Floating body-type base isolation system and adjustment method for floating body-type base isolation system

Abstract

This floating body-type base isolation system 100 comprises: a floating body-type structure 110 that is disposed so as to float in a liquid; mooring parts 120 that are provided around the floating body-type structure 110 and erected in the vertical direction; and mooring cables 130 that have one end side connected to the floating body-type structure 110 and the other end side connected to the mooring parts 120, and on which a tensile load acts.

Description

Floating body type seismic isolation system and adjustment method for floating body type seismic isolation system

[0001] The present disclosure relates to a floating body type seismic isolation system and an adjustment method for the floating body type seismic isolation system. This application claims the benefit of priority based on Japanese Patent Application No. 2024-170018 filed on September 30, 2024, the content of which is incorporated herein by reference.

[0002] Conventionally, a floating body type seismic isolation system using liquid has been developed. As a floating body type seismic isolation system, for example, Patent Document 1 discloses a technique in which the foundation of a structure is used as a floating body, water storage is interposed between the floating body and the ground, and the structure is supported above the ground by the buoyancy of the floating body. Further, in the technique of Patent Document 1, one end side of a non-linear spring member is connected to the floating body, and the other end side of the non-linear spring member is connected to a winding device provided on the ground, thereby ensuring both seismic isolation performance and stability during strong winds.

[0003] Japanese Patent Application Laid-Open No. 2000-352064

[0004] In the technique of Patent Document 1 described above, there is a risk that an excessive load, for example, a load on the order of several hundred tons dynamically, may be applied to the winding device during an earthquake or strong wind. For this reason, it is necessary to set the load-bearing capacity of the winding device to several hundred tons or more, and there is a problem that the cost required for strengthening the strength of the winding device itself and the support base that supports the lower part of the winding device becomes extremely large.

[0005] In view of such problems, an object of the present disclosure is to provide a floating body type seismic isolation system and an adjustment method for the floating body type seismic isolation system that can achieve both seismic isolation performance and stability during strong winds at low cost.

[0006] In order to solve the above problems, a floating body type seismic isolation system according to an aspect of the present disclosure includes a floating body type structure that is arranged to float in a liquid, a mooring part that is provided around the floating body type structure and erected in the vertical direction, and a mooring cable having one end side connected to the floating body type structure and the other end side connected to the mooring part, on which a tensile load acts.

[0007] The spring constant of the mooring rope may be set such that the natural period of the mooring system, including the floating structure and the mooring rope, is different from the natural period of the floating structure, the natural period of the equipment mounted on the floating structure, and the natural period of the system that responds to seismic waves.

[0008] The tensile load acting on the mooring ropes may be set such that the natural period of the mooring system, including the floating structure and the mooring ropes, is different from the natural period of the floating structure, the natural period of the equipment mounted on the floating structure, and the natural period of the system that responds to seismic waves.

[0009] The floating structure and mooring section may be arranged such that the other end of the mooring rope is positioned higher than one end.

[0010] The floating structure may be equipped with multiple mooring lines and have a first surface extending vertically and a second surface extending vertically and located on the back side of the first surface. One end of the first mooring line may be connected to the first surface of the floating structure, and one end of a second mooring line, which is different from the first mooring line, may be connected to the second surface of the floating structure.

[0011] The mass of the mooring rope may be less than the tensile load acting on it.

[0012] The mooring rope may have a first rope section, one end of which is connected to a floating structure and the other end of which is connected to a movable pulley, and a second rope section, which is wrapped around the movable pulley, one end of which is connected to a first location of the mooring section and the other end of which is connected to a second location of the mooring section that is different from the first location.

[0013] The mooring section may be columnar in shape.

[0014] The mooring section may be a mooring bit, and the mooring cable may be connected to the mooring bit by being wound around it.

[0015] To solve the above problems, a method for adjusting a floating seismic isolation system according to one aspect of the present disclosure comprises a floating structure that is floated and positioned on a liquid, a mooring section provided around the floating structure and erected vertically, and a mooring rope having one end connected to the floating structure and the other end connected to the mooring section, to which a tensile load is applied, and the method for adjusting a floating seismic isolation system comprises determining a spring constant of the mooring rope such that the natural period of the mooring system including the floating structure and the mooring rope is different from the natural period of the floating structure, the natural period of the equipment mounted on the floating structure, and the natural period of the system that responds to seismic waves, and adjusting the tensile load applied to the mooring rope so that the determined spring constant is obtained.

[0016] According to this disclosure, it is possible to achieve both seismic isolation and stability against strong winds at a low cost.

[0017] Figure 1 is a schematic diagram of a floating seismic isolation system according to an embodiment of the present disclosure. Figure 2 is a view of the floating seismic isolation system according to the same embodiment from above. Figure 3 is a first diagram showing an adjustment method for the floating seismic isolation system according to the same embodiment. Figure 4 is a second diagram showing an adjustment method for the floating seismic isolation system according to the same embodiment. Figure 5 is a schematic diagram of a floating seismic isolation system according to a first modification. Figure 6 is a schematic diagram of a floating seismic isolation system according to a second modification.

