JPH0361810B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a construction method for constructing a basement floor of a building or the like.

To explain in more detail, when constructing multiple underground floors, multiple underground columns are constructed, formwork for the first basement floor is provided in the area surrounded by these underground columns, and concrete is poured into this formwork. By repeating the process of excavating the ground below, installing formwork for the lower basement floor, and pouring concrete into this formwork, the structure is supported by underground pillars. This invention relates to a construction method called the so-called reverse construction method, in which multiple underground floors are built sequentially from top to bottom.

[Conventional technology]

Conventionally, in the above-mentioned reverse construction method, each basement floor has been constructed using the following method.

In other words, as shown in Figure 6, after excavating the ground corresponding to a certain basement floor,
Pipe support 24 as formwork shoring on BL
The pipe supports 24 support the floor slab and beam formwork 25 consisting of plywood boards 25a as weir plates, joists, steel pipe ends 25b as extensions, etc., and the floor reinforcement arrangement is completed. After this formwork 2
Concrete 26 is placed inside 5 (there is no specific literature). In the figure, 1 is a continuous retaining wall;
25c is a formwork for a column whose lower part is V-shaped.

However, the conventional method described above has the following problems, and there is room for improvement.

First, since the formwork 25 for floors and beams and the concrete poured into the formwork 25 are supported by the pipe supports 24, until this concrete develops sufficient strength (usually for 28 days), This support cannot be removed, and therefore, excavation of the part corresponding to the next basement floor cannot be started immediately after concrete is poured.

In addition, if the root cut bottom surface BL is soft, subsidence will occur if only the pipe support 24 is used, so a concrete plate 27 for reinforcement is placed on the root cut bottom surface BL.
It is necessary to install a ground or improve the ground. Therefore, in the former case, the concrete slab 27 must be further destroyed after the formwork support is removed before excavation, and in the latter case, special construction is required and costs are high.

Therefore, overall, there was a risk that the construction period for constructing the basement floor would be unduly extended and the construction cost would increase.

[Problem that the invention seeks to solve]

In view of the above-mentioned circumstances, an object of the present invention is to shorten the construction period when constructing a basement floor using the reverse construction method.

[Means for solving problems]

The feature of the basement floor construction method according to the present invention is that a plurality of basement floors are constructed through the following steps.

(A) Construct multiple underground pillars.

(B) From those underground columns, via a hanging mechanism,
Hang and secure the formwork for the first basement floor.

(C) Pour concrete into this formwork.

(D) After pouring concrete, excavate the ground below the formwork.

(E) Extend the suspension mechanism to the next basement floor and suspend and secure the formwork at that floor.

(F) Pour concrete into this formwork.

(G) By repeating the steps (D) to (F) above, multiple underground floors are constructed sequentially from above to below.

The effects of the above characteristic method are as follows.

[Effect]

In other words, the formwork for constructing each basement floor is suspended and supported from underground pillars, so even if the strength of the concrete has not yet reached the design standard strength after pouring, The ground below the formwork, corresponding to the next basement floor, can be excavated and the next process can proceed. Moreover, even if the bottom surface of the root cut after excavation is soft, it is possible to support the formwork of the upper floor without the need for any special measures.

Furthermore, if the strength of the concrete on the upper floor was developed at approximately the same time as or before the completion of excavation on the lower floor, the formwork used to construct the upper basement floor may be damaged as the suspension mechanism is extended. It can be lowered and used for constructing the basement floor below.

〔Effect of the invention〕

As a result, when constructing a basement floor using the reverse pouring method, when excavating the portion corresponding to each basement floor, it was necessary to wait for the concrete strength of the upper floor to develop, which was previously required, and to remove formwork supports. There is no need to install or remove a reinforcing concrete plate for the cut bottom surface, which makes it possible to significantly shorten the construction period.

In addition, as mentioned above, if the scale of the building increases to a certain extent and it is possible to reuse formwork for floor slabs and beams, it will be possible to reduce costs, and it will also be possible to reduce costs in narrow spaces with poor working conditions. Assembling and dismantling the formwork and formwork supports can be reduced, and work efficiency can be improved.

〔Example〕

EMBODIMENT OF THE INVENTION Below, based on drawings, the Example of the construction method of several basement floors by this invention is demonstrated step by step.

(b) Construct a continuous retaining wall 1 around the planned building site. A plurality of piles 2 are constructed inside the retaining wall 1. Each pile 2 is obtained by drilling a vertical hole 3 in the ground using an earth auger or the like, and injecting cement milk into the vertical hole 3 to almost the same level as the base of the building to be constructed. . Then, the subway pillars 4a are built into the vertical holes 3 on the inner periphery, and the lower ends of the pillars 4a are inserted into the upper ends of the piles 2 where the cement milk has not hardened yet, and each subway pillar 4a is , and hold it in a state where its upper end protrudes above the ground level GL to harden the cement milk (first
(See Figure A).

