Simple base-isolation structure

Abstract

To provide a simple base-isolation structure capable of improving base-isolation performance in a rather low cost.SOLUTION: A simple base-isolation structure 2 supports a building BL, being provided with: ballast 10 including crushed rocks and gravel; a base 20 arranged on the ballast 10; a collapse prevention structure 30 covering surroundings of the ballast 10; and a frame body 40 arranged around the collapse prevention structure 30. The ballast 10 is formed in a target area A1 set on the ground level GL as reference. The collapse prevention structure 30 is arranged around the ballast 10. The collapse prevention structure 30 includes soil, pebbles, and sand. The soil is preferably material such that it is allowed to penetrate into gaps between the crushed rocks and the pebbles constituting the ballast 10. The frame body 40 is arranged around the ballast 10 on the ground level GL as reference. Concrete is preferably material to form the frame body 40.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] As a recent seismic isolation technology, it is common to install a seismic isolation device that utilizes a laminated rubber body, a bearing, etc. between a building and the foundation of the base to prevent the shaking of an earthquake from being directly transmitted to the building.

[0003] However, in the construction method with a seismic isolation device installed, since it is difficult for seismic motion to be directly transmitted to the building, even though it has been found to be effective in reducing the toppling of furniture, fixtures, etc., the initial investment (design cost and construction cost) related to seismic isolation detached houses is high, and regular maintenance for maintaining the functions of the seismic isolation device and replacement work at regular intervals are required. At present, the spread to the detached house market has not advanced.

[0004] As a countermeasure for this, there is a simple seismic isolation structure for imparting a seismic isolation function to lightweight structures such as detached houses, equipment, and devices using crushed stones and gravel (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, although the simple seismic isolation method of Patent Document 1 can be implemented at a relatively low cost, its seismic isolation performance is not sufficient.

[0007] Therefore, an object of the present invention is to provide a simple seismic isolation structure and a simple seismic isolation method that can improve seismic isolation performance at a relatively low cost.

Means for Solving the Problems

[0008] The simple seismic isolation structure of the present invention is characterized by comprising a ballast, a foundation provided on the ballast, and a landslide prevention structure covering the periphery of the ballast.

[0009] The landslide prevention structure preferably includes at least one of soil, sand, or small stones that can penetrate into the gaps between the gravel or crushed stones constituting the ballast. It is preferable to provide a frame body surrounding the ballast. The ballast and the frame body are preferably provided above the ground surface or on a common underground surface.

[0010] The simple seismic isolation construction method of the present invention includes a ballast formation step of providing a ballast on a target area, a landslide prevention structure formation step of providing a landslide prevention structure so as to cover the periphery of the ballast, and a foundation formation step of providing a foundation on the ballast. The landslide prevention structure is characterized by including soil that can penetrate into the gaps between the gravel or crushed stones constituting the ballast.

[0011] It includes a frame body formation step of forming a frame body around the target area. In the landslide prevention structure formation step, it is preferable to fill the landslide prevention structure between the frame body and the ballast.

Advantages of the Invention

[0012] According to the present invention, it is possible to provide a simple seismic isolation structure and a simple seismic isolation construction method with improved seismic isolation performance at a relatively low cost.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0014] As shown in FIG. 1, the simple seismic isolation structure 2 supports the building BL, and includes a ballast 10 containing crushed stones or gravel, a foundation 20 provided on the ballast 10, a landslide prevention structure 30 covering the periphery of the ballast 10, and a frame body 40 provided around the landslide prevention structure 30.

[0015] The ballast 10 is formed in a target area A1 set on the reference ground surface GL. The ballast 10 is formed in a frustum shape. The dimensions of the target area A1 in plan view may be the area of the ballast 10 necessary to support the intended building BL and the foundation 20.

[0016] The ballast 10 contains crushed stones or gravel. The size of the stones constituting the crushed stones or gravel is not particularly limited as long as it does not contradict the gist of the present invention. For example, it is 30 mm or more and 60 mm or less. The thickness of the ballast 10 is not particularly limited as long as it does not contradict the gist of the present invention. For example, it is preferably 200 mm or more and 500 mm or less, and more preferably 250 mm or more and 300 mm or less.

[0017] The foundation 20 is a monolithic foundation. As the forming material of the foundation 20, reinforcing bars and concrete are used. The thickness of the foundation 20 is not particularly limited as long as it does not contradict the gist of the present invention. For example, it is preferably 100 mm or more and 200 mm or less, and more preferably 100 mm or more and 150 mm or less. Here, the thickness of the foundation 20 refers to the vertical thickness for the portion extending in the horizontal direction, and the horizontal thickness for the portion extending in the vertical direction.

[0018] The landslide prevention structure 30 is provided around the ballast 10. The landslide prevention structure 30 contains soil, small stones, and sand. This soil is preferably one that can penetrate into the gaps between the crushed stones or gravel constituting the ballast 10. Further, the landslide prevention structure 30 preferably covers the slope surface 10NM of the ballast 10. Note that the landslide prevention structure 30 more preferably covers not only the slope surface 10NM of the ballast 10 but also the upper surface 10UM.

[0019] The frame body 40 is provided around the ballast 10 on the reference ground surface GL. As the forming material of the frame body 40, concrete is preferable. The size of the frame body 40 is not particularly limited as long as it does not conflict with the gist of the present invention. For example, it is preferably 120% or more and 140% or less based on the size of the ballast 10 in plan view.

[0020] Next, the simple seismic isolation method will be described.

[0021] As shown in FIG. 2, the simple seismic isolation method 100 includes a frame body forming step 110, a ballast forming step 120, a landslide prevention structure forming step 130, and a foundation forming step 140.

