JP2010275802A - Base-isolated structure and building - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a base-isolated structure which can surely perform base isolation by utilizing a liquefaction phenomenon regardless of the quality of ground, and furthermore which can be executed in a simpler structure. <P>SOLUTION: This base-isolated structure 1 includes: an earth tank 10 which is formed in an excavated section A obtained by excavating a ground surface and in which water can be stored; a horizontal displacement device 11 which is installed on the bottom surface 10a of the earth tank 10, which allows the horizontal displacement of a building B, and which bears a vertical load of the building B; liquefaction-inducing soil 12 which is infilled into the earth tank 10 and which attenuates the horizontal vibrations of the building B by inducing the liquefaction in the earth tank 10; and a water supply device 13 which supplies water to the liquefaction-inducing soil in the earth tank 10. The horizontal displacement device 11 comprises a plurality of rollable spheres 20 which bear the vertical load of the building B, and a frame body 21 which houses and surrounds the plurality of rollable spheres 20. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a base isolation structure using liquefaction-induced soil and a building having the base isolation structure.

  Buildings built according to the latest seismic standards in the middle and lower floors resonate when built on relatively hard ground, closer to the dominant period of seismic motion and the natural period of the building than when built on so-called soft ground. Tend to be damaged by vibration. On the other hand, if the area has an extremely high earthquake hazard such as the vicinity of the fault of the Tokai / Tonankai earthquake, vibration damage can be reduced if liquefaction occurs.

  Patent Document 1 proposes a seismic isolation building using a liquefaction phenomenon. That is, in Patent Document 1, the ground improvement specification is adjusted so that liquefaction occurs when seismic motion of a certain level or more acts, and the ground improvement that reduces earthquake input to the building by liquefaction during strong earthquake operation. The construction method is described. It is possible to reduce vibration damage (damage of structures, damage to secondary members, equipment) due to the occurrence of liquefaction. However, in Patent Document 1, the building is subsided with liquefaction. It is difficult to prevent superstructure damage from being induced.

  Therefore, in Patent Document 2, it is proposed to construct a liquefied layer partitioned by pumping up groundwater and to support the building with a pile. However, in this case, the liquefaction conditions depend on the groundwater condition of the ground. That is, the groundwater supply in Patent Document 2 utilizes the increase in pore water pressure due to ground strain at the time of an earthquake, and liquefaction may not occur on the ground where the pore water pressure does not increase. Therefore, in the technique of Patent Document 2, there is a case where seismic isolation cannot be performed depending on the ground.

  Moreover, in patent document 2, it is necessary to penetrate the pile with an internal passage deeply in the ground, and the structure for seismic isolation becomes complicated and large, and construction becomes difficult.

Japanese Patent No. 4035744 JP 11-315544 A

  The present invention has been made in view of the above points, and is capable of performing seismic isolation utilizing the liquefaction phenomenon reliably regardless of the quality of the ground and yet having a simpler structure. Its purpose is to provide structures and buildings.

  In order to achieve the above object, the present invention provides a soil basin formed on an excavation where the ground surface is excavated and capable of storing water, and provided on the bottom surface of the soil basin, allowing horizontal movement of the structure and A horizontal movement device that supports the vertical load of the structure, a liquefaction-induced soil that fills the earth tub and induces liquefaction in the earth tub to attenuate horizontal vibration of the structure, and liquefaction in the earth tub A water supply device that supplies water to the induced soil, and the horizontal movement device supports a vertical load of the structure and can roll, and a frame that houses and surrounds the plurality of spheres, It is a seismic isolation structure characterized by having.

  According to the present invention, water can be supplied to the liquefaction-induced soil in the soil tank by the water supply device, so that the seismic isolation utilizing the liquefaction phenomenon can be reliably performed regardless of the ground quality. In addition, since the structure is supported using a plurality of spheres on the bottom surface of the earth tub, seismic isolation can be performed with a simple structure. In addition, by using a sphere, the horizontal mobility of the structure required for seismic isolation can be sufficiently secured.

