JPH02261196A - Concrete placing method - Google Patents

Abstract

PURPOSE:To reduce a mold frame in its size by providing a device to vacuum- dehydrate concrete not yet hardened and a device to press at least one mold frame against concrete. CONSTITUTION:A propulsion jack 3, a rod 4 and a press ring 11 are provided. Then, an inner mold frame 15, a porous filter 16 whose surface is covered with a cotton cloth 17 on the outer peripheral surface of the mold frame 15, and a packing 18 are provided, with the press ring 11 and a lining 13 used as end frames. Further, a concrete supply tube 20 and multiple suction pipes 21 are attached to the mold frame 15. With this arrangement, concrete is placed with the concrete tube 20 and the suction pipes 21 connected to a concrete pressure-feed device and a vacuum pump, respectively. Concrete is then pressed by a pressing mold frame and a vacuum-dehydration mold frame. These process cause a reduced size of the mold frame.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for pouring concrete into a space formed by formwork.

[Conventional technology]

Conventionally, as one aspect of the shield construction method, a cast-in-place lining construction method that does not use segments has been proposed.

In this cast-in-place lining construction method, reinforcing bars, inner formwork, and end formwork are generally assembled along the inner peripheral surface of the shield tail, and concrete is poured and filled into the space formed by these formworks. The jerking thrust of the shield machine, etc. is applied to the gable formwork.

Therefore, unhardened concrete is pressed and moved to the gable formwork, and the o-to-cut part of the shield machine,
Fills tail voids to prevent ground collapse and subsidence. Additionally, by pressing with the gable formwork, unnecessary water for hardening is pushed out of the concrete, reducing the water-cement ratio and increasing the strength of the concrete.

[Invention or problem to be solved]

However, in this construction method, by pressing the concrete, the inner formwork is pressed with a large force toward the center of the tunnel. Therefore, the inner formwork is required to be resistant to deformation, resulting in an increase in size.

In addition, water pushed out of the concrete may flow into the tunnel or into the ground, damaging the existing concrete lining.
Sushi requires a lot of effort to clean, and it damages the natural environment.

[Means to solve the problem]

The purpose of the present invention is to solve these problems and provide a method for placing concrete that can reduce the size of the 411 frame and maintain a clean environment by recovering water pushed out of the concrete. This was done as a.

The concrete pouring method of the present invention involves pouring concrete into a space formed by formwork of Pg number, vacuum dehydrating moisture in the unhardened concrete at the concrete contact area of at least one formwork, and at least A formwork is pressed into concrete.

In addition, the pressing force of the concrete is the propulsive reaction force of the shield machine,
Alternatively, the supporting force may be obtained from the supporting force of another formwork.

[Effect]

According to the concrete placing method, Conc J-1.
The concrete is shaken by the formwork that suppresses it.

Construction of the tunnel 10 will be explained.

When propulsion/excavation for a predetermined distance is completed, the rod 4 of the propulsion jack 3 is pulled in the direction of arrow a. At this time, rod 4
An annular press ring 11 provided at the tip of the main body 2 also moves in the direction of arrow a along the inner surface of the main body 2.

Next, the rear part of the main body (hereinafter referred to as "Shield Tail J")
In Step 12, reinforcing bars are assembled along the inner circumferential surface of the shield tail 12 between the press ring 11 and the lining 13 that has already been constructed, and an inner formwork I5 is formed using the press ring 11 and the lining 13 as the end formwork. assemble. As shown in FIG. 2, a porous filter 16 is disposed on the outer peripheral surface of the inner formwork 15 (the surface that comes into contact with concrete to be poured), and the surface of the filter 16 is covered with real cotton cloth 1.
Covered by 7. Furthermore, a concrete supply pipe 20 and a plurality of suction vibrators 21 are attached to the inner formwork. Furthermore, the inner formwork 15, press ring 11, and existing lining 1
3, the water that is not needed for hardening is forced out of the concrete and the water-cement ratio decreases. The water pushed out of the concrete is vacuum dehydrated and is pressed against the formwork or concrete on the vacuum dewatering surface, and the concrete is pressed.

That is, concrete is pressed using a pressing form and a vacuum dewatering form.

〔Example〕

Embodiments embodying the present invention will be described below with reference to the accompanying drawings.

In FIG. 1, 1 is a /-held machine. shield machine 1
is equipped with a plurality of propulsion jacks 3 inside a cylindrical body 2,
The propulsion jack 3 provides forward thrust (in the direction of arrow a). Further, the shielding machine 1 is equipped with a cutter 5 on the front part, and the cutter 5 is rotationally driven by a motor (not shown), and the cutter 5 is rotated by a motor (not shown) to cut the ground.
Or excavated. The excavated sand is collected into the main body 2 by the scraping conveyor 7 and is appropriately discharged outside the mine to the IIF.

A tunnel 10 is constructed 18 in the excavation trace of the shield machine 1.

Next, the concrete supply pipe 20 is connected to the concrete feeder 1 and the pressure feeding device (not shown), the suction pipe 21 is connected to the vacuum pump (not shown), and the inner formwork 15, press ring 11,
A space 22 surrounded by the existing lining 13 and the shield tail 12 or the ground 6 is filled with concrete 23 by being force-fed from the concrete supply pipe 20.

Then, the rod 4 of the propulsion jack 3 is extended in the direction opposite to the direction of the arrow a, and the shielding machine 1 is propelled while pressing the filled concrete 23, which has not hardened yet, via the press ring 11, and the vacuum pump is driven.