(b) Excavate the part of the ground surrounded by retaining wall 1 that corresponds to the first basement floor. Regarding the outer peripheral part close to the retaining wall 1, a steel column 4b is placed on the bracket 5 fixed to the inner peripheral surface of the retaining wall 1 at a position corresponding to the upper part of each vertical hole 3, and the steel frame at the inner peripheral part is Like the pillar 4a, it is fixed so that it protrudes above the ground level GL at its upper end.
Then, the steel girders 6x, 6y connecting the subway frame columns 4a, 4b are attached, and the bolts are fully tightened. A bracket 7 is attached in advance to the top of each steel frame column 4a, 4b, and supports 15 for the formwork of the first basement floor are suspended via jacks 8 and rods 9 fixed on the bracket 7. (See Figure 1B).

As shown in FIGS. 3 to 5, on each bracket 7 is a support base 1 made of a pair of C-shaped steel.
1 are placed back to back with an interval slightly wider than the diameter of the rod 9, and are welded to the bracket 7. One center hole jack 8 is fixed to each end of the support stand 11,
Through the gap between both C-beams, the upper and lower parts of jack 8
The rod 9 held between the two rams is extended downward. A support fitting 12 consisting of a pair of C-beams placed back to back is fitted onto the lower end of the rod 9, and is fixed by tightening from above and below with a nut 13 fitted onto the rod 9. Then, form support beams 14 made of a pair of shaped steels extending in the direction between the beams are erected over the upper parts of the supporting metal fittings 12 suspended from adjacent subway pillars, with the rods 9 sandwiched between the two shaped steels. Then, this formwork support beam 1
4, a support 15 for the formwork of the floor slab and beams is erected. Each support 15 includes a pair of large support beams 15a made of H-shaped steel extending between adjacent formwork support beams 14, and a plurality of telescopic steel combination girders extending between the two large support beams 15a. (Peco Beam)
A large pull 15b consisting of, and this large pull 15b
It is composed of steel pipe joists 15c placed on top, and these large support beams 15a, large support beams 15b, and joists 15c are assembled in advance and integrated on the ground surface within the site. Then, on this support body 15, a plywood board 16 which becomes a weir plate of the floor slab formwork 10F is spread.

On the other hand, as shown in FIG. Supports 17 are strung across the bridge at appropriate intervals, and the supports 1
7, a concrete girder formwork 10 Gy is assembled to cover the steel girder 6y in the inter-beam direction.
As shown in FIG. 5, in the direction (girder row direction) where there are no formwork support beams 14 on both sides of the steel beam 6x,
Z-shaped brackets 18 are suspended at appropriate intervals from the flanges of the H-beams that are the large support beams 15a, and the steel beams 6x in the girder direction are suspended on the supports 17 that span between the brackets 18. Assemble formwork 10Gx for the concrete girders to be covered.
As shown in FIG. 5, the formwork 10B of the small beam made of reinforced concrete, which is spanned in the girder row direction, is constructed of a pair of H-shaped steel beams, which are large support beams 15a, located near the formwork 10B of the small beam. Supports 1 spanned at appropriate intervals over the upper part of the flange of
7 Assemble on top. The concrete column formwork 10C covering each subway frame column 4a, 4b is the fourth
As shown in the figure, the lower surface is formed into a V-shape in side view for later pouring, and this formwork 10
C is suspended and supported from the subway bone column 4a.
Regarding the outer periphery, as shown in Figure 4, the formwork of the columns and girders 10C, 10Gx, 10Gy
are suspended from the steel columns 4b and the steel girders 6x, 6y with their downward slopes, and a concrete portion 19a that is integrated with the floor slab and girder is placed on top of the continuous peak retaining wall 1 to form a continuous peak. The outer periphery is supported by the stopper wall 1. And the above girder formwork 10Gx,
10Gy, small beam formwork 10B and column formwork 10C,
Each is connected and fixed to the floor slab formwork 10F. After this, the reinforcement for columns, beams, and floors, as well as the embedded piping for each facility, are completed, and the concrete 19 for this floor is poured.

(c) After concrete was poured, the column formwork 10C, which had been left for 4 to 6 days for curing, was dismantled and removed;
Floor slab and beam formwork still in place 10F, 10
The next underground floor will be excavated below G and 10B (see Figure 1 C). The excavated earth and sand is carried out to the outside through a temporary opening 20 formed in a part of the floor slab, as shown in FIGS. 1C and 2.

(d) After the excavation is completed, add the steel columns 4b on the outer periphery downward, attach the girders connecting each steel column 4a and 4b, and fully tighten the bolts. When the concrete 19 on the upper floor that was poured earlier reaches the design standard strength, the formwork 1 used for pouring concrete on this floor
0F, 10G, 10B, 10C and their supports 15 are suspended, fixed at the next underground floor position, and concrete is poured into the formworks 10F, 10G, 10B, 10C (see Figure 1 D). .