[0018] Embodiments of this disclosure will be described in detail below with reference to the attached drawings. The dimensions, materials, and other specific numerical values ​​shown in the embodiments are merely examples for the purpose of facilitating understanding and do not limit this disclosure unless otherwise specified. In this specification and in the drawings, elements having substantially the same function or configuration are denoted by the same reference numerals to avoid redundant explanations. Elements not directly related to this disclosure are omitted from the illustrations.

[0019] [1. Overview of the Floating Seismic Isolation System] First, an overview of the floating seismic isolation system 100 according to the embodiment of this disclosure will be described with reference to Figure 1. Figure 1 is a schematic diagram of the floating seismic isolation system 100 according to the embodiment of this disclosure. Figure 2 is a view of the floating seismic isolation system 100 according to the embodiment of this disclosure from above. In Figures 1 and 2, the vertically intersecting X-axis (horizontal direction), Y-axis (horizontal direction), and Z-axis (vertical direction) are defined as shown. Also, in Figure 1, the hoisting machine 150 is omitted for ease of understanding.

[0020] As shown in Figures 1 and 2, the floating seismic isolation system 100 according to this embodiment comprises a floating structure 110, a mooring section 120, and a mooring rope 130.

[0021] The floating structure 110 is positioned to float on the liquid L. The floating structure 110 is positioned to float on the liquid L stored in the liquid storage section 20, for example. The liquid storage section 20 is provided in a hole or depression formed by digging the ground 10, for example. The liquid storage section 20 has a wall section 22. The liquid storage section 20 stores the liquid L in a storage space partitioned by the inner wall of the wall section 22. The floating structure 110 is positioned at a distance from the inner wall of the wall section 22 of the liquid storage section 20.

[0022] Liquid L is, for example, water. However, it is not limited to this, and liquid L may be any other liquid besides water, or it may be another liquid with water as its main component (for example, seawater). Furthermore, the floating structure 110 may be floated and positioned on seawater in the ocean, lake water in a lake, swamp water in a marsh, or pond water.

[0023] The floating structure 110 is, for example, a floating nuclear power plant. However, it is not limited to this, and the floating structure 110 may be a structure of other plants such as a wind power plant, a wave power plant, or a solar power plant, or any other structure on which any equipment is mounted.

[0024] The floating structure 110 is preferably provided with one or more gas-containing spaces 112. A gas G is contained within the gas-containing space 112. In the example shown in Figure 1, the gas-containing space 112 is formed by a depression approximately in the center of the bottom surface of the floating structure 110. The gas G contained within the gas-containing space 112 comes into contact with the liquid L. The gas-containing space 112 only needs to be provided in a location that comes into contact with the liquid L and be sealed; it does not need to be formed in the floating structure 110. For example, the gas-containing space 112 may be provided in the liquid L or in the liquid storage section 20. The gas G contained within the gas-containing space 112 may be, for example, air or nitrogen.

[0025] The volume of the gas containment space 112 is set based on the natural period A of the system that responds to seismic waves propagating through a fluid containing liquid L and gas G. Preferably, the volume of the gas containment space 112 is set so that the natural period A of the system that responds to seismic waves is different from the natural period B of the floating structure 110 and the natural period C of the equipment mounted on the floating structure 110. For example, the volume of the gas containment space 112 is set so that the natural period A of the system that responds to seismic waves is smaller than the natural period B of the floating structure 110 and the natural period C of the equipment mounted on the floating structure 110. Note that the natural period C of the equipment mounted on the floating structure 110 is shorter than the natural period B of the floating structure 110. For example, the volume of the gas containment space 112 is set so that the natural period A of the system that responds to seismic waves is less than 1 Hz. The system that responds to seismic waves includes a floating structure 110, liquid L, and gas G.

[0026] The mooring section 120 is provided around the floating structure 110. The mooring section 120 is erected vertically (in the -Z direction in Figures 1 and 2). The mooring section 120 is erected vertically (in the -Z direction in Figures 1 and 2) from, for example, the upper surface of the wall 22 of the liquid storage section 20, or from the ground 10. As shown in Figures 1 and 2, the mooring section 120 is, for example, columnar. In this embodiment, the mooring section 120 is a mooring bit. A mooring bit is also called a bollard or mooring post and is generally used for mooring ships. A single mooring bit may consist of one post, or it may consist of a pair of posts (double mooring posts). The mooring section 120 may also include, for example, an eye plate provided on the post and a shackle connected to the eye plate. The eye plate is a metal member with a through hole formed in it. The shackle is an annular metal component that is inserted through the eye plate. The mooring section 120 can be any vertically erected structure, and its shape is not limited to a columnar shape; for example, it may be a wall.

