Floating-type base isolation system

Abstract

A floating-type base isolation system 100 comprises: a storage space 116 in which a liquid for floating a floating-type structure 120 is stored; a first chamber 132 which accommodates therein a compressive fluid and which has a volume variable in accordance with pressure variation of the liquid; and a second chamber 134 which accommodates therein a compressive fluid and which has a pressure or a volume that passively varies in accordance with volume variation of the first chamber 132.

Description

Floating seismic isolation system

[0001] This application claims the benefit of priority from Japanese Patent Application No. 2023-207130, filed on December 7, 2023, the contents of which are incorporated herein by reference.

[0002] Floating seismic isolation systems that use liquid have been developed. For example, Patent Document 1 discloses a floating seismic isolation system in which liquid is stored in a depression formed in the ground and a floating structure is floated in the liquid.

[0003] In the technology of Patent Document 1, a plurality of air chambers are provided at the bottom of a floating structure, and these air chambers function as dampers that absorb vertical shaking during an earthquake.

[0004] Japanese Patent Application Laid-Open No. 2004-1667

[0005] However, the above-mentioned Patent Document 1 does not disclose a mechanism for reducing shaking during an earthquake in parts other than the floating structure, and there is room for further reduction in shaking during an earthquake.

[0006] In view of these problems, the present disclosure aims to provide a floating seismic isolation system that can reduce shaking during an earthquake by using a seismic isolation structure installed in a space containing liquid.

[0007] In order to solve the above problems, a floating seismic isolation system according to one embodiment of the present disclosure comprises a storage space in which a liquid that buoys a floating structure is stored, a first chamber in which a compressible fluid is contained and whose volume is variable in response to pressure fluctuations of the liquid, and a second chamber in which a compressible fluid is contained and whose pressure or volume changes passively in response to changes in the volume of the first chamber.

[0008] The floating seismic isolation system may also include a throttled flow path that connects the first chamber and the second chamber.

[0009] Furthermore, a rigid wall surface may be interposed between the compressible fluid in the second chamber and the liquid.

[0010] The first chamber may also include an elastic membrane in contact with the liquid.

[0011] The first chamber may also include a cylinder and a piston having a top surface in contact with the liquid and slidably provided within the cylinder.

[0012] The floating seismic isolation system may also include a wall surface that defines the storage space, and the throttle channel may be provided on the wall surface.

[0013] The first chamber may have a plurality of sub-chambers, each of which has a volume that can be individually changed in response to pressure fluctuations in the liquid, and the throttle flow path may be made up of a plurality of throttle flow paths that extend individually from the sub-chambers of the first chamber.

[0014] The second chamber may include a plurality of sub-chambers, and each of the sub-chambers of the second chamber may be in communication with at least one of the plurality of throttle channels.

[0015] The floating seismic isolation system may further include a third chamber that is connected to the second chamber and is provided on the ground.

[0016] According to the present disclosure, it is possible to reduce shaking during an earthquake by using a seismic isolation structure provided in a space containing a liquid.

[0017] Fig. 1 is a diagram illustrating a floating seismic isolation system according to an embodiment of the present disclosure. Fig. 2 is a diagram illustrating a seismic isolation structure according to the same embodiment. Fig. 3 is a diagram illustrating a seismic isolation structure according to a first modified example. Fig. 4 is a diagram illustrating a seismic isolation structure according to a second modified example. Fig. 5 is a diagram illustrating a seismic isolation structure according to a third modified example.

[0018] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Dimensions, materials, and other specific numerical values ​​shown in the embodiments are merely examples for ease of understanding and do not limit the present disclosure unless otherwise specified. In this specification and drawings, elements having substantially the same functions and configurations are designated by the same reference numerals to avoid redundant explanation. Elements not directly related to the present disclosure are not shown.

[0019] [Floating-body seismic isolation system 100] Figure 1 is a diagram illustrating a floating-body seismic isolation system 100 according to an embodiment of the present disclosure. As shown in Figure 1, the floating-body seismic isolation system 100 according to this embodiment includes a liquid storage section 110, a floating structure 120, a plurality of seismic isolation structures 130, and a mooring section 140. Note that in Figure 1 and the following figures, cross-hatching represents liquid.

