JP2019143315A - Construction method of raft foundation and raft foundation structure - Google Patents

Abstract

To provide a construction method of a raft foundation and a raft foundation structure allowing productivity and in-site workability to be improved, construction cost to be reduced, and construction period to be reduced through securing connection strength between an inner foundation and a bottom base, and standardizing the inner foundation.SOLUTION: A construction method of a raft foundation provided at least with a concrete bottom base 10 and an outer foundation and an inner foundation comprises: a first step of arranging a plurality of precast concrete materials 40 without connecting each other, the precast concrete materials 40 composing the inner foundation, which is provided with a concrete body 41, leg parts 42 extending downward from the concrete body, and a plurality of vertical bars 43 of which one end are buried in the concrete body and the other end extend downward from the concrete body and bend; a second step of binding the vertical bars 43 and bottom base bars 11; and a third step of integrating the bottom base and the inner foundation through filling concrete in a lower part of the concrete body 41 to such an extent the lower part is fully filled.SELECTED DRAWING: Figure 2

Description

  The present invention can secure sufficient joint strength between the internal foundation and the bottom base, and further standardize the internal foundation to improve productivity, improve workability on site, control construction costs, and shorten the construction period. The construction method and solid foundation structure.

In solid foundations for buildings such as ordinary houses, rebars are assembled at the construction site, the formwork is fixed at the position where the rebars are sandwiched, and concrete is poured into the formwork, so that the bottom board (pressure board) and the rising part (external foundation and internal) (Base) is firmly connected (for example, see Patent Document 1).
In addition, concrete members (hereinafter referred to as “precast concrete members”) are mass-produced in advance at a factory, etc., which are transported to a construction site, and a plurality of precast concrete members are connected in the longitudinal direction at the construction site. A construction method for constructing a solid foundation made of concrete in a short period of time is known (for example, see Patent Document 2).
In Patent Document 3, as a method for forming an internal foundation, a bottom plate is formed in advance, and then a boulder column (precast concrete member) is moved to a predetermined position on the bottom plate. The technique which fixes the columnar body for boulders to a pressure board by using the reinforcing bar which stands up from or embedding an anchor bolt in the pressure board is disclosed. In Patent Document 3, a bottom plate is also formed in advance, and then the casing is moved to a predetermined position on the bottom plate, and then concrete is placed in the housing to form a columnar body for bundling, and the reinforcing bars and There is also disclosed a technique for fixing a boulder columnar body to a pressure plate with an anchor bolt.

JP2016-223118A Japanese Patent No. 5821116 Japanese Patent No. 2829313

However, in the above-mentioned Patent Document 1, there is a problem that the reinforcing bar arranging and binding work and the formwork attaching work for forming the internal foundation are complicated, and the work is prolonged because the formwork cannot be removed until the concrete is solidified. There was also a problem that the material cost of rebar and concrete increased.
In Patent Document 2, since it is necessary to change the shape of the precast concrete according to the shape of the internal foundation, there is also a problem that the manufacturing cost of the mold for precast concrete increases.
In Patent Document 3, since a precast concrete member is attached and fixed to a pre-formed bottom plate using a reinforcing bar or an anchor bolt, it is difficult to ensure the bonding strength between the bottom plate and the precast concrete member. There is.

  In view of such a problem, the present invention can secure sufficient bonding strength between the internal foundation and the bottom base, and further improve the productivity by standardizing the internal foundation, improve workability on site, control construction costs, An object is to provide a solid foundation construction method and a solid foundation structure that can be shortened.