  The frame may be formed in a lattice shape, and a sphere may be accommodated in each square frame of the lattice shape. In such a case, since the positional relationship between the spheres and the positional relationship between the sphere and the structure do not change, it is possible to reliably and stably ensure horizontal movement in all directions of the structure.

  A plate-like body may be interposed between the plurality of spheres and the structure. In such a case, the load applied to the plurality of spheres from the structure can be equalized. Moreover, a plate-shaped object can play the role of the formwork at the time of foundation concrete placement of a structure.

  The seismic isolation structure is provided on the inner wall of the earth tub, and is provided on an outer wall of the structure or an elastic device that generates elastic force against the contact of the structure. It may further have an elastic device that generates an elastic force. In such a case, the structure can be pushed back in the direction of returning to the original position against the lateral displacement of the structure due to the earthquake, so that the displacement of the structure due to the earthquake can be reduced.

  The elastic device may be made of foamed rubber.

  The clay tank may have a box shape of reinforced concrete with an open top surface.

  The soil tank may be formed by laying a water shielding sheet on the surface of the dug. Moreover, a bottom plate may be installed on the water-impervious sheet of the earth tub, and the horizontal movement device may be provided on the bottom plate.

  The water supply device is based on a pipe that supplies water into the earth tub, an on-off valve that opens and closes the pipe, a sensor that detects a water level in the earth tub, and a detection result of the water level by the sensor. And a controller that opens and closes the on-off valve so that the water level is equal to or higher than a predetermined height. In such a case, it is possible to reliably maintain the amount of water in the soil tank and to perform seismic isolation due to the liquefaction phenomenon.

  According to this invention from another viewpoint, the building which has the said seismic isolation structure is provided.

  According to the present invention, the seismic isolation using the liquefaction phenomenon can be reliably performed regardless of the quality of the ground, and can be performed with a simple structure.

It is explanatory drawing which shows the outline of a structure of the building which has a seismic isolation structure concerning this Embodiment. (A) is a top view which shows the outline of a structure of a horizontal displacement apparatus. (B) is a longitudinal cross-sectional view of a horizontal moving device. It is explanatory drawing which shows the elastic device seen from the side. It is explanatory drawing which looked at the elastic device from the upper part. It is explanatory drawing which shows the elastic device of the state which the structure contacted. It is explanatory drawing which shows the state which installed the horizontal displacement apparatus at the time of construction. It is explanatory drawing which shows the state which filled the sphere with the liquefaction induction soil at the time of construction. It is explanatory drawing which shows the structure of the seismic isolation structure which has the soil tank of a water shielding sheet.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. Drawing 1 is an explanatory view showing the outline of the composition of building 2 which has seismic isolation structure 1 concerning this embodiment.

  The seismic isolation structure 1 is formed in, for example, a dug A where the ground surface is excavated, and is provided on a soil tank 10 capable of storing water and a bottom surface 10a of the soil tank 10, and allows horizontal movement of the structure B. And the horizontal movement apparatus 11 which supports the vertical load of the structure B, the liquefaction induction soil 12 which is filled in the earth tub 10 and induces liquefaction in the earth tub 10 to attenuate the horizontal vibration of the structure B, and the earth tub 10 has a water supply device 13 for supplying water to the liquefaction-inducing soil 12 in the inside.

  The earth tub 10 has, for example, a box shape of reinforced concrete with an open upper surface. The horizontal movement device 11 includes, for example, a plurality of spheres 20 that can roll while supporting the vertical load of the structure B, and a frame body 21 that houses and surrounds the plurality of spheres 20. As the sphere 20, for example, an industrial glass sphere, an industrial porcelain sphere, a concrete sphere, or the like is used. For example, as shown in FIG. 2A, the frame body 21 is formed in a rectangular lattice shape, and the spherical body 20 is accommodated in each of the lattice-shaped square frames 21a. As will be described later, the sphere 20 can roll in a rectangular frame 21a when an earthquake occurs, and the sphere 20 and the frame 21 move horizontally on the bottom surface 10a together (the frame 21 is fixed to the bottom plate of the earth tub 10). Absent). Further, the frame body 21 is formed such that the vertical dimension (the height at which the frame body 21 protrudes from the bottom surface 10a of the earth tub 10) is shorter (lower) than the diameter of the sphere body 20, as shown in FIG. When the sphere 20 is accommodated, the upper side of the sphere 20 protrudes from the frame 21. Thereby, the spherical body 20 can support the plate-like body 22 to be described later on the upper surface. Further, the laying range of the sphere 20 and the frame body 21 with respect to the bottom surface 10a has substantially the same area as the bottom surface of the structure B.

