Seismic isolation building and nuclear facility

Abstract

To provide a seismic isolation building and nuclear facility that improves earthquake resistance and ensures safety during earthquakes.SOLUTION: A reactor building 10 is disposed with a gap between it and a retaining wall 20. An upper external pedestal 22 is fixed to one of the retaining wall 20 or the reactor building 10 and extends toward the other. A lower external pedestal 23 is also fixed to one side and extends toward the other side below the upper external pedestal 22, facing the upper external pedestal 22. An inner pedestal 12 is fixed to the other side and extends toward one side between the upper external pedestal 22 and the lower external pedestal 23. An upper side seismic isolation bearing 101 is disposed between the upper external pedestal 22 and the inner pedestal 12 and fixed thereto. A lower side seismic isolation bearing 102 is disposed between the inner pedestal 12 and the lower external pedestal 23 and fixed thereto. A bottom seismic isolation bearing 103 is connected between the reactor building 10 and a bottom member 21, respectively, to support the reactor building 10.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a seismically isolated building and a nuclear facility. [Background technology]

[0002] Horizontal seismic isolation structures, which reduce horizontal loads during earthquakes by supporting the entire building with seismic isolation materials such as laminated rubber, have been put into practical use. In particular, a horizontal seismic isolation structure in which the entire building is supported from under the floor by seismic isolation materials is called a base isolation structure, or Base Isolation in English. In a base isolation structure, multiple seismic isolation materials are placed in the seismic isolation layer between the ground and the bottom of the building.

[0003] Since buildings normally support their own weight, they are strong against forces applied in the vertical direction, but weak against forces applied in the horizontal direction. For this reason, horizontal seismic isolation structures such as base isolation structures are required to reduce horizontal earthquake motion while supporting the building's own weight. Therefore, seismic isolation materials such as laminated rubber used in horizontal seismic isolation structures such as base isolation structures are hard in the vertical direction and soft in the horizontal direction, in other words, they have high rigidity in the vertical direction and low rigidity in the horizontal direction. In horizontal seismic isolation structures such as base isolation structures, seismic isolation materials are structured in this way to reduce earthquake damage to buildings.

[0004] In particular, nuclear facilities require strong earthquake safety measures to prevent the loss of safety-critical facilities and radiation exposure to the surrounding area due to earthquakes, and therefore the introduction of seismic isolation structures is being considered for nuclear facilities.

[0005] For example, a technology has been proposed to provide a horizontal seismic isolation structure for the reactor building by installing a seismic isolation support device called a seismic isolation bearing between the upper foundation located at the bottom of the reactor building and the support frame connected to the lower foundation formed on the foundation bedrock. Also, a technology has been proposed to provide three-dimensional seismic isolation for the reactor vessel by combining a foundation seismic isolation structure with a vertical seismic isolation structure using a machine seismic isolation method. Furthermore, while the seismic isolation layer in a horizontal seismic isolation structure is usually an air layer in most cases, a technology has been proposed to reduce the number of seismic isolation members by injecting liquid such as water into the seismic isolation layer, utilizing buoyancy.

[0006] Furthermore, a recent trend in the location of next-generation reactor buildings is the increasing number of proposals for "underground reactor buildings" in which the main part of the reactor is located underground. Underground reactor buildings are structures that take into consideration nuclear security, such as the layout of equipment around the reactor, effective use of the site, and the risk of aircraft collisions. In terms of earthquake countermeasures, nuclear facilities often consider earthquake-resistant structures rather than seismic isolation structures, in the hope that earthquake motion will be smaller the further underground they are located. However, it is expected that the safety of nuclear facilities will be improved by adding seismic isolation structures rather than simply burying them underground. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 56-022833 [Patent Document 2] JP 2010-037789 A [Patent Document 3] JP 2004-027732 A Summary of the Invention [Problem to be solved by the invention]

[0008] However, in the behavior of horizontal seismic isolation structures including base isolation structures during earthquakes, the positions of the lines of action of the "inertial force acting on the center of gravity of the upper building" and the "restoring force acting on the seismic isolation layer" are different in the height direction and do not match, so the upper building rotates. This rotation generates tensile loads on the end seismic isolation members arranged on the underside of the building. When laminated rubber is used as the seismic isolation member, the laminated rubber is strong in compression but weak in tension, so rocking rotation and tensile loads are weak points of the seismic isolation structure. This effect becomes more noticeable the higher the shape of the upper building and the more slender the cross-sectional shape. If the upper building becomes more likely to rotate, the laminated rubber becomes more likely to be subjected to tension, which may cause the laminated rubber to break. Thus, if a base isolation structure is simply introduced to an underground reactor building, it is difficult to improve the seismic resistance and ensure safety during an earthquake.

[0009] The issues related to rocking rotation and tensile loads are common to horizontal isolation structures that use base isolation structures. In other words, even with technology that combines base isolation structures with vertical isolation structures using mechanical isolation methods and technology that reduces the number of isolation components by utilizing buoyancy by injecting liquids such as water into the isolation layer, rocking rotation and tensile loads are not reduced, and there is a risk of damage to the isolation components. Therefore, it is difficult to improve earthquake resistance and ensure safety during earthquakes.

