Existing foundation reinforcement method and existing foundation reinforcement structure

Abstract

To provide an existing foundation reinforcing method capable of more effectively reinforcing a foundation of an existing building, and a more effectively reinforced existing foundation reinforcing structure.SOLUTION: A method for reinforcing an existing footing when a new building is constructed by reusing a footing 1 of an existing building, comprising the steps of: forming a cotter mold 14 by cutting a part of 10a and 11a of concrete surfaces of footing slabs 10 and / or footing beams 11 defining a pit 12 of the footing 1; and filling the pit 12 with filling concrete 20 to form a mat slab 30 by the footing 1 and the filling concrete 20.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a method and structure for reinforcing an existing foundation when constructing a new building by reusing the foundation of an existing building. [Background technology]

[0002] For example, when constructing a new building such as an office building, hotel, or apartment building, it has been proposed to reuse the foundations of existing buildings in order to shorten the construction period and reduce costs associated with the construction of the new building (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-142687 Summary of the Invention [Problem to be solved by the invention]

[0004] When constructing a new building by reusing the foundation of an existing building, it is common to remove the above-ground portion of the existing building and then reinforce the foundation before constructing the new building.

[0005] However, when constructing a new building that is heavier than the existing building, such as when the new building is taller than the existing building, it is necessary to reinforce the foundation of the existing building more effectively, and there was a need for a new existing foundation reinforcement method and structure that could handle such cases.

[0006] The present invention has been made in consideration of such problems, and its purpose is to provide an existing foundation reinforcement method that can more effectively reinforce the foundation of an existing building, and an existing foundation reinforcement structure that is more effectively reinforced. [Means for solving the problem]

[0007] The existing foundation reinforcement method of the present invention is a method for reinforcing an existing foundation when constructing a new building by reusing the foundation of an existing building, and is characterized in that a cotter mold is formed by chipping off a portion of the concrete surface of the foundation slab and / or foundation beam that defines the foundation pit, and then filling concrete is filled into the pit to form a mat slab from the foundation and the filled concrete, thereby providing a cotter between the foundation slab and / or foundation beam and the filled concrete.

[0008] The existing foundation reinforcement structure of the present invention is an existing foundation reinforcement structure that reinforces the foundation of an existing building, and is characterized by having a cotter mold formed by chipping away a portion of the concrete surface of the foundation slab and / or foundation beam that defines a pit in the foundation, filled concrete that is filled into the pit and forms a mat slab together with the foundation, and a cotter formed by the cotter mold and the filled concrete filled into the cotter mold, and installed between the foundation slab and / or foundation beam and the filled concrete. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide an existing foundation reinforcing method that can more effectively reinforce the foundation of an existing building, and an existing foundation reinforcing structure that is more effectively reinforced. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a cross-sectional view of a portion of a foundation of an existing building to which an existing foundation reinforcing method according to one embodiment of the present invention is applied. [Figure 2] 2 is a cross-sectional view of the foundation shown in FIG. 1 with a cotter die provided. FIG. [Figure 3] FIG. 3 is a plan view of a portion of the foundation shown in FIG. 2. [Figure 4] 3 is an enlarged cross-sectional view of a portion of the foundation shown in FIG. 2 where a cotter die is provided. [Figure 5] 3 is a cross-sectional view of the foundation shown in FIG. 2 with the pit filled with filler concrete. [Figure 6] FIG. 6 is an enlarged cross-sectional view of a portion of the foundation shown in FIG. 5 where a cotter is provided. DETAILED DESCRIPTION OF THE INVENTION

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An existing foundation reinforcing method and an existing foundation reinforcing structure according to an embodiment of the present invention will be described in detail below with reference to the drawings.

[0012] The foundation 1 shown in Figure 1 constitutes part of an already constructed building, i.e., an existing building 2. When the existing building 2 is replaced with a new building, i.e., a newly constructed building (not shown), the foundation 1 is reinforced using the existing foundation reinforcement method according to this embodiment and reused as the foundation of the new building. The foundation 1 reinforced using the existing foundation reinforcement method according to this embodiment is configured into an existing foundation reinforcement structure according to this embodiment. Figure 1 shows the foundation 1 in a state where the superstructure (not shown) of the existing building 2 and part of the underground structure 3 (portion indicated by the two-dot chain line) have been removed.