The solid foundation construction method of the present invention is a solid foundation construction method comprising at least a concrete base, an external foundation and an internal foundation, wherein the precast concrete member constituting the internal foundation includes a concrete main body portion and the concrete main body portion. At least two leg portions extending downward from the lower surface of the concrete body, and a plurality of vertical bars that have one end embedded in the concrete body portion and the other end extending downward from the lower surface of the concrete body portion and bent horizontally. A first step of arranging a plurality of the precast concrete members without being connected to each other, a second step of binding the vertical bars and the bottom base bars, and the extent to which the lower part of the concrete body portion is buried Characterized in that it comprises at least a third step of integrating the bottom plate and the internal foundation by placing concrete in .
Furthermore, the method further comprises a positioning step of adjusting the vertical height and inclination of the precast concrete member.
Further, the leg portion is made of concrete and is integrally formed with the concrete main body portion.
The leg portion is made of metal.

  The solid foundation structure of the present invention is a solid foundation structure comprising at least a concrete base, an external foundation and an internal foundation, wherein the precast concrete member constituting the internal foundation is below the concrete main body and the lower surface of the concrete main body. And at least two legs that extend, and one end is embedded in the concrete body, and the other end extends downward from the bottom surface of the concrete body and includes a plurality of vertical bars that are bent horizontally. A plurality of the precast concrete members are arranged without being connected to each other, the vertical bars are bound to the bottom bar, and the bottom board is formed by a concrete layer having a thickness sufficient to fill the lower part of the concrete main body. And the internal base are integrated.

In the present invention, by placing concrete in a state where the vertical bars and bottom bar bars of a plurality of precast concrete members constituting the internal foundation are bound, a plurality of precast concrete members (inner foundation) and the bottom board are integrated with concrete. To do. The method of joining such a precast concrete member (internal foundation) and the bottom plate is in accordance with the method approved by the Architectural Institute of Japan. It can secure sufficient bonding strength between the internal foundation and the bottom plate and has sufficient structural strength. A strong internal foundation can be formed.
Moreover, since an internal foundation is comprised with a some precast concrete member, the construction property in a field can be improved. Moreover, since precast concrete members (internal foundations) can be standardized, it is possible to improve productivity, shorten delivery times, and improve workability through prospective production.

In the present invention, a plurality of precast concrete members are arranged without being connected to each other. Each precast concrete member is a well-known layer or member formed so as not to sink the precast concrete member before placing concrete for a bottom plate (pressure platen) such as abandoned concrete layer, improved ground layer, precast plate, etc. Place on top.
Therefore, if the above-mentioned discarded concrete layer is formed only on the place where the legs of each precast concrete member are placed, compared to the case where a plurality of precast concrete members are connected as in the prior art (see FIG. 7). It is possible to reduce construction costs and shorten the construction period by reducing the amount of concrete used. Moreover, the effect that an internal foundation can be formed with few workers and the freedom degree of the design of an internal foundation improve are also acquired. In addition, since the ventilation of the internal foundation is improved, the generation of moisture and condensation can be suppressed, and it is particularly suitable for air conditioning floor heating. In addition, it is easy to secure a person passage. Moreover, the effect that the quantity of abandoned concrete can be reduced compared with the former is also acquired.
Moreover, an internal foundation can be formed with high precision by positioning the precast concrete member.
If the legs are made of concrete, the manufacturing cost can be reduced because the legs can be integrally formed with the concrete body.
If the legs are made of metal, the weight of the precast concrete member can be suppressed and the degree of freedom in height and position can be increased, so that the range of use of the precast concrete member can be expanded.

Perspective view of a solid foundation structure (a), perspective view of a solid foundation structure after the foundation is laid down (b), and perspective view of a precast concrete member (c) Longitudinal section of solid foundation structure Perspective view (a) and longitudinal section (b) of precast concrete member Longitudinal section (a) and front view (b) of precast concrete member with positioning brackets The perspective view of the precast concrete member of a 2nd embodiment Longitudinal sections (a) to (d) showing construction methods for solid foundation structures Perspective view of conventional solid foundation structure

[First embodiment]
A first embodiment of the solid foundation structure of the present invention will be described.
As shown in FIGS. 1 and 2, the solid foundation structure 1 includes at least a concrete bottom board 10, an external foundation 20, and an internal foundation 30. Since the base 10 and the external foundation 20 are well known, detailed description thereof will be omitted.
The inner foundation 30 is composed of a plurality of precast concrete members 40. The precast concrete members 40 are not connected to each other and are arranged independently. As described above, each precast concrete member 40 is disposed on a discarded concrete layer 50, an improved ground layer, a precast board, or the like. In the present embodiment, it is assumed that the material is disposed on the discarded concrete layer 50.