  As shown in FIG. 1, a plate-like body 22 is placed on a plurality of spheres 20, and a structure B is supported thereon. The plate-like body 22 has a size that covers the entire bottom surface of the structure B, and can move horizontally with respect to the sphere 20. The plate-like body 22 can be a resin plate, a steel plate, or the like.

  As shown in FIG. 3, the inner wall 10 b of the earth tub 10 is provided with an elastic device 30 that generates an elastic force against the contact with the structure B, for example. The elastic device 30 is made of foamed rubber, for example. The elastic device 30 protrudes inward from the inner wall 10b of the earth tub 10, for example, and has a trapezoidal shape when viewed from a tapered side. Moreover, the elastic device 30 is formed long in the horizontal direction along the inner wall 10b of the earth tub 10 as shown in FIG. The elastic device 30 is formed on the inner wall 10b of each side (in plan view) of the box-shaped earth tub 10, for example. A plurality of elastic devices 30 may be provided at equal intervals according to the size (depth or width) of the structure B. With this elastic device 30, as shown in FIG. 5, when the structure B moves in the horizontal direction due to an earthquake, the elastic device 30 comes into contact with the elastic device 30 to generate an elastic force, and pushes the structure B in a direction to return the structure B to the original position. it can.

  For example, as shown in FIG. 1, the water supply device 13 includes a pipe 40 that supplies water into the earth tub 10, an on-off valve 41 that opens and closes the pipe 40, and a water level of the liquefaction-induced soil 12 in the earth tub 10. And a control unit 43 that opens and closes the on-off valve 41 so that the water level becomes equal to or higher than a predetermined height based on the detection result of the water level by the sensor 42. The pipeline 40 is connected to a water supply source 44 such as water. As the on-off valve 41, for example, an electromagnetic valve is used, and for the sensor 42, for example, a water pressure gauge is used. As the control unit 43, for example, a computer having a CPU, a memory, and the like is used.

  As the liquefaction-inducing soil 12, for example, a relatively uniform sandy soil having a low fine particle size content of about 10% and a majority particle size of 0.1 mm to 1.0 mm is used. Moreover, the liquefaction induction soil 12 may be other than earth and sand, and for example, materials such as resin beads and glass beads having a uniform particle diameter can be used.

  Next, the construction method of the above seismic isolation structure 1 is demonstrated. First, the excavation A is excavated on the ground surface, and the earth tub 10 is formed in the excavation A. The earth tub 10 may be supported from below by a pile or the like. After that, as shown in FIG. 6, the frame body 21 of the horizontal movement device 11 is installed on the bottom surface 10 a of the earth tub 10, and the sphere body 20 is accommodated in each rectangular frame 21 a of the frame body 21. Furthermore, a water supply device 13 and an elastic device 30 are installed in the earth tub 10.

  Next, as shown in FIG. 7, the liquefaction-induced soil 12 is placed in the earth tub 10 so that the sphere 20 is buried. Thereafter, the plate-like body 22 is placed on the sphere 20. Next, as shown in FIG. 1, the foundation of the structure B is constructed on the plate-like body 22, and the liquefaction-inducing soil 12 is placed in the earth tub 10 so as to have the same height as the ground surface. Next, the structure B is constructed, and then water is supplied into the earth tub 10 by the water supply device 13 so that the water level in the earth tub 10 becomes a predetermined height. After construction, the water level in the earth tub 10 is monitored by the sensor 42. When the water level falls below a predetermined water level, the control valve 43 opens the on-off valve 41, and water is supplied into the earth tub 10 through the pipeline 40.