[0013] In this embodiment, the existing building 2 is a complex building equipped with a theater, accommodation facilities, conference facilities, etc., and the new building is an office building. The office building to be constructed as a new building will be taller than the complex building that is the existing building 2. Note that the existing building 2 and the new building are not limited to a complex building and an office building, respectively, but may also be buildings used for other purposes such as a hotel or an apartment building. Furthermore, the existing building 2 and the new building may have different purposes. Furthermore, the new building is not limited to being taller than the existing building 2.

[0014] In this embodiment, the foundation 1 is made of reinforced concrete. For convenience, reinforcing bars arranged inside the foundation 1 are omitted from Figures 1 to 6. Note that the foundation 1 is not limited to being made of reinforced concrete, and may be made of other structures such as reinforced steel concrete, as long as it is made of concrete.

[0015] The foundation 1 has a foundation slab 10 supported on the ground 4, and a plurality of foundation beams 11 that are integrally connected to the foundation slab 10 and protrude upward from the foundation slab 10. The plurality of foundation beams 11 are arranged in a grid pattern on the upper surface of the foundation slab 10. The foundation slab 10 may also be configured to be supported on the ground 4 via a direct foundation (raft foundation).

[0016] The foundation 1 includes a pit 12 partitioned by a foundation slab 10 and multiple foundation beams 11. In this embodiment, the foundation 1 includes multiple pits 12. The pit 12 is a space that was previously used as, for example, a heat storage tank or a fire water tank. In this embodiment, the pit 12 is open upward by removing a portion of the upper side of the foundation beams 11 and the upper slab 13 along with the superstructure of the existing building 2 and a portion of the underground structure 3. Note that the foundation 1 may be configured to include only one pit 12.

[0017] In the existing foundation reinforcing method according to this embodiment, when a new building is constructed by reusing the foundation 1 of the existing building 2 having the above-described configuration, the foundation 1 is reinforced in the following manner.

[0018] First, as shown in Figures 2, 3, and 4, portions of the concrete surfaces 10a, 11a of the foundation slab 10 and / or foundation beams 11 that define the pit 12 of the foundation 1 are chipped away to form cotter dies 14. In this embodiment, a plurality of cotter dies 14 are formed on both the concrete surface 10a of the foundation slab 10 that defines the pit 12 of the foundation 1 and the concrete surface 11a of the foundation beams 11 that define the pit 12 of the foundation 1. For convenience, in Figures 2 and 3, only some of the cotter dies 14 provided on the concrete surface 10a of the foundation slab 10 and some of the cotter dies 14 provided on the concrete surface 11a of the foundation beams 11 are labeled with reference numerals.

[0019] More specifically, in the foundation slab 10, a plurality of cotter dies 14 are formed by chipping away a portion of the concrete surface 10a, which is the upper surface of the foundation slab 10 facing the pit 12. At this time, it is preferable that the plurality of cotter dies 14 are formed so as to be arranged in a plurality of rows (for example, three rows) at predetermined intervals from any of the foundation beams 11 (foundation beams 11 extending in the vertical direction in FIG. 3) that define the pit 12 and spaced apart from each other along the foundation beam 11.

[0020] On the other hand, in the foundation beam 11, a plurality of cotter dies 14 are formed by chipping off a portion of each of a plurality of concrete surfaces 11a on both sides facing the pit 12. In this case, it is preferable to form the plurality of cotter dies 14 so that they are arranged in a plurality of rows and a plurality of stages at intervals across the entire concrete surface 11a on the side surfaces of the foundation beam 11.

