Base-isolated structure

Abstract

To provide a base-isolated structure capable of effectively suppressing shaking due to an earthquake of a structure body arranged on a liquid body.SOLUTION: A base isolated structure 1 is provided with: a first roller group 10 including a plurality of first rollers 11 each having a specific gravity of less than 1 with respect to a liquid body 40 and arranged in parallel to each other in a horizontal direction in a posture in which an axis line is horizontal, and arranged in the liquid body 40; a second roller group 20 including a plurality of second rollers 21 each having a specific gravity with respect to the liquid body 40 of less than 1 and arranged in parallel to each other in a horizontal direction in a posture in which an axis line is horizontal, and arranged in the liquid body 40 so as to be stacked below the first roller group 10 with the plurality of second rollers 21 intersecting the plurality of first rollers 11; and a structure body 30 which is installed on the first roller group 10 and floats on the liquid body 40.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a seismic isolation structure.

Background Art

[0002] For example, as structures such as office buildings, factories, and apartment houses, there is known a seismic isolation structure in which a seismic isolation device using laminated rubber is provided between the structure and a foundation fixed to the ground so as to suppress the shaking caused by an earthquake during an earthquake (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] New town construction in which structures such as office buildings are placed floating, for example, on the sea, is being considered.

[0005] For a structure placed floating on a liquid such as seawater as well, in order to enhance the sense of security of users, it has been desired to have a seismic isolation structure capable of effectively suppressing the shaking caused by an earthquake.

[0006] The present invention has been made in view of such problems, and an object thereof is to provide a seismic isolation structure capable of effectively suppressing the shaking caused by an earthquake of a structure main body placed on a liquid.

Means for Solving the Problems

[0007] The seismic isolation structure of the present invention includes a plurality of first rollers each having a specific gravity less than 1 with respect to the liquid and arranged parallel to each other and horizontally in a posture where the axis is horizontal, and a first roller group disposed in the liquid; and a plurality of second rollers each having a specific gravity less than 1 with respect to the liquid and arranged parallel to each other and horizontally in a posture where the axis is horizontal, and a second roller group disposed in the liquid by crossing the plurality of second rollers with the plurality of first rollers and overlapping them under the first roller group; and a structure body installed above the first roller group and floating on the liquid. It is characterized by having these components.

[0008] In the seismic isolation structure of the present invention, in the above configuration, it is preferable that the liquid is a dilatant fluid.

Advantages of the Invention

[0009] According to the present invention, it is possible to provide a seismic isolation structure capable of effectively suppressing the shaking of a structure body disposed on a liquid due to an earthquake.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Modes for Carrying Out the Invention

[0011] Hereinafter, with reference to the drawings, a seismic isolation structure 1 according to an embodiment of the present invention will be illustrated and described in more detail.

[0012] As shown in Fig. 1, a seismic isolation structure 1 according to an embodiment of the present invention includes a first roller group 10, a second roller group 20, and a structure body 30. In the present embodiment, the seismic isolation structure 1 is disposed floating on the sea, that is, on the sea water 2a of the sea 2.

[0013] As shown in Figs. 1 and 2, the first roller group 10 includes a plurality of first rollers 11. The plurality of first rollers 11 are each cylindrical, and are arranged in parallel to each other and horizontally with their axes in a horizontal posture. A predetermined interval is provided between a pair of adjacent first rollers 11. The axis of the first roller 11 is an axis passing through the centers of both circular end faces.

[0014] In the present embodiment, the first roller group 10 includes three first rollers 11, but the number thereof can be variously changed as long as a plurality of first rollers 11 are provided.

[0015] The second roller group 20 includes a plurality of second rollers 21. The plurality of second rollers 21 are each cylindrical, and are arranged in parallel to each other and horizontally with their axes in a horizontal posture. A predetermined interval is provided between a pair of adjacent second rollers 21. The axis of the second roller 21 is an axis passing through the centers of both circular end faces.