[0010] The disclosed technology has been made in consideration of the above, and aims to provide a seismically isolated building and nuclear facility that improves earthquake resistance and ensures safety during earthquakes. [Means for solving the problem]

[0011] In one embodiment of the seismically isolated building disclosed in the present application, an excavation space is formed by excavating the ground. A retaining wall is provided to cover the inner side surface of the excavation space. A bottom surface member is provided to cover the inner bottom surface of the excavation space. A building is disposed in a space formed by the retaining wall and the bottom surface member with a gap between the retaining wall and the building. A first pedestal is fixed to one of the retaining wall or the building and extends from the one side toward the other side of the building or the retaining wall. A second pedestal is fixed to the one side and extends from the one side toward the other side so as to face the first pedestal at a position on the bottom surface member side with respect to the first pedestal. A third pedestal is fixed to the other side and extends from the other side toward the one side between the first pedestal and the second pedestal, and has two surfaces facing the first pedestal and the second pedestal. A first seismic isolation member is disposed between the first pedestal and the third pedestal and is fixed to each of them. A second seismic isolation member is disposed between the third pedestal and the second pedestal and fixed thereto. A third seismic isolation member is disposed between the building and the bottom member and fixed thereto. Effect of the Invention

[0012] In one aspect, the present invention can improve earthquake resistance and ensure safety during earthquakes. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a perspective view of a nuclear facility according to an embodiment. [Diagram 2] FIG. 2 is a schematic diagram of the AA cross section of the base-isolated building in FIG. [Diagram 3] FIG. 3 is a diagram showing the forces acting on a reactor building when no sudden external force such as an earthquake acts on the reactor building and only the effect of gravity acts on the reactor building. [Figure 4] FIG. 4 is a diagram showing an example of the relationship between the draft and the static acting force. [Diagram 5] FIG. 5 is a diagram showing an example of the arrangement of side seismic isolation bearings when the lower pedestal is annular. [Figure 6]FIG. 6 is a plan view showing an example of the arrangement of side seismic isolation bearings when the lower pedestal is rectangular. [Figure 7] FIG. 7 is a diagram showing the balance of horizontal earthquake loads in a seismically isolated building. [Figure 8] FIG. 8 is a diagram showing the rocking rotational motion that occurs in a cylindrical building placed in an excavated space and equipped with a conventional base isolation structure. [Figure 9] FIG. 9 is a diagram showing the balance of horizontal earthquake loads in a seismically isolated building. [Figure 10] FIG. 10 is a schematic cross-sectional view of a base-isolated building according to the first modified example. [Figure 11] FIG. 11 is a schematic cross-sectional view of a base-isolated building according to the second modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, examples of the seismic isolated building and nuclear facility disclosed in the present application will be described in detail with reference to the drawings. Note that the seismic isolated building and nuclear facility disclosed in the present application are not limited to the following examples. EXAMPLES

[0015] (Structure of nuclear facilities and seismically isolated buildings) 1 is a perspective view of a nuclear facility according to an embodiment. The nuclear facility 1 has a reactor building 10 and a retaining wall 20. Although not shown, the nuclear facility 1 is also provided with an auxiliary building in which a cooler that cools steam and turns it back into water is disposed. If the nuclear facility 1 is a power generation facility, a turbine or a generator may be disposed in the auxiliary building. The reactor building 10 and the auxiliary building are connected by a connecting pipe that transports steam and water.

[0016] As shown in Fig. 1, the reactor building 10 is installed in an excavated space obtained by excavating the ground including the position where the reactor building 10 is to be placed. The surrounding ground 2 is the ground surrounding the excavated space obtained by excavating the ground. Furthermore, a retaining wall 20 is provided on the inner wall of the excavated space. A clearance 30 exists between the reactor building 10 and the retaining wall 20. Furthermore, in this embodiment, a liquid such as water is injected into the clearance 30.

[0017] Fig. 2 is a schematic diagram of the AA cross section in Fig. 1. Next, the details of the installation state of the reactor building 10 will be described with reference to Fig. 2. The building having a seismic isolation structure including the reactor building 10, the retaining wall 20, the bottom member 21, and the clearance 30 shown in Fig. 2 is a "seismically isolated building."

[0018] Of the seismically isolated building, the retaining wall 20, bottom member 21, upper external pedestal 22, and lower external pedestal 23 have seismic responses similar to that of the surrounding ground 2. On the other hand, the inner pedestal 12, reactor building 10, and reactor pressure vessel 11 are seismically isolated areas that are structurally insulated from the surrounding ground 2 by the boundary areas of the upper side seismic isolation bearing 101, the lower side seismic isolation bearing 102, the bottom seismic isolation bearing 103, the clearance 30, and the liquid 31, and therefore the inner pedestal 12, reactor building 10, and reactor pressure vessel 11 have seismic responses similar to each other and significantly different from that of the surrounding ground 2.

[0019] In the following, the direction of gravity, i.e., the direction perpendicular to the Earth's surface toward the center of the Earth, will be referred to as "down," and the opposite direction to the direction of gravity, i.e., the direction perpendicular to the Earth's surface from the center of the Earth toward the Earth's surface, will be referred to as "up." Additionally, the direction parallel to a horizontal plane perpendicular to the direction of gravity will be referred to as "horizontal."

[0020] As described above, the ground including the position where the reactor building 10 is to be placed is excavated downward to a size large enough to accommodate the reactor building 10, forming an excavated space. For example, if the reactor building 10 is cylindrical, the ground is excavated so that the excavated space becomes a cylinder having a diameter larger than the diameter of the reactor building 10. However, as long as the reactor building 10 can be accommodated in the excavated space, the shape does not have to match the horizontal cross section of the reactor building 10.

[0021] The retaining wall 20 is arranged so as to cover the inner wall of the excavation space. The retaining wall 20 arranged on the inner wall is subjected to earth pressure from the surrounding ground 2 toward the excavation space. The retaining wall 20 holds down the surrounding ground 2 from the excavation space toward the surrounding ground 2 so as not to collapse into the excavation space in which the reactor building 10 is arranged due to the earth pressure. Here, since the excavation space becomes deeper according to the size of the reactor building 10, the retaining wall 20 receives a larger earth pressure from the surrounding ground 2 as the height of the reactor building 10 increases. Therefore, the retaining wall 20 is provided with a thickness to prevent it from collapsing into the excavation space. However, in this embodiment, since the retaining wall 20 receives pressure from the excavated space toward the surrounding ground 2 due to water pressure as described later, it does not need to have a thickness sufficient to withstand the entire earth pressure of the surrounding ground 2.