As shown in FIGS. 3 (a) and 3 (b), the precast concrete member 40 includes a concrete main body 41, leg portions 42, and vertical bars 43, and those previously produced in a factory or the like are transported to the construction site. .
The concrete main body 41 is a member formed by solidifying concrete. The shape of the concrete main body 41 is not particularly limited, and may be appropriately selected from a rectangular shape, a cross shape, a T shape, an L shape, an I shape, etc. when viewed in plan as shown in FIG. The upper surface of the concrete main body 41 is preferably a horizontal plane.
The leg portion 42 is a member extending downward from the lower surface of the concrete main body portion 41. At least two legs 42 are required for one concrete body 41. The leg portion 42 of the present embodiment is made of concrete integrally formed with the concrete body portion 41.

One end of the vertical bar 43 is embedded in the concrete main body 41, and the other end is a metal member that extends downward from the lower surface of the concrete main body 41 and bends in the horizontal direction. As will be described later, the precast concrete member 40 is placed on the discarded concrete layer 50 or the like using the legs 42, and the vertical bars 43 are the surface of the discarded concrete layer 50 and the lower surface of the concrete body 41. It bends in the space formed between and extends horizontally. In a state where the precast concrete member 40 is disposed at a predetermined position on the discarded concrete layer 50 or the like, the vertical bars 43 are bound to the bottom base bars 11 (rebars extending in the horizontal direction).
A positioning fitting 60 as shown in FIGS. 4 (a) and 4 (b) may be disposed between the leg portion 42 and the discarded concrete layer 50 or the like. Although a known member may be used for the positioning fitting 60, in this embodiment, a metal plate 61 having a U-shaped longitudinal section and a plurality of screws that are screwed into the plate 61 so as to penetrate the plate 61 vertically. (2 to 3 bolts are preferable). By turning the bolt 62 to change the exposed length of the bolt tip with respect to the plate 61, the vertical height and inclination of the precast concrete member 40 can be adjusted. As will be described later, the positioning bracket 60 may be attached to the bottom of the leg portion 42 with bolts 63 or the like in advance, or the positioning bracket 60 may be disposed at a predetermined position on the discarded concrete layer 50 or the like to some extent. You may decide to attach the leg part 42 of the precast concrete member 40 to the positioning metal fitting 60 with the volt | bolt 63 etc. after adjusting height and inclination.
The concrete layer 70 integrates the bottom plate 10 and the internal foundation 30 (a plurality of concrete main body portions 41), and has a thickness that allows the lower portion of the concrete main body portion 41 to be buried.

[Second Embodiment]
The second embodiment of the solid basic structure 1 of the present invention will be described, but the same reference numerals are given to the same parts as those in the first embodiment, and the description thereof will be omitted.
As shown in FIG. 5, the solid foundation structure 1 of the present embodiment is characterized in that the leg portion 44 is made of metal.
Specifically, the leg portion 42 has a U-shaped vertical cross section, and is attached to the lower surface of the concrete main body portion 41 with the opening facing the horizontal direction. Finally, the concrete body 41 is firmly integrated with the bottom plate 10 by the concrete layer 70, and the metal legs 42 are embedded in the bottom plate 10, so that the metal legs 42 are embedded in the concrete body 41. There is no need to fix it firmly. In addition, the vertical cross-sectional shape of the leg portion 42 can be appropriately changed to an I shape, a B shape, or the like.