[0016] The second roller group 20 is disposed below the first roller group 10 with a plurality of second rollers 21 intersecting a plurality of first rollers 11. In the present embodiment, the angle at which the plurality of second rollers 21 intersect the plurality of first rollers 11 is 90 degrees.

[0017] In the present embodiment, the second roller group 20 includes three second rollers 21, but the number thereof can be variously changed as long as a plurality of second rollers 21 are provided. Also, in the present embodiment, the number of the first rollers 11 and the number of the second rollers 21 are the same, but the number of the first rollers 11 and the number of the second rollers 21 may be different from each other.

[0018] The plurality of first rollers 11 and the plurality of second rollers 21 may be made of various materials, such as steel materials or the like formed into a hollow cylindrical shape, or logs or cylindrical timbers.

[0019] The structure main body 30 is installed on the first roller group 10. In the present embodiment, the structure main body 30 has, for example, a building 31 such as an office building, a factory, or an apartment building, and a plate-shaped base body 32 that supports the building 31. Note that the structure main body 30 may have various structures such as a steel tower, a utility pole, or a pedestrian bridge instead of or in addition to the building 31. Also, the base body 32 may not be provided.

[0020] The first roller group 10 and the second roller group 20 are arranged in the liquid 40.

[0021] In the present embodiment, a region partitioned from the seawater 2a by a semipermeable membrane 41 connected continuously around the base body 32 is provided below the structure main body 30, and the liquid 40 fills the inside of the region inside the semipermeable membrane 41. That is, the seismic isolation structure 1 floats on the seawater 2a via the semipermeable membrane 41 and the liquid 40. The first roller group 10 and the second roller group 20 are respectively arranged in the liquid 40 filled inside the semipermeable membrane 41.

[0022] In the present embodiment, a part of the base body 32 of the structure main body 30 is also submerged in the liquid 40, and in the first roller group 10, the entire of each first roller 11 is submerged in the liquid 40. Note that the first roller group 10 may be arranged such that a part of each first roller 11 is exposed above the liquid level of the liquid 40.

[0023] Each of the plurality of first rollers 11 has a specific gravity less than 1 with respect to the liquid 40. That is, the density of the plurality of first rollers 11 is less than the density of the liquid 40. Similarly, each of the plurality of second rollers 21 has a specific gravity less than 1 with respect to the liquid 40. That is, the density of the plurality of second rollers 21 is less than the density of the liquid 40. Therefore, the plurality of first rollers 11 constituting the first roller group 10 and the plurality of second rollers 21 constituting the second roller group 20 each receive a buoyancy force greater than their own weight in the liquid 40. The load of the structure body 30 installed on the first roller group 10 is supported by the buoyancy force received by the first roller group 10 and the second roller group 20, whereby the seismic isolation structure 1 floats on the liquid 40 or seawater 2a.

[0024] Each of the plurality of first rollers 11 constituting the first roller group 10 is rotatable in both forward and reverse directions about its axis in the liquid 40. That is, the plurality of first rollers 11 can rotate in the same direction so as to roll on the lower surface of the base body 32 and on the second rollers 21 while being in contact with the liquid 40 in the liquid 40. Similarly, each of the plurality of second rollers 21 constituting the second roller group 20 is also rotatable in both forward and reverse directions about its axis in the liquid 40. That is, the plurality of second rollers 21 can rotate in the same direction so as to roll under the first rollers 11 while being in contact with the liquid 40 in the liquid 40.

[0025] The liquid 40 filled inside the region inside the semipermeable membrane 41 is preferably a dilatant fluid. A dilatant fluid, also called a shear thickening fluid, is a mixture of a liquid and solid powder particles. A dilatant fluid has the property of behaving like a liquid under slow shear stimulation and exerting a resistance like that of a solid against shear stimulation faster than a certain speed. Therefore, when a dilatant fluid is used as the liquid 40, when a plurality of first rollers 11 to a plurality of second rollers 21 rotate in the liquid 40, if the rotation speed is less than a certain speed, a rolling resistance proportional to the speed is imparted to the plurality of first rollers 11 to the plurality of second rollers 21 from the liquid 40. However, when the rotation speed becomes equal to or higher than a certain speed, a rolling resistance greater than the rolling resistance proportional to the speed is imparted to the plurality of first rollers 11 to the plurality of second rollers 21 from the liquid 40.