[0022] A bottom surface member 21 is disposed so as to cover the bottom surface, which is the lowest surface of the excavated space. The bottom surface member 21 is joined to the retaining wall 20 so as to prevent the liquid 31 stored inside from leaking out.

[0023] However, the watertightness of the retaining wall 20 and the bottom member 21 does not need to be so high, and cracks may be tolerated. This is because groundwater is likely to be present in the surrounding ground 2, and even if cracks occur in the retaining wall 20 or the bottom member 21, the seismic isolated building of this embodiment in which the liquid 31 is stored in the clearance 30 will have a steady balance between the internal and external water pressures.

[0024] The reactor building 10 is disposed in a space formed by a retaining wall 20 and a bottom member 21. Moreover, the reactor building 10 is disposed so that a clearance 30 exists between the retaining wall 20 and the reactor building 10. The reactor building 10 houses, for example, a reactor pressure vessel 11 and the like therein.

[0025] The upper external pedestal 22 is a flat plate-like member extending horizontally from the retaining wall 20 toward the space formed by the retaining wall 20 and the bottom member 21. In other words, the upper external pedestal 22 extends horizontally toward the reactor building 10 when the reactor building 10 is disposed in the space formed by the retaining wall 20 and the reactor building 10. The upper external pedestal 22 is joined and fixed to the retaining wall 20. The upper external pedestal 22 has a length that does not reach the reactor building 10.

[0026] The upper external pedestal 22 according to this embodiment is provided so as to surround the entire periphery of the inner wall of the retaining wall 20. Here, in this embodiment, as an example, the upper external pedestal 22 is described as surrounding the entire periphery of the inner wall of the retaining wall 20, but the upper external pedestal 22 may be provided in a range corresponding to a part of the entire periphery of the inner wall of the retaining wall 20 as long as it has an area in which the upper side seismic isolation bearing 101 described later is arranged.

[0027] In this embodiment, the upper external pedestal 22 is formed to have an inner periphery with the same shape as the horizontal cross section of the space formed by the retaining wall 20. For example, when the retaining wall 20 forms a cylindrical space, the upper external pedestal 22 has an annular shape with an opening facing in the vertical direction, and its outer periphery is joined to the inner wall of the retaining wall 20. Furthermore, multiple upper external pedestals 22 are arranged at different positions in the vertical direction to form multiple layers. This upper external pedestal 22 is an example of a "first pedestal."

[0028] The lower external pedestal 23 is a flat plate-like member extending horizontally from the retaining wall 20 toward the space formed by the retaining wall 20 and the bottom member 21. In other words, the lower external pedestal 23 also extends horizontally toward the reactor building 10 when the reactor building 10 is disposed in the space formed by the retaining wall 20 and the reactor building 10. The lower external pedestal 23 is provided below the upper external pedestal 22 and at a position facing the upper external pedestal 22. The lower external pedestal 23 is also joined and fixed to the retaining wall 20. The lower external pedestal 23 has a length that does not reach the reactor building 10. In this embodiment, the lower external pedestal 23 has the same length toward the reactor building 10 as the upper external pedestal 22.

[0029] The lower external pedestal 23 according to this embodiment is also provided so as to surround the entire periphery of the inner wall of the retaining wall 20. In this embodiment, the lower external pedestal 23 is also formed so as to have an inner periphery having the same shape as the horizontal cross section of the space formed by the retaining wall 20. Furthermore, the lower external pedestal 23 is arranged corresponding to each of the layers of the upper external pedestal 22, and forms multiple layers together with the upper external pedestal 22. The lower external pedestal 23 supports the inner pedestal 12 from below via the lower side seismic isolation bearing 102, thereby supporting the reactor building 10 from below on the side. This lower external pedestal 23 is an example of a "second pedestal."

[0030] The inner pedestal 12 is provided on the side surface of the reactor building 10 that faces the retaining wall 20, and is a flat plate-like member extending toward the retaining wall 20. The inner pedestal 12 is joined and fixed to the side surface of the reactor building 10. The inner pedestal 12 has a length that does not reach the retaining wall 20.

[0031] The inner pedestal 12 according to this embodiment is provided so as to surround the entire periphery of the side surface of the reactor building 10. In addition, in this embodiment, the inner pedestal 12 is formed in the same shape as the upper outer pedestal 22 and the lower outer pedestal 23. For example, when the upper outer pedestal 22 has a circular ring shape, the inner pedestal 12 also has a circular ring shape with an opening facing in the vertical direction, and the inner periphery is joined to the side surface of the reactor building 10. Furthermore, the inner pedestals 12 are also arranged in multiple positions corresponding to each of the layers formed by the upper outer pedestal 22 and the lower outer pedestal 23, forming multiple layers together with the upper outer pedestal 22 and the lower outer pedestal 23. Specifically, the inner pedestals 12 are provided in the same number as the upper outer pedestal 22, at positions sandwiched between the upper outer pedestal 22 and the lower outer pedestal 23. This inner pedestal 12 is an example of a "third pedestal".

[0032] Here, the number of layers formed by the upper external pedestal 22, the internal pedestal 12, and the lower external pedestal 23 is preferably determined according to the number of upper side seismic isolation bearings 101 and lower side seismic isolation bearings 102 used to provide a seismic isolation structure to the reactor building 10. The upper external pedestal 22, the internal pedestal 12, and the lower external pedestal 23 may be located at opposing positions so as to be able to sandwich the upper side seismic isolation bearings 101 and the lower side seismic isolation bearings 102. If the strength is sufficient, the upper external pedestal 22, the internal pedestal 12, and the lower external pedestal 23 may be members that sandwich the upper side seismic isolation bearings 101 and the lower side seismic isolation bearings 102 with a width capable of sandwiching the upper side seismic isolation bearings 101 and the lower side seismic isolation bearings 102.