When an earthquake occurs, the sphere 20 itself vibrates horizontally on the bottom surface 10 a together with the frame body 21 (not fixed to the bottom plate of the earth tub 10), and the structure B placed on the plate-like body 22 on the sphere 20 is also easy. Vibrates horizontally. At this time, since the horizontal movement width of the sphere 20 and the frame body 21 is smaller than the horizontal movement width of the structure B, the structure B may be in a cantilevered state (see FIG. 5).
When the structure B moves horizontally and contacts the elastic device 30, the elastic device 30 contracts to generate a repulsive force, and pushes the structure B back to the center side of the earth tub 10. Further, when the structure B passes through the center of the earth tub 10 and moves horizontally and contacts the elastic device 30 on the opposite inner wall 10b, the elastic device 30 contracts to generate a repulsive force, and the structure B is transferred to the earth tub 10. Push it back to the center. By such repetition, the displacement (the displacement (amplitude) due to horizontal vibration) of the structure B after the earthquake is restored. On the other hand, the liquefaction-induced soil 12 liquefies and becomes a viscous body, which damps the horizontal vibration of the structure B. Thereby, the structure B is seismically isolated. In addition, since the frame 21 is aligned, the plurality of spheres 20 are not scattered from the lower surface of the structure B due to horizontal vibration, and the support state of the structure B is maintained.

  According to the above embodiment, since water can be supplied to the liquefaction induction soil 12 by the water supply device 13, the seismic isolation utilizing the liquefaction phenomenon can be reliably performed regardless of the ground quality. Moreover, since the structure B can be supported using the plurality of spheres 20 on the bottom surface 10a of the earth tub 10, seismic isolation can be performed with a simple structure. In addition, by using the sphere 20, the horizontal mobility of the structure B necessary for seismic isolation can be sufficiently secured.

  The frames 21 are formed in a lattice shape, and the spheres 20 are accommodated in the respective rectangular frames 21a. Therefore, the positional relationship between the spheres 20 remains unchanged, and the structures B in all directions of the structures B on the spheres 20 are invariable. The horizontal movement can be secured reliably and stably.

  Since the plate-like body 22 is interposed between the plurality of spheres 20 and the structure B, the load applied to the plurality of spheres 20 from the structure B can be equalized. In addition, the plate-like body can serve as a formwork when the foundation B of the structure B is placed.

  Since the inner wall 10b of the earth tub 10 is provided with the elastic device 30 that generates an elastic force against the contact with the structure B, the displacement of the structure B due to the earthquake (displacement due to horizontal vibration) can be restored. In addition, in the said embodiment, although the elastic apparatus 30 was provided in the inner wall 10b of the earth tub 10, you may be provided in the outer side wall of the structure B. FIG. Also in this case, when the structure B moves horizontally and the earth tub 10 contacts the elastic device 30, the elastic device 30 contracts to generate a repulsive force and pushes the structure B back to the center side of the earth tub 10. Furthermore, when the structure B passes through the center of the earth tub 10 and comes into contact with the elastic device 30 on the inner wall 10b on the opposite side, the elastic device 30 contracts to generate a repulsive force, and the structure B is moved toward the center of the earth tub 10. Push back. By such repetition, the displacement of the structure B after the earthquake (horizontal vibration displacement (amplitude)) is restored.

  Moreover, in the said embodiment, since the earth tub 10 has the box shape shape of the reinforced concrete with which the upper surface was open | released, the water retention for liquefaction can be performed appropriately.

  The on / off valve 41 is controlled by the control unit 43 of the water supply device 13 based on the detection result of the water level in the earth tub 10 by the sensor 42 so that the water level becomes a predetermined height or more. It is possible to reliably maintain seismic isolation due to the liquefaction phenomenon.

