JP4852450B2 - Reinforcing method of existing building and reinforcing structure of existing building - Google Patents

Description

  The present invention relates to a reinforcing method and a reinforcing structure for an existing building, and more particularly, to a reinforcing method for an existing building and a reinforcing structure for an existing building that are reinforced by fixing the foundation of the existing building to an anchoring ground of the anchor with an anchor.

Conventionally, as a seismic reinforcement method for an existing building, a method of adding a brace frame made of a steel frame member to the outside of the existing building has been used. According to this seismic reinforcement method, it is possible to resist the pulling force and pushing force that act on the existing building during an earthquake. However, since a braced frame is added outside the existing building, there is a problem that it cannot be used when the building is crowded.
By the way, Patent Document 1 describes a pile foundation structure that can resist an earthquake force by placing an anchor inside the foundation pile and causing the foundation pile to function as a resistor that resists the pulling direction. It is possible to apply this pile foundation structure to seismic reinforcement.
Japanese Patent Laid-Open No. 10-82056

However, when anchors are installed for seismic reinforcement as described above, tension is introduced in advance in consideration of the anchor's extension when an earthquake load is applied. Sufficient strength against vertical loads is required. Therefore, when a solid foundation constructed on soft ground is used as the foundation structure, or the pile foundation with a pile foundation does not have sufficient strength against vertical loads, the strength against vertical loads is insufficient. The anchor cannot be placed.
Although it is conceivable to newly provide a foundation pile, it is difficult to construct a foundation pile below the existing building and it is not suitable for use as a reinforcing structure for the existing building.

  The present invention has been made in view of the above-mentioned problems, and the object thereof is to enable construction even when buildings are densely packed around, and the ground below the existing building is soft ground. The present invention provides a reinforcing method of an existing building and a reinforcing structure of an existing building that can be applied even when the pile of the foundation structure does not have sufficient proof stress.

In order to solve the above problems, the present invention employs the following means.
That is, the invention according to claim 1 is a method for reinforcing an existing building, wherein the ground is improved at least part of the ground below the existing building up to the anchoring ground of the anchor, and the anchor has one end thereof. an anchor Da設step of pouring as Ru is fixed to a fixing ground of said anchor, characterized in that it comprises a anchor installation step of fixing the other end of the anchor to a structure of the existing building.

According to the method for reinforcing an existing building according to the present invention, in the ground improvement process, at least a part of the ground below the existing building is improved to the anchor fixing ground, and in the anchor placing process, the anchor is fixed at one end. The existing building can be reinforced by placing it so as to be fixed on the ground and fixing the other end of the anchor to the structure of the existing building in the anchor installation step.

The invention according to claim 2 is the method for reinforcing an existing building according to claim 1, wherein the other end of the anchor is fixed to the structure of the existing building in a state where tension is applied to the anchor. It is characterized by.
According to the method for reinforcing an existing building according to the present invention, the other end of the anchor is fixed to the structure of the existing building in a state where tension is applied to the anchor.

The invention according to claim 3 is the method for reinforcing an existing building according to claim 1, wherein the other end of the anchor is fixed to the structure of the existing building in a state where no tension is applied to the anchor. Features.
According to the method for reinforcing an existing building according to the present invention, the other end of the anchor is fixed to the structure of the existing building in a state where no tension is applied to the anchor.

The invention according to claim 4 is the method for reinforcing an existing building according to any one of claims 1 to 3, wherein the head of the other end of the anchor is fixed to the structure of the existing building via a fixing tool. It is characterized by that.
According to the method for reinforcing an existing building according to the present invention, the other end of the anchor is fixed to the head of the existing building structure via the fixing tool.

  The invention which concerns on Claim 5 is the reinforcement method of the existing building in any one of Claim 1 to 4, Comprising: In the said ground improvement process, the through-hole which reaches | attains the said ground to the lower part or foundation of the said existing building is provided. And improving the ground by injecting a ground improver into the ground below the existing building from the through hole.

