JP3451948B2 - Construction method of seismic retrofit structure - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly relates to a method of constructing a seismic strengthening structure having piles and underground buried portions.

[0002]

2. Description of the Related Art Foundation types of structures are roughly classified into direct foundations, pile foundations, caisson foundations, etc., but when the ground strength near the surface is relatively small compared to the weight of the structure, In addition to adopting a pile foundation that drives piles up to a good-quality support layer, a structure is often provided with a certain underground buried portion.

Here, there are cases where the external seismic force used at the time of designing is insufficient and needs to be reviewed, but if there is no problem with the soundness of the pile, regardless of the problem with the pile itself. In many cases, the soundness of a structure can be maintained by seismically strengthening the structure, especially its underground buried part.
Then, at the time of earthquake-proof reinforcement, it is desirable to increase the strength without increasing the weight of the structure as much as possible, and for example, reinforcement by winding a carbon fiber sheet is effective.

[0004]

However, the above-mentioned seismic retrofitting method has a problem that the service of the facility must be interrupted during the construction period and that the seismic retrofitting itself is costly. .

On the other hand, with respect to the newly constructed structure, the above-mentioned problems in service of the facility do not occur, but it is still costly to increase the strength while suppressing the weight of the structure. New seismic retrofitting measures to replace seismic retrofitting were desired.

The present invention has been made in consideration of the above-mentioned circumstances, and an object thereof is to provide a method for constructing a seismic strengthening structure which does not interrupt the service of the facility during the construction period and is excellent in economic efficiency. And

[0007]

In order to achieve the above object, in the method for constructing a seismic strengthening structure according to the present invention, as described in claim 1, a hollow space is formed by digging around the underground outer wall of the structure. After that, a method for constructing a seismic strengthening structure in which the hollow space is filled with a cushioning material to construct a relative displacement absorption region, wherein the relative displacement between the underground buried portion of the structure and the surrounding ground at the time of an earthquake is the relative displacement. It is configured to absorb in the absorption region.

Further, according to the method of constructing a seismic strengthening structure of the present invention, as described in claim 2, the ground around the structure is dug down with a stirrer, and the foam is injected and stirred from the tip of the stirrer. A method for constructing a seismic strengthening structure in which the foam is used as a cushioning material, and a relative displacement absorbing region is constructed by a stirring mixture of the cushioning material and soil particles, which is an underground buried portion and the periphery of the structure during an earthquake. The relative displacement with the ground is absorbed by the relative displacement absorption region.

In the method for constructing a seismic strengthening structure according to the present invention, a relative displacement absorbing region for absorbing a relative displacement between the underground buried portion and the surrounding ground at the time of an earthquake is provided between the underground buried portion of the structure and the surrounding ground. Since it is provided, the earthquake input from the side at the time of an earthquake will be small, the seismic energy input to the entire structure will be reduced accordingly, and the earth pressure from the surrounding ground will act on the underground buried part of the structure. Since it disappears, the member force of the underground buried part of the structure is significantly reduced. In addition, since the surrounding ground does not constrain the underground buried part of the structure, the natural period of the structure becomes longer, and it is possible to expect a seismic isolation effect, which deviates from the dominant period of seismic waves.

The structure and shape of the relative displacement absorption region are arbitrary. For example, it is conceivable that the surrounding outer wall of the structure is made into a hollow space like a dry area. If a predetermined cushioning material is arranged between the ground and the surrounding ground, the structure is shaken at the time of an earthquake, and the shock absorbing material damps the structure to quickly converge. As the cushioning material, not only rubber, which has the ability to absorb and deform itself, foam such as styrofoam and urethane, asphalt, silicon, soft clay, etc., but also those which are expected to exert deformation and absorbency as an aggregate , Backfill soil, saturated loose sand, for example
It also includes lightweight soil, gravel, and crushed stone.

It is also arbitrary how to dispose the cushioning material. After the underground outer wall of the structure is dug down to form a hollow space, the hollow space may be filled with the cushioning material, The foam around the structure may be dug down with a stirrer such as an earth auger and the foam may be injected and stirred from the tip thereof.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a method of constructing a seismic reinforcing structure according to the present invention will be described below with reference to the accompanying drawings. It should be noted that parts and the like which are substantially the same as those of the conventional technique are designated by the same reference numerals and the description thereof is omitted.