[0027] Furthermore, in this embodiment, the floating seismic isolation system 100 includes a plurality of mooring sections 120. The plurality of mooring sections 120 are arranged to surround the floating structure 110. For example, as shown in Figure 2, in this embodiment, the floating seismic isolation system 100 includes eight mooring sections 120a, mooring section 120a, mooring section 120b, mooring section 120b, mooring section 120c, mooring section 120c, mooring section 120d, and mooring section 120d.

[0028] For example, as shown in Figure 2, if the horizontal cross-sectional shape of the floating structure 110 is rectangular, the floating structure 110 has four faces extending in the vertical direction (Z direction in Figures 1 and 2), namely, a front face 114a, a back face 114b, a left side face 114c, and a right side face 114d. The back face 114b (second face) is located behind the front face 114a (first face). The front face 114a and the back face 114b are, for example, approximately parallel. The left side face 114c (second face) is located behind the right side face 114d (first face). The left side face 114c and the right side face 114d are, for example, approximately parallel.

[0029] If the horizontal cross-sectional shape of the floating structure 110 is rectangular, mooring sections 120a, 120a are provided at positions facing the front surface 114a. Mooring sections 120b, 120b are provided at positions facing the rear surface 114b of the floating structure 110. Mooring sections 120c, 120c are provided at positions facing the left side surface 114c of the floating structure 110. Mooring sections 120d, 120d are provided at positions facing the right side surface 114d of the floating structure 110.

[0030] The mooring rope 130 is connected at one end to the floating structure 110 and at the other end to the mooring section 120. A tensile load is applied to the mooring rope 130. For example, the floating structure 110 and the mooring section 120 are positioned such that the height (vertical position) of one end of the mooring rope 130 and the height (vertical position) of the other end are approximately equal. The mooring rope 130 is, for example, elastic. The mooring rope 130 is, for example, a rope formed by twisting fibers together. The material of the mooring rope 130 is, for example, a resin such as nylon and / or metal.

[0031] There are no limitations on the connection mechanism between the mooring rope 130 and the floating structure 110. For example, the floating structure 110 may be provided with a mooring bit, and one end of the mooring rope 130 may be wound around the mooring bit of the floating structure 110 to connect it to the floating structure 110. Alternatively, for example, the floating structure 110 may be provided with an eye plate and a shackle, and one end of the mooring rope 130 may be fixed to the shackle of the floating structure 110 to connect it to the floating structure 110.

[0032] Similarly, there are no limitations on the connection mechanism between the mooring rope 130 and the mooring section 120. For example, if the mooring section 120 is a mooring bit, the other end of the mooring rope 130 is connected to the mooring bit of the mooring section 120 by being wrapped around it. Alternatively, for example, if the mooring section 120 includes an eye plate and a shackle, the other end of the mooring rope 130 may be fixed to the shackle and connected to the mooring section 120.

[0033] Furthermore, in this embodiment, the floating seismic isolation system 100 is equipped with a plurality of mooring ropes 130, and each of the plurality of mooring ropes 130 is provided corresponding to a plurality of mooring sections 120.

[0034] For example, as shown in Figure 2, one end of each of the two mooring ropes 130 is connected to the front surface 114a of the floating structure 110, and the other end is connected to the mooring sections 120a, 120a, respectively. Preferably, the two mooring ropes 130 are installed at different positions in the horizontal direction (the X direction in Figure 2) on the front surface 114a of the floating structure 110.

[0035] Similarly, as shown in Figure 2, one end of each of the two mooring ropes 130 is connected to the back surface 114b of the floating structure 110, and the other end is connected to the mooring sections 120b, 120b, respectively. It is preferable that the two mooring ropes 130 are installed at different horizontal positions (the X direction in Figure 2) on the back surface 114b of the floating structure 110.

[0036] Furthermore, as shown in Figure 2, one end of each of the two mooring ropes 130 is connected to the left side surface 114c of the floating structure 110, and the other end is connected to the mooring sections 120c, 120c, respectively. It is preferable that the two mooring ropes 130 are installed at different positions in the horizontal direction (Y direction in Figure 2) on the left side surface 114c of the floating structure 110.

[0037] Similarly, as shown in Figure 2, one end of each of the two mooring ropes 130 is connected to the right side surface 114d of the floating structure 110, and the other end is connected to the mooring sections 120d, 120d, respectively. It is preferable that the two mooring ropes 130 are installed at different positions in the horizontal direction (Y direction in Figure 2) on the right side surface 114d of the floating structure 110.

