JPS61172997A - Method of lining shielding tunnel and formwork device used for said method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a shield tunnel lining method and a formwork device used therein.

Conventionally, when constructing tunnel lining using the shield method, ready-made segments were assembled in the tail section of the shield machine, lining was done, and the shield was excavated, but because ready-made segments were expensive and heavy, Transportation and assembly from the factory to the site required time and effort.

Furthermore, in this case, the quality of backfill injection into the Cheelmoid area has a large effect on the subsidence of the ground surface, and careful construction is required. These are considered to be bottlenecks in reducing the construction costs of shield tunnels.
As a solution to this problem, a lining method using cast-in-place concrete has been devised, but in this construction method, the entire earth load acts on the cast-in-place concrete lining immediately after the concrete formwork is removed, so it can cope with this problem. Since the formwork must be left in place until concrete with the strength of For example, in the case of a conventional shield construction method using cast-in-place concrete lining, several tens of rings of formwork are required. Furthermore, this type of formwork has a high-strength structure that can withstand the force that compresses the concrete due to the reaction force of the propulsion jack, so it is very expensive.

This invention was made to solve the problems of the conventional method using cast-in-place concrete as described above, and it allows concrete to harden quickly, and requires fewer formworks for construction. The purpose of the present invention is to provide a shield tunnel lining method that can be constructed quickly and at low cost, and a formwork device used therein.

Generally, the minimum amount of water required to harden concrete is considered to be around 25% water-cement ratio (W/C), but due to workability issues, a water-cement ratio higher than necessary is generally used, around 55%. to obtain the necessary softness for construction. This excess water that does not contribute to the hardening (water conservation) effect in the concrete not only reduces the strength and durability of the concrete, but also acts only on unfavorable aspects. Conversely, concrete with such a high water-cement ratio is pressurized,
Dehydration increases the curing speed and significantly increases the initial compressive strength and initial bending strength.

This invention focuses on the fact that the properties of concrete are improved by pressurizing and dewatering it as described above, and by providing a large number of dewatering holes in the formwork. The lining method is characterized by sucking and dewatering excess water in concrete through dewatering holes.

According to the method of this invention, excess moisture in concrete is removed, and at the same time, air is also removed, which not only accelerates the hardening of concrete but also provides a high-strength and high-quality concrete lining. By accelerating curing, it becomes possible to reduce the number of molds to 14 to 1/4 of the conventional number.

The formwork device of the present invention used in carrying out the above method consists of a hollow box having inner and outer circumferential plates spaced apart from each other and side plates around the outer circumferential plates, and a large number of dewatering holes are provided in the outer circumferential plate, It is characterized by comprising a formwork with a filter attached to the inner surface of the outer circumferential plate, and a suction member connected to the formwork to suck air inside the formwork.

According to the formwork lid of this invention, the formwork is made of a hollow box and the suction member is connected to it, so the inside of the formwork becomes a vacuum chamber, and therefore vacuum pressure is applied equally to each dehydration hole. Excess moisture can be evenly sucked out and a homogeneous concrete lining can be constructed.

An embodiment shown in the drawings will be described below.

Figure 1 shows the state in which the shield machine 2 has dug into the ground 1 by a unit excavation length (the length of one ring of the normal formwork), and then the rod of the propulsion jack 14 is moved as shown in Figure 2. The formwork 4 is assembled by shrinking it and connecting it to the formwork 4' assembled in the previous operation inside the tail part 3. These formwork 4
4' is divided into a plurality of blocks along the circumferential direction of the shield machine 2.

As shown in detail in FIG. 3, the formwork 4 consists of a hollow box having inner and outer circumferential plates 5m, 5b spaced apart from each other and side plates 6 around them, and a large number of dewatering holes 7 are provided in the outer circumferential plate 5b. A filter cloth 8 and a wire mesh 9 are sequentially attached to the inner surface of the outer peripheral plate 5b. Inner peripheral plate 5a of formwork 4
A vacuum pump 18 is connected to the fc sex hose 10.
The ends are connected and open into the formwork 4. Further, a heater 11 (for example, a hot wire type) is arranged inside the formwork 4. A press ring 12 constituting the end frame part is installed between the tail part 3 and the frame 4 via a sealing material 13 so as to be movable in the axial direction of the shielding machine.