[0021] The arrangement and number of the multiple cotter dies 14 formed on the concrete surface 10a of the foundation slab 10 are not limited to the above, and may be arranged over the entire concrete surface 10a of the foundation slab 10. Similarly, the arrangement and number of the multiple cotter dies 14 formed on the concrete surface 11a of the foundation beam 11 are not limited to the above, and may be arranged over only a portion of the concrete surface 11a of the foundation beam 11.

[0022] The cotter die 14 is formed as a recess recessed into the concrete surfaces 10a, 11a by chipping (scraping) a part of the concrete surface 10a of the foundation slab 10 or a part of the concrete surface 11a of the foundation beam 11. The shape of the cotter die 14 can be various shapes as long as it is a recess recessed into the concrete surfaces 10a, 11a.

[0023] As shown in Figure 4, in this embodiment, each of the multiple cotter dies 14 has a square, flat bottom surface 14a parallel to the concrete surface 10a, and four side surfaces 14b provided between the four sides of the bottom surface 14a and the concrete surface 10a, with each of the four side surfaces 14b sloping outward toward the concrete surface 10a rather than the bottom surface 14a. Note that while Figure 4 illustrates an example of a cotter die 14 provided on the concrete surface 10a of the foundation slab 10, the cotter dies 14 provided on the concrete surface 11a of the foundation beam 11 also have a similar shape.

[0024] When forming the cotter dies 14 by chipping away portions of the concrete surfaces 10a, 11a of the foundation slab 10 and / or the foundation beam 11, anchors 15 may be provided by post-construction on the concrete surfaces 10a, 11a of the foundation slab 10 and the concrete surfaces 11a of the foundation beams 11. In this embodiment, the anchors 15 are provided so as to stand up from the bottom surfaces 14a of the cotter dies 14 provided on the foundation slab 10 and the foundation beams 11. Note that a configuration in which the anchors 15 are not provided may also be adopted.

[0025] When forming cotter dies 14 by chipping away portions of the concrete surfaces 10a, 11a of the foundation slab 10 and / or foundation beam 11, cotter dies 16 may also be formed on the concrete surface 11b, which is the upper surface of the foundation beam 11 that does not face the pit 12. In this case, the shape of the cotter dies 16 may be the same as that of the cotter dies 14, but may also be other shapes, such as a groove-like shape extending straight from the concrete surface 11a on one side to the concrete surface 11a on the other side of the concrete surface 11b on the upper surface of the foundation beam 11. Furthermore, cotter dies 16 may be arranged in multiple rows on the concrete surface 11b on the upper surface of the foundation beam 11. Furthermore, anchors 15 may be provided on the concrete surface 11b so as to stand up from each cotter dies 16.

[0026] 2 and 3, for the sake of convenience, only some of the anchors 15 and some of the cotter dies 16 are labeled with reference numerals.

[0027] After chipping away a portion of the concrete surfaces 10a, 11a of the foundation slab 10 and / or foundation beam 11 to form the cotter mold 14, the pit 12 is filled with filled concrete 20 to form a mat slab 30 from the foundation 1 and the filled concrete 20, as shown in Fig. 5. More specifically, the filled concrete 20 is poured into the pit 12 so that the entire pit 12 is filled with the filled concrete 20, and the foundation 1 is formed into a mat slab 30 from the foundation 1 and the hardened filled concrete 20.

[0028] When the filled concrete 20 is filled into the pit 12, cotters 40 are provided between the foundation slab 10 and the filled concrete 20, and between the foundation beam 11 and the filled concrete 20. That is, the filled concrete 20 filled into the pit 12 is also filled into each of the multiple cotter dies 14 provided on the foundation slab 10 and the foundation beam 11. When the filled concrete 20 hardens, as illustrated for the part of the foundation beam 11 in FIG. 6, the cotter dies 14 and the convex portions 22 of the filled concrete 20 hardened inside the cotter dies 14 form cotters 40 between the foundation slab 10 and the filled concrete 20, and between the foundation beam 11 and the filled concrete 20. Note that in FIG. 5, for convenience, only some of the cotter dies 14, convex portions 22, and cotters 40 are labeled.

