JPS63233198A - Method of executing pc tunnel - 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 <Industrial Application Field> The present invention relates to a PC tunnel construction technique for constructing a tunnel frame by removing prestress.

<Conventional technology> The technology of constructing a tunnel by pouring concrete on-site using formwork immediately after excavation with a shield machine is widely known.

By the way, in order to prevent the collapse of the ground during construction, it is necessary to maintain the pressure of fresh concrete until the concrete hardens by applying a pressure that does not resist the collapse force of the hole wall.

As a means of applying and maintaining pressure on concrete, methods of construction using jack pressure or pumping pressure using a concrete pump are known.

Problems to be Solved by the Present Invention> The tunnel construction techniques described above have the following problems.

(a) Demolding work cannot be performed at all until the lining concrete has hardened.

Other work must be suspended until the concrete hardens, prolonging the construction period.

(b) In order to shorten the hardening time of concrete, materials with ultra-early strength are used, which increases construction costs.

(c) Since the jacking pressure and pumping pressure are maintained until the poured concrete has hardened to a certain extent, the jacking and concrete pouring piping will get in the way, and reinforcing materials such as reinforcing bars and steel frames will be installed inside the lining structure. cannot be placed.

Therefore, concerns remain about the tunnel's ability to withstand bending and tension after completion.

OBJECT OF THE INVENTION The present invention has been made to solve these problems, and provides a construction technology for PC tunnels that is excellent in workability and economical efficiency, and can improve strength against bending and tension. The purpose is to provide.

Configuration of the Present Invention> An embodiment of the present invention will be described below with reference to the drawings.

First, the main equipment used in this example will be explained.

Kui〉shield machine An example of a shield machine 1 is shown in FIG.

This shield machine 1 has a tail plate 12 protruding from the tail portion of the main body 11 at the rear of the main body 11.

The tail plate 12 is connected to a slide jack 13 fixed to the main body 11 so as to be slidable.

The shield machine 1 also includes a formwork moving jack 14, an excavation jack 15, and a press jack 16.

A plurality of all these jacks 13 to 16 are arranged in the main body 11 in the circumferential direction.

The tip of the digging jack 15 is connected to the reaction force device 2 for obtaining the digging reaction force of the shield machine 1.

As shown in FIG. 1, the reaction force device 2 includes a plurality of expansion/contraction tubes 21, a connecting rod 22 with an expansion/contraction function that connects these expansion/contraction surfaces 2, and a running wheel 23 shown in FIG. Consisting of

Each cylindrical expansion/contraction tube 21 is made up of two arc-shaped split rings 24 and a plurality of shirts 4:25 interposed between the two split rings 24, and each expansion/contraction tube is 21 is configured to expand or contract the diameter.

In order to obtain the digging reaction force of the shield machine 1 from the reaction force device 2, one end of an extension rod 17 extending from the digging jack 15 is connected to the front end of the reaction device 2.

In addition, in order to prevent buckling of the rod 17 of the digging jack 15, for example, as shown in an enlarged view in FIG. A plurality of plates 18 are provided, and each support plate 18 supports the rod 17.

Movable formwork device (FIG. 1) The movable formwork device 3 consists of a formwork moving jack 14 and a movable formwork 31 connected to the formwork moving jack 14.

The movable formwork 31 consists of a liner plate and circumferential ribs.

The movable formwork 31 is moved forward by the expansion and contraction operation of the formwork movement jack 14-.

2> Mobile shoring device (FIG. 1) The mobile shoring device 4 is a known shoring device having a traveling means for preventing the collapse of a structure immediately after lining.

When the movable formwork device 3 also serves as a shoring, the movable shoring device 4 can be omitted.

Press ring (Fig. 2.3) The press ring 5 is an annular plate, and is used by assembling arc-shaped segments into an annular shape.

The press ring 5 is also a member that functions to cooperate with and hold the movable formwork 31.

The press ring 5 has an I-shaped cross section and is composed of an inner ring 51, an outer ring 52, and a shielding plate 53 connecting both rings 51 and 52.

A large number of holes 54 are formed in the plate surface of the shielding plate 53 of the press ring 5.

This hole 54 is a guide hole for passing through the end of the tendon material 6 buried in the lining structure and guiding it out of the formwork.

Further, as another press ring 5, it is also possible to use a type in which a continuous concrete layer 55 is adhered to the inner circumferential surface of an inner ring 51 and the outer circumferential surface of an outer ring 52, as shown in FIG.

Next, the construction method will be explained.

Excavation of the shield machine (Fig. 1.5) The reaction device 2 is placed inside the already hardened lining 7, and then each expansion tube 2 is expanded in diameter to harden the lining lining. A reaction force is obtained from 7, and the digging jack 15 is extended to advance the main body 11 of the shield machine 1 toward the face side.