  In the above embodiment, the earthen basin 10 is reinforced concrete, but it may be an earthen basin 51 formed by laying a water shielding sheet 50 on the surface of the digging A as shown in FIG. In such a case, a bottom slab 52 made of, for example, reinforced concrete may be installed on the water-impervious sheet 50 of the earth tub 10, and the sphere 20 and the frame 21 of the horizontal movement device 11 may be provided on the bottom slab 52. In this case, the elastic device 30 is provided on the outer wall surface of the structure B, and the outer edge of the bottom slab 52 made of reinforced concrete is raised for the reaction wall so that the elastic device 30 is repelled by the outer edge portion 52a of the bottom slab 52. May be. Moreover, the reaction force wall and the structure B can be connected using the elastic device 30 as a spring. In such a case, an inexpensive seismic isolation structure 1 with a simpler structure can be realized.

  The preferred embodiments of the present invention have been described above with reference to the accompanying drawings, but the present invention is not limited to such examples. It is obvious for those skilled in the art that various modifications or modifications can be conceived within the scope of the idea described in the claims, and these naturally belong to the technical scope of the present invention. It is understood.

For example, in the above embodiment, the laying range of the sphere 20 and the frame body 21 with respect to the bottom surface 10a is provided in accordance with substantially the same area as that of the bottom surface of the structure B. May be. This is to prevent the structure B from tilting when the structure B protrudes greatly from the laying range (see FIG. 5).
Further, as another configuration of the horizontal movement device, the frame body 21 is fixed to the plate-like body 22 side, and when the sphere 20 is accommodated, the lower side of the sphere 20 protrudes from the frame body 21 so that the earth tub 10. You may make it roll on the bottom face 10a.
Further, although the elastic device 30 is foamed rubber, it may be other rubber such as high damping rubber as long as it generates an elastic force, or a spring or a spring mechanism using a spring. There may be.

DESCRIPTION OF SYMBOLS 1 Seismic isolation structure 2 Building 10 Earth tank 11 Horizontal movement apparatus 12 Liquefaction induction soil 13 Water supply apparatus 20 Sphere 21 Frame A A digging B Structure

Claims (10)

A soil tank that is formed in an excavation where the ground surface is excavated and can store water;
A horizontal movement device that is provided on the bottom surface of the earth tub and allows horizontal movement of the structure and supports the vertical load of the structure;
Liquefaction-induced soil filled in the earth basin and inducing liquefaction in the earth basin to attenuate horizontal vibrations of the structure;
A water supply device for supplying water to the liquefaction-induced soil in the clay tank,
The horizontal movement device includes a plurality of spheres capable of supporting and rolling the vertical load of the structure, and a frame body that houses and surrounds the plurality of spheres.   The seismic isolation structure according to claim 1, wherein the frame is formed in a lattice shape, and a sphere is accommodated in each square frame of the lattice shape.   The seismic isolation structure according to claim 1, wherein a plate-like body is interposed between the plurality of spheres and the structure.   An elastic device that is provided on the inner wall of the earth tub and generates elastic force against the contact of the structure, or an elastic device that is provided on the outer wall of the structure and generates elastic force against the contact of the inner wall of the earth tub The seismic isolation structure according to claim 1, further comprising a device.   The seismic isolation structure according to claim 4, wherein the elastic device is made of foamed rubber.   The seismic isolation structure according to any one of claims 1 to 5, wherein the earth tub has a box shape of reinforced concrete with an open upper surface.   The seismic isolation structure according to claim 1, wherein the earth tub is formed by laying a water shielding sheet on a surface of the excavation.   The seismic isolation structure according to claim 7, wherein a bottom plate is installed on a water shielding sheet of the earth tub, and the horizontal movement device is provided on the bottom plate.   The water supply device is based on a pipe for supplying water into the earth tub, an on-off valve for opening and closing the pipe, a sensor for detecting the water level in the earth tub, and a detection result of the water level by the sensor. And a control unit that opens and closes the on-off valve so that the water level in the earth tub is equal to or higher than a predetermined height. .   A building having the base-isolated structure according to claim 1.

Images