[0033] The upper side seismic isolation bearing 101 is disposed between the upper external pedestal 22 and the internal pedestal 12, with its upper surface joined to the upper external pedestal 22 and its lower surface joined to the internal pedestal 12. The upper side seismic isolation bearing 101 is a seismic isolation member that absorbs horizontal forces generated by the difference in displacement between the upper external pedestal 22 and the internal pedestal 12 when an earthquake occurs, thereby making it difficult for earthquake vibrations to be transmitted to the reactor building 10. This upper side seismic isolation bearing 101 is an example of a "first seismic isolation member."

[0034] The lower side seismic isolation bearing 102 is disposed between the inner pedestal 12 and the lower external pedestal 23, with its upper surface joined to the inner pedestal 12 and its lower surface joined to the lower external pedestal 23. The lower side seismic isolation bearing 102 is a seismic isolation member that absorbs horizontal forces generated by the difference in displacement between the inner pedestal 12 and the lower external pedestal 23 when an earthquake occurs, thereby making it difficult for earthquake vibrations to be transmitted to the reactor building 10. This lower side seismic isolation bearing 102 is an example of a "second seismic isolation member."

[0035] The upper side seismic isolation bearing 101 and the lower side seismic isolation bearing 102 are preferably arranged in industrial facilities such as power plants and factories where windows do not need to be provided in the outer wall, called the outer wall, of the reactor building 10. In general buildings, it is normal to provide windows for residential use in the outer wall, and it is difficult to apply the seismic isolation structure in which the upper side seismic isolation bearing 101 and the lower side seismic isolation bearing 102 according to this embodiment are arranged. Therefore, the seismic isolation structure according to this embodiment is suitable mainly as a seismic isolation structure for non-residential buildings such as nuclear facilities 1.

[0036] Furthermore, the upper side seismic isolation bearings 101, the lower side seismic isolation bearings 102, the upper external pedestal 22, the internal pedestal 12, and the lower external pedestal 23 are all made to have a structure with high vertical rigidity. As a result, the seismic isolated building according to this embodiment can reduce the upward vertical displacement of the side surface of the reactor building 10, and can reduce the rotational rocking motion of the entire reactor building 10.

[0037] Furthermore, the combinations of the upper side seismic isolation bearings 101, the lower side seismic isolation bearings 102, the upper outer pedestal 22, the inner pedestal 12, and the lower outer pedestal 23 are arranged in multiple layers at different positions in the vertical direction. The vertical positions of each of these combinations are determined so that the center of gravity of the reactor building 10 and the center of rigidity of the reactor building 10 coincide with each other when an earthquake occurs. This makes it possible to suppress the rotational rocking motion of the entire reactor building 10.

[0038] A plurality of bottom seismic isolation bearings 103 are provided on the bottom surface facing the bottom member 21 of the reactor building 10. The bottom seismic isolation bearings 103 are joined to the bottom member 21. The bottom seismic isolation bearings 103 support the reactor building 10 on the bottom member 21. The bottom seismic isolation bearings 103 are seismic isolation members that absorb horizontal forces generated by the difference in displacement between the reactor building 10 and the surrounding ground 2 during an earthquake, thereby making it difficult for earthquake shaking to be transmitted to the reactor building 10. The bottom seismic isolation bearings 103 are an example of a "third seismic isolation member".

[0039] The construction sequence up to this point is, for example, as follows: The reactor building 10 with the bottom seismic isolation bearing 103 placed on the bottom is inserted into the space formed by the retaining wall 20 and the bottom member 21, and the bottom member 21 of the reactor building 10 is placed with the bottom member 21 supported by the bottom seismic isolation bearing 103. Next, starting from the bottom, the lower external pedestal 23 is joined to the retaining wall 20, then the lower side seismic isolation bearing 102 is joined to the lower external pedestal 23, then the internal pedestal 12 is joined to the lower side seismic isolation bearing 102 and joined to the retaining wall 20, then the upper side seismic isolation bearing 101 is joined to the internal pedestal 12, and then the upper external pedestal 22 is joined to the upper side seismic isolation bearing 101 and joined to the retaining wall 20. The combination of the upper side seismic isolation bearings 101, the lower side seismic isolation bearings 102, the upper external pedestal 22, the internal pedestal 12 and the lower external pedestal 23 forms a predetermined number of layers and is arranged so that the distance between the center of gravity of the reactor building 10 and the center of rigidity of the reactor building 10 is as small as possible in the event of an earthquake.

[0040] The clearance 30 is a gap provided so that if a displacement difference occurs between the reactor building 10 and the retaining wall 20 due to the seismic isolation structure during an earthquake, the reactor building 10 will not collide with the retaining wall 20 due to the displacement difference.

[0041] During an earthquake, the reactor building 10 moves horizontally within the stretched range of the upper side seismic isolation bearings 101 and the lower side seismic isolation bearings 102 due to the displacement difference with the surrounding ground 2. In other words, the clearance 30 should be a distance that ensures that the inner pedestal 12 does not come into contact with the inner wall of the retaining wall 20 and that the upper external pedestal 22 and the lower external pedestal 23 do not come into contact with the side of the reactor building 10 when the upper side seismic isolation bearings 101 and the lower side seismic isolation bearings 102 are fully stretched.

[0042] In this embodiment, a liquid 31 such as water is injected into the clearance 30. The liquid 31 may be something other than water, for example, heavy muddy water. The liquid 31 injected into the clearance 30 exerts buoyancy on the reactor building 10.

[0043] In the seismic isolated building according to this embodiment, the reactor building 10 is not completely lifted off the bottom member 21, and the bottom seismic isolation bearing 103 bears part of the weight of the reactor building 10. Since the bottom seismic isolation bearing 103 sits on the bottom member 21, it is structurally connected, generating horizontal rigidity and transmitting horizontal earthquake loads. In other words, the reactor building 10 receives, in addition to its own weight, a force due to the buoyancy of the liquid 31 from below upwards, a force by the lower outer pedestal 23 supporting the inner pedestal 12 via the lower side seismic isolation bearing 102, and a force from the bottom member 21.