When the assembly of the formwork 4 is completed as described above, the rond of the propulsion jack 14 is extended to press the press ring 13, and in this state, the gap formed by the tail part 3, the formwork 4, and the existing concrete lining 15' is Place concrete.

Concrete is placed by force-feeding the concrete using a concrete pump (not shown), and is carried out through the opening 12' at the top of the press ring 12 through the concrete placement pipe 16.
3 and 4), when pouring is completed, the concrete pouring opening 12' is closed by a shutter 17 attached to the connection between the press ring 12 and the concrete pouring pipe 16. After completion of pouring the concrete IJ-) 15, the propulsion jack 14 is extended to push the press ring 12, and the concrete 15 is used as a reaction force to propel the shield machine 2 and pressurize the concrete 15. At this time, the vacuum pump 18 makes the inside of the mold 4 evacuated through the suction hose 10, and the excess water and air bubbles in the compressed concrete IJ-t 15 are sucked through the dewatering holes 6. After shield machine 2 completes digging,
After completing the compression of the concrete 15 and suction of excess water, remove the suction hose 10 from the formwork 4, plug the plug 19 into its connection opening, and use the heater 11 inside the formwork 4 to remove the air inside. The concrete 15 is heated and cured by heating until it reaches a predetermined strength. By heating and curing with the heater 11 in this manner, the hardening of the concrete is further promoted in conjunction with the dehydration of excess water.

As described above, this invention compresses concrete using a propulsion jack and removes excess water and air bubbles from the concrete by suctioning it through dewatering holes provided in the formwork, thereby hardening the concrete early and increasing its This method has excellent effects such as being able to construct concrete lining with high strength and high quality, reducing the number of formworks, simplifying work, and reducing construction costs.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a longitudinal sectional front view showing the state of the shield machine after digging, FIG. 2 is a longitudinal sectional front view showing the concrete lining construction state following the first drawing, FIG. 3 is a detailed view of the formwork, FIG. 4 is a vertical cross-sectional side view of FIG. 2, and FIG. 5 is a cross-sectional plan view showing the concrete injection part. 1... Earth 2... Shield machine 3...
Tail portion 4, 4'...Formwork 5a...Inner circumferential plate 5b...Outer circumferential plate 6...Side plate
7... Dehydration hole 8... Filter cloth 9... Wire mesh 10... Suction hose 11... Heater 12.
...Press ring 14...Propulsion jack 15.
...conc')-'p5 Inning 15'...Existing concrete lining 18...Vacuum pump whistle 1, flame 2, figure 3

Claims (1)

[Claims] 1. After the shield machine is excavated, a formwork having an end frame part movable in the axial direction is placed inside the tail part of the shield machine, and this formwork and the tail part are connected to the existing structure. Concrete is poured into the gap surrounded by the concrete lining, the end frame is pressed by a jack for propelling the shield machine, and the reaction force is used to propel the shield machine,
In the shield tunnel lining method in which the poured concrete is pressurized, a large number of dewatering holes are provided in a portion of the formwork that is in contact with the inner circumferential surface of the poured concrete, and when the concrete is pressurized by the jack, the A lining method characterized by sucking and dewatering excess water in concrete through dewatering holes. 2. A formwork consisting of a hollow box having inner and outer circumferential plates spaced apart from each other and side plates around the outer circumferential plates, the outer circumferential plate having a large number of dewatering holes, and a filter attached to the inner surface of the outer circumferential plate. A formwork apparatus for use in the method according to claim 1, comprising: a suction member connected to the formwork to suck air inside the formwork.