JP6099337B2 - Temporary support method for foundation - Google Patents

Description

  The present invention relates to a temporary provisional support method. Specifically, the present invention relates to a temporary support method for a foundation of an existing building having a foundation without a pile when the existing building is subjected to seismic isolation under the foundation.

Conventionally, there has been known a base-isolated retrofit construction for making an existing building base-isolated under the foundation (see Patent Document 1).
Specifically, for this seismic isolation retrofit work, for example, when an existing building with a foundation without piles is to be seismically isolated, an excavation is made directly under the foundation of the existing building, and a support work is installed on this excavated part. Then, the foundation is temporarily supported by taking a reaction force on the bottom of the excavated portion. Then, attach a seismic isolation device such as laminated rubber directly under the foundation, and then remove the jack. As a result, the base is supported by the seismic isolation device and the existing building is seismically isolated.

  Here, since the vertical load of the upper layer of the building is transmitted mainly to the lower layer through the pillar, the part of the foundation of the existing building located directly below the pillar (hereinafter referred to as the lower part of the pillar) is the remaining part ( Hereinafter, a large vertical load is applied as compared to a portion immediately below the non-column. Therefore, when temporarily supporting the foundation of an existing building, supporting a position away from the lower part of the column will cause a large moment and shearing force in the part from the lower part of the foundation to the support point, thus reinforcing the foundation. Since the necessity arises, the construction cost becomes high. Therefore, it is necessary to support a portion as close as possible to the lower part of the column as much as possible.

  Therefore, as shown in Patent Document 1, it has been proposed that a simple vertical retaining wall is provided so as to surround the ground directly below the pillar, and the vicinity of the retaining wall is temporarily supported by a supporting work. .

JP 2002-242450 A

  However, even if the ground supporting the lower part of the pillar is surrounded by a retaining wall, a large load is applied to the lower part of the pillar, so depending on the strength and properties of this ground, the stability of the ground should be ensured. It was difficult.

  An object of this invention is to provide the temporary support method of the foundation which can base-isolate an existing building at low cost, ensuring the stability of a ground.

  The temporary support method for a foundation according to claim 1 is a temporary support method for a foundation of an existing building (for example, a foundation 3 to be described later) when the existing building (for example, an existing building 1 to be described later) is subjected to seismic isolation. And excavating the ground located below between the columns of the existing building (for example, below-mentioned column 5) to form a drilling space that becomes narrower toward the bottom (for example, step S1 described later), A step (for example, steps S2 to S4 described later) for temporarily supporting the foundation by providing a support structure (for example, a support structure 30 described later) that expands in the excavation space upward. To do.

According to this invention, the ground located below between the columns is excavated to form an excavation space that becomes narrower as it goes downward. Therefore, the ground located below the pillar has a shape that expands downward. Thereby, it is possible to prevent the ground supporting the pillar from slipping and to ensure the stability of the ground.
In addition, since the support work that expands upward is used, the position of the foundation as close to the pillar as possible can be temporarily supported, so that a large moment and shearing force can be prevented from occurring on the foundation, and existing buildings can be exempted at low cost. It can be shaken.

The temporary support method for a foundation according to claim 1 is characterized in that a reaction force board (for example, a mat slab 22a described later) is provided at the bottom of the excavation space, and the support work is provided on the reaction force disk.

  According to the present invention, since the reaction force plate is provided at the bottom of the excavation space and the support plate is provided on the reaction force plate, the reaction force of the support method can be reliably transmitted to the ground via the reaction force plate.

  The temporary support method for a foundation according to claim 3 is characterized in that the excavation space extends in a tunnel shape in a direction intersecting in a horizontal plane.

  According to this invention, the excavation space is formed so as to extend in a tunnel shape in a direction intersecting in the horizontal plane. Therefore, for example, a support work can be assembled in a wide area such as the ground, and the assembled support work can be put into the excavation space, moved, and installed, so there is no need to assemble the support work in a narrow excavation space. Therefore, the support work can be easily installed, and the construction cost can be further reduced while improving the safety of the worker.

  According to a temporary support method for a foundation according to claim 4, the support works include a gantry (for example, a later-described base) including a plurality of steel members (for example, a base 33, a vertical frame 34, a horizontal frame 35, and a reinforcing frame 36 to be described later). A gantry 31) and a jack (for example, a jack 32 described later) provided on the gantry are provided.

  According to the present invention, the support work is configured to include a gantry made of a plurality of steel members and a jack provided on the gantry. Therefore, the support work can be easily manufactured, and the construction cost can be reduced.

According to the present invention, the ground located below between the columns is excavated to form an excavation space that becomes narrower as it goes downward. Therefore, the ground located below the pillar has a shape that expands downward. Thereby, it is possible to prevent the ground supporting the pillar from slipping and to ensure the stability of the ground.
In addition, since the support work that expands upward is used, the position of the foundation as close to the pillar as possible can be temporarily supported, so that a large moment and shearing force can be prevented from occurring on the foundation, and existing buildings can be exempted at low cost. It can be shaken.