[0022] In the frame body forming step 110, the frame body 40 is provided around the target area A1 set on the reference ground surface GL. When performing the frame body forming step 110, the reference ground surface GL is preferably flat.

[0023] In the ballast forming step 120, the ballast 10 is provided in the target area A1. The ballast 10 is preferably formed in a frustum shape.

[0024] In the landslide prevention structure forming step 130, the landslide prevention structure 30 is provided so as to cover the periphery of the ballast 10. The soil as the landslide prevention structure 30 is preferably filled between the frame body 40 and the ballast 10.

[0025] In the foundation forming step 140, the foundation 20 is provided on the ballast 10. In the foundation forming step 140, after providing the foundation 20, the landslide prevention structure 30 may be provided so as to cover the periphery of the foundation 20 in the foundation forming step 140.

[0026] In this way, the simple seismic isolation structure 2 is formed by the simple seismic isolation method 100.

[0027] Next, according to the simplified seismic isolation structure 2, since the foundation 20 is provided on the ballast 10, the seismic vibration energy becomes the energy of the flow and friction of the crushed stones or gravels that make up the ballast 10, so the energy transmitted to the building BL is reduced.

[0028] In addition, since the anti-collapse structure 30 is provided around the ballast 10, the shape of the ballast 10 is maintained in the state at the time of construction. As a result, the vibration energy absorption performance of the ballast 10 can be maintained as expected. Furthermore, due to the anti-collapse structure 30, the shape of the ballast 10 is maintained in the state at the time of construction, so the displacement (horizontal and vertical directions) of the position of the building BL provided thereon can be suppressed.

[0029] Furthermore, since the soil included in the anti-collapse structure 30 can penetrate into the gaps between the crushed stones or gravels that make up the ballast 10, after the simplified seismic isolation method 100, over time, the soil solidifies in a state where the soil has entered the gaps between the crushed stones or gravels that make up the ballast 10. As a result, a mixed structure K in which the gaps between the crushed stones or gravels are filled with soil is formed in the vicinity of the slope surface 10NM and the upper surface 10UM of the ballast 10. When the seismic vibration energy is transmitted to the mixed structure K, in the mixed structure K, the soil portion filled in the gaps between the crushed stones or gravels and integrating them is more likely to be preferentially destroyed compared to the anti-collapse structure 30 other than the mixed structure K. That is, the seismic vibration energy is utilized as the energy to destroy the mixed structure K. Furthermore, after that, since the mixed structure K has fluidity, the seismic vibration energy becomes the energy of the flow and friction of the soil and the crushed stones or gravels that make up the ballast 10. The horizontal length of the mixed structure K is preferably 5% or more and 15% or less of the length of the target area A1, respectively.

[0030] Thus, according to the simplified seismic isolation structure 2, since the performance of absorbing seismic vibration energy is high, the vibration energy transmitted to the building BL can be suppressed. The mixed structure K can be formed in the vicinity of the slope surface 10NM and the upper surface 10UM of the ballast 10 in a short time.

[0031] In addition, in the anti-collapse structure forming step 130, it may be possible to compact from the upper surface of the anti-collapse structure 30 filled between the frame body 40 and the ballast 10, or to sprinkle water on the upper surface of the anti-collapse structure 30. This allows the hybrid structure K to be formed in a short time.

[0032] In the above embodiment, the ballast 10 is provided in the target area A1 set on the reference ground surface GL. However, the present invention is not limited to this. Holes GL may be formed in the ground surface GL, the ballast 10 may be provided on the bottom surface GM of the holes GL, and the foundation 20 may be provided on the ballast 10 (FIG. 3). In this case, if the wall surface of the hole GL performs the same function as the frame body 40, the frame body 40 may be omitted.

[0033] In the above embodiment, the ballast 10 is formed in a frustum shape. However, the present invention is not limited to this, and the ballast 10 may be formed in a rectangular parallelepiped shape.

[0034] In the above embodiment, the foundation 20 is assumed to be a monolithic foundation. However, the present invention is not limited to this, and as the foundation 20, independent foundations, mat foundations, deep foundations, and pile foundations can also be used.

[0035] Note that the present invention is not limited to the above-described embodiments, and it goes without saying that various changes can be made without departing from the gist of the present invention.

Explanation of Reference Numerals

[0036] 2 Simple seismic isolation structure 10 Ballast 20 Foundation 30 Anti-collapse structure 40 Frame body 100 Simple seismic isolation method 110 Frame body forming step 120 Ballast forming step 130 Anti-collapse structure forming step 140 Foundation forming step K Hybrid structure

Claims

1. A ballast, a foundation provided on the ballast, and a landslide prevention structure covering the periphery of the ballast, wherein the simple seismic isolation structure is characterized by comprising the same.

2. The simple seismic isolation structure according to Claim 1, wherein the landslide prevention structure contains at least one of soil, sand, or small stones that can penetrate into the gaps between the gravel or crushed stones constituting the ballast.

3. The simple seismic isolation structure according to Claim 2, characterized by comprising a frame body surrounding the ballast.

4. The simple seismic isolation structure according to Claim 3, wherein the ballast and the frame body are provided above the ground surface or on a common underground surface.

5. A ballast formation step of providing a ballast on a target area, a landslide prevention structure formation step of providing a landslide prevention structure so as to cover the periphery of the ballast, and a foundation formation step of providing a foundation on the ballast, wherein the simple seismic isolation method is characterized by comprising the same, and the landslide prevention structure contains soil that can penetrate into the gaps between the gravel or crushed stones constituting the ballast.

6. The simple seismic isolation method according to Claim 5, characterized by comprising a frame body formation step of forming a frame body around the target area, and in the landslide prevention structure formation step, filling the landslide prevention structure between the frame body and the ballast.

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