[0044] FIG. 3 is a diagram showing the forces that the reactor building receives when only the effect of gravity acts without the action of a sudden external force such as an earthquake. The reactor building 10 receives its own weight P0 downward due to gravity. The reactor building 10 also receives bottom buoyancy P1 from the liquid 31 from the bottom to the top. The lower side seismic isolation bearing 102 receives a downward load from the internal pedestal 12 and a compressive force acts on it. The internal pedestal 12 receives an upward side reaction force P2 from the lower side seismic isolation bearing 102 in response to the compressive force. All the internal pedestals 12 on which the lower side seismic isolation bearings 102 are arranged receive the side reaction force P2. The bottom seismic isolation bearing 103 also receives a compressive force in response to the load of the reactor building 10 downward. The reactor building 10 receives an upward bottom reaction force P3 from the bottom seismic isolation bearing 103 in response to the compressive force. Then, the reactor building 10 comes to rest as a result of the self-weight P0 of the reactor building 10 being balanced with the sum of the bottom buoyancy P1, the side reaction force P2 and the bottom reaction force P3.

[0045] The buoyancy acting on the reactor building 10 acts not only on the bottom surface but also on the undersides of the upper external pedestal 22, the inner pedestal 12 and the lower external pedestal 23. However, since the bottom surface buoyancy force P1 is overwhelmingly large and the buoyancy forces of the upper external pedestal 22, the inner pedestal 12 and the lower external pedestal 23 are expected to be negligibly small, they are ignored in this embodiment.

[0046] For example, the total weight of the reactor building 10 is 66,400 tf, and the volume is 41 m length x 41 m width x 49 m height = 82.369 m 3 Consider the case where the above equation is satisfied. Figure 4 is a diagram showing an example of the relationship between the draft depth and the static acting forces. The static acting forces include the weight P0 of the reactor building 10, the bottom buoyancy P1, the side reaction force P2, and the bottom reaction force P3. In Table 50, the total amount of the side reaction force P2 is simply represented as P2. The total amount of the seismic isolation bearing reaction force is P2+P3.

[0047] As shown in Table 50 in Fig. 4, when the draft is 39.5 m, the bottom buoyancy P1 balances with the weight of the reactor building 10, and the total amount of seismic isolation bearing reaction force P2+P3 becomes zero. When the draft is set to less than 39.5 m, the total amount of seismic isolation bearing reaction force P2+P3 becomes a positive value, and the bottom seismic isolation bearing 103 reliably bears part of the weight of the reactor building 10. That is, range 51 in Table 50 is a suitable range for this embodiment in which the reactor building 10 according to the embodiment has a seismic isolation structure in a state where it is supported by the bottom seismic isolation bearing 103 without being completely floated.

[0048] In Table 50, the weight reaction force ratio (P2+P3) / P0 indicates the proportion of the weight of the reactor building 10 borne by the upper side seismic isolation bearing 101, the lower side seismic isolation bearing 102, and the bottom seismic isolation bearing 103. For example, when the draft is 39.5 m, the bottom buoyancy P1 is equal to the weight of the reactor building 10, so the upper side seismic isolation bearing 101, the lower side seismic isolation bearing 102, and the bottom seismic isolation bearing 103 do not bear the weight P0 of the reactor building 10, and the weight reaction force ratio is 0%. Also, for example, when the draft is 0 m, that is, when the liquid 31 is not injected, the bottom buoyancy P1 is zero, so the weight P0 of the reactor building 10 must be borne entirely by the upper side seismic isolation bearing 101, the lower side seismic isolation bearing 102, and the bottom seismic isolation bearing 103, and the weight reaction force ratio is 100%. As described above, by increasing the water depth, the bottom buoyancy P1 gradually increases, and the burden ratio of the side reaction force P2 and the bottom reaction force P3 can be reduced. From this, it can be said that the higher the water depth and the higher the weight reaction force ratio, the easier it is to plan the layout of the bottom seismic isolation bearings 103, and thus the possibility of modifications in preparation for an increase in the design load and the redundancy for changes in seismic loads increase.

[0049] FIG. 5 is a diagram showing an example of the arrangement of the lower side seismic isolation bearings when the inner pedestal is annular. In FIG. 5, the upper outer pedestal 22, the upper side seismic isolation bearing 101, and the inner pedestal 12 are omitted so that the lower side seismic isolation bearing 102 can be seen. The dotted line 121 indicates the end of the inner pedestal 12. The upper side seismic isolation bearing 101 is arranged on the opposite side of the lower side seismic isolation bearing 102 shown in FIG. 5 across the inner pedestal 12. In order to stably support the reactor building 10, it is preferable to arrange at least three lower side seismic isolation bearings 102A to 102C in a balanced manner so that they are evenly spaced on the circumference of the inner pedestal 12 on each floor as shown in FIG. 5.

[0050] Here, as the number of lower side seismic isolation bearings 102 per story increases, the load distribution and stress distribution of the internal pedestal 12 and the reactor building 10 approach a uniform spatial distribution, and local destruction due to stress concentration can be prevented. Therefore, from the viewpoint of local destruction due to stress concentration, the more the number of lower side seismic isolation bearings 102 per story, the more preferable. Therefore, it is preferable to determine the number of lower side seismic isolation bearings 102 per story in consideration of the size of the space to be provided and local destruction due to stress concentration. Furthermore, in this embodiment, the upper side seismic isolation bearings 101 and the lower side seismic isolation bearings 102 are arranged on opposite sides of the internal pedestal 12, but the numbers of upper side seismic isolation bearings 101 and lower side seismic isolation bearings 102 may be different.