Formwork 10F, 10G, 10B, 10 mentioned above
When lowering C and the support body 15, first, each center hole jack 8 is driven to lower the rod 9 slightly. In this state, each girder formwork 1
Dismantle and remove 0G. Then, add a new rod 9 by screwing it into the upper end of each rod 9 via a coupler, and feed this extended rod 9 downward while alternately pinching it with the ram of the jack 8. Both the formwork support beam 14 and the support body 15 supported by the rod 9 are lowered to the next underground floor position. Rod 9
The length of one rod is approximately equal to the height of one basement floor (approximately 3.5 m), so that it is sufficient to add one new rod 9 to lower the height one basement floor. It's getting old. On the next basement floor, the formwork of each beam is 10Gx, as in the basement floor above.
10Gy, 10B and the formwork 10C for each column are assembled, plywood boards 16 are laid on each support 15 as a weir board for the floor slab formwork 10F, and connected and fixed to the formwork 10Gx, 10Gy, 10B, 10C for each beam and column. do. After that, reinforcement and equipment piping were done, and this formwork 10Gx, 10Gy, 10B, 10
Concrete is poured into C.

(e) By repeating the steps (c) and (d) above, multiple underground floors are constructed sequentially from top to bottom (see Figure 1, e). In addition, 22 in Figure 1,
It is a backing member installed as necessary to bear the earth pressure during foundation construction.

(f) Bottom floor slab 21 in the bottom basement part
and the foundation 23, and the retaining members 22 are removed to complete the construction of the plurality of underground floors (see Fig. 1).

When constructing each basement floor, for example, the pillars that make up the second basement floor are generally referred to as the second basement floor columns.
The beams and floor slabs between the second basement floor and the first basement floor are generally referred to as the first basement floor beam and the first basement floor slab, respectively, but in this specification, these two
Since the story columns, the beams on the first basement floor, and the first basement floor are cast in concrete, the formwork used for pouring concrete is called the formwork for the second basement floor. Therefore, the formwork used for pouring concrete for the columns, beams, and floor slabs that make up a certain basement floor is referred to as the formwork 10 for that floor.

To suspend and support the formwork 10 on each basement floor, instead of supporting the support 15 on which the formwork 10 is placed by a combination of jacks 8 and wires 9, a combination of winches and wires is used. may also be used, and they are referred to as hanging mechanisms H.

Instead of forming each support body 15 integrally in advance, it may be assembled and disassembled at a predetermined location underground each time concrete is poured. In addition, the shape of each support 15 and the material used,
Alternatively, the specific dimensions and the like can be changed as appropriate.

Furthermore, if the ceiling level of the first basement floor, that is, the floor level of the first floor, is relatively higher than the ground surface level GL, the step of excavating the first basement floor part described in the above embodiment may be omitted. .

The present invention may be applied to a reinforced concrete building in addition to the steel-framed reinforced concrete structure described in the previous embodiment, and in that case, the subway frame columns 4a and 4b in the previous embodiment may be replaced. hand,
It is sufficient to provide pillars called structural pillars for supporting the weight of the main body, and these are referred to as underground pillars 4.

[Brief explanation of drawings]

Figures 1 to 5 show an embodiment of the basement floor construction method according to the present invention, Figure 1 A to F are sectional views showing the construction process of the basement floor, and Figure 2 is the first floor of the building. A partial plan view, Figure 3 is an enlarged plan view of the main part, Figure 4 is a sectional view taken along the - line in Figure 3, Figure 5 is a
It is a - line sectional view in a figure. FIG. 6 is a sectional view corresponding to FIG. 4 showing a conventional example. 4... Underground pillar, 8... Jacket, 9... Rod, 10... Formwork, H... Hanging mechanism.

Claims (1)

[Claims] 1. An implementation method for constructing a plurality of underground floors through the following steps. (A) Build multiple underground pillars 4. (B) The formwork 10 for the first basement floor is suspended and fixed from the underground pillar 4 via the hanging mechanism H. (C) Concrete is poured into this formwork 10. (D) After concrete placement, excavate the ground below the formwork 10. (E) The suspension mechanism H is extended to the next basement floor, and the formwork 10 on that floor is suspended and fixed. (F) Concrete is poured into this formwork 10. (G) By repeating the steps (D) to (F) above, multiple underground floors are constructed sequentially from above to below. 2. Claim 1, wherein the hanging mechanism H includes a jack 8 provided at the top of the underground pillar 4, and a rod 9 held between the jack 8.
Construction methods for basement floors as described in section. 3. The underground floor construction method according to claim 1 or 2, wherein the underground column 4 is a structural column in a steel-framed reinforced concrete building.