[0038] Furthermore, in this embodiment, it is preferable that the spring constant of the mooring rope 130 is set such that the natural period D of the mooring system, including the floating structure 110 and the mooring rope 130, is different from the natural period A of the system that responds to seismic waves, the natural period B of the floating structure 110, and the natural period C of the equipment mounted on the floating structure 110. Specifically, the natural period D of the mooring system changes according to the spring constant of the mooring rope 130. More specifically, the natural period is inversely proportional to the spring constant. The spring constant of the mooring rope 130 changes according to the tensile load acting on the mooring rope 130. More specifically, the spring constant is proportional to the tensile load. Therefore, it is preferable to apply a tensile load to the mooring rope 130 such that the spring constant of the mooring rope 130 is different from the natural period D of the mooring system, the natural period A of the system that responds to seismic waves, the natural period B of the floating structure 110, and the natural period C of the equipment mounted on the floating structure 110. Furthermore, it is preferable to set the spring constant of the mooring rope 130 such that the natural period A of the system that responds to seismic waves, the natural period B of the floating structure 110, and the natural period C of the equipment mounted on the floating structure 110 differ from the natural period D of the mooring system by 20% or more. This makes it possible to suppress resonance between the mooring rope 130 and the system that responds to seismic waves, resonance between the mooring rope 130 and the floating structure 110, and resonance between the mooring rope 130 and the equipment mounted on the floating structure 110 when an earthquake occurs. Furthermore, it is preferable that the natural period D of the mooring system is greater than the natural period A of the system that responds to seismic waves, the natural period B of the floating structure 110, and the natural period C of the equipment mounted on the floating structure 110. This makes it possible to further suppress resonance between the mooring rope 130 and the system that responds to seismic waves, resonance between the mooring rope 130 and the floating structure 110, and resonance between the mooring rope 130 and the equipment mounted on the floating structure 110 when an earthquake occurs. Note that the natural period A of the system that responds to seismic waves, the natural period B of the floating structure 110, the natural period C of the equipment mounted on the floating structure 110, and the natural period D of the mooring system only need to include the natural periods in the horizontal and vertical directions, and may also include the natural period of rotational motion. Furthermore, it is preferable that the tensile load of the mooring rope 130 is greater than it is. The greater the tensile load of the mooring rope 130, the better the stability during strong winds.The maximum tensile load of the mooring rope 130 is determined according to the load capacity of the mooring rope 130.

[0039] Furthermore, the floating seismic isolation system 100 according to this embodiment may also be equipped with a hoisting machine 150. The hoisting machine 150 adjusts the tensile load applied to the mooring rope 130. The hoisting machine 150 is provided on the upper surface of the wall portion 22 of the liquid storage section 20. For example, the floating seismic isolation system 100 may be equipped with four hoisting machines 150a to 150d. For example, hoisting machine 150a is provided in a position facing the front 114a of the floating structure 110. Hoisting machine 150b is provided in a position facing the rear 114b. Hoisting machine 150c is provided in a position facing the left side 114c. Hoisting machine 150d is provided in a position facing the right side 114d. Furthermore, the hoisting machine 150 in this embodiment is used to adjust the tension of the mooring rope 130. In other words, the hoisting machine 150 is not used to activate the seismic isolation function during an earthquake. Therefore, the possibility of the hoisting machine 150 and the floating structure 110 being connected during an earthquake is extremely low. Accordingly, it is sufficient to set the load capacity of the hoisting machine 150 in this embodiment to approximately 20 tons or more and 30 tons or less.

[0040] Furthermore, it is preferable that the mass of the mooring rope 130 is smaller than the tensile load acting on the mooring rope 130. For example, the mass of the mooring rope 130 is, for example, 0.01% or more and 1% or less of the tensile load acting on the mooring rope 130.

[0041] [2. Adjustment Method for Floating Seismic Isolation System] Next, the adjustment method for the floating seismic isolation system 100 will be described with reference to Figures 3 and 4. Figure 3 is a first diagram showing the adjustment method for the floating seismic isolation system 100 according to this embodiment. Figure 4 is a second diagram showing the adjustment method for the floating seismic isolation system 100 according to this embodiment. In Figures 3 and 4, the vertically intersecting X-axis (horizontal direction), Y-axis (horizontal direction), and Z-axis (vertical direction) are defined as shown in the figures.

[0042] In the adjustment method for the floating seismic isolation system 100, first, the spring constant K of the mooring rope 130 is determined such that the natural period D of the mooring system is different from the natural period A of the system that responds to seismic waves, the natural period B of the floating structure 110, and the natural period C of the equipment mounted on the floating structure 110. In order to improve stability during strong winds, it is preferable to adjust the tensile load of the mooring rope 130 to be as large as possible. Increasing the tensile load means that the spring constant K is also large. For this reason, in the adjustment method for the floating seismic isolation system 100 according to this embodiment, it is preferable to determine a spring constant K of the mooring rope 130 such that the natural period D of the mooring system is different from the natural period A of the system that responds to seismic waves, the natural period B of the floating structure 110, and the natural period C of the equipment mounted on the floating structure 110, and the spring constant K is such that the tensile load is as large as possible. Then, the tensile load acting on the mooring rope 130 is adjusted so that the spring constant of the mooring rope 130 becomes the spring constant K.

