JP3769716B2 - Structure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a structure forming a building or the like, and more particularly, to a structure constructed so as to reduce vibration response during an earthquake.
[0002]
[Prior art]
As a typical example of this type of structure, for example, a seismic isolation device such as laminated rubber is interposed between the lower structure and the upper structure of the building, thereby increasing the natural period of the building. Seismic isolation buildings are known.
[0003]
[Problems to be solved by the invention]
In recent years, seismic isolation buildings have become known for their excellent seismic isolation effects, and are spreading throughout the country. However, with the spread, the need to build seismic isolation buildings on soft ground is also increasing. .
[0004]
In soft ground and easily liquefied ground, the ground layer may be softly deformed, and the ground itself may function as a kind of seismic isolation mechanism. Even if a conventional seismic isolation mechanism is installed in such a building on the ground, in order to obtain a sufficient seismic isolation effect, it may be necessary to further increase the period of the seismic isolation device. That may not be the case.
[0005]
The present invention has been made in view of such circumstances, and provides a structure capable of satisfactorily reducing vibration response during an earthquake when constructed on soft ground or liquefied ground. This is the issue.
[0006]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention adopts the following means in consideration of positively using soft ground or liquefied ground as a seismic isolation ground.
That is, the structure according to claim 1 is a structure erected on the ground having a support layer and a soft ground or a surface layer made of a liquefied ground ,
A pile provided so that its lower end reaches the support layer;
A lower structure connected to the upper end of the pile and provided so that at least a portion thereof is located in the surface layer;
An upper structure provided on the lower structure,
The lower structure has a double bottom plate that can obtain a predetermined buoyancy from the groundwater retained in the surface layer or the earth and sand fluidized during liquefaction at the bottom, and by adjusting the amount of water inside There is a water tank to adjust the buoyancy,
The pile is formed with a predetermined spring rigidity in the horizontal direction so as to elastically restrict the horizontal displacement of the upper structure and the lower structure ,
Even if the ground vibrates during an earthquake, the surface layer acts to block transmission of the ground vibration to the lower structure and the upper structure .
[0007]
In order to obtain such a configuration, in this structure, the weight of the upper structure and the lower structure can be greatly reduced by making the lower structure a floating structure, and the load supported by the pile can be greatly reduced. This allows the pile to have a smaller cross section than normal, so that the pile acts as a soft spring and restores the position of the superstructure and substructure, even if the superstructure and substructure are displaced horizontally be able to.
[0009]
Moreover, in this structure, it is possible to keep the buoyancy constant even if the buoyancy from the soil that has been fluidized during liquefaction changes due to changes in the groundwater level, An axial force can be prevented from acting.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram schematically showing an embodiment of the present invention, and reference numeral 1 indicates a building (structure) formed as a building.
[0011]
As shown in the figure, the building 1 is erected on a ground G having a support layer 2 and a surface layer 3. The surface layer 3 has a relatively high groundwater level Ws, a soft ground or a ground that is liable to be liquefied.
[0012]
The building 1 is roughly composed of piles 5,... And an RC structure lower structure 6 and upper structure 7. The piles 5,... Are formed of steel pipes, and are placed in the ground G so that the lower end 5 a reaches the support layer 2, and the upper end 5 b is connected to the bottom 6 a of the lower structure 6. It has been configured.
[0013]
Further, the bottom structure 6 has a bottom 6a which is a double bottom board 8. By having this double bottom board 8, buoyancy is generated from the groundwater W staying in the surface layer 3 or from the earth and sand fluidized during liquefaction. Can be received. This buoyancy is set so as to significantly reduce the weight of the lower structure 6 and the upper structure 7.
[0014]
The lower structure 6 has a water tank 9 inside. The water tank 9 is configured to freely introduce and discharge water therein, and the buoyancy acting on the lower structure 6 can be adjusted by adjusting the amount of water inside.
[0015]
The piles 5,... Are formed with a predetermined spring rigidity in the horizontal direction. In this case, since the lower ends 5a of the piles 5 are fixed to the support layer 2, the horizontal displacement of the lower structure 6 and the upper structure 7 connected to the upper end 5b is elastically restricted. Function. The horizontal spring stiffness of the piles 5,... Is set to such an extent that the horizontal displacement expected to occur in the lower structure 6 and the upper structure 7 due to the earthquake motion can be eliminated by the elastic force of the piles 5,. Has been.
[0016]