It is sectional drawing of the foundation part of the existing building with which the temporary support method of the foundation which concerns on one Embodiment of this invention is applied. It is a cross section which shows the state where the existing building which concerns on the said embodiment was seismically isolated. It is a flowchart of the procedure which makes the existing building based on the said embodiment seismic isolation. It is FIG. (1) for demonstrating the procedure which makes the existing building which concerns on the said embodiment seismic isolation. It is FIG. (2) for demonstrating the procedure which makes the existing building which concerns on the said embodiment a seismic isolation. It is FIG. (3) for demonstrating the procedure which makes the existing building which concerns on the said embodiment a seismic isolation. It is FIG. (4) for demonstrating the procedure which makes the existing building which concerns on the said embodiment seismic isolation. It is FIG. (5) for demonstrating the procedure to make the existing building based on the said embodiment a seismic isolation. It is FIG. (6) for demonstrating the procedure to make the existing building based on the said embodiment a seismic isolation.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view of a foundation portion of an existing building 1 to which a foundation temporary support method according to an embodiment of the present invention is applied.
The existing building 1 has an underground frame 2, and the underground frame 2 includes a foundation 3, a floor 4 provided on the foundation 3, a plurality of pillars 5 extending upward from the foundation 3, and It has.

The foundation 3 is a solid foundation without piles built on the ground 6, and this foundation 3 is provided between the footing 10, the foundation beam 11 that connects these footings 10, and the foundation beams 11. A pressure-resistant plate 12.
The aforementioned pillar 5 extends upward from the center of the footing 10.
Hereinafter, the central portion of the footing 10 in the foundation 3 is referred to as a column direct lower portion 13 positioned immediately below the columns 5, and the remaining portion such as between the columns 5 is referred to as a non-column direct lower portion 14.

  In the present invention, as shown in FIG. 2, an installation space 21 is formed under the foundation 3 of the existing building 1, and the seismic isolation device 20 is installed in the installation space 21. By supporting the foundation 3, the foundation 3 of the existing building 1 is seismically isolated.

Specifically, an installation space 21 for installing the seismic isolation device 20 is formed under the foundation 3 of the existing building 1. A reinforced concrete mat slab 22 is constructed over the entire bottom surface of the installation space 21. In the mat slab 22, a base isolation base 23 made of reinforced concrete is provided immediately below the center of the footing 10 (under the column 13), and the base isolation device 20 is provided on the base isolation base 23. ing.
The seismic isolation device 20 supports the center portion of the footing 10 of the foundation 3 from below by applying a reaction force to the mat slab 22 while keeping the foundation 3 movable in the horizontal direction.

FIG. 3 is a flowchart showing a procedure for isolating the foundation 3 of the existing building 1.
In step S1, an excavation port is provided outside the existing building 1 and the excavation port digs under the foundation 3 of the existing building 1, and as shown in FIG. The excavation space 21a which becomes narrow as it goes down is formed.

The excavation space 21a extends in a tunnel shape in a direction intersecting in the horizontal plane, and becomes a part of the installation space 21 described above.
In addition, the ground 6 below the pillar lower portion 13 has a shape that expands downward from the pillar lower portion 13, and the surface 6 a of the ground 6 becomes a slope.

  In step S2, as shown in FIG. 5, a mat slab 22a as a reaction disk, which is a part of the mat slab 22, is constructed by placing concrete at the bottom of the excavation space 21a. . In the excavation space 21a, a pair of rails 24, which are I-shaped steel extending from the excavation port, are attached to the lower surface of the foundation 3 exposed by excavation.

  In step S3, a plurality of supporters 30 as shown in FIG. 6 are assembled in advance on the ground, and a plurality of transfer devices 40 as shown in FIG. 6 are prepared. Then, the assembled support work 30 is put into the excavation port, and the support work 30 is horizontally moved in the excavation space 21a using the transfer device 40, and is installed on a predetermined mat slab 22a.

The support structure 30 has a shape that expands toward the top. The support 30 includes a gantry 31 made of a plurality of steel members that can be installed on the mat slab 22a, and a jack 32 provided on the gantry 31.
The gantry 31 includes a base 33 that can be installed on the mat slab 22a, a pair of vertical frames 34 that extend substantially vertically from the base 33, and a horizontal frame 35 that extends between the pair of vertical frames 34 and extends substantially horizontally. And a reinforcing frame 36 extending obliquely from the lower end side of the vertical frame 34 toward the front end portion of the horizontal frame 35.
The jacks 32 are placed on both ends of the horizontal frame 35.

The transport device 40 includes a device main body 41, a pair of wheels 42 provided on the device main body 41 and capable of traveling on the upper surface of the lower flange of the rail 24, a small lifting device 43 attached to the device main body 41, Is provided.
The transport device 40 is movable along the rail 24 by wheels 42.
The small lifting device 43 is, for example, a lever block (registered trademark).