  According to the method for reinforcing an existing building according to the present invention, in the ground improvement process, a through hole reaching the ground is provided in the lower part or foundation of the existing building, and the ground improving agent is formed on the ground below the existing building using the through hole. The portion can be improved by injecting.

The invention according to claim 6 is the method for reinforcing an existing building according to claim 5, wherein, in the anchor placing step, the anchor is placed through the through hole.
According to the method for reinforcing an existing building according to the present invention, an anchor can be placed using a through hole in the anchor placing step.

The invention according to claim 7 is the method for reinforcing an existing building according to claim 5 or 6, wherein the ground improvement agent is cement-based or silica-based.
According to the method for reinforcing an existing building according to the present invention, the ground is improved by a cement-based or silica-based ground improver.

  The invention according to claim 8 is the method for reinforcing an existing building according to any one of claims 1 to 7, wherein the anchor is a permanent anchor.

The invention according to claim 9 is the reinforcing structure of an existing building, the a ground improvement unit at least a portion constructed by ground improvement to the fixing ground anchors of the ground beneath the existing building, one said The anchor is fixed to the anchoring ground of the anchor, and the anchor is fixed to the structure of the existing building in a state where the other end is applied with a tension force or a state where no tension force is applied.

  According to the present invention, by improving the soft ground below the existing building, even if the existing building is built on the soft ground or the foundation pile of the existing building does not have sufficient strength, Tension can be applied. As a result, the existing building can be anchored to the anchor anchorage ground by the anchor, and seismic reinforcement can be performed even in the case where the building is crowded around without providing a new frame outside. .

Hereinafter, an embodiment of the seismic reinforcement structure for an existing building of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing a state in which an existing building 1 is reinforced with the earthquake-proof reinforcement structure 10 of the present embodiment. As shown in the figure, the seismic reinforcement structure 10 of the present embodiment is on a ground provided with, for example, a ground 3 that is a soft layer and an anchoring ground 4 (for example, a support layer) of an anchor below the ground 3. It is constructed for seismic reinforcement of an existing building 1 having a solid foundation 2 as a foundation structure.

  As shown in FIG. 1, the seismic reinforcement structure 10 of the present embodiment has a ground improvement portion 30 formed by ground improvement of at least a part of the ground 3 below the solid foundation 2 of the existing building 1 and a lower end thereof. The upper end is fixed to the solid foundation 2 of the existing building 1 while being fixed to the fixing ground 4 and in a state where tension is introduced or in a state where tension is not introduced (in this embodiment, tension is introduced). And a permanent anchor 20.

  For example, the ground improvement unit 30 stirs the ground 3 and mixes or stirs cement-based or silica-based ground improver into the earth and sand produced by the ground stirring of the ground 3 or by injecting it. Built. As the cement-based ground improving agent mixed and stirred in the earth and sand, a grout excellent in long-term durability such as a permanent grout is suitable.

2A and 2B are diagrams showing a detailed configuration of the permanent anchor 20, wherein FIG. 2A is a vertical cross-sectional view, FIG. 2B is an AA ′ cross-sectional view that is an anchor free length portion, and FIG. 2C is an anchor fixing length portion. It is BB 'sectional drawing which is. As shown in the figure, the permanent anchor 20 includes a cylindrical corrugated sheath 21 having a spiral unevenness on the surface, inserted into a borehole 29, an inner grout 23 filled in the corrugated sheath 21, and an inner A plurality of PC steel strands 22 embedded in the grout 23, an outer grout 24 filled between the inner wall of the excavation hole 29 and the outer periphery of the corrugated sheath 21, and the PC steel strand 22 are fixed to the solid foundation 2. And a fixing tool 25. Further, a grout hose 26 for filling grout is inserted into the corrugated sheath 21 and is buried in the inner grout 23.
Instead of using the fixing tool 25, the PC steel strand 22 may be fixed and fixed to the solid foundation 2 by grouting.