In the building 1 having such a configuration, even if the ground G vibrates at the time of an earthquake, the surface layer 3 acts to block transmission of vibration of the ground G to the lower structure 6 and the upper structure 7. As a result, the building 1 is seismically isolated. In this case, since the piles 5 are formed with a predetermined spring rigidity in the horizontal direction, even if the lower structure 6 and the upper structure 7 are displaced by the vibration of the ground G, the elasticity of the piles 5. This displacement can be eliminated by force, and the residual displacement after the earthquake can be minimized.
[0017]
Further, when the groundwater level Ws rises or falls, the amount of water in the water tank 9 is adjusted. As a result, the axial force acting on the piles 5,... Can be kept constant. The excessive axial force acts to damage the piles 5, or the buoyancy increases and the building 1 is lifted. Can be prevented.
[0018]
As described above, in the building 1, the lower structure 6 is configured to be able to obtain a predetermined buoyancy from the groundwater W staying in the surface layer 3 or from the earth and sand fluidized during liquefaction. In addition, the lower structure 6 and the upper structure 7 can be insulated from the ground G as a floating structure, and thereby the seismic isolation effect can be obtained by actively using the surface layer 3. In this case, unlike conventional seismic isolation buildings, seismic isolation mechanisms such as laminated rubber are not required, seismic isolation pits and retaining walls are not required, and the cross-sections of the piles 5,. A seismic isolation effect can be obtained at low cost. Furthermore, because the piles 5,... Are formed with a predetermined spring rigidity in the horizontal direction, the horizontal displacement of the upper structure 7 and the lower structure 6 is elastically restricted. The residual displacement of the building 1 after the earthquake can be suppressed, and the function of the building 1 after the earthquake can be ensured.
[0019]
In addition, in the building 1, the buoyancy received by the lower structure 6 is adjusted by adjusting the amount of water in the aquarium 9 to prevent an excessive axial force from acting on the pile 5. There is no risk of damage and high safety.
[0020]
In addition, this invention is not limited to the said embodiment, You may make it employ | adopt another structure as needed.
For example, in the above embodiment, the lower structure 6 and the upper structure 7 are made of RC, but instead of this, SRC or S may be used.
Moreover, in the said embodiment, the magnitude | size of the buoyancy which the lower structure 6 can receive can be arbitrarily set in the range of about 30%-100% of the weight of the upper structure 7. FIG. Moreover, in the said embodiment, although the piles 5 ... are steel pipe piles, it may replace with this and may make it employ | adopt a steel pipe winding cast-in-place concrete pile.
Further, the connection between the upper end 5b of the pile and the lower structure 6 may be a normal fixing method or a pin fixing method.
[0021]
【The invention's effect】
As described above, the structure according to claim 1 has a structure in which the lower structure can obtain a predetermined buoyancy from the groundwater retained in the surface layer or the earth and sand fluidized during liquefaction. In addition, the lower structure and the upper structure can be isolated from the ground as a floating structure, and thereby the seismic isolation effect can be obtained by actively utilizing the surface layer. In this case, unlike conventional seismic isolation buildings, there is no need for seismic isolation mechanisms such as laminated rubber. A seismic effect can be obtained. Further, since the pile is formed with a predetermined horizontal spring rigidity, the horizontal displacement of the superstructure and the substructure is elastically restricted, so that the residual after the earthquake The displacement can be suppressed and the function of the structure after the earthquake can be secured.
[0022]
Moreover, by adjusting the amount of water in the aquarium, the buoyancy received by the substructure is adjusted to prevent excessive axial force from acting on the pile, so there is no risk of pile damage, etc., and safety Is expensive.
[Brief description of the drawings]
FIG. 1 is an elevational sectional view of a building schematically showing an embodiment of the present invention.
[Explanation of symbols]
1 building (structure)
2 Support layer 3 Surface layer 5 Pile 5a Lower end 5b Upper end 6 Lower structure 7 Upper structure 9 Water tank G Ground W Ground water Ws Ground water level

Claims (1)

A structure standing on a ground having a support layer and a soft ground or a surface layer made of a liquefied ground ,
A pile provided so that its lower end reaches the support layer;
A lower structure connected to the upper end of the pile and provided so that at least a portion thereof is located in the surface layer;
An upper structure provided on the lower structure,
The lower structure has a double bottom plate that can obtain a predetermined buoyancy from the groundwater retained in the surface layer or the earth and sand fluidized at the time of liquefaction, and adjusts the amount of water inside the bottom structure. There is a water tank to adjust the buoyancy,
The pile is formed with a predetermined spring rigidity in the horizontal direction so as to elastically restrict the horizontal displacement of the upper structure and the lower structure ,
A structure characterized in that even if the ground vibrates during an earthquake, the surface layer acts to block transmission of the ground vibration to the lower structure and the upper structure .

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