[0051] Fig. 6 is a plan view showing an example of the arrangement of lower side seismic isolation bearings when the lower pedestal is rectangular. In this case as well, in order to stably support the reactor building 10, it is preferable to arrange at least four lower side seismic isolation bearings 102A-102D in the internal pedestal 12 on each floor, one at the center of each side of the rectangle, as shown in Fig. 6. In this case as well, from the viewpoint of localized destruction due to stress concentration, the more lower side seismic isolation bearings 102 on each floor, the better.

[0052] (effect) Next, some effects obtained by the nuclear facility 1 according to this embodiment will be described. The first effect is as follows. Fig. 7 is a diagram for explaining a rocking rotation prevention mechanism in a seismically isolated building, and illustrates a case where a rightward inertial force acts on the reactor building 10. Fig. 8 is a diagram showing a rocking rotation motion that occurs in a structure in which a building placed in an excavated space is provided with a conventional base isolation, and illustrates a case where a rightward inertial force acts on the reactor building 10.

[0053] In the seismic isolated building according to this embodiment, the horizontal loads, ie, the horizontal restoring force P4 associated with the horizontal deformation of the upper side seismic isolation bearing 101, the horizontal restoring force P5 associated with the horizontal deformation of the lower side seismic isolation bearing 102, and the horizontal restoring force P6 associated with the horizontal deformation of the bottom seismic isolation bearing 103, are balanced with the inertial forces acting on each part of the reactor building 10. The inertial force of the reactor building 10 is replaced with the sum P7 of inertial forces acting on one point of the center of gravity. On the other hand, the horizontal restoring force P4 associated with the horizontal deformation of the upper side seismic isolation bearing 101, the horizontal restoring force P5 associated with the horizontal deformation of the lower side seismic isolation bearing 102, and the horizontal restoring force P6 associated with the horizontal deformation of the bottom seismic isolation bearing 103 are also replaced with the sum P8 of restoring forces acting on one point of the center of rigidity.

[0054] As shown in FIG. 7, when the sum of inertial forces P7 and the sum of restoring forces P8 occur at different positions in the vertical direction, a rocking rotation P20 occurs around the center of gravity. When the rocking rotation P20 occurs, a compressive force is generated in the upper side seismic isolation bearing 101 on the left side of the paper, and a tensile force is generated in the lower side seismic isolation bearing 102 on the left side of the paper. In this case, the pressure stiffness of the upper side seismic isolation bearing 101 is large and hardly deforms, so the tensile force of the lower side seismic isolation bearing 102 on the left side of the paper does not increase and does not break. Also, when the rocking rotation P20 occurs, a tensile force is generated in the upper side seismic isolation bearing 101 on the right side of the paper, and a compressive force is generated in the lower side seismic isolation bearing 102 on the right side of the paper. In this case, the pressure stiffness of the lower side seismic isolation bearing 102 is large and hardly deforms, so the tensile force of the upper side seismic isolation bearing 101 on the right side of the paper does not increase and does not break. Then, a reaction force P9 against the compressive force of the upper side seismic isolation bearing 101 on the left side of the page acts on each upper external pedestal 22, and a reaction force P10 against the compressive force of the lower side seismic isolation bearing 102 on the right side of the page acts on each lower external pedestal 23. This prevents rocking rotational deformation of the reactor building 10, and the bottom seismic isolation bearing 103 does not break because no upward tensile load is applied. Even if the buoyancy of the reactor building 10 is large and the bottom seismic isolation bearing 103 is in a floating state, an unstable seismic response such as only one side floating up does not occur, and a stable state can be maintained.

[0055] In contrast, in a conventional structure with base isolation, when the vertical positions of the center of gravity and the center of rigidity are displaced during an earthquake, the mechanism for restraining the rotation of the reactor building 10 is weak. Therefore, as shown in FIG. 8, the inertial force P11 of the center of gravity and the sum P12 of the restoring forces of the center of rigidity are generated at different positions in the vertical direction. When such a force acts, a rocking rotational force P13 is generated around the center of gravity. The rocking rotational force P13 lifts the bottom end of the reactor building 10 on the opposite side to the direction of the inertial force P11 of the center of gravity. In this case, for example, the tensile force acting on the seismic isolation members 103C to 103F in FIG. 8 is smaller than the respective durability, so no rupture occurs, but the seismic isolation members 103A and 103B may be subjected to a large tensile force and rupture occurs. If the seismic isolation members 103A and 103B rupture, the appropriate seismic isolation structure cannot be maintained, resulting in a dangerous state. In this way, the seismic isolation building according to this embodiment can improve safety compared to a conventional structure with base isolation.

[0056] Furthermore, in the seismic isolation building according to the embodiment, the height of the rigidity center can be changed by adjusting the rigidity of the bottom seismic isolation bearing 103 and the position and rigidity of each of the upper side seismic isolation bearing 101 and the lower side seismic isolation bearing 102. Therefore, in the seismic isolation structure of the reactor building 10 according to the embodiment, the height of the rigidity center can be adjusted to the height of the center of gravity by adjusting the rigidity of the bottom seismic isolation bearing 103 and the position and rigidity of each of the upper side seismic isolation bearing 101 and the lower side seismic isolation bearing 102. FIG. 9 is a diagram showing the balance of horizontal earthquake loads in a seismic isolation building. If the positions of the rigidity center and the center of gravity are adjusted to match, it is also possible to match the positions of the sum of inertia forces P7 and the sum of restoring forces P8 as shown in FIG. 9. As a result, in the seismic isolation building according to the embodiment, the rocking rotational motion that occurs in a base-isolated building can be more reliably suppressed, and safety can be improved.

[0057] The second effect is as follows. The concept of "existing non-conformity" that is acceptable for general buildings does not apply to the nuclear facility 1 and the reactor building 10, and it is required to ensure a state that conforms to regulations and standards based on the latest knowledge. For example, if the seismic load has increased based on the latest knowledge, it is necessary to improve the structure of the nuclear facility 1 and the reactor building 10 to be compatible with the increased seismic load. For this reason, it is desirable to leave space in consideration of expandability when designing and constructing the nuclear facility 1.