Assembling the press ring Once the shield machine 1 has finished moving forward, the excavation jack 15
is contracted to form a space in the tail plate 12 for assembling the press ring 5.

Next, the divided press ring 5 is carried into the tunnel and assembled inside the tail plate 12.

When assembling the press ring 5, as shown in FIG. 6, separate tendons 6b are connected to each tendon 6a protruding from the lining 7 constructed in the previous step via connectors 61a.

Then, each tension member 6 is inserted into the hole 54 of the press ring 5 that has been carried in.
An annular press ring 5 is assembled by passing through the free end of b.

Kuha〉Placement of concrete (Fig. 7) Reaction force is obtained from the shield machine 1 and the movable formwork 31 is advanced toward the face side.

As a result, a shielded space is formed between the earth and the movable formwork 31.

Next, piping for concrete placement is performed, and concrete is press-fitted into the shielded space formed between the tail plate 12 and the movable formwork 31.

<2> Application of prestress (FIGS. 7 to 9) Next, the press jack 16 is extended to pressurize the concrete filled in the entire area of the shielded space at a predetermined pressure. (FIG. 8) Then, the press ring 5 retreats in a direction that reduces the volume of the shielded space, and as a result, the concrete in the shielded space is pressurized and most of the excess water is discharged.

Furthermore, when the slide jack 13 is retracted and the tail plate 12 is moved forward toward the face side while continuing the concrete pressurization work, the pressurized concrete comes into close contact with the ground.

After a model or nut-type fixture 62 is attached and fixed to the tension material 6b protruding from the press ring 5, the press jack 16 is contracted.

As a result, the pressing force applied to the press ring 5 is replaced by the tension material 6. (FIG. 9) As described above, in the present invention, the prestress applied to the lining 7 does not disappear even if the press jack 16 is contracted.

Kube> Process of moving the construction equipment Next, reduce the diameter of each expansion/contraction cylinder 21 of the reaction force device 2, and then move the reaction force device 2 to 1 without contracting the digging jack 15.
Move forward to the face side by the span.

While repeating each of the above steps, the lining 7 is successively extended and constructed alternately or in parallel with the excavation.

Note that the movable shoring device 4 moves to the face side every time one span of lining 7 is constructed.

Effects of the Present Invention> Since the present invention is as explained above, the following effects can be obtained.

(b) Construction is performed by applying prestress to the lining structure in the direction of the tunnel axis.

Therefore, compressive force remains in the axial direction of the tunnel, and a strong structure can be constructed in the axial direction of the tunnel.

(b) Prestress is also applied in the circumferential direction of the lining structure, and the axial force is more dominant than the bending moment.

As a result, generation of tensile stress in the lining structure is suppressed.

(c) Since the concrete before hardening is pressurized in an environment where it is not affected by the fineness of the ground, excess water in the concrete is discharged and the water-cement ratio is improved.

Therefore, the lining structure can be constructed with high quality.

(2) Since the concrete is pressurized between the tail plate and the movable formwork and then pressed against the ground, the quality of the concrete is not affected by the properties of the ground.

(e) By using a prefabricated press ring, the next step can be carried out without waiting for the concrete to harden.

Therefore, the construction period is shortened.

(f) Replace the pressing force of the press jack with tension material,
Press jacks can be deflated while concrete is being pressurized.

Reinforcing materials such as reinforcing bars and steel frames can be placed in the space created by shrinking the press jack.

(1.) Material costs can be reduced because there is no particular need for ultra-early strength materials as in the past.

[Brief explanation of the drawing]

Fig. 1 2 An explanatory diagram of the entire embodiment of the present invention Fig. 2 An explanatory diagram of a nib ring Fig. 3: A cross-sectional view taken along ■-■ in Fig. 2 Fig. 4 A cross-sectional view of another press ring Fig. 5 Figure: Explanatory diagram of the reaction device when the diameter is reduced Figure 6: Partial sectional view of the terminal end of the lining Figure 7.8
Figure: Explanatory diagram when applying pressure to the lining Figure 9: Explanatory diagram when tension material is fixed to the nib ring

Claims (1)

[Claims] In a method of constructing a tunnel by pouring concrete on-site between the ground formed by excavating with a shield machine and formwork, and lining the tunnel, a press disposed within the tail of the shield machine With the jack in the retracted state, multiple tension members are placed between the formwork and the ground in the direction of the tunnel, and an annular press ring is placed between the ground and the end of the formwork on the face side. , Concrete is poured into the formwork, and then the press jack is extended to apply pressure to the ring plate in a direction that reduces the formwork space, the ends of the tendons are fixed to the press ring, and the lining is completed. A construction method for PC tunnels in which the lining is sequentially extended onto the ground where the shield machine has passed, while applying prestress to the lining.