[0043] For example, as shown in Figure 3, when adjusting the tensile load of a mooring rope 130 connected to the front surface 114a of a floating structure 110, a hoisting machine 150b is used. Specifically, one end of the mooring rope 130 is connected to the front surface 114a of the floating structure 110, and the other end of the mooring rope 130 is temporarily connected to the mooring section 120a. The wire 152 of the hoisting machine 150b is also connected to the back surface 114b of the floating structure 110. Then, the wire 152 is wound up by the hoisting machine 150b, pulling the floating structure 110 toward the hoisting machine 150b (in the +Y direction in Figure 3). This causes a tensile load to begin acting on the temporarily connected mooring rope 130. By continuing to wind up the wire 152 by the hoisting machine 150b, the tensile load acting on the temporarily connected mooring rope 130 increases. When the tensile load acting on the temporarily connected mooring rope 130 reaches a tensile load P that causes the spring constant of the mooring rope 130 to be equal to the spring constant K, the winding of the wire 152 by the hoisting machine 150b is stopped, and the connection between the mooring rope 130 and the mooring section 120a is made permanent. Then, the connection between the wire 152 of the hoisting machine 150b and the back surface 114b of the floating structure 110 is released.

[0044] Also, as shown in FIG. 4, when adjusting the tensile load of the mooring cable 130 connected to the rear surface 114b of the floating structure 110, the winch 150a is used. Specifically, one end side of the mooring cable 130 is connected to the rear surface 114b of the floating structure 110, and the other end side of the mooring cable 130 is temporarily connected to the mooring portion 120b. Further, the wire 152 of the winch 150a is connected to the front surface 114a of the floating structure 110. Then, the winch 150a winds up the wire 152 to pull the floating structure 110 toward the winch 150a side (the -Y direction in FIG. 3). Then, a tensile load starts to act on the temporarily connected mooring cable 130. By continuously winding up the wire 152 by the winch 150a, the tensile load acting on the temporarily connected mooring cable 130 increases. When the tensile load acting on the temporarily connected mooring cable 130 reaches the tensile load P at which the spring constant of the mooring cable 130 becomes the spring constant K, the winding up of the wire 152 by the winch 150a is stopped, and the connection between the mooring cable 130 and the mooring portion 120b is made a permanent connection. Then, the connection between the wire 152 of the winch 150a and the front surface 114a of the floating structure 110 is released.

[0045] Similarly, when adjusting the tensile load of the mooring cable 130 connected to the left side surface 114c of the floating structure 110 and the mooring portion 120c, the winch 150d is used to adjust the tension. Also, when adjusting the tensile load of the mooring cable 130 connected to the right side surface 114d of the floating structure 110 and the mooring portion 120d, the winch 150c is used to adjust the tension.

[0046] [3. Summary] As described above, the floating seismic isolation system 100 according to the present embodiment includes a floating structure 110 that is floatingly disposed in the liquid L, a mooring portion 120 that is provided around the floating structure 110 and erected vertically, and a mooring cable 130 having one end side connected to the floating structure 110 and the other end side connected to the mooring portion 120 and on which a tensile load acts.

[0047] In the floating seismic isolation system 100 according to the present embodiment, since the floating structure 110 is floatingly arranged in the liquid L, the seismic isolation performance can be enhanced as compared with the case where the floating structure 110 is directly placed in contact with the ground 10. Further, since a tensile load acts on the mooring cable 130 of the floating seismic isolation system 100 according to the present embodiment, it is possible to prevent the horizontal movement of the floating structure 110 during strong winds, and to maintain the stability of the floating structure 110 during normal times. Here, normal times refer to periods other than the occurrence of an earthquake. Also, in the prior art where one end of a non-linear spring member is connected to the floating structure and the other end is connected to a winding device, and the spring constant of the non-linear spring member is changed by the winding device to ensure seismic isolation performance and stability against strong winds, there is a problem that the seismic isolation performance or the stability against strong winds is impaired when a strong wind blows during an earthquake. In contrast, in the floating seismic isolation system 100 according to the present embodiment, since the floating structure 110 is floatingly arranged in the liquid L and a tensile load acts on the mooring cable 130, it is possible to maintain both the seismic isolation performance of the floating structure 110 and the stability against strong winds even when a strong wind blows during an earthquake. Further, the mooring portion 120 of the floating seismic isolation system 100 according to the present embodiment is not a complex machine such as a winding device, but a structure such as a pillar or a wall. Therefore, a load-bearing capacity for withstanding the load applied during an earthquake can be set for the mooring portion 120 at a lower cost as compared with a winding device. As described above, the floating seismic isolation system 100 according to the present embodiment can achieve both seismic isolation performance and stability against strong winds at a low cost.

[0048] Further, the spring constant K of the mooring cable 130 may be set such that the natural period D of the mooring system including the floating structure 110 and the mooring cable 130 is different from each of the natural period B of the floating structure 110, the natural period C of the equipment mounted on the floating structure 110, and the natural period A of the system that responds to seismic waves.