[0058] When a conventional base isolation is provided for a building to be placed in an excavated space, a seismic isolation member such as laminated rubber is laid out in the base, and the seismic isolation member is placed directly below the vertical support member of the upper building. A large number of seismic isolation members are placed in order to support the entire weight of the building with the seismic isolation members placed in the base. For this reason, at the time of new construction, seismic isolation members have already been placed in most of the positions that meet the placement conditions for the seismic isolation members. Even if new knowledge is used to respond to an increase in the design earthquake motion, it is difficult to secure additional space for the seismic isolation members or the installation work space. In contrast, in the nuclear facility 1 having the seismic isolation structure according to this embodiment, the number of seismic isolation bearings can be suppressed to about 1 / 4 of the conventional base isolation method. Therefore, sufficient extra space can be secured for the placement space of the upper side seismic isolation bearing 101 and the lower side seismic isolation bearing 102. If the design earthquake motion is updated and the building needs to be remodeled, the secured extra space can be used to consider adding or replacing new upper side seismic isolation bearings 101 and lower side seismic isolation bearings 102. In this way, in the nuclear facility 1 having the seismic isolation structure according to this embodiment, it is possible to provide redundancy in design and modification.

[0059] In addition, in this embodiment, since the liquid 31 is injected into the clearance 30, the following effects can be obtained. For example, the following effect can be cited as the third effect. Comparing the base isolation and the base isolation structure in the reactor building 10 according to this embodiment, when a conventional base isolation is provided in a building placed in an excavated space, the retaining wall 20 receives all of the earth pressure from the surrounding ground 2. In contrast, in the base isolation structure in the reactor building 10 according to this embodiment, water pressure is generated on the inside of the retaining wall 20 in the direction toward the surrounding ground 2, and the earth pressure received from the outside can be offset by the amount of this water pressure. Therefore, the retaining wall 20 can be made thinner by the amount of the reduced earth pressure, making it possible to ensure ease of construction and reduce costs.

[0060] In addition, the fourth effect is as follows: In the nuclear facility 1, it is necessary to estimate the risk of an aircraft collision as a countermeasure against terrorism. As for this risk, it is desirable to consider not only the risk of the load at the time of the aircraft collision, but also the risk when aircraft fuel flows into the seismic isolation layer where the seismic isolation members are arranged.

[0061] In relation to this, if a conventional base isolation system is provided for a building to be placed in the excavated space, there is a concern that a fire may break out due to fuel flowing into the clearance 30. In contrast, in the nuclear facility 1 having the seismic isolation structure according to this embodiment, the clearance 30 is filled with liquid 31, so that the flow of aircraft fuel into the clearance 30 is suppressed. This makes it possible to prevent the upper side seismic isolation bearing 101 and the lower side seismic isolation bearing 102 from being deteriorated or damaged by high heat, and to maintain seismic resistance. However, if the draft depth is 0 m without injecting liquid 31, it is difficult to obtain the third and fourth effects.

[0062] In addition, in this embodiment, an example has been described in which liquid 31 is injected into the clearance 30, but it is possible to construct a seismically isolated building without injecting liquid 31. Even in a seismically isolated building that does not have liquid 31 injected, it is possible to obtain effects such as suppressing rocking rotational motion and ensuring redundancy in design and remodeling, thereby improving earthquake resistance and ensuring safety during earthquakes.

[0063] (First Modification) Fig. 10 is a schematic cross-sectional view of a seismically isolated building according to the first modified example. In the seismically isolated building according to this embodiment, the positions of the upper external pedestal 22, the lower external pedestal 23, and the internal pedestal 12 are reversed to those of the seismically isolated building according to Example 1. The seismically isolated building according to the first modified example will be described below with reference to Fig. 10.

[0064] 10 , the upper external pedestal 22 and the lower external pedestal 23 according to this modification are fixed to the reactor building 10 and extend from the reactor building 10 toward the retaining wall 20. In this case, the upper external pedestal 22 and the lower external pedestal 23 have a length that does not reach the retaining wall 20.

[0065] Moreover, the inner pedestal 12 according to this modification is fixed to the retaining wall 20 and extends from the retaining wall 20 toward the reactor building 10. In this case, the inner pedestal 12 has a length that does not reach the reactor building 10.

[0066] Thus, even in the configuration in which the upper external pedestal 22 and the lower external pedestal 23 are fixed to the retaining wall 20 and the internal pedestal 12 is fixed to the reactor building 10, the following effects are obtained. That is, even if the sum of the inertial forces and the sum of the restoring forces occur at different positions in the vertical direction and a rocking rotational force occurs around the center of gravity, the upper side seismic isolation bearing 101 and the lower side seismic isolation bearing 102 have a large compressive rigidity and are hardly deformed, so that the upper side seismic isolation bearing 101 and the lower side seismic isolation bearing 102 do not experience a large tensile force and do not break. Then, the reaction force of the lower side seismic isolation bearing 102 against the compressive force and the reaction force of the upper side seismic isolation bearing 101 against the compressive force can suppress rocking rotational deformation of the reactor building 10. Then, by suppressing the rocking rotational deformation, the breakage of the bottom seismic isolation bearing 103 is suppressed. Also, it is possible to provide redundancy in design and modification. Therefore, it is possible to improve seismic resistance and ensure safety during earthquakes.

[0067] (Second Modification) Fig. 11 is a schematic cross-sectional view of a seismically isolated building according to the second modified example. The seismically isolated building according to this embodiment differs from Example 1 in that the upper external pedestal 22 and the lower external pedestal 23 are integrated into a single member, the intermediate external pedestal 24. The seismically isolated building according to the first modified example will be described below with reference to Fig. 10.

[0068] 11, in the seismically isolated building according to this modification, an upper external pedestal 22 is disposed from the upper end of a retaining wall 20. Below the upper external pedestal 22 extending from the upper end of the retaining wall 20, intermediate external pedestals 24 are disposed in multiple layers at different positions in the vertical direction.