As shown in FIG. 2 (B), an unbonded tube 27 is surrounded by the PC steel stranded wire 22 of the anchor free length portion. The unbonded tube 27 adheres the stranded wire 22 and the inner grout 23 to the PC steel stranded wire. Hindering.
On the other hand, as shown in FIG. 2 (C), the unbonded tube 27 is not surrounded by the PC steel strand 22 of the anchor fixing length portion, and between the PC steel strand 22 and the inner grout 23. Adhesion is secured. A corrugated sheath 21 is interposed between the inner grout 23 and the outer grout 24. Since the corrugated sheath 21 has irregularities on the surface, the inner grout 23 and the surrounding ground are integrated. Force is transmitted to and from the outer grout 24. Therefore, the tension transmitted from the solid foundation 2 of the existing building 1 to the PC steel strand 22 is transmitted to the anchorage ground 4 via the inner grout 23 and the outer grout 24 at the anchor anchoring length, and this tension is thereby transmitted. Can resist force.

  When seismic motion occurs in the existing building 1 and a lifting load is applied to a part of the building, a tension force acts on the permanent anchor 20, but the permanent anchor 20 resists the tension force as described above. The floating of the building 1 can be prevented. Moreover, when a sinking load acts on a part of the existing building 1, the ground improvement part 30 resists this sinking load, Therefore The sinking of the existing building 1 can be prevented. Thus, according to the seismic reinforcement structure 10 of the present embodiment, even when a load is applied to the existing building 1 due to an earthquake or the like, it is possible to resist the load.

In addition, when tension | tensile_strength acts on the permanent anchor 20 at the time of an earthquake, there exists a possibility that the wire 22 may extend from PC steel, Therefore The tension | tensile_strength is previously introduced into the strand 22 of PC steel. For this reason, although a compressive load acts on the ground 3 between the solid foundation 2 and the fixed ground 4 of the existing building 1, the ground improvement part 30 is obtained by improving the ground at least a part of the ground 3 as described above. Can resist this compressive load.
For example, when the elongation amount of the wire 22 is smaller than that of the PC steel, it is not necessary to introduce a tension to the wire 22 of the PC steel.

Hereinafter, a method for constructing the seismic reinforcement structure 10 for an existing building according to the present embodiment will be described.
Drawing 3 is a figure for explaining the process of constructing earthquake proof reinforcement structure 10 of the existing building of this embodiment. As shown in FIG. 1A, first, the solid foundation 2 of the existing building 1 is cored and a through hole 31 is provided so as to reach the ground 3.
Next, as shown in FIG. 3 (B), at least the ground 3 below the solid foundation 2 is injected by injecting permanent grout from the through holes 31 provided in the solid foundation 2 while stirring the ground 3. A part of the ground is improved to form a ground improvement unit 30.

  Next, as shown in FIG. 3C, the permanent anchor 20 is driven on the fixing ground 4 from the through hole 31 provided in the solid foundation 2, and the tip of the permanent anchor 20 is fixed on the fixing ground 4. The permanent anchor 20 has a casing installed on the outer peripheral surface of the excavation hole while drilling the ground 3, a corrugated sheath 21 having a PC steel strand 22 inserted through the casing is inserted into the casing, and an inner grout is passed through the grout hose 26. After injecting 23 and injecting the outer grout 24, the casing can be pulled out.

Next, as shown in FIG. 3 (D), a fixing tool 25 is attached to the PC steel strand 21 with a tension applied to the PC steel strand 21 using a jack or the like, and the upper end of the PC steel strand 21 is attached. Is fixed and fixed to the solid foundation 2.
The seismic reinforcement structure 10 of the existing building can be constructed by the above process.

  According to the reinforcing structure 10 of the present embodiment, it is not necessary to newly provide a brace frame on the outer periphery of the existing building 1 and can be constructed from a through hole provided in the solid foundation 2 of the existing building 1. Even in the case where the buildings are densely packed, the existing building 1 can be seismically strengthened. Moreover, since the compressive strength of the ground is improved by improving the ground 3, tension can be introduced into the permanent anchor 20 in advance, and the permanent anchor 20 is stretched even when earthquake motion is applied. Can be prevented.