[0049] By setting the spring constant K of the mooring rope 130 such that the natural period D of the mooring system is different from the natural period B of the floating structure 110, the floating seismic isolation system 100 according to this embodiment can avoid the situation in which the mooring rope 130 and the floating structure 110 resonate when an earthquake occurs. Similarly, by setting the spring constant K of the mooring rope 130 such that the natural period D of the mooring system is different from the natural period C of the equipment mounted on the floating structure 110, the floating seismic isolation system 100 according to this embodiment can avoid the situation in which the mooring rope 130 and the equipment mounted on the floating structure 110 resonate when an earthquake occurs. Furthermore, by setting the spring constant K of the mooring rope 130 such that the natural period D of the mooring system is different from the natural period A of the system that responds to seismic waves, the floating seismic isolation system 100 according to this embodiment can avoid a situation in which the mooring rope 130 and the system that responds to seismic waves resonate when an earthquake occurs. Therefore, the mooring rope 130 of the floating seismic isolation system 100 according to this embodiment can avoid a situation in which the seismic isolation performance of the gas containment space 112 of the floating structure 110 is reduced.

[0050] The tensile load P acting on the mooring rope 130 may be set such that the natural period D of the mooring system, including the floating structure 110 and the mooring rope 130, is different from the natural period B of the floating structure 110, the natural period C of the equipment mounted on the floating structure 110, and the natural period A of the system that responds to seismic waves.

[0051] By setting the tensile load P acting on the mooring rope 130 such that the natural period D of the mooring system is different from the natural period B of the floating structure 110, the floating seismic isolation system 100 according to this embodiment can avoid the situation in which the mooring rope 130 and the floating structure 110 resonate during an earthquake. Similarly, by setting the tensile load P acting on the mooring rope 130 such that the natural period D of the mooring system is different from the natural period C of the equipment mounted on the floating structure 110, the floating seismic isolation system 100 according to this embodiment can avoid the situation in which the mooring rope 130 and the equipment mounted on the floating structure 110 resonate during an earthquake. Furthermore, by setting the tensile load P acting on the mooring cable 130 such that the natural period D of the mooring system is different from the natural period A of the system that responds to seismic waves, the floating seismic isolation system 100 according to this embodiment can avoid a situation in which the mooring cable 130 and the system that responds to seismic waves resonate when an earthquake occurs. Therefore, the mooring cable 130 of the floating seismic isolation system 100 according to this embodiment can avoid a situation in which the seismic isolation performance of the gas containment space 112 of the floating structure 110 is reduced.

[0052] The floating structure 110 may be equipped with multiple mooring ropes 130, and may have a first surface extending vertically and a second surface extending vertically and located on the back side of the first surface, with one end of the first mooring rope 130 connected to the first surface of the floating structure 110, and one end of a second mooring rope 130, which is different from the first mooring rope 130, connected to the second surface of the floating structure 110.

[0053] As a result, the floating seismic isolation system 100 according to this embodiment can effectively prevent the horizontal movement of the floating structure 110 during strong winds, regardless of the wind direction.

[0054] The mass of the mooring rope 130 may be less than the tensile load acting on the mooring rope 130.

[0055] As a result, the floating seismic isolation system 100 according to this embodiment can reduce the inertial force of the mooring ropes 130 when an earthquake occurs. Therefore, the floating seismic isolation system 100 according to this embodiment can avoid a situation in which the seismic isolation performance of the floating structure 110 is hindered by the inertial force of the mooring ropes 130.

[0056] The mooring section 120 may be columnar in shape.

[0057] As a result, the floating seismic isolation system 100 according to this embodiment can be easily equipped with a mooring section 120.

[0058] The mooring section 120 may be a mooring bit, and the mooring rope 130 may be connected to the mooring bit by being wound around it.

[0059] As a result, the floating seismic isolation system 100 according to this embodiment allows for easy installation of the mooring section 120. Furthermore, the floating seismic isolation system 100 according to this embodiment allows for easy connection and disconnection of the mooring section 120 and the mooring rope 130.

[0060] The adjustment method for the floating seismic isolation system 100 according to this embodiment includes: a floating structure 110 that floats and is positioned in a liquid L; a mooring section 120 provided around the floating structure 110 and erected vertically; and a mooring rope 130, one end of which is connected to the floating structure 110 and the other end of which is connected to the mooring section 120, and to which a tensile load is applied; and the adjustment method for the floating seismic isolation system 100, which includes: determining the spring constant K of the mooring rope 130 such that the natural period D of the mooring system including the floating structure 110 and the mooring rope 130 is different from the natural period B of the floating structure 110, the natural period C of the equipment mounted on the floating structure 110, and the natural period A of the system that responds to seismic waves; and adjusting the tensile load P acting on the mooring rope 130 so that the determined spring constant K is achieved.

