JP2023108327A - Reconstruction method of building having underground structure - Google Patents

Abstract

To provide a reconstruction method of a building having an underground structure, reduced in a construction period and cost, and improved in construction accuracy.SOLUTION: In a reconstruction method of a building having an underground structure, a floor slab of an existing underground structure is dismantled and concrete is placed, a temporary floor slab 18 is constructed by reinforcing an existing foundation skeleton formed of an existing bottom and existing foundation beams, a pedestal 40 is constructed on the temporary floor slab 18, and underground pile columns 4 are constructed by installing lower columns 41 and upper columns 42 on the pedestal 40. A diameter of a lower end part 41a of the underground pile column 4 is expanded.SELECTED DRAWING: Figure 2

Description

The present invention relates to a rebuilding method for a building having an underground structure.

BACKGROUND ART Conventionally, when constructing an underground frame of a building, a reverse construction method is known in which permanent floor beams are used as shoring and the construction of the underground frame proceeds from the upper floor to the lower floor. In general, when constructing a building with a deep basement, it is possible to shorten the construction period by adopting this reverse construction method and simultaneously constructing the above-ground frame while proceeding with the construction of the underground frame.

In the case of rebuilding an existing building with an underground structural part, it may take a long time to construct a new underground structure because the existing underground structure must be dismantled. In this case, the reverse construction method, which allows construction of the underground and above-ground frameworks at the same time, is effective in terms of shortening the construction period.

The pillars that support the preceding floor and the ground frame, which serve as earth retaining shoring during construction, are called structural pillars. In the case of the reverse construction method, it is necessary to construct the structural column first (see Patent Documents 1 and 2, for example). Structural columns in the reverse casting method are constructed by inserting steel columns into cast-in-place concrete piles.

In the case of rebuilding an existing building with an underground structure, the cast-in-place concrete pile work and the construction of the steel frame structural column will be carried out after the existing ground frame has been dismantled and the construction ground for building the cast-in-place concrete piles has been completed. . The construction ground is often accompanied by backfilling of the existing underground skeleton with fluidized soil or the like, or reinforcement work of the existing underground skeleton.

JP-A-11-050480 JP 2020-84579 A

However, the construction of structural columns by the reverse casting method requires a construction period and cost for the cast-in-place concrete pile driving. In addition, the work of inserting steel columns into cast-in-place concrete piles is highly difficult, requiring a lot of time and effort for accuracy control. Even if it is possible to use a direct foundation from the design point of view, there is a construction problem that it is necessary to construct cast-in-place concrete piles for erecting the structural columns.

In the case of rebuilding an existing building with an underground structure, after the above-ground frame of the existing building has been dismantled and the construction ground for the cast-in-place concrete piles is constructed, the cast-in-place concrete piles are constructed. Therefore, there is a problem that the construction period before starting construction of the ground frame becomes long.

SUMMARY OF THE INVENTION In view of the above circumstances, the present invention provides a rebuilding method for a building having an underground structure that can reduce construction period and cost and improve construction accuracy.

In order to achieve the above object, the present invention employs the following means.
That is, the method for rebuilding a building having an underground structure according to the present invention is a method for rebuilding a building having an underground structure, in which the existing foundation skeleton composed of the existing base plate and existing foundation beams of the existing underground structure is reinforced. Then, a temporary floor slab is constructed, a pedestal is constructed on the temporary floor slab, and a structural column is constructed on the pedestal.

In the rebuilding method for a building having an underground structural part configured in this way, cast-in-place concrete piles for erecting structural columns become unnecessary, and the construction period and cost can be reduced. In addition, in constructing the structural column, there is no need to insert the steel frame into the cast-in-place concrete pile, and normal steel frame erection work can be performed, so the construction accuracy of the structural column can be improved.
In addition, the work of reinforcing the existing foundation frame consisting of the existing base plate and the existing foundation beams to construct the temporary floor slab and the work of constructing the pedestal can be carried out during the dismantling work of the existing ground frame. By carrying out these works in parallel with the ground frame dismantling work, it is possible to further shorten the construction period.

Further, in the method for rebuilding a building having an underground structure according to the present invention, the diameter of the lower end of the structural column may be increased.

In the rebuilding method for a building with an underground structure configured in this way, since the lower end of the structural column is expanded in diameter, the axial force acting on the pedestal is distributed over a wide range, reducing the stress generated in the temporary floor slab. It can be made even smaller.

According to the method for rebuilding a building having an underground structure according to the present invention, construction period and costs can be reduced, and construction accuracy can be improved.