As a result, the concrete 23 flows and the shield machine 1
The tail voids and overcut portions of the concrete 23 are filled with water, and the water is pushed out of the concrete 23, resulting in a decrease in the water-cement I ratio.

Further, breathing water and the like that do not contribute to the hardening of the concrete 23 are sucked and collected by the vacuum pump through the cotton cloth 17 and the filter 16. At the same time, the inner formwork 15 is pressed against the concrete 23 by the negative pressure generated inside the filter I6. That is, the concrete 23 is pressed by the inner formwork J5 and the press ring 11.

Therefore, the concrete 23 becomes dense and impermeable to water. In addition, since the cement paste moves to the surface of the concrete 23, no coarse aggregate is exposed on the concrete surface, and since the air in the surface layer is sucked into the vacuum pump, no air bubbles remain on the concrete surface, and the lining The surface becomes beautiful. Furthermore, the strength of the concrete 23 is increased by reducing the water-cement ratio, making it possible to obtain a highly durable lining. Furthermore, breathing water, etc. leaked from the gaps in the formwork and caused damage to the existing lining 1.
It doesn't pollute 3. Since the inner formwork I5 receives a force directed toward the concrete 23, it is not required to have high strength and can be simplified.

The following is an experiment regarding the change in strength when concrete filled in a formwork is compressed and vacuum dehydrated.Unit amount of cement...1.1.4. kg water-cement ratio: 52°0% Slump: 18cm Fine aggregate ratio: 45.9% 7th day of specimens A and H prepared as described above.
The compressive strength after 28 days (σ7.σ3.) and the strength increase rate ασ7 of specimen A relative to specimen B were determined. Conclusion 4! : is shown in the table below.

σ7 328 227
Good σ, 8377 294
28 Also, the density of specimen A is 2.35 and that of specimen B is 2.35.
．． 30, the specimen according to the present invention has a higher density.
)Ta.

From the above, when the concrete in the formwork is compressed and vacuum dewatered, the concrete becomes denser, the water-cement ratio decreases, and the compressive strength increases.

Figure 3 shows the formwork used in the experiment. The formwork 30 is the side frame 3
1. Consists of a bottom frame 32 and a pressing form 36.

For the side frame 31, a cylindrical body having an inner diameter (D) of −150 mm was used.

The bottom frame 32 has a wire mesh 33 on its side and a filter paper 3 on top of it.
4 was provided, and a vacuum pipe 35 was connected under the wire mesh 33.

'' A part of the pressing formwork 36 was formed into a disk shape that could be moved along the inner surface of the side frame 31.

The formwork 30 is filled with concrete 37, and the press formwork 3
6 was pressed with a force of 2 kg/cm2, and the water in the concrete 37 was suctioned and dehydrated for 1 hour at a pressure of 2 Q mm11 g through a vacuum pipe 35, thereby creating a specimen A having a height (I() = 30 Q mm).

At the same time, as a comparative example, a specimen B was created using a mold 30 of the same size without compressing or vacuum dehydrating the concrete 1)-1-37.

The mix of concrete 37 from which specimens A and B were made is as follows.

Nominal strength: -300kg/am' Unit water volume: 187kg. In particular, it can be seen that the initial strength increase is large and that mold removal can be carried out at an early stage.

Although the present invention has been described above for placing cast-in-place lining concrete for shield lining, it is also applicable to methods of constructing structures by continuously pouring concrete, for example. The present invention can also be applied to the Devidark construction method.

〔Effect of the invention〕

As is clear from the following explanation, according to the concrete strengthening method according to the present invention, the concrete is pressed by a formwork that pressurizes the concrete, and the formwork on the vacuum dewatering surface is pressed against the concrete. Therefore, the concrete becomes dense. In addition, unnecessary breathing, etc. for concrete hardening is removed, increasing the water-cement ratio. Therefore, the strength of concrete increases significantly. In particular, since the initial strength is increased, the formwork can be removed early and construction of the next span can be started, shortening the overall construction period. It also improves the water impermeability of concrete.

Vacuum dewatering removes the air in the cement paste on the concrete surface, leaving the concrete looking clean.

111. The water dehydrated from the concrete is sucked and collected by a vacuum pump, etc., so it does not contaminate the existing concrete.

11. If the pressing force of the concrete is obtained from the propulsive reaction force of the shield machine or the supporting force of the formwork of the structure to be constructed next, the pressing force of the concrete can be easily assured (1
can be constructed.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of the lead and tunnel, FIG. 2 is a partial cross-sectional view of the cast-in-place lining, and FIG. 3 is a cross-sectional view of the formwork used in the experiment. 1. Shield machine, 2. Main body, 3. Propulsion jack, 1
0-1-Failure, 1 Doble ring, 12・Seal tail, 13・Existing lining, 15・・Inner formwork, 16
・Filter, 17・・Genuine cotton cloth, 18・Packkin, 20
・Concrete supply pipe, 21. Suction pipe, 22.. Space, 23. Concrete.

Claims (2)

[Claims] (1) Concrete is poured into a space formed by multiple formworks, moisture in the unhardened concrete is vacuum-dehydrated at the concrete contact area of at least one formwork, and at least one formwork is pressed against the concrete. A concrete placing method characterized by: (2) Propulsion reaction force of the shield machine to reduce the pressing force of the concrete,
2. The method of placing concrete according to claim 1, wherein the concrete is obtained from the supporting force of another formwork.