  In addition, although this embodiment demonstrated the case where it applied to the existing building 1 which has the solid foundation 2, it is applicable not only to this but also to the existing building which has other foundation structures, such as a pile foundation and a footing foundation. Can do.

  In the present embodiment, the case where the permanent anchor 20 is driven in the vertical direction has been described. However, in the case where the permanent anchor 20 cannot be driven in the vertical direction, as shown in FIG. It is also possible to drive the permanent anchor 120 in the direction.

Moreover, although this embodiment demonstrated the case where a VSL-J1 anchor was used as the permanent anchor 20, not only this but an anchor with high durability can be used.
Moreover, in this embodiment, the through-hole 31 was provided in the solid foundation 2, and the ground improvement and the permanent anchor 20 were placed from the through-hole 31. However, the present invention is not limited to this, and reaches the ground 3 at the lower part of the existing building 1. Such a through hole may be provided, and the ground improvement and the permanent anchor 20 may be placed through the through hole.

It is a figure which shows the state which reinforced the existing building with the earthquake-proof reinforcement structure of this embodiment. It is a figure which shows the structure of a permanent anchor, (A) is a vertical sectional view, (B) is AA 'sectional drawing which is an anchor-shaped oil length part, (C) is BB' which is an anchor fixing length part. It is sectional drawing. It is a figure for demonstrating the method to construct | assemble the earthquake-proof reinforcement structure of the existing building of this embodiment. It is a figure which shows the earthquake-proof reinforcement structure which provided the anchor so that it might incline in the diagonal direction.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Existing building 2 Solid foundation 3 Ground 4 Fixed ground 10 Seismic reinforcement structure 20, 120 Permanent anchor 21 Corrugated sheath 22 PC steel strand 23 Inner grout 24 Outer grout 25 Fixing tool 26 Grout injection hose 27 Unbonded tube 29 Drilling holes 30, 130 Ground improvement department

Claims (9)

A method of reinforcing an existing building,
A ground improvement step of improving the ground to at least a part of the ground below the existing building to the anchor ground ;
An anchor, an anchor Da設step of one end to pouring as Ru is fixed to a fixing ground of the anchor,
An anchor installation step of fixing the other end of the anchor to the structure of the existing building;
A method of reinforcing an existing building, comprising:   2. The method of reinforcing an existing building according to claim 1, wherein the other end of the anchor is fixed to the structure of the existing building in a state where tension is applied to the anchor.   The method for reinforcing an existing building according to claim 1, wherein the other end of the anchor is fixed to the structure of the existing building in a state where no tension is applied to the anchor.   The method of reinforcing an existing building according to any one of claims 1 to 3, wherein the other end of the anchor is fixed to the head of the structure of the existing building via a fixing tool. In the ground improvement process,
Provide a through hole that reaches the ground at the bottom or foundation of the existing building,
The method for reinforcing an existing building according to any one of claims 1 to 4, wherein the ground is improved by injecting a ground improver into the ground below the existing building from the through hole. In the anchor placing process,
The method for reinforcing an existing building according to claim 5, wherein the anchor is driven through the through hole.   The method for reinforcing an existing building according to claim 5 or 6, wherein the ground improvement agent is cement-based or silica-based.   The said anchor is a permanent anchor, The reinforcement method of the existing building in any one of Claim 1 to 7 characterized by the above-mentioned. A reinforcement structure for an existing building,
A ground improvement section constructed by improving the ground to at least a part of the ground below the existing building to the anchorage ground ;
One end is fixed to a fixing ground for the anchor, the anchor and the other end is fixed to the structure of the existing building in a state in which the state or tensioning force tensioning force is applied is not applied,
A reinforcement structure for an existing building, characterized by comprising:

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