It is a figure which shows the basement part of the existing building before rebuilding. 1 is a diagram showing an underground part of a newly built building reconstructed by the method for reconstructing a building having an underground structure according to one embodiment of the present invention; FIG. It is a figure which shows a rebuilding procedure. It is a figure which shows a rebuilding procedure, and shows a post-process of FIG. It is a figure which shows a rebuilding procedure, and shows a post-process of FIG. It is a figure which shows a rebuilding procedure, and shows a post-process of FIG. It is a figure which shows a rebuilding procedure, and shows a post-process of FIG. It is a figure which shows a rebuilding procedure, and shows a post-process of FIG. It is a figure which shows a rebuilding procedure, and shows a post-process of FIG. It is a figure which shows a rebuilding procedure, and shows a post-process of FIG. It is a figure which shows a rebuilding procedure, and shows a post-process of FIG. FIG. 4 shows a cross-bar of the foundation slab;

Hereinafter, a method for rebuilding a building having an underground structure according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an existing building (hereinafter referred to as "existing building") 1 before reconstruction, and FIG. 2 shows a new building (hereinafter referred to as "new building") 2 after reconstruction. The plans for the existing building 1 and the new building 2 are examples.

As shown in FIG. 1, the existing building 1 has an underground structure 10 and an above-ground structure (not shown). The underground structure section 10 has an underground floor section 11 and an underground pit 13 which are composed of a plurality of stories. In this embodiment, the underground floor section 11 is composed of four layers, but the number of layers can be set as appropriate.

An underground outer wall 14 is arranged around the outer periphery of the underground structure portion 10 . The underground outer wall 14 receives lateral earth pressure. An existing bottom slab 15 is arranged at the bottom of the existing foundation beams 12 of the existing foundation skeleton. The existing bottom slab 15 receives earth pressure from below.

As shown in FIG. 2, the new building 2 has an underground structural section 20 and an aboveground structural section (not shown). The underground structural section 20 has an underground floor section 21 and a foundation slab 22 which are composed of a plurality of stories. Although the details will be described later, the foundation slab 22 is provided above the existing foundation beam 12 from which the floor slab 16 has been removed and the concrete 17 filled in the underground pit 13 . In this embodiment, the underground floor section 21 has floor structure sections 45 , 47 and 49 , floor slabs 46 , 48 and 50 and new pillars 5 . The new pillar 5 is a pillar utilizing the structural pillar 4 at the time of temporary construction. The underground floor section 21 is composed of three layers, but the number of layers can be set appropriately.

Next, a method for rebuilding the existing building 1 to the new building 2 will be described.
As shown in FIG. 3, the demolishing of the existing building 1 begins with the underground structure 10 . A floor slab 16 on the fourth basement floor is dismantled by a dismantling machine 91. - 特許庁A temporary floor slab 18 is constructed by reinforcing an existing foundation framework consisting of an existing bottom slab 15 and existing foundation beams 13. - 特許庁Specifically, concrete is sent from a ready-mixed concrete car 92 and a pump car 93 installed on the ground, and poured into the underground pit 13 . A temporary floor slab 18 is constructed by filling the underground pit 13 with concrete 17 . The temporary floor slab 18 has sufficient strength and bearing capacity to support the load applied to the structural column 4 to be constructed in a later process.

Concrete is sent from a ready-mixed concrete car 92 and a pump car 93 and placed on the inner peripheral side of the underground outer wall 14 . A reinforcing wall 25 made of concrete is constructed.

In the first basement floor and the second basement floor, a plurality of vertically extending supports 23 support between the upper and lower floor slabs and between the floor slab and the beams. A plurality of supports 23 are connected by connecting members 24 extending in the horizontal direction.

As shown in FIG. 4, a pedestal 40 is constructed on the temporary floor slab 18 . The pedestal 40 is provided at the lower end of the structural column 4 to be constructed in a later process. By providing the pedestal 40, the axial force of the structural column 4 is dispersed. In this embodiment, the pedestal 40 is made of concrete that is sent from the ready-mixed concrete car 92 and the pump car 93 .

As shown in FIG. 12 , connection reinforcements 43 to be connected to the bottom reinforcements 52 of the base slab 51 to be constructed in a later process may be attached in advance to the pedestal 40 . A mechanical joint 44 is provided on the end face side of the pedestal 40 .

As shown in FIG. 5, the supports 23 and connecting members 24 are removed from the existing basement 1st floor, and the framework including the floor slabs 28, columns 29 and beams 30 of the first floor is dismantled.
In the existing second basement floor, the supports 23 and the connecting members 24 are removed at the locations where they interfere with the structural columns 4, and the skeleton such as the floor slabs 32 and the beams 33 is dismantled. At the site where the floor slab 32 has been dismantled, a reinforcing member 37 is installed around the dismantled site for reinforcement.
In the existing 3rd basement floor, the skeleton such as the floor slab 34 and the beam 35 is dismantled at the location where it interferes with the structural column 4. - 特許庁At the site where the floor slab 32 has been dismantled, a reinforcing member 37 is installed around the dismantled site for reinforcement.
In addition, the dismantling of above-ground structures will be promoted.

As shown in FIG. 6, the floor slab 38 is dismantled at the location where it interferes with the structural column 4 on the existing first basement floor. At a location where the floor slab 38 has been dismantled, a reinforcing member 37 is installed around the dismantled location to reinforce it.
In the existing 2nd basement floor and 3rd basement floor, the pillar 39 (see FIG. 5) is dismantled at the location where it interferes with the structure pillar 4 . A reinforcing member 37 is installed on the floor slab 32 to reinforce the portion where the pillar 39 has been dismantled.
In the existing 4th basement floor, the pillar 39 (see FIG. 5) is dismantled at the location where it interferes with the structure pillar 4 in the post-process.

