JPH0452375A - Method for constructing subsequent placing member in construction method of reverse placing - Google Patents

Abstract

PURPOSE:To enhance the workability, safety, and efficiency by constructing concrete placing of a subsequent placing member by means of press-in of concrete from the lower portion of a mold. CONSTITUTION:A mold tie-in jig 15 having a nonreturn valve mechanism is interposed in the end of a hose 2 and concrete is placed from the lower portion of a mold using the hose 2. As a result, air that tends to be contained in the concrete is also pushed out toward the upper portion of the mold and the concrete is raised while in a uniformly mixed state wherein separation of aggregates does not occur. Dense, strong, and durable concrete can thus be placed without leaving any hollow portion and can also be finished in such a manner that only a protrusion which can be easily hoisted is left.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a method for constructing a post-cast member in a reverse casting method.

``Conventional technology'' The reverse construction method does not involve cutting out or restoring temporary members (mounting retaining members) that support retaining walls, but instead involves excavating and constructing the floor slab-1 beams and columns for the underground framework. This is a construction method in which the excavation is carried out one after another while applying the burden of water pressure.

This construction method uses the beams and floor slabs of the underground structure as retaining members, so less stress is generated compared to other construction methods.Also, the first floor floor is constructed first, and the head of the retaining wall is fixed. Therefore, the amount of deformation during the root pruning period is relatively small. The first-floor floor slab can be used as a work floor from an early stage, and the construction period is shortened because the ground floor and basement floor are constructed at the same time. Therefore, columns, walls, etc. that are not used as retaining members are constructed as post-cast members after the basement floor slab is constructed. The construction mode is as shown in Fig. 2.3.

That is, in FIG. 2, a hose 2 for concrete pouring is opened from the upper end of a formwork 1 such as a wall with a jaw 3 extending diagonally upward so that it can be inserted and air removed, and the concrete pouring hose 2 is opened from the upper end of a formwork 1 such as a wall. This is a case where the hose 2 is inserted and concrete 4 is poured.

On the other hand, in Fig. 3, an upper floor slab 5
This is a case where a sleeve 6 for concrete pouring is attached through the sleeve 6 and the concrete 4 is poured through the sleeve 6.

Incidentally, for post-casting on the floor of the slab 5, which corresponds to the first basement floor, as shown in the figure, a sleeve 9 is inserted through the pipe 8 hanging down from the first floor slab 7, and a sleeve 9 is inserted through the sleeve 9. Sometimes it is set up. This is because the walls have not yet been constructed on the first floor, so it is possible to penetrate through the wall thickness of the lower floor.

The after-stroke shown in Fig. 3 above is done under the condition that the upper end is closed with the katana 8, so like the chin extension 3 mentioned above,
Air ventilation must be ensured at the upper end of the formwork 1, such as a wall.

Figures 4a-d show these various air venting means. That is, the wall formwork 1 that abuts the lower end surface of the beam 8 is spaced at a predetermined gap (1
(a)
. A formwork 1 such as a wall is set so as to be shifted forward by a predetermined gap (about 10 m) from the tip end surface of the katana 8, and a slit 11 is interposed therebetween (b). A group of 16 through holes having a predetermined diameter (approximately 10 to 18 mm) are bored in the upper end of the formwork 1, such as a wall that abuts the lower end surface of the casing 8 (c). Decompression pipes 12 are installed at predetermined intervals at the upper end of the formwork 1, such as a wall that abuts the lower end surface of the casing 8 (d).

"Problems to be Solved by the Invention" In conventional post-casting, in the case shown in Figure 2, jaw forms must be installed, and scaffolding 13 is also required when pouring concrete. Not this scaffolding 13
It has to withstand the hard work of supporting the hose 2 on top. Furthermore, after removing the formwork l, the concavities of the jaws protruded in a row as shown in Figure 5! I-) There is a hassle of having to fold 14.

Incidentally, the folding of this jaw part is shown in Figures 6a and b,
If the floor slab 5 etc. on the upper floor is not a flat slab and there is a sufficient distance between the lower end of the floor 8 and the floor slab 5, there is no problem with (a), but if it is a flat slab and there is sufficient space. If the distance cannot be secured (b), the head gets stuck and the person is forced to take an awkward posture, which is both dangerous and inefficient. This situation is the same when concrete is poured as shown in FIG.

In the case of Fig. 3, the sleeve 6.9 after concrete pouring
There are some troubles such as having to remove the sleeve, making it extremely difficult to insert the sleeve, and having to fill in the hole where the sleeve was removed. Furthermore, in any case,
Since concrete is poured from above, the free fall height of the concrete becomes large, and the concrete is likely to collide with obstacles such as reinforcing bars during the fall, causing aggregate separation of the concrete.
This effect is particularly likely to occur when the floor height is high or when reinforcing bars are placed with a concave inspection.In addition, the air entrained when concrete falls can cause junk and large air bubbles to form in the poured concrete. There are problems such as:

The present invention is useful for supporting concrete pouring hoses on unstable scaffolding, for severe work such as jaw grinding, for concrete pouring through sleeves, and for pouring concrete from above. It is an object of the present invention to provide a method for constructing a post-cast member that eliminates all the inconveniences caused by.