  Specifically, the supporting work 30 is lowered from the ground to the depth level of the excavation space 21a through the excavation port by a crane or the like. Next, as shown in FIG. 6, the workers A and B attach the conveying device 40 to each of the pair of rails 24, and the horizontal frame 35 of the support 30 is suspended by the lifting device 43 of the conveying device 40. To support. In this state, the carrier device 40 is moved along the rails 24 so that the support 30 is moved horizontally and placed at a predetermined position in the excavation space 21a, for example, directly below the foundation beam 11.

  In step S4, as shown in FIG. 7, the lifting device 43 is operated by the workers A and B to install the base 31 of the support 30 on the mat slab 22a. Then, by pressing the lower surface of the foundation beam 11 with the jack 32 of the support 30, the support 3 applies a reaction force to the mat slab 22 a to temporarily support the foundation 3 from below. As a result, the support 30 temporarily supports the position of the foundation 3 near the column lower portion 13.

  In step S5, as shown in FIG. 8, the ground 6 below the column direct lower part 13 is excavated, and the installation space 21 is completed. Further, the rest of the mat slab 22 is constructed to complete the mat slab 22.

  In step S6, as shown in FIG. 9, the base isolation base 23 is constructed on the mat slab 22, and the base isolation device 20 is installed on the base isolation base 23. Support.

  In step S7, the temporary support by the support work 30 is released. Next, the supporting work 30 is removed by moving the supporting work 30 along the rails 24 using the transfer device 40. Thereafter, the rail 24 is also removed.

According to this embodiment, there are the following effects.
(1) The ground 6 located below the non-column direct lower portion 14 was excavated to form an excavation space 21a that becomes narrower as it goes downward. Therefore, the ground 6 below the pillar lower portion 13 has a shape that expands downward. Thereby, it is possible to prevent the ground 6 supporting the pillar lower portion 13 from slipping and to ensure the stability of the ground 6.
Moreover, since the supporting work 30 that expands toward the upper side is used, the position near the column lower part 13 can be temporarily supported as much as possible, so that a large moment and shearing force can be prevented from being generated in the foundation 3, and the existing building 1 Seismic isolation is possible at low cost.

  (2) Since the mat slab 22a is provided at the bottom of the excavation space 21a and the support 30 is provided on the mat slab 22a, the reaction force of the support 30 can be reliably transmitted to the ground 6 via the mat slab 22a.

  (3) The excavation space 21a is formed so as to extend in a tunnel shape in a direction intersecting in the horizontal plane. Therefore, the support work 30 is assembled on the ground, and the assembled support work 30 can be placed in the excavation space 21a, moved, and installed, so there is no need to assemble the support work in the narrow excavation space 21a. Therefore, the support cost 30 can be easily installed, and the construction cost can be further reduced while improving the safety of the worker.

  (4) The support 30 is configured to include the gantry 31 including the base 33, the vertical frame 34, the horizontal frame 35, and the reinforcing frame 36, and the jack 32 provided on the gantry 31. Therefore, the support work 30 can be easily manufactured, and the construction cost can be reduced.

  It should be noted that the present invention is not limited to the above-described embodiment, and modifications, improvements, etc. within a scope that can achieve the object of the present invention are included in the present invention.

DESCRIPTION OF SYMBOLS 1 ... Existing building 2 ... Underground frame 3 ... Foundation 4 ... Floor 5 ... Column 6 ... Ground 6a ... Ground surface 10 ... Footing 11 ... Foundation beam 12 ... Pressure-resistant plate 13 ... Directly under pillar 14 ... Non-pillar directly under 20 ... Exempt Seismic device 21 ... installation space 21a ... excavation space 22, 22a ... mat slab (reaction force board)
DESCRIPTION OF SYMBOLS 23 ... Base for isolation 24 ... Rail 30 ... Supporting work 31 ... Base 32 ... Jack 33 ... Base 34 ... Vertical frame 35 ... Horizontal frame 36 ... Reinforcement frame 40 ... Conveying device 41 ... Device main body 42 ... Wheel 43 ... Lifting device

Claims (4)

It is a temporary support method for the foundation of the existing building when the existing building is seismically isolated,
Excavating the ground located below the pillars of the existing building, forming a drilling space that narrows toward the bottom;
Rutotomoni provided part of the mat slab to the bottom of the excavation space as a reaction force plate, in the drilling space, the lower surface of the base exposed by excavation, and attaching a pair of rails extending from the drilling opening,
On the ground, a plurality of support structures having a shape that expands in the upward direction are assembled in advance, the assembled support works are inserted into the excavation port, and a transport device is attached to the pair of rails. The support is suspended and supported, and in this state, the support device is moved along the pair of rails, so that the support is horizontally moved in the excavation space and installed on a predetermined reaction force plate. And a process of
And a step of temporarily supporting the foundation by applying a reaction force to the reaction force board by the support work .   2. The temporary support method for a foundation according to claim 1, wherein the reaction force plate is located at a substantially center between columns of the existing building and has a thickness substantially equal to the mat slab.   3. The temporary support method for a foundation according to claim 1, wherein the excavation space extends in a tunnel shape in a direction intersecting in a horizontal plane.   4. The temporary support method for a foundation according to claim 1, wherein the support is provided with a gantry composed of a plurality of steel frame members and a jack provided on the gantry. 5.

Images