As shown in FIG. 7, a floor structure 45 and a floor slab 46 are installed on the newly built second basement floor.
A lower pillar 41 is installed on a pedestal 40 on a newly built third basement floor. In this embodiment, the diameter of the lower end portion 41a of the lower column 41 is increased, but the diameter need not be increased.

As shown in FIGS. 8 and 9, a floor structure 47 and a floor slab 48 are installed on the first floor of a new building.
An upper pillar 42 is joined above a lower pillar 41 in a newly constructed second basement floor and first basement floor. A structural column 4 is composed of the lower column 41 and the upper column 42 .

As shown in FIGS. 10 and 11, the existing basement 1 floor slab 38, the existing basement 2 floor slab 32 and column 39, the existing basement 3 floor slab 34 and column 39, the existing basement 4 The floor pillars 39 are dismantled one by one.
As shown in FIG. 2, a floor structure 49 and a floor slab 50 are installed on the first basement floor of a new building. A foundation slab 51 is installed on the newly constructed third basement floor. As shown in FIG. 12 (the concrete portion of the foundation slab 51 is indicated by a two-dot chain line), the bottom reinforcement 52 of the foundation slab 51 is connected to the mechanical joint 44 of the pedestal 40 . Thereby, the bottom reinforcement 52 of the base slab 51 and the connection reinforcement 43 of the base 40 are connected via the mechanical joint 44 . A foundation slab 51 is constructed by pouring concrete. The lower part of the structural column 4 is embedded in the foundation slab 51 .

In the new building 2, the pedestal 40 on which the framing column 4 is installed diffuses the axial force of the framing column 4 within its thickness, and the stress generated in the temporary floor slab 18 can be reduced.

A new column 5 is constructed by using a structural true column 4 of steel structure. In this embodiment, the new column 5 is a steel-framed reinforced concrete structure, and is constructed, for example, by arranging main reinforcing bars and ties around the steel frame of the structural column 4 and pouring concrete.

In the rebuilding method for a building having an underground structural part configured in this way, cast-in-place concrete piles for erecting the structural columns 4 are not required, and the construction period and cost can be reduced. In addition, in the construction of the structural column 4, there is no need to insert steel frames into cast-in-place concrete piles, and ordinary steel frame erection work can be performed, so that the construction accuracy of the structural column 4 can be improved. can.

Moreover, the concrete filling work in the underground pit 13 of the existing underground structure 10 and the construction work of the pedestal 40 can be carried out during the dismantling work of the existing above ground frame. By carrying out these works in parallel with the ground frame dismantling work, it is possible to further shorten the construction period.

In addition, the concrete pedestal 40 functions to disperse the axial force applied to the structural column 4 in a plane and to reduce the stress generated in the temporary floor slab 18 . By making the concrete strength of the pedestal 40 higher than that of the existing frame, it is possible to support a larger axial force. In addition, the connection bars 43 that serve as the reinforcing bars of the base slab 51 can be arranged on the pedestal 40 in advance, and the lower end bars 52 of the base slab 51 and the connection bars 43 of the base 40 can be spliced together during the reinforcing work of the base slab 51 . can.

Further, since the lower end portion 41a of the structural column 4 is enlarged in diameter, the axial force acting on the pedestal 40 is dispersed over a wide range, and the stress generated in the temporary floor slab 18 can be further reduced.

Also, if the structure column 4 is installed on the temporary floor slab 18 without providing the pedestal 40, the bottom reinforcement of the foundation slab 51 will not pass through the structure column 4 due to the column steel frame of the structure column 4 or the like. In this embodiment, by inserting the lower end reinforcement of the foundation slab 51 into the pedestal 40 in advance, the problem of reinforcement arrangement can be solved, and the foundation slab 51, the pedestal 40, and the structural column 4 can be integrated. can be done.

An embodiment of the method for rebuilding a building having an underground structure according to the present invention has been described above, but the present invention is not limited to the above-described embodiment, and can be modified as appropriate without departing from the scope of the present invention. .

In the embodiment shown above, the procedure for constructing from the floor structure part of the intermediate part of the underground floor has been described, but the procedure for constructing the floor structure part can be set as appropriate.

Further, in the embodiment shown above, the underground pit 13 is filled with concrete 17, but the present invention is not limited to this. The underground pit 13 may be filled with fluidized soil instead of the concrete 17 .

1 Existing building 2 New building 4 Structural column 10 Existing underground structure 18 Temporary floor slab 20 New underground structure 40 Pedestal 41a Lower end

Claims (2)

A rebuilding method for a building having an underground structure,
Temporary floor slabs are constructed by reinforcing the existing foundation frame consisting of the existing basement and existing foundation beams of the existing underground structure,
Build a pedestal on the temporary floor slab,
A rebuilding method for a building having an underground structural section for constructing structural columns on the pedestal. 2. The method for rebuilding a building having an underground structural part according to claim 1, wherein the lower end of said structural column has an enlarged diameter.

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