[0020] The liquid storage section 110 is provided, for example, in a depression or hole formed by digging the ground 10. The liquid storage section 110 has a bottom wall 112 and a side wall 114. The bottom wall 112 is a wall that extends horizontally or approximately horizontally. The side wall 114 is a wall that extends vertically or approximately vertically. A storage space 116 is defined by the bottom wall 112 and the side wall 114. In other words, the bottom wall 112 and the side wall 114 can be said to be wall surfaces that define the storage space 116. The bottom wall 112 forms a bottom surface 116a of the storage space 116. The side wall 114 forms a side surface 116b of the storage space 116. Liquid is stored in the storage space 116 of the liquid storage section 110.

[0021] The liquid stored in the liquid storage unit 110 is, for example, water. However, the liquid is not limited to this and may be any liquid other than water, or may be another liquid containing water as a main component (for example, seawater).

[0022] The floating structure 120 is disposed so as to float in the liquid stored in the storage space 116 of the liquid storage section 110. The floating structure 120 is disposed at a distance from the bottom wall 112 and the side wall 114 of the liquid storage section 110. The floating structure 120 is, for example, a floating nuclear power plant. However, the floating structure 120 is not limited thereto, and may be a structure for other plants such as a wind power plant, a wave power plant, or a solar power plant, or may be a structure on which any other equipment is mounted. Note that, although no air chamber is provided in the floating structure 120 in this embodiment, an air chamber may be provided in the floating structure 120.

[0023] The seismic isolation structure 130 absorbs and dissipates a portion of the energy of longitudinal waves (compression waves) caused by an earthquake that propagates through the liquid stored in the liquid storage portion 110, thereby suppressing the propagation of waves to the floating structure 120. In this embodiment, the floating seismic isolation system 100 includes a plurality of seismic isolation structures 130. A compressible fluid is contained inside the seismic isolation structures 130. The compressible fluid contained in the seismic isolation structures 130 can be, for example, a gas such as air or nitrogen.

[0024] 2 is a diagram illustrating the seismic isolation structure 130 according to this embodiment. As shown in FIG. 2, the seismic isolation structure 130 according to this embodiment includes one first chamber 132, one second chamber 134, and one throttle channel 136.

[0025] The first chamber 132 is provided near the bottom wall 112 of the storage space 116 of the liquid storage portion 110. In this embodiment, the first chamber 132 is in contact with, for example, the bottom surface 116a of the liquid storage portion 110. The first chamber 132 is provided in the liquid stored in the storage space 116 of the liquid storage portion 110. A compressible fluid is accommodated inside the first chamber 132.

[0026] The volume of the first chamber 132 is variable in response to pressure fluctuations of the liquid stored in the storage space 116 of the liquid storage unit 110. In this embodiment, at least a portion of the portion of the first chamber 132 that contacts the liquid is made of, for example, a stretchable material. The stretchable material is, for example, an elastic material. The stretchable material is, for example, rubber or an elastomer. At least a portion of the portion of the first chamber 132 that contacts the liquid may be, for example, an elastic membrane. In other words, the first chamber 132 is provided with a pressure-receiving surface on which the pressure of the liquid stored in the storage space 116 acts. Here, the volume being variable in response to pressure fluctuations of the liquid does not necessarily mean that the first chamber 132 is provided with a pressure-receiving surface, as in this embodiment. For example, there is a space between the pressure-receiving surface on which the pressure of the liquid acts and the first chamber 132, where the compressible fluid is sandwiched between two pistons and the pressure fluctuation of the liquid is transmitted to the first chamber 132 via the sealed space. This also includes a case where the pressure-receiving surface is not included in the boundary between the first chamber 132 and the liquid, but an intervening object is present between the pressure-receiving surface and the first chamber 132, and pressure is transmitted by the intervening object. Note that in this embodiment, the seismic isolation structure 130 does not include an external power that works in conjunction with the pressure-receiving surface to perform work on the first chamber 132.

[0027] The second chamber 134 is provided within the bottom wall 112 of the liquid storage section 110. A compressible fluid is contained within the second chamber 134. In other words, a rigid wall is interposed between the compressible fluid in the second chamber 134 and the liquid in the storage space 116. Therefore, the compressible fluid in the second chamber 134 is affected by the pressure of the liquid stored in the storage space 116 via the first chamber 132. The second chamber 134 in this embodiment is configured so that its volume changes little or nothing with pressure changes. The pressure in the second chamber 134 changes passively in response to changes in the volume of the first chamber 132.