[0069] One internal pedestal 12 is disposed between the upper external pedestal 22 extending from the upper end of the retaining wall 20 and the intermediate external pedestal 24 immediately below it. Furthermore, the internal pedestal 12 is disposed between each of the vertically adjacent intermediate external pedestals 24. In addition, in this embodiment, the internal pedestal 12 is also disposed between the lowest intermediate external pedestal 24 and the bottom member 21.

[0070] The upper side seismic isolation bearing 101 is disposed between the upper external pedestal 22 extending from the upper end of the retaining wall 20 and the internal pedestal 12 immediately below it. The upper side seismic isolation bearing 101 is also disposed between the intermediate external pedestal 24 and the internal pedestal 12 immediately below it.

[0071] The lower side seismic isolation bearings 102 are disposed between the inner pedestal 12 and the intermediate outer pedestal 24 immediately below it. The lower side seismic isolation bearings 102 are also disposed between the bottom member 21 and the intermediate outer pedestal 24 immediately above it.

[0072] In other words, the seismically isolated building of the second variant is configured by integrating the upper external pedestal 22 and the lower external pedestal 23, which are adjacent to each other in the vertical direction without sandwiching the internal pedestal 12 in between in the first embodiment, into a single component called the intermediate external pedestal 24.

[0073] In this way, even if the upper external pedestal 22 and the lower external pedestal 23 are integrated into one member, the upper external pedestal 22 and the intermediate external pedestal 24 can suppress rocking rotation deformation of the reactor building 10. Furthermore, suppression of rocking rotation deformation suppresses fracture of the bottom seismic isolation bearing 103. In addition, it becomes possible to provide redundancy in design and modification. Therefore, it becomes possible to improve seismic resistance and ensure safety during earthquakes. [Explanation of symbols]

[0074] 1. Nuclear Facilities 2 Surrounding ground 10 Reactor Building 11 Reactor Pressure Vessel 12 Inner pedestal 20 Retaining Wall 21 Bottom member 22 Upper external pedestal 23 Lower external pedestal 30 Clearance 31 liquid 101 Upper side seismic isolation bearing 102 Lower side seismic isolation bearing 103 Bottom seismic isolation bearing

Claims

1. An excavation space formed by excavating the ground; A retaining wall provided to cover the inner side surface of the excavation space; A bottom member provided to cover an inner bottom surface of the excavation space; A building disposed in a space formed by the retaining wall and the bottom member with a gap between the retaining wall and the building; A first base fixed to one of the retaining wall or the building and extending from the one toward the other of the building or the retaining wall; a second seat fixed to the one side and extending from the one side to the other side so as to face the first seat at a position on the bottom member side with respect to the first seat; a third seat fixed to the other seat, extending from the other seat toward the one seat between the first seat and the second seat, and having two surfaces facing the first seat and the second seat; a first seismic isolation member disposed between the first base and the third base and fixed to each of them; a second seismic isolation member disposed between the third base and the second base and fixed to each of them; a third seismic isolation member disposed between the building and the bottom member and fixed thereto; and A seismic isolation building comprising:

2. The seismically isolated building according to claim 1, characterized in that the building receives buoyancy from liquid injected into a space formed by the retaining wall and the bottom member.

3. The first pedestal is provided at a plurality of different positions in a direction from the bottom member toward the building, The second seats are provided at positions opposite to the first seats, and the number of the second seats is the same as that of the first seats; The third pedestals are provided in the same number for each pair of the first pedestal and the second pedestal facing each other, The first seismic isolation member is disposed between the first base and the third base which face each other, The second seismic isolation member is disposed between the third base and the second base which face each other. The seismic isolation building according to claim 1 .

4. The seismically isolated building described in claim 3, characterized in that each of the combinations of the first pedestal, the second pedestal, the third pedestal, the first seismic isolation member and the second seismic isolation member is positioned in a direction from the bottom member toward the building so that the center of gravity of the building coincides with the center of rigidity of the building in the event of an earthquake.

5. The seismically isolated building described in claim 3, characterized in that the first pedestal and the second pedestal, which are adjacent to each other in the direction from the bottom member toward the building without the third pedestal in between, are arranged in an overlapping position in the direction from the bottom member toward the building, and are integrated as a single member.

6. The first base and the second base are fixed to the retaining wall and extend from the retaining wall toward the building. The third base is fixed to the building and extends from the building toward the retaining wall. The seismic isolation building according to claim 1 .

7. The first base is provided around the entire inner periphery of the retaining wall, The second base is provided around the entire inner periphery of the retaining wall at a position opposite to the first base, The third pedestal is provided around the entire periphery of the building at a position between the first pedestal and the second pedestal, The first seismic isolation members are arranged in plurality between a pair of the first base and the third base that face each other, The second seismic isolation members are arranged in a plurality between a pair of the third base and the second base that face each other. The seismic isolation building according to claim 6.

8. An excavation space formed by excavating the ground; A retaining wall provided to cover the inner side surface of the excavation space; A bottom member provided to cover an inner bottom surface of the excavation space; a reactor building that houses a reactor pressure vessel and is disposed in a space defined by the retaining wall and the bottom member with a gap between the retaining wall and the reactor building; a first base fixed to one of the retaining wall or the reactor building and extending from the one toward the other of the building or the retaining wall; a second seat fixed to the one of the first and extending from the one to the other so as to face the first seat at a position on the bottom member side with respect to the first seat; a third seat fixed to the other seat, between the first seat and the second seat, extending from the other seat toward the one seat, and having two surfaces facing the first seat and the second seat; a first seismic isolation member disposed between the first base and the third base and fixed to each of them; a second seismic isolation member disposed between the third base and the second base and fixed to each of them; a third seismic isolation member disposed between the building and the bottom member and fixed thereto; and A nuclear facility characterized by comprising:

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