bolt fastening portion 77 may be omitted. In this case, the above effect is obtained without going through the process of the bolt 77a breaking.

[0037] Here, the lengths of the wires 71c at the four wire connection parts 71 may be changed to change the variation width (lift width) of the grating 57 at each position. With this configuration, the grating 57 that is lifted up by receiving strong run-up waves is likely to assume an inclined posture. Since the grating 57 receives the run-up waves along the substantially vertical outer peripheral surface 3a in an inclined posture, the force of the run-up waves is more efficiently deflected.

[0038] As described above, the displacement width of the grating 57 due to run-up waves can be adjusted by the length of the wires 71c, and it is preferable that the lengths of the wires 71c at the four wire connection parts 71 are adjusted so that the displaced grating 57 does not reach the transition piece 3 (particularly the flange 3b). This prevents the grating 57 from colliding with the transition piece 3, particularly the flange 3b, due to run-up waves.

[0039] Also, for example, the wires 71c of the two wire connection parts 71 on the outer periphery out of the four locations may be adjusted to be shorter than the wires 71c of the two wire connection parts 71 on the inner periphery. In this case, similar to the rotation of the grating 57 about the hinge joint part 75 (see FIG. 7(a)), the grating 57 rotates and tilts counterclockwise in FIG. 7(b), so that the grating 57 is prevented from colliding with the transition piece 3, in particular the flange 3b.

[0040] In addition, the wire connection part 71 may be omitted in the external platform 10. In this case, after the grating 57 receives a strong run-up wave and the bolt 77a breaks, as shown in FIG. 7(c), the grating 57 rotates so as to float upward about the hinge joint part 75. As a result, the grating 57 receives the run-up wave along the substantially vertical outer peripheral surface 3a in an inclined position. In addition, the run-up wave is more likely to pass through the gap between the grating 57 and the outer peripheral surface 3a and the gap between the gratings 57. Therefore, the grating 57 can deflect the force of the run-up wave, and damage to the grating 57 and damage to the frame 55 can be suppressed. In addition, the possibility that the grating 57 will separate from the frame 55 is suppressed, and for example, the possibility that the grating 57 will fall into the sea and be lost can be reduced. In addition, the bolt fastening part 77 may be further omitted here. In this case, the above-mentioned action and effect are achieved without going through the process of breaking the bolt 77a.

[0041] Furthermore, in the external platform 10, the hinge joint 75 and the wire connection 71 may be omitted. In this case, the bolt fastening portion 77 can prevent the grating 57 from moving unintentionally under normal circumstances. When the grating 57 receives a strong run-up wave, the bolt 77a breaks and the grating 57 floats up, thereby preventing damage to the grating 57 and the frame 55.

[0042] The present invention can be implemented in various forms including the above-described embodiment and various modifications and improvements based on the knowledge of those skilled in the art. It is also possible to configure modified examples by utilizing the technical matters described in the above-described embodiment. The configurations of each embodiment may be used in appropriate combination.

[0043] For example, in the above embodiment, an example is described in which the structure of the present invention is applied to the passage portion 10A, which has a relatively narrow width, of the external platform 10, but the present invention can be similarly applied to other portions of the external platform 10. However, in the passage portion 10A, since the grating 57 is disposed at a position relatively close to the outer peripheral surface 3a, the grating 57 is highly likely to be subjected to strong run-up waves, and therefore it is highly necessary to apply the structure of the present invention. Also, in the above embodiment, an example is described in which the dock structure and dock repair method of the present invention are applied to the offshore wind power generator 1, but the present invention can be applied to other offshore structures. [Explanation of symbols]

[0044] 1...offshore wind turbine (offshore structure), 3...transition piece, 3a...outer surface, 10...external platform, 41...leg, 55...frame, 57...grating, 71c...wire, 75...hinge joint, 77a...bolt (weak bolt), 78b...constricted portion (weak portion), W...sea surface.

Claims

1. A platform structure provided on a leg of an offshore structure, A frame constructed so as to protrude laterally above sea level from the outer circumferential surface of the leg; A plate-shaped grating placed and laid on the frame; A rope body connecting the grating and the frame, A platform structure in which the displacement width of the grating in the direction floating upward from the frame is restricted by the rope to a width corresponding to the length of the rope.

2. A platform structure provided on a leg of an offshore structure, A frame constructed so as to protrude laterally above sea level from the outer circumferential surface of the leg; A plate-shaped grating placed and laid on the frame; A platform structure comprising: a hinge joint portion that hinges the grating to the frame and serves as a rotation center of the grating in a direction floating upward from the frame.

3. Further, a rope is provided connecting the grating and the frame at another location of the hinge joint, 3. The platform structure according to claim 2, wherein the range of rotation of the grating in a direction floating upward from the frame is restricted by the rope to a range of rotation corresponding to the length of the rope.

4. The platform structure according to any one of claims 1 to 3, further comprising a fragile bolt that fastens the grating to the frame and has a fragile portion that breaks when a predetermined upward force acts on the grating.

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