"Another Means to Solve the Problem" In order to achieve the above object, in the construction method of the present invention, concrete is poured into the post-cast member by press-fitting the concrete from the lower part of the formwork.

``Operation'' If the method for constructing the post-cast member configured as described above is used, all the problems that occur when concrete is poured from above, as described above, are solved. In other words, the construction method in which concrete is pressed in from the bottom instead of from above is known as the sequential pouring method and was developed in Japanese Patent Application Laid-Open No. 56-93.
This method has been proposed in Japanese Patent Publication No. 974, Japanese Patent Application Laid-Open No. 64-62555, etc., but by press-fitting concrete from the bottom in this way, it is possible to pour concrete continuously without entraining air, and it is possible to cover the press-in range. Concrete is placed under pressure due to the pressure from the concrete pumping device and its own weight, so any air that would otherwise be contained inside the concrete is forced upwards, so no hollow space remains in the middle of the concrete. Dense, strong, and durable concrete is poured, and the concrete rises in an evenly mixed state with no aggregate separation, so there are no obstacles such as reinforcing bars, and the internal structure of the concrete due to differences in specific gravity is eliminated. It is possible to form concrete walls, etc. with average strength without any change in quality.

Furthermore, since the concrete pouring hose 2 is connected to the lower part of the formwork 1 such as a wall, the hose 2 is supported on unstable scaffolding, jaws are generated, and concrete pouring through the sleeve is difficult. All the essential points will be lost.

"Example" An example will be described with reference to the drawings. In FIG. 1, a concrete casting hose 2 is connected to the lower part of a formwork 1.

Unlike when concrete is poured from above, the hose 2 will be subjected to the pressure of the poured concrete, so a jig 15 for connecting to the formwork should be interposed at the tip of the hose 2. At the same time, it is necessary to ensure that the jig 15 etc. has a non-return valve mechanism to prevent the backflow of the press-fitted concrete.

For example, in the method proposed in the above-mentioned publication, an injection port metal fitting equipped with an on-off valve is attached to the outside of a connecting hole bored in the lower part of the formwork, and the tip of the concrete hose 2 is connected to this.

The fact that the upper end of the formwork 1 is blocked by the beam 8 remains an obstacle even when pouring from the lower part, and the measures listed in Figures 4a-d are taken in the same way. .

As a result, concrete can be placed in the post-cast member without causing problems such as separation of concrete aggregates, formation of junks, and generation of air bubbles. Further, when pouring concrete, the scaffolding 13 is not required, there are no jaws, and there is no troublesome sleeve.

"Effects of the Invention" Since the present invention is configured as described above, it produces the effects described below.

(1) The formwork can be the same as before (no jaw formwork).

(2) Scaffolding is no longer required when pouring concrete;
It's safe.

(3) The opening that must be secured at the top of the formwork is not for inserting a hose for concrete placement, but is a small opening for venting air, so there is less spillage of concrete, and the finish folding can be done easily using the projections. Only that remains.

(4) There are no jaws and there is no need to sharpen the jaws, so there is no need for troublesome repairs.

(5) By making the poured concrete non-settling (no volume change), there is no need for grouting at the joints, resulting in labor savings.

(6) Separation of concrete materials and the introduction of a large amount of air are extremely reduced.

[Brief Description of the Drawings] Fig. 1 is an explanatory diagram of the method of the present invention, Figs. 2 and 3 are explanatory diagrams of the conventional method, Fig. 4 a % d are explanatory diagrams of each side of the air venting means in the formwork, Figure 5 is an explanatory diagram of the jaw, Figure 6a,
b is an explanatory diagram of jaw polishing work. 1...Formwork, 2...Hose for concrete placement, 3...Jaw extension, 4...Concrete,
5...Upper floor slab, 6...Sleeve, 7
・9.1st floor slab, 8...beam, 9...sleeve, 1o...slit, 11...slit,
12... pressure reducing pipe, 13... scaffolding, concrete,
15...Jig, 16...Through hole. 14... Brush 7 So 2 --- Con 7 Lit j 1 Choral - Cho 1 Su 5 --- Above? 7
Tokosurazu 8-'J! 9 12-Li 1c+ 13 16-, l) L Do type rod 4---Con 7+1-Door 1? 1 special slot 11-m-slit 15--shishako (3---Ako'tshi6---three-zu' three 7゛ 1o-11 slit

Claims (1)

[Claims] (1) A method for constructing a post-cast member in a reverse casting method, characterized in that concrete is poured into the post-cast member from the bottom of the formwork.