[0061] The adjustment method for the floating seismic isolation system 100 according to this embodiment provides the same effects as the floating seismic isolation system 100 described above. Furthermore, the adjustment method for the floating seismic isolation system 100 according to this embodiment can avoid the situation in which the mooring ropes 130 and the floating structure 110 resonate when an earthquake occurs. Furthermore, the adjustment method for the floating seismic isolation system 100 according to this embodiment can avoid the situation in which the mooring ropes 130 and the equipment mounted on the floating structure 110 resonate when an earthquake occurs. Moreover, the adjustment method for the floating seismic isolation system 100 according to this embodiment can avoid the situation in which the mooring ropes 130 and the system that responds to seismic waves resonate when an earthquake occurs.Therefore, the adjustment method for the floating seismic isolation system 100 according to this embodiment can avoid the situation in which the seismic isolation performance of the gas containment space 112 of the floating structure 110 is reduced.

[0062] [4. First Modification] In the above embodiment, the floating structure 110 and the mooring section 120 were arranged such that the height of one end of the mooring rope 130 and the height of the other end were approximately equal. However, the height of one end of the mooring rope 130 and the height of the other end may be different.

[0063] Figure 5 is a schematic diagram of a floating seismic isolation system 100A according to the first modified example. In Figure 5, the X-axis (horizontal direction), Y-axis (horizontal direction), and Z-axis (vertical direction) intersecting perpendicularly are defined as shown in the figure.

[0064] As shown in Figure 5, in the first modified example, the floating structure 110 and the mooring section 120 are arranged such that the other end of the mooring rope 130 connected to the mooring section 120 is located above the one end connected to the floating structure 110.

[0065] Furthermore, in the first modified example, it is preferable that the height of the center of gravity of the floating structure 110 (vertical position) and the height of the connection point between the floating structure 110 and the mooring rope 130 (vertical position) coincide. This prevents the floating structure 110 from rotating with the horizontal direction as the axis of rotation.

[0066] As a result, the floating seismic isolation system 100A according to the first modified example can avoid the situation in which the mooring cable 130 and the floating structure 110 resonate even when horizontal and vertical shaking occurs during an earthquake. Furthermore, the floating seismic isolation system 100A according to the first modified example can avoid the situation in which the mooring cable 130 and the equipment mounted on the floating structure 110 resonate even when horizontal and vertical shaking occurs during an earthquake. Moreover, the floating seismic isolation system 100A according to the first modified example can avoid the situation in which the mooring cable 130 and the system that responds to seismic waves resonate even when horizontal and vertical shaking occurs during an earthquake. Therefore, the mooring cable 130 of the floating seismic isolation system 100A according to the first modified example can further avoid the situation in which the seismic isolation performance of the gas containment space 112 of the floating structure 110 is reduced.

[0067] [5. Second Modification] In the above embodiment, the mooring rope 130 was given as an example in which it is continuous from one end connected to the floating structure 110 to the other end connected to the mooring section 120. However, the mooring rope 130 may have other members provided between the one end connected to the floating structure 110 and the other end connected to the mooring section 120.

[0068] Figure 6 is a schematic diagram of a floating seismic isolation system 100B according to the second modified example. In Figure 6, the X-axis (horizontal direction), Y-axis (horizontal direction), and Z-axis (vertical direction) intersecting perpendicularly are defined as shown. Also, in Figure 6, the hoisting machine 150 is omitted for ease of understanding.

[0069] As shown in Figure 6, in the second modified example, the mooring rope 230 has a first rope section 232, a movable pulley 234, and a second rope section 236.

[0070] The first rope section 232 is connected at one end to the floating structure 110 and at the other end to the movable pulley 234.

[0071] The second rope section 236 is wrapped around the movable pulley 234, with one end connected to a first location on the mooring section 120 and the other end connected to a second location on the mooring section 120 that is different from the first location. For example, one end of the second rope section 236 is connected to one mooring section 120, and the other end is connected to a mooring section 120 that is different from the mooring section 120 to which the other end is connected.

[0072] In the example shown in Figure 6, when the first rope section 232 is connected to the front surface 114a of the floating structure 110, one end of the second rope section 236 is connected to the mooring section 120a, and the other end of the second rope section 236 is connected to a different mooring section 120a than the one to which the first end is connected. Also, when the first rope section 232 is connected to the back surface 114b of the floating structure 110, one end of the second rope section 236 is connected to the mooring section 120b, and the other end of the second rope section 236 is connected to a different mooring section 120b than the one to which the first end is connected. When the first rope section 232 is connected to the left side surface 114c of the floating structure 110, one end of the second rope section 236 is connected to the mooring section 120c, and the other end of the second rope section 236 is connected to a different mooring section 120c than the one to which the first end is connected. When the first rope section 232 is connected to the right side surface 114d of the floating structure 110, one end of the second rope section 236 is connected to the mooring section 120d, and the other end of the second rope section 236 is connected to a different mooring section 120d than the one to which the first end is connected.