[0026] Note that the liquid 40 filled inside the region inside the semipermeable membrane 41 is not limited to a dilatant fluid.

[0027] The semipermeable membrane 41 has the property of allowing liquids to pass through but not solids. Therefore, when the liquid 40 is a dilatant fluid, the liquid or seawater 2a constituting the liquid 40 can pass through the semipermeable membrane 41, but the solid powder particles constituting the liquid 40 are retained inside the semipermeable membrane 41. As a result, the liquid 40 inside the semipermeable membrane 41 is always maintained as a dilatant fluid with an appropriate concentration.

[0028] Next, the operation of the seismic isolation structure 1 having the above configuration when suppressing vibrations caused by an earthquake during an earthquake will be described.

[0029] When an earthquake occurs and the vibrations of the earthquake are transmitted to the seawater 2a of the sea 2 and the liquid 40 vibrates horizontally together with the seawater 2a, a plurality of first rollers 11 to a plurality of second rollers 21 arranged in the liquid 40 receive the vibrations of the liquid 40 and rotate so as to vibrate in the forward and reverse directions.

[0030] For example, in FIG. 3, when an earthquake occurs and the liquid 40 vibrates in the left - right direction of the paper surface, as shown by the solid line and the two - dot chain line in FIG. 3, a plurality of second rollers 21 receive the vibration of the liquid 40 and rotate in the forward and reverse directions under a plurality of first rollers 11. Although not shown in detail, in FIG. 3, when an earthquake occurs and the liquid 40 vibrates in a direction perpendicular to the paper surface, a plurality of first rollers 11 receive the vibration of the liquid 40 and rotate in the forward and reverse directions under the base body 32 and above a plurality of second rollers 21. Further, in FIG. 3, when an earthquake occurs and the liquid 40 vibrates in a direction inclined with respect to both the axial direction of a plurality of first rollers 11 and the axial direction of a plurality of second rollers 21, a plurality of first rollers 11 and a plurality of second rollers 21 receive the vibration of the components decomposed in the corresponding axial directions of the liquid 40 and rotate in the forward and reverse directions.

[0031] Thereby, the vibration of the liquid 40 generated by the earthquake is absorbed by the rotation of a plurality of first rollers 11 or the rotation of a plurality of second rollers 21, and the transmission of the vibration to the structure main body 30 is suppressed.

[0032] Thus, according to the seismic isolation structure 1 according to the present embodiment, in the configuration where the structure main body 30 floats on the liquid 40, the vibration of the liquid 40 generated by the earthquake can be absorbed by the rotation of a plurality of first rollers 11 or the rotation of a plurality of second rollers 21. Therefore, the transmission of the vibration to the structure main body 30 is suppressed, and the shaking of the building 31 of the structure main body 30 disposed on the liquid 40 due to the earthquake can be effectively suppressed.

[0033] In addition, in the seismic isolation structure 1 according to the present embodiment, since a dilatant fluid is used as the liquid body 40, when the amplitude or frequency of the liquid body 40 vibrating due to an earthquake increases and the rotation of the plurality of first rollers 11 or the rotation of the plurality of second rollers 21 is at a high speed equal to or higher than a predetermined speed, a large rotational resistance can be imparted from the liquid body 40 to the rotation of the plurality of first rollers 11 or the plurality of second rollers 21. Thereby, even if the liquid body 40 vibrates with a large amplitude or frequency, it is possible to effectively suppress the transmission of the vibration to the structure main body 30 disposed on the liquid body 40.