[0029] Furthermore, in this embodiment, by pouring the filled concrete 20 up to a position higher than the upper end of the foundation beam 11, the pit 12 is filled with the filled concrete 20, and the concrete surface 11b on the upper surface of the foundation beam 11 is covered with the filled concrete 20. As a result, a cotter 41 is also formed between the concrete surface 11b on the upper surface of the foundation beam 11 and the filled concrete 20 by the cotter mold 16 provided on the concrete surface 11b on the upper surface of the foundation beam 11 and the convex portion 23 of the filled concrete 20 that has hardened inside the cotter mold 16.

[0030] Furthermore, in this embodiment, when the pit 12 is filled with filled concrete 20, the portions of the anchors 15 provided on the concrete surface 10a of the foundation slab 10 and the concrete surface 11a of the foundation beam 11 that protrude from the foundation slab 10 or the foundation beam 11 are buried inside the filled concrete 20.

[0031] In addition, before filling the pit 12 with the filled concrete 20, steel bars 21 may be arranged on the upper side of the multiple foundation beams 11 so that they span the multiple foundation beams 11, thereby resulting in a configuration in which steel bars 21 are arranged inside the filled concrete 20 so that they span the multiple foundation beams 11.

[0032] As described above, in the existing foundation reinforcement method according to this embodiment, when a new building is constructed by reusing the foundation 1 of an existing building 2, portions of the concrete surfaces 10a, 11a of the foundation slab 10 and foundation beam 11 that define the pit 12 of the foundation 1 are chipped off to form a cotter mold 14, and then the pit 12 is filled with filled concrete 20 to form a mat slab 30 from the foundation 1 and the filled concrete 20, thereby providing cotters 40 between the foundation slab 10 and the filled concrete 20 and between the foundation beam 11 and the filled concrete 20.

[0033] In this way, in the existing foundation reinforcement method of this embodiment, the foundation 1 having the pit 12 is formed into a mat slab 30 in which the pit 12 is filled with filled concrete 20, thereby increasing the strength of the foundation 1.

[0034] Furthermore, in the existing foundation reinforcing method according to this embodiment, cotters 40 are provided between the foundation slab 10 and the filled concrete 20 and between the foundation beam 11 and the filled concrete 20, respectively. This allows the cotters 40 to support the long-term load at the interface between the concrete surfaces 10a, 11a facing the pit 12 of the foundation 1 and the filled concrete 20, thereby reinforcing the foundation 1 more effectively than in a case where the cotters 40 are not provided. In other words, if the concrete surfaces 10a, 11a facing the pit 12 of the foundation 1 and the filled concrete 20 were simply in contact with each other at flat surfaces, the long-term load could not be sufficiently supported between the concrete surfaces 10a, 11a and the filled concrete 20, and there is a risk of long-term misalignment between the foundation 1 and the filled concrete 20. However, by providing the cotters 40 between the concrete surfaces 10a, 11a and the filled concrete 20, the long-term load is supported by the cotters 40, preventing such misalignment and effectively reinforcing the foundation 1. Therefore, according to the existing foundation reinforcement method of this embodiment, the strength of the foundation 1 of the existing building 2 can be effectively increased to the extent that it can be reused as the foundation for a new building that is heavier than the existing building 2, for example, that is taller than the existing building 2.

[0035] Furthermore, in this embodiment, a plurality of cotters 40 are provided at the interface between the foundation slab 10 and the filled concrete 20, arranged in multiple rows (three rows) at intervals from each other along the foundation beam 11 while leaving a predetermined distance from the foundation beam 11, so that the long-term load at the interface between the foundation slab 10 and the filled concrete 20 can be effectively supported by a small number of cotters 40.

[0036] Furthermore, in this embodiment, cotters 40 are provided at both the interface between the foundation slab 10 and the filled concrete 20 and the interface between the foundation beam 11 and the filled concrete 20, thereby enabling the foundation 1 to be reinforced even more effectively.