[0073] Furthermore, in the second modified example, it is preferable that the spring constants of the first rope section 232 and the second rope section 236 are set such that the natural period E of the mooring system including the floating structure 110 and the mooring rope 230 is different from the natural period A of the system that responds to seismic waves, the natural period B of the floating structure 110, and the natural period C of the equipment mounted on the floating structure 110. It is also preferable that a tensile load is applied to the first rope section 232 and the second rope section 236 such that the spring constants of the first rope section 232 and the second rope section 236 are different from the natural period E of the mooring system including the floating structure 110 and the mooring rope 230, the natural period A of the system that responds to seismic waves, the natural period B of the floating structure 110, and the natural period C of the equipment mounted on the floating structure 110.

[0074] In the second modified example, the mooring rope 230 is equipped with a movable pulley 234, which allows the tensile load of the first rope section 232 to be different from the tensile load of the second rope section 236. Specifically, the tensile load of the first rope section 232 can be set to twice the tensile load of the second rope section 236. Therefore, the floating seismic isolation system 100B according to the second modified example can more efficiently prevent the horizontal movement of the floating structure 110 during strong winds by the first rope section 232. Furthermore, the floating seismic isolation system 100B according to the second modified example can suppress the propagation of seismic waves from the mooring rope 230 to the floating structure 110 during an earthquake by the second rope section 236.

[0075] While embodiments have been described above with reference to the attached drawings, it goes without saying that this disclosure is not limited to the embodiments described above. It will be obvious to those skilled in the art that various modifications or alterations can be conceived within the scope of the claims, and these will naturally also fall within the technical scope of this disclosure.

[0076] For example, in the above embodiment, the floating seismic isolation system 100 is provided with a hoisting machine 150. However, the floating seismic isolation system 100 may be provided with a vessel capable of moving liquid L instead of the hoisting machine 150. In this case, the tension of the mooring rope 130 may be adjusted by pulling the floating structure 110 using a wire attached to the vessel.

[0077] 100: Floating seismic isolation system 100A: Floating seismic isolation system 100B: Floating seismic isolation system 110: Floating structure 114a: Front (first side) 114b: Rear (second side) 114c: Left side (second side) 114d: Right side (first side) 120: Mooring section 120a: Mooring section 120b: Mooring section 120c: Mooring section 120d: Mooring section 130: Mooring rope 230: Mooring rope 232: First rope section 234: Movable pulley 236: Second rope section

Claims

1. A floating seismic isolation system comprising: a floating structure that floats and is positioned on a liquid; a mooring section provided around the floating structure and erected vertically; and a mooring rope, one end of which is connected to the floating structure and the other end of which is connected to the mooring section, and to which a tensile load is applied.

2. The floating seismic isolation system according to claim 1, wherein the spring constant of the mooring rope is set such that the natural period of the mooring system including the floating structure and the mooring rope is different from the natural period of the floating structure, the natural period of the equipment mounted on the floating structure, and the natural period of the system that responds to seismic waves.

3. The floating seismic isolation system according to claim 1, wherein the tensile load acting on the mooring rope is set such that the natural period of the mooring system including the floating structure and the mooring rope is different from the natural period of the floating structure, the natural period of the equipment mounted on the floating structure, and the natural period of the system that responds to seismic waves.

4. The floating seismic isolation system according to any one of claims 1 to 3, wherein the floating structure and the mooring section are arranged such that the other end of the mooring rope is located above the one end.

5. A floating seismic isolation system according to any one of claims 1 to 3, comprising a plurality of mooring ropes, wherein the floating structure has a first surface extending vertically and a second surface extending vertically and located on the back side of the first surface, one end of the first mooring rope is connected to the first surface of the floating structure, and one end of a second mooring rope, different from the first mooring rope, is connected to the second surface of the floating structure.

6. The floating seismic isolation system according to any one of claims 1 to 3, wherein the mass of the mooring rope is less than the tensile load acting on the mooring rope.

7. The floating seismic isolation system according to any one of claims 1 to 3, wherein the mooring rope comprises: a first rope portion having one end connected to the floating structure and the other end connected to a movable pulley; and a second rope portion wrapped around the movable pulley, having one end connected to a first location of the mooring portion and the other end connected to a second location of the mooring portion different from the first location.

8. The floating seismic isolation system according to any one of claims 1 to 3, wherein the mooring section is columnar.

9. The floating seismic isolation system according to any one of claims 1 to 3, wherein the mooring portion is a mooring bit, and the mooring cable is connected to the mooring bit by being wound around the mooring bit.

10. A method for adjusting a floating seismic isolation system, comprising: a floating structure that is suspended and positioned in a liquid; a mooring section provided around the floating structure and erected vertically; and a mooring rope, one end of which is connected to the floating structure and the other end of which is connected to the mooring section, and on which a tensile load is applied, the method comprising: determining the spring constant of the mooring rope such that the natural period of the mooring system including the floating structure and the mooring rope is different from the natural period of the floating structure, the natural period of the equipment mounted on the floating structure, and the natural period of the system that responds to seismic waves; and adjusting the tensile load applied to the mooring rope so that the determined spring constant is obtained.

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