FIG. 1 shows a seismic strengthening structure for a structure constructed by the method for constructing a seismic strengthening structure according to this embodiment. As can be seen in the figure, the seismic retrofit structure of the structure according to the present embodiment has an underground buried portion 2 of the structure 1.
A relative displacement absorbing region 4 is provided between the ground and the surrounding ground 3.

The relative displacement absorption region 4 is constructed by arranging a cushioning material 5 between the underground buried portion 2 and the surrounding ground 3.
It is designed to absorb the relative displacement between the underground buried portion 2 and the surrounding ground 3 during an earthquake.

The cushioning material 5 is made of rubber, which has the ability to absorb and deform itself, foam such as styrene foam and urethane foam,
In addition to asphalt, silicon, soft clay, etc., it is possible to use one that is expected to exhibit deformation and absorption ability as an aggregate, such as backfilled soil, saturated loose sand, lightweight soil, gravel, crushed stone, and the like.

In constructing the structure for earthquake-proof reinforcement of the structure according to the present embodiment, a hollow space is formed by digging around the underground outer wall of the structure 1 and then the hollow space is filled with a buffer material 5 for relative displacement. The absorption region 4 may be constructed.

In the method of constructing the seismic strengthening structure according to the present embodiment, the relative displacement absorbing region 4 is provided between the underground buried portion 2 of the structure 1 and the surrounding ground 3, and during an earthquake,
The relative displacement between the underground buried portion 2 and the surrounding ground 3 is absorbed in the relative deformation absorption region 4 and the relative deformation absorption region 4
The vibration absorbing energy of the structure 1 absorbs the vibration energy of the structure 1 due to the earthquake.

As described above, according to the method of constructing the seismic strengthening structure according to the present embodiment, the relative displacement absorption region 4 absorbs the relative displacement between the underground buried portion 2 and the surrounding ground 3 during the earthquake. , Earthquake input from the surrounding ground 3 on the side at the time of an earthquake becomes small, and the structure 1
Since the seismic energy input to the whole is reduced and the earth pressure from the surrounding ground 3 does not act on the underground buried portion 2 of the structure 1, the member force of the underground buried portion 2 of the structure is significantly reduced. Further, since the surrounding ground 3 does not restrain the underground buried portion 2 of the structure 1, the natural period of the structure 1 becomes longer, and it is possible to expect a so-called seismic isolation effect, which deviates from the dominant period of seismic waves.

In other words, unlike the conventional way of thinking that the seismic performance of a structure is improved by enlarging the structural cross section of the structure itself or reinforcing it with a carbon fiber sheet or the like,
By providing the relative displacement absorption region 4, the seismic input can be reduced, and as a result, the seismic performance of the structure 1 can be improved.

Therefore, even if the design external force is reviewed, it can be easily dealt with whether it is a design surface or a construction surface, and the service of the structure 1 is suspended to construct the relative displacement absorption region 4. There is no need.

FIG. 2 is a graph showing the results of a dynamic response analysis performed to confirm the effect of the seismic reinforcement structure of the structure constructed by the method for constructing the seismic reinforcement structure according to this embodiment. It is understood that the provision of the relative deformation absorption region 4 can significantly reduce the horizontal earth pressure acting on the structure 1 during an earthquake.

Further, since the inside of the structure 1 is not reinforced by earthquake resistance, it is possible to suppress the cost required for the earthquake resistance reinforcement.

Further, according to the method of constructing the seismic strengthening structure according to the present embodiment, the relative displacement absorption region 4 is formed in the underground buried portion 2.
Since the buffer material 5 is arranged between the ground and the surrounding ground 3, the vibration of the structure 1 at the time of an earthquake is attenuated by the buffer material 5, and the vibration can be quickly converged.

In the present embodiment, after the underground outer wall of the structure 1 is dug down to form a hollow space, the hollow space is filled with the cushioning material 5. However, instead of this, a stirrer such as an earth auger is used. The foam may be used as a cushioning material by digging into the ground around the structure 1 and pouring and stirring the foam from the tip thereof. In this configuration, the relative displacement absorption area is configured as a stirring mixture of the foamed material that is the cushioning material and the soil particles.