[0034] Furthermore, in the seismic isolation structure 1 according to the present embodiment, since a part of the base body 32 is submerged in the liquid body 40 and the structure main body 30 receives buoyancy from the liquid body 40, the load applied by the structure main body 30 installed on the first roller group 10 can be reduced by the amount of the buoyancy, and the rolling resistance of the plurality of first rollers 11 and the plurality of second rollers 21 can be reduced. Thereby, the vibration transmitted from the liquid body 40 to the structure main body 30 during an earthquake can be made to have a longer period, and the transmission of the vibration to the structure main body 30 disposed on the liquid body 40 can be more effectively suppressed.

[0035] The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist thereof.

[0036] For example, in the above embodiment, the configuration is such that one first roller group 10 and one second roller group 20 are provided under the structure main body 30. However, when the weight of the structure main body 30 is large, such as when a plurality of buildings 31 are installed on the base body 32, as shown in the modification example in FIG. 4, the number of the first roller group 10 and the second roller group 20 provided under the structure main body 30 can be variously changed, such as a configuration in which two first roller groups 10 and two second roller groups 20 are alternately provided under the structure main body 30.

[0037] Note that the sizes (diameter and length), number, concentration or density of the liquid 40, etc. of the plurality of first rollers 11 and the plurality of second rollers 21 can be appropriately set according to the weight, height, natural period, etc. of the structure body 30.

[0038] In the above embodiment, the inside of the semipermeable membrane 41 connected to the base body 32 is filled with the liquid 40 which is a dilatant fluid, and the plurality of first rollers 11 constituting the first roller group 10 and the plurality of second rollers 21 constituting the second roller group 20 are arranged in the liquid 40 which is a dilatant fluid. However, the present invention is not limited to this. As shown as another modification example in FIG. 5, without providing the semipermeable membrane 41, the plurality of first rollers 11 constituting the first roller group 10 and the plurality of second rollers 21 constituting the second roller group 20 may be arranged in the sea water 2a of the sea 2. In this case, the sea water 2a corresponds to the liquid, and the plurality of first rollers 11 and the second roller group 20 constituting the first roller group 10 absorb vibrations by rotating in the sea water 2a. With such a configuration, the configuration of the seismic isolation structure 1 can be further simplified and its cost can be reduced.

[0039] In the seismic isolation structure 1 according to the present embodiment, as described above, logs can be used as the plurality of first rollers 11 and the plurality of second rollers 21. In this case, by installing the seismic isolation structure 1 downstream of a river, at the estuary or near the estuary of the sea adjacent to the forest land where the trees that are the source of the logs are planted, the logs cut in the forest land can be easily transported to the construction site of the seismic isolation structure 1 by flowing them into the river without using land transportation. Thereby, the cost of the seismic isolation structure 1 can be reduced.

[0040] Furthermore, in the above embodiment, the seismic isolation structure 1 is configured to float on the sea. However, the present invention is not limited to this. As long as it floats on a liquid, for example, it may be configured to float on a river, a lake, a pond, a pool, etc. In this case, the liquid may be various liquids such as water, for example.

Explanation of reference numerals

[0041] 1 Seismic isolation structure 2 Sea 2a Seawater 10 First roller group 11 First roller 20 Second roller group 21 Second roller 30 Structure body 31 Building 32 Base body 40 Liquid 41 Semipermeable membrane

Claims

1. A seismic isolation structure comprising: a first roller group disposed in the liquid, the first roller group including a plurality of first rollers each having a specific gravity less than 1 with respect to the liquid and arranged parallel to each other and horizontally with their axes horizontal; a second roller group disposed in the liquid, the second roller group including a plurality of second rollers each having a specific gravity less than 1 with respect to the liquid and arranged parallel to each other and horizontally with their axes horizontal, the plurality of second rollers intersecting the plurality of first rollers and being stacked under the first roller group; and a structure body installed above the first roller group and floating on the liquid.

2. The seismic isolation structure according to Claim 1, wherein the liquid is a dilatant fluid.

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