[0037] Furthermore, in this embodiment, a cotter 41 is also provided between the concrete surface 11b on the upper surface of the foundation beam 11 and the filled concrete 20, so that the long-term load at the interface between the concrete surface 11b on the upper surface of the foundation beam 11 and the filled concrete 20 is supported by the cotter 41, thereby further effectively reinforcing the foundation 1.

[0038] In addition, short-term loads such as earthquake shaking that are applied to the interface between the concrete surfaces 10a, 11a facing the pit 12 of the foundation 1 and the filled concrete 20 can be effectively supported by anchors 15 provided in the foundation slab 10 and foundation beam 11.

[0039] A foundation 1 reinforced by the existing foundation reinforcing method according to this embodiment is configured as an existing foundation reinforcing structure 50 according to this embodiment. That is, the existing foundation reinforcing structure 50 is configured to include a cotter mold 14 formed by chipping away parts of the concrete surfaces 10a, 11a of the foundation slab 10 and foundation beam 11 that define the pit 12 of the foundation 1, filled concrete 20 that is filled into the pit 12 and forms a mat slab 30 together with the foundation 1, and a cotter 40 formed by the cotter mold 14 and the filled concrete 20 filled into the cotter mold 14 and installed between the foundation slab 10, foundation beam 11, and the filled concrete 20. According to the existing foundation reinforcing structure 50 according to this embodiment, the foundation 1 is formed as a mat slab 30 in which the filled concrete 20 is filled into the pit 12, and the cotter 40 installed between the concrete surfaces 10a, 11a and the filled concrete 20 supports long-term loads between the foundation 1 and the filled concrete 20, thereby providing the foundation 1 with high strength.

[0040] The present invention is not limited to the above-described embodiment, and it goes without saying that various modifications can be made without departing from the spirit and scope of the present invention.

[0041] For example, in the above embodiment, the cotter molds 14 are formed on both the concrete surface 10a of the foundation slab 10 that defines the pit 12 of the foundation 1 and the concrete surface 11a of the foundation beam 11 that defines the pit 12 of the foundation 1, but they may be formed on only one of them. Even in this case, the cotter molds 40 can support long-term loads at either the interface between the foundation slab 10 and the filled concrete 20 or the interface between the foundation beam 11 and the filled concrete 20, thereby effectively reinforcing the foundation 1.

[0042] In addition, in the above embodiment, the pit 12 is opened upward by removing part of the upper part of the foundation beam 11 and the upper slab 13 together with the upper part of the existing building 2, and filling concrete 20 is filled into the pit 12 through this opening.However, it is also possible to provide a filling opening in the upper slab 13 without removing part of the upper part of the foundation beam 11 and the upper slab 13, and fill the filling concrete 20 into the pit 12 through the filling opening. [Explanation of symbols]

[0043] 1 Basics 2 Existing buildings 3 Underground structure 4 Ground 10 Foundation slab 10a Concrete surface 11 Foundation beam 11a Concrete surface 11b Concrete surface 12 Pit 13 Upper slab 14 Cotter type 14a bottom 14b Side 15 Anchor 16 Cotter type 20 Filled concrete 21 Reinforced concrete 22 Convex part 23 Convex part 30 Matte Slab 40 Cotter 41 Cotter 50 Existing foundation reinforcement structure

Claims

1. A method for reinforcing an existing foundation when constructing a new building by reusing the foundation of an existing building, A method for reinforcing an existing foundation, characterized in that a portion of the concrete surface of the foundation slab and / or foundation beam that defines the foundation pit is chipped off to form a cotter mold, and then the pit is filled with filling concrete to form a mat slab from the foundation and the filled concrete, thereby providing a cotter between the foundation slab and / or foundation beam and the filled concrete.

2. An existing foundation reinforcement structure that reinforces the foundation of an existing building, A cotter mold formed by chipping off a part of the concrete surface of the foundation slab and / or foundation beam that defines the foundation pit; Filled concrete is filled into the pit to form a mat slab together with the foundation; An existing foundation reinforcement structure characterized by having a cotter formed by the cotter mold and the filled concrete filled into the cotter mold, and arranged between the foundation slab and / or the foundation beam and the filled concrete.

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