[0028] The throttle channel 136 communicates with the first chamber 132 and the second chamber 134. At least a portion of the throttle channel 136 is provided, for example, within the bottom wall 112. That is, the throttle channel 136 can be said to be provided on the wall surface (bottom surface 116a) of the bottom wall 112. The flow path cross-sectional area of ​​the throttle channel 136 is smaller than those of the first chamber 132 and the second chamber 134. In this embodiment, the horizontal cross-sectional area of ​​the throttle channel 136 is smaller than those of the first chamber 132 and the second chamber 134. The throttle channel 136 is formed, for example, by an orifice or a thin tube. In this embodiment, the compressible fluid is sealed in a space including the first chamber 132, the second chamber 134, and a flow path (throttle channel 136) connecting them.

[0029] Returning to FIG. 1 , at least one of the first chambers 132 of the seismic isolation structure 130 is provided directly below the floating structure 120 .

[0030] The mooring portion 140 is a column extending horizontally or approximately horizontally. The mooring portion 140 is, for example, a circular column or a rectangular column. One end of the mooring portion 140 is fixed to the side surface 122 of the floating structure 120. The other end of the mooring portion 140 is fixed to the side surface 116b of the side wall 114 of the liquid storage portion 110.

[0031] The mooring section 140 is made of a material that does not undergo plastic deformation (e.g., buckling deformation) when a load less than a predetermined seismic intensity is applied, but undergoes plastic deformation when a load equal to or greater than the predetermined seismic intensity is applied. The mooring section 140 may also be made of a material that undergoes compressive failure when a load equal to or greater than the predetermined seismic intensity is applied. The predetermined seismic intensity is set depending on the floating structure 120 and the equipment installed thereon.

[0032] As explained above, the seismic isolation structure 130 of the floating body seismic isolation system 100 according to this embodiment is provided in the liquid storage section 110, not in the floating structure 120. Therefore, the floating body seismic isolation system 100 according to this embodiment can reduce vibration of the floating structure 120 caused by an earthquake, regardless of whether or not the floating structure 120 has an air chamber.

[0033] Furthermore, the seismic isolation structure 130 can be installed in the liquid storage section 110 before the floating structure 120 is installed and before the liquid is stored. This makes it possible to easily install the seismic isolation structure 130.

[0034] Furthermore, as described above, the seismic isolation structure 130 according to this embodiment includes the first chamber 132 provided in the liquid stored in the storage space 116 of the liquid storage section 110. This allows the seismic isolation structure 130 to absorb part of the energy of earthquake-induced waves propagating to the liquid stored in the liquid storage section 110. Therefore, the seismic isolation structure 130 according to this embodiment can reduce the energy of waves propagating from the liquid to the floating structure 120 and the onboard equipment. Therefore, the seismic isolation structure 130 according to this embodiment can prevent the floating structure 120 and the onboard equipment from vibrating significantly due to an earthquake.

[0035] Furthermore, as described above, the volume of the first chamber 132 according to this embodiment is variable in response to fluctuations in liquid pressure. Therefore, when the pressure of the liquid fluctuates due to waves caused by an earthquake, the volume of the first chamber 132 changes, and compressible fluid moves from the first chamber 132 to the second chamber 134 or from the second chamber 134 to the first chamber 132 through the throttle channel 136. This causes a pressure loss due to the movement of compressible fluid through the throttle channel 136, allowing the absorbed energy to be dissipated. In other words, a portion is provided between the first chamber 132 and the second chamber 134 where energy can be dissipated by the movement of compressible fluid. Therefore, the seismic isolation structure 130 according to this embodiment can further reduce the wave energy propagated from the liquid stored in the storage space 116 of the liquid storage section 110 to the floating structure 120, thereby enabling further suppression of vibrations of the floating structure 120 and its onboard equipment.

[0036] Furthermore, as described above, the floating seismic isolation system 100 includes the mooring section 140. Therefore, when no earthquake occurs or when an earthquake of less than a predetermined seismic intensity occurs, it is possible to prevent the floating structure 120 from moving horizontally due to wind or the like. Furthermore, as described above, when an earthquake of a predetermined seismic intensity or higher occurs, the mooring section 140 undergoes plastic deformation or compressive failure. Therefore, when an earthquake of a predetermined seismic intensity or higher occurs, it is possible to suppress the propagation of waves from the side wall 114 to the floating structure 120.

[0037] [First Modification] Figure 3 is a diagram illustrating a seismic isolation structure 230 according to a first modification. As shown in Figure 3, the seismic isolation structure 230 according to the first modification includes a cylinder 232, a piston 234, and an orifice plate 236. Note that components that are substantially the same as those in the floating-body seismic isolation system 100 described above are given the same reference numerals, and descriptions thereof will be omitted.

[0038] The cylinder 232 is installed inside the bottom wall 112. The central axis of the cylinder 232 is vertical.