Further, in the present embodiment, the relative displacement absorption region 4 is constructed by disposing the cushioning material 5 between the underground buried portion 2 and the surrounding ground 3, but instead of this, as shown in FIG. A hollow space such as a dry area may be formed around the underground buried portion 2 (underground outer wall) of the structure 1 and used as the relative displacement absorption region 21. In such a configuration, the effect of damping the vibration of the structure by the cushioning material cannot be obtained,
The point that the seismic input can be reduced is no different from the above-described embodiment.

Further, in the present embodiment, the boundary between the relative displacement absorption region 4 and the surrounding ground 3 is set to the vertical plane, but it is not always required to be the vertical plane, and for example, as shown in FIG.
A hollow space may be formed between the slope 32 formed on the surrounding ground 3 and the underground buried portion 2 (underground outer wall) of the structure 1, and this may be used as the relative displacement absorption region 31, as shown in FIG. As described above, the cushioning material 5 may be filled between the slope 32 formed in the surrounding ground 3 and the underground buried portion 2 of the structure 1 to form the relative displacement absorbing area 33.

Although not particularly mentioned in the present embodiment, when the surrounding ground is soft, there is a concern that the ground will collapse toward the relative displacement absorption region side during an earthquake. In such a case, as shown in FIG. 5, an earth retaining wall 41 composed of an underground continuous wall, a steel plate, a steel pipe sheet pile, or the like may be provided in the surrounding ground 3 on the side facing the relative displacement absorption areas 4 and 21. As shown in FIG. 6, a ground stabilizer 42 made of shotcrete or the like may be provided on the slope of the surrounding ground 3 on the side facing the relative displacement absorption regions 31, 33.

According to such a structure, not only the peripheral ground 3 is not collapsed to the relative displacement absorption area side at the time of an earthquake but also excessive earth pressure is prevented from being generated on the cushioning material 5, and the relative displacement as described above is prevented. By providing the displacement area, it is possible to reliably and long-term obtain the effect of reducing the earthquake input.

[0029]

As described above, according to the method of constructing a seismic strengthening structure according to the present invention, the relative displacement absorbing region absorbs the relative displacement between the underground buried portion and the surrounding ground during an earthquake. Therefore, the earthquake input from the side at the time of an earthquake will be small, and the seismic energy input to the entire structure will be reduced accordingly, and the earth pressure from the surrounding ground will not act on the underground buried part of the structure, The member strength of the underground buried part of the structure is significantly reduced. Further, there is an effect that the vibration of the structure at the time of an earthquake is attenuated by the cushioning material, and the vibration can be quickly converged.

[0030]

[0031]

[Brief description of drawings]

1A and 1B are diagrams of a structure for earthquake-proof reinforcement of a structure according to the present embodiment, where FIG. 1A is a vertical sectional view and FIG. 1B is a horizontal sectional view taken along the line AA.

FIG. 2 is a graph showing a result of an analysis performed to confirm a function and effect of the seismic strengthening structure for a structure according to the present embodiment.

FIG. 3 is a vertical cross-sectional view of a seismic retrofit structure for a structure according to a modification.

FIG. 4 is a vertical cross-sectional view of a seismic strengthening structure for a structure according to another modification.

FIG. 5 is a vertical cross-sectional view of an earthquake-proof reinforcing structure for a structure according to another modification.

FIG. 6 is a vertical sectional view of a seismic retrofit structure for a structure according to another modification.

[Explanation of symbols]

1 structure 2 underground part 3 surrounding ground 4, 21, 31, 33 Relative displacement absorption area 5 cushioning material 41 Earth retaining wall 42 Ground stabilization material

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Claims (2)

(57) [Claims] 1. A method for constructing a seismic strengthening structure in which a hollow space is formed by digging around the outer wall of a structure to form a hollow space, and then the hollow space is filled with a cushioning material to construct a relative displacement absorption region, which is a method for constructing a relative earthquake absorption structure during an earthquake. The method for constructing an earthquake-proof reinforcing structure, characterized in that the relative displacement between the underground buried portion of the structure and the surrounding ground is absorbed in the relative displacement absorption region. 2. The foam around the structure is dug down with a stirrer while pouring and stirring the foam from the tip of the stirrer to use the foam as a cushioning material, and a stirring mixture of the cushioning material and soil particles. In the method of constructing a seismic strengthening structure for constructing a relative displacement absorption area in, the relative displacement absorption area absorbs the relative displacement between the underground buried portion of the structure and the surrounding ground during an earthquake. A method of constructing a characteristic seismic reinforcement structure.