The solid foundation construction method of the present invention will be described.
First, the operator excavates and levels the area where the foundation is to be formed to form the excavated ground 80.
Then, as shown in FIG. 6 (a), a crushed stone rolling layer 81 is provided by laying and rolling the crushed stone, simultaneously providing a discarded concrete layer 50, and a moisture-proof sheet 82 is laid thereon.
In Fig. 6 (a) (a), when a discarded concrete layer 50 having a thickness smaller than that of the crushed stone rolled layer 81 is provided, (b) is provided with a discarded concrete layer 50 having the same thickness as the crushed stone rolled layer 81. Shows the case. In both (a) and (b), the discarded concrete layer 50 is formed only on the place where the legs 42 of the precast concrete member 40 are placed, but as shown in (c), the discarded concrete layer 50 is formed on the entire surface. May be.
Next, as shown in FIG. 6 (b), the base metal strip 11 is placed and the positioning fitting 60 is placed at the place where the leg portion 42 is placed. The positioning bracket 60 may be attached to the bottom of the leg portion 42 in advance.
Next, an operator arranges the precast concrete member for the external foundation 20 on the outer edge of the foundation. In the case where the precast concrete member 40 is not used, the external foundation 20 may be formed by installing a formwork along the outer edge of the foundation and placing the concrete by so-called double hitting or single shot.
Next, as shown in FIG. 6 (c), the operator arranges a plurality of precast concrete members 40 and adjusts the positions with the positioning fittings 60. At this time, the precast concrete members 40 are not connected to each other.
Next, the operator binds the vertical bars 43 and the bottom base bars 11 of the precast concrete member 40.
Then, as shown in FIG. 6 (d), the concrete layer 70 is formed by placing the concrete so that the lower portion of the concrete body 41 is buried, and the bottom board 10 and the internal foundation 30 are firmly integrated, At the same time, the external foundation 20 is formed.
This completes the construction of the foundation.

  A solid foundation construction method that can secure sufficient joint strength between the internal foundation and the bottom base, further improve productivity, improve workability on site, control construction costs, and shorten the construction period by standardizing the internal foundation and It has a solid foundation and has industrial applicability.

1 Solid foundation structure
10 Bottom
11 Bottom muscle
20 External foundation
30 Internal basics
40 Precast concrete components
41 Concrete body
42 legs
43 Longitudinal muscle
44 Leg
50 discarded concrete layer
60 Positioning bracket
61 plates
62 volts
63 volts
70 Concrete layer
80 excavated ground
81 Crushed stone crushing layer
82 Moisture-proof sheet

Claims (5)

In the construction method of a solid foundation comprising at least a concrete base, an external foundation and an internal foundation,
The precast concrete member constituting the internal foundation includes a concrete main body, at least two legs extending downward from the lower surface of the concrete main body, one end embedded in the concrete main body, and the other end A plurality of vertical bars extending downward from the lower surface of the concrete body portion and bending in the horizontal direction;
A first step of arranging a plurality of the precast concrete members without being connected to each other;
A second step of binding the longitudinal muscles and the floor muscles,
A solid foundation construction method comprising at least a third step of integrating the bottom plate and the internal foundation by placing concrete so that a lower portion of the concrete main body is filled.   2. The solid foundation construction method according to claim 1, further comprising a positioning step of adjusting a vertical height and inclination of the precast concrete member.   3. The solid foundation construction method according to claim 1, wherein the leg portion is made of concrete and is integrally formed with the concrete main body portion.   3. The solid foundation construction method according to claim 1, wherein the legs are made of metal. In a solid foundation with at least a concrete base, an external foundation and an internal foundation,
The precast concrete member constituting the internal foundation includes a concrete main body, at least two legs extending downward from the lower surface of the concrete main body, one end embedded in the concrete main body, and the other end A plurality of vertical bars extending downward from the lower surface of the concrete body portion and bending in the horizontal direction;
The plurality of precast concrete members are arranged without being connected to each other,
The longitudinal muscle is tied to the floor muscle,
A solid foundation structure characterized in that the bottom plate and the internal foundation are integrated by a concrete layer having a thickness sufficient to fill a lower portion of the concrete main body.

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