[0039] The piston 234 is provided slidably within the cylinder 232. A liquid is contained in the space above the piston 234 in the cylinder 232. The top surface (upper surface) of the piston 234 contacts the liquid. A compressible fluid (gas) is contained in the space below the piston 234 in the cylinder 232.

[0040] The orifice plate 236 is provided in the space below the piston 234 in the cylinder 232. The orifice plate 236 divides the space below the piston 234 in the cylinder 232 into upper and lower two sections.

[0041] The space between the orifice plate 236 and the piston 234 in the cylinder 232 functions as a first chamber 242. The space below the orifice plate 236 in the cylinder 232 functions as a second chamber 244.

[0042] Furthermore, holes 236a are formed in the orifice plate 236. The holes 236a function as throttle channels.

[0043] As described above, the seismic isolation structure 230 according to the first modified example is provided in the liquid storage section 110, and therefore the structure of the floating structure 120 can be simplified.

[0044] Furthermore, like the seismic isolation structure 130, the seismic isolation structure 230 according to the first modification includes a first chamber 242 provided in the liquid stored in the storage space 116 of the liquid storage section 110. This allows the seismic isolation structure 230 according to the first modification to absorb part of the energy of earthquake-induced waves propagating to the liquid stored in the liquid storage section 110. Therefore, the seismic isolation structure 230 according to the first modification can reduce the energy of waves propagating from the liquid to the floating structure 120 and the onboard equipment. Therefore, the seismic isolation structure 230 according to the first modification can prevent the floating structure 120 and the onboard equipment from vibrating significantly due to an earthquake.

[0045] Furthermore, the first chamber 242 according to the first modification has a volume that can be changed in response to pressure fluctuations of the liquid, similar to the first chamber 132 of the seismic isolation structure 130. Therefore, the seismic isolation structure 230 according to the first modification can absorb part of the energy of earthquake-induced waves that propagate to the liquid stored in the storage space 116 of the liquid storage section 110, thereby making it possible to further suppress vibrations of the floating structure 120 and the onboard equipment.

[0046] [Second Modification] Figure 4 is a diagram illustrating a seismic isolation structure 330 according to a second modification. As shown in Figure 4, the seismic isolation structure 330 according to the second modification includes a first chamber 332, a plurality of throttle channels 136, and one second chamber 134. Note that components that are substantially the same as those in the floating-body seismic isolation system 100 described above are given the same reference numerals, and descriptions thereof will be omitted.

[0047] In the second modified example, the first chamber 332 includes a plurality of sub-chambers 332a. The volumes of the plurality of sub-chambers 332a are individually variable in response to pressure fluctuations of the liquid stored in the storage space 116. The plurality of throttle channels 136 extend individually from the plurality of sub-chambers 332a. In the second modified example, the plurality of throttle channels 136 are connected to the second chamber 134. In other words, the plurality of throttle channels 136 connect the plurality of sub-chambers 332a to one second chamber 134.

[0048] As described above, the base isolation structure 330 according to the second modification has a smaller number of second chambers 134 than the base isolation structure 130. This makes it easier to construct the second chambers 134 in the base isolation structure 330 according to the second modification.

[0049] [Third Modification] Figure 5 is a diagram illustrating a seismic isolation structure 430 according to a third modification. As shown in Figure 5, the seismic isolation structure 430 according to the third modification includes a first chamber 332, a plurality of throttle channels 136, one second chamber 434, and one third chamber 438. Note that components that are substantially the same as those in the floating seismic isolation system 100 and the seismic isolation structure 330 described above are denoted by the same reference numerals, and descriptions thereof will be omitted.

[0050] In the third modified example, the second chamber 434 communicates the plurality of throttle channels 136 with the third chamber 438. The second chamber 434 is provided in the bottom wall 112. The second chamber 434 is, for example, a tube. The flow path cross-sectional area of ​​the second chamber 434 is larger than that of the throttle channels 136.

[0051] The third chamber 438 is provided on the ground. The third chamber 438 is provided on the ground 10, for example.

[0052] The base isolation structure 430 according to the third modification has a third chamber 438 provided on the ground. This allows the base isolation structure 430 according to the third modification to easily perform maintenance on the third chamber 438.

[0053] Although the embodiments have been described above with reference to the accompanying drawings, it goes without saying that the present disclosure is not limited to the above-described embodiments. It is clear that a person skilled in the art can conceive of various modifications or alterations within the scope of the claims, and it is understood that these also naturally fall within the technical scope of the present disclosure.

