JPH0251040B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for tensioning a PC material in a concrete lining of a cast-in-place lined shield tunnel.

As a method to prevent subsidence under the shield tunnel and to prevent water leakage between segment rings against bending stress during earthquakes, a set of multiple segments with matching sheath holes is assembled and prestressed steel is fixed to this. The main girder, which serves as a plate, and the anchoring segment, which allows for the desired amount of expansion and contraction, are connected to form one unit.
After assembling one or more units, the PC steel material is passed through the sheath hole of the segment, and both ends of the PC steel material are attached to the anchor between the rear main girder of the front anchoring segment and the front main girder of the rear anchoring segment. A method of tension fixing is disclosed in Japanese Patent Application Laid-Open No. 140499/1983. This method is mainly effective for shield construction methods that use concrete segments, but the lining concrete is poured directly within the tail of the shield and the lining concrete takes on the jacking reaction force to promote the shield. The so-called cast-in-place lining shield construction method was not possible.

The present invention was proposed in view of the above-mentioned points, and its purpose is to increase the strength of the concrete lining of a shield tunnel constructed by the cast-in-place lining shield method, and to prevent uneven settlement of the shield tunnel. To provide a method for tensioning PC material in lining concrete of a cast-in-place lining shield tunnel, capable of applying prestress to lining concrete in order to prevent damage due to stress during earthquakes, water leakage from concrete lining joints, etc. It is in.

The present invention installs a fixing segment that fixes the PC material, fixes one end of the unbonded PC strand wound on a winding drum installed in a shield excavation device, and unbonds the PC material by the winding drum.
While paying out the PC strands, they are buried in the lining concrete by repeating excavation and concrete pouring. After one unit of shield excavation is completed, the unbonded PC strands are tensioned between the anchoring segments by holding them with a fixing tool. By fixing, the PC material consisting of unbonded PC strands is tensioned and fixed in the concrete lining of the cast-in-place lining shield tunnel, and prestress can be applied to the concrete lining, increasing the strength of the concrete lining. , it is possible to prevent uneven settlement, improve seismic resistance, prevent water leakage from concrete pouring joints, and unbond one unit.
Since the PC strands can be buried seamlessly in the concrete lining, there is no hindrance to excavation and concrete pouring, and these can be carried out efficiently.

Hereinafter, the present invention will be explained in detail based on examples.

1 to 4 show an embodiment using unbonded PC strands, and a cast-in-place lining shield excavation device 1 includes a cylindrical shield body 2 with a tail portion 3 formed at the rear, and a shield body 2.
A cutting edge 4 provided in a conical shape at the front of the shield body 2, a reinforcing ring gutter 5 of the shield body 2, a propulsion jack 6 attached to the ring gutter 5, and a propulsion jack 6 are connected to the propulsion jack 6, and the reaction force is applied to the lining concrete. A press ring 7 that doubles as a weir plate that can slide back and forth within the tail portion 3 of the shield to be borne, a cylindrical steel form on which concrete is poured on the outer surface, or a segment type formwork 8, which is provided in the formwork 8. The lining concrete 10 is installed directly within the tail portion 3 of the shield.
A press ring 7 is pressed against the cast lining concrete 10, and the reaction force of the propulsion jack 6 is applied to the excavation.

11 is a through hole provided in the press ring 7;
Reference numeral 2 denotes an unbonded PC strand winding drum that is rotatably installed in the tail portion 3 of the shield via a bracket, and 13 is a fixing segment that is installed at both ends of one unit of lining concrete and allows the desired amount of expansion and contraction. , the segment 13 has a pair of front main girders 14 and rear main girders 1 as shown in FIG.
5 and skin plates 16 and 17 made of thin iron plates that form the outer surface of the segment and are in contact with the ground, a rubber gasket 18 that is connected between the skin plates 16 and 17 and for expanding and contracting the fixing segment, skin plates 16 and 17, and a rubber gasket. 18
Bolts 19 and springs 20 for tightening the main girder 1
4 and the sheath through hole 2 provided in the rear main girder 15
1 and 22, a space 23 formed by the front main spar 14, the rear main spar 15, and the skin plates 16, 17.
It is composed of etc.

24 is a concrete casting space, 25 is an unbonded PC strand buried in the concrete lining 10, 26 is a fixing device for tension-fixing the buried unbonded PC strand 25 between the fixing segments 13, and 27 is a ground.

Next, unbond the lining concrete 10.
A method for tension-fixing the PC strand 25 will be explained.