[0054] For example, in the above embodiment and the first to third modified examples, the second chambers 134, 244, 434 are provided in the bottom wall 112 of the liquid storage portion 110. However, the second chambers 134, 244, 434 may be provided in the side wall 114 of the liquid storage portion 110.

[0055] Furthermore, in the above embodiment and the first to third modified examples, the case where the first chamber 132, 242, 332 is provided near the bottom wall 112 in the storage space 116 of the liquid storage portion 110 has been described as an example. However, the first chamber 132, 242, 332 may be provided near the side wall 114 in addition to near the bottom wall 112. Furthermore, the first chamber 132, 242, 332 may be provided near the side wall 114 instead of near the bottom wall 112.

[0056] In the second modified example, the base isolation structure 330 includes the second chamber 134 having one space. However, the base isolation structure 330 may include the second chamber 134 having multiple sub-chambers. For example, the base isolation structure 330 may include a first chamber 332 having multiple sub-chambers 332a, multiple throttle channels 136 communicating with each of the multiple sub-chambers 332a of the first chamber 332, and multiple sub-chambers of the second chamber 134, the number of which is smaller than the sub-chambers 332a of the first chamber 332, and at least one of the multiple throttle channels 136 is connected to the second chamber 134. This allows the base isolation structure 330 to easily construct the second chamber 134.

[0057] Furthermore, in the above embodiment and the first to third modified examples, the case where the volume of the second chamber 134, 244, 434 does not change due to a change in pressure has been described as an example. However, the volume of the second chamber 134, 244, 434 may change passively in response to a change in the volume of the first chamber 132, 242. In this case, at least a portion of the second chamber 134, 244, 434 may be made of, for example, an elastic material. In this case, the pressure outside the second chamber 134, 244, 434 can change independently of the pressure of the liquid stored in the storage space 116.

[0058] Furthermore, in the above embodiment and the first to third modified examples, the case where the seismic isolation structures 130, 230, 330, 430 include the throttle channel 136 has been given as an example. However, the throttle channel 136 is not an essential component. The seismic isolation structure according to this embodiment may include a first chamber that contains a compressible fluid and whose volume changes in response to pressure fluctuations of the liquid stored in the storage space 116, and a second chamber that contains a compressible fluid and whose pressure or volume changes passively in response to volume changes in the first chamber.

[0059] In the above embodiment, the floating seismic isolation system 100 is provided with the mooring section 140. However, the mooring section 140 is not an essential component.

[0060] 100: Floating seismic isolation system 110: Liquid storage section 112: Bottom wall 114: Side wall 116: Storage space 120: Floating structure 130: Seismic isolation structure 132: First chamber 134: Second chamber 136: Throttle flow path 230: Seismic isolation structure 236a: Hole (throttle flow path) 242: First chamber 244: Second chamber 330: Seismic isolation structure 332: First chamber 332a: Branch chamber 430: Seismic isolation structure 434: Second chamber 438: Third chamber

Claims

1. A floating seismic isolation system comprising: a storage space in which a liquid for buoying a floating structure is stored; a first chamber in which a compressible fluid is contained and whose volume is variable in response to pressure fluctuations of the liquid; and a second chamber in which the compressible fluid is contained and whose pressure or volume changes passively in response to volume changes in the first chamber.

2. A floating seismic isolation system as described in claim 1, comprising a throttle passage connecting the first chamber and the second chamber.

3. A floating seismic isolation system as described in claim 1 or 2, wherein a rigid wall is interposed between the compressible fluid in the second chamber and the liquid.

4. A floating seismic isolation system as described in claim 1 or 2, wherein the first chamber includes an elastic membrane in contact with the liquid.

5. A floating seismic isolation system as described in claim 1 or 2, wherein the first chamber includes: a cylinder; and a piston having a top surface in contact with the liquid and slidably disposed within the cylinder.

6. A floating seismic isolation system as described in claim 2, comprising a wall surface defining the storage space, and the throttle channel is provided in the wall surface.

7. A floating seismic isolation system as described in claim 2, wherein the first chamber has a plurality of sub-chambers, each of the sub-chambers of the first chamber has a volume that can be individually changed in response to pressure fluctuations of the liquid, and the throttle flow path is made up of a plurality of throttle flow paths extending individually from the sub-chambers of the first chamber.

8. A floating seismic isolation system as described in claim 7, wherein the second chamber has a plurality of sub-chambers, and each of the sub-chambers of the second chamber is in communication with at least one of the plurality of throttle channels.

9. A floating seismic isolation system as described in claim 1 or 2, further comprising a third chamber connected to the second chamber and provided on the ground.

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