First, after installing the anchoring segment 13 in the space surrounded by the tail portion 3 of the shield excavation device 1, the formwork 8, and the previously cast lining concrete 10, the propulsion jack 6 is extended and the press ring 7 is attached to the anchoring segment. Press it to 13. The unbonded PC strand 25 is installed in the shield excavation device 1. The unbonded PC strand is wound on the winding drum 12, and one end is connected to the unbonded PC strand through hole 11 provided in the press ring 7 and the fixing segment 1.
3 and is fixed to the front main beam 14 of the fixing segment 13 so as not to fall off.

In this state, the ground 27 is excavated using an excavator (not shown) or input. In parallel with excavation, the propulsion jack 6 is extended to press the anchoring segment 13 via the press ring 7, and the shield excavation device 1 is advanced. After the propulsion work is completed, the propulsion jack 6 is retracted and the formwork 8 is advanced to form a concrete placement space 24 as shown in FIG. By promoting excavation in this way, the casting space 24
The unbonded PC strand 25 is automatically placed in the area.

Next, fresh concrete sent from a concrete transport device (not shown) is placed into the concrete placement space 24 through a concrete placement port 9 attached to the formwork 8.

Immediately after concrete placement, the propulsion jack 6 is extended while excavating the ground 27, and the lining concrete 10 that was placed this time is removed via the press ring 7.
The shield excavation device 1 is advanced while pressing .

Repeat the above work to perform excavation work.

When the shield excavation for one unit (see Fig. 4) is completed, the anchorage segment 13 is installed in the space surrounded by the tail part 3 of the shield, the formwork 8, and the lining concrete 10 previously cast, and the rear main girder 15 is The other end of the unbonded PC strand 25 is passed through the through hole 22.

Through the above operations, the unbonded PC strands 25 penetrate and are buried in one unit of lining concrete.

To introduce prestress into the lining concrete 10, the rear main girder 1 of the front anchorage segment 13 is
5 and the front main beam 14 of the rear fixing segment 13, tensioning the unbonded PC strand 25 with a jack (not shown), and fixing it with the fixing tool 26.

In this way, prestress is introduced into the lining concrete of cast-in-place lining shield tunnels to increase the strength of the lining concrete.
It can prevent uneven settlement due to heavy loads, improve earthquake resistance, and prevent water leakage from concrete pour joints.

Note that, as described above, the fixing drums 12, 32, 4
By using 2, you can unbond one unit.
Since PC strands can be seamlessly and automatically buried in the lining concrete, excavation promotion,
Concrete placement work can proceed smoothly.

[Brief explanation of drawings]

1 to 4 show embodiments of the present invention. FIG. 1 is a vertical cross-sectional view of a cast-in-place lining shield excavation device, and FIG. FIG. 3 is a longitudinal sectional view of the lining shield excavation device, FIG. 3 is a sectional view showing the structure of the fixing segment, and FIG. 4 is a sectional view showing the state in which the PC material is tensioned and fixed. DESCRIPTION OF SYMBOLS 1...Shield excavation device, 2...Shield main body, 3...Tail part, 4...Blade mouth, 5...Ring gutter, 6...Propulsion jack, 7...Press ring, 8...Formwork, 9 ... Concrete pouring opening, 1
1... Through hole, 12, 32, 42... Winding drum, 13... Fixing segment, 14... Front main girder, 15... Rear main girder, 16, 17... Skin plate, 18... Rubber gasket , 19... Bolt, 20... Spring, 21, 22... Through hole, 23
...Space part, 24...Concrete pouring space, 25
...Unbonded PC strand, 26...Fixer,
27...Jiyama.

Claims (1)

[Claims] 1 In the space surrounded by the concrete lining of the cast-in-place lining shield tunnel, the tail part of the shield, and the formwork, we installed an anchoring segment consisting of the main girder and skin plate that anchors the PC material made of unbonded PC strands, and After inserting and fixing one end of the unbonded PC strand wound on the winding drum installed in the shield through the through hole of the press ring into the through hole of the fixing segment,
Unbonded PC strands are placed in the concrete placement space by digging, then concrete is placed, and this digging and concrete placement is repeated the required number of times while feeding the unbonded PC strands from the winding drum to complete the lining. After burying the unbonded PC strand in concrete and completing shield excavation for one unit, install the anchoring segment, and fix the other end of the unbonded PC strand to the main girder through the anchoring segment. Inside the lining concrete of a cast-in-place lining shield tunnel, which is characterized by tension-fixing with an anchor between segments.
How to tension PC material.