JPH0461957B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a cast-in-place PC lining construction method for a shield tunnel constructed underground.

[Prior art]

In recent years, when constructing shield tunnel linings, attempts have been made to construct them using cast-in-place concrete instead of conventional steel or precast concrete segments from the viewpoint of economy. When the concrete for lining is moved, there is a significant movement of the fresh concrete for lining, and as a result, the reinforcing bars and PC
It becomes difficult to hold the steel in place.

Conventionally, as a construction method for cast-in-place concrete lining for shield tunnels, (1) as shown in Figs. Arrange each reinforcing annular segment 1
(2) A method in which lining concrete 15 is cast between 4 and 4, and prestressed prestress is introduced into the annular segment 14, and then concrete 17 is filled into the segment; (2) A method is known in which a large number of reinforcing bars are placed individually or in a cage-like manner in a shield tunnel, and then lining concrete is poured.

[Problem that the invention seeks to solve]

However, in the case of method (1), the reinforcing annular segment becomes large, which is economically disadvantageous, and there is a problem in that smooth introduction of prestress throughout the tunnel lining cannot be expected. In the case of method (2) above, it is difficult to insert the reinforcing bar cage between the ground and the lining inner peripheral formwork, and the stroke of the propulsion jack is not constant, so it is difficult to reach the specified reinforcing bar cover thickness. difficult to secure. Furthermore, when reinforcing bars are used alone, there is a problem in that it is difficult to hold the reinforcing bars in a predetermined and accurate position because the concrete moves due to the reaction force of the propelling jack.

[Purpose and structure of the invention]

The purpose of this invention is to provide a cast-in-place PC lining construction method for shield tunnels that can advantageously solve the above-mentioned problems. A pressurizing ring 3, which has a plurality of recesses 2 for fitting the fixing part formwork on the inner circumferential side, is attached to the rear of the propulsion jack 5 in the shield machine 4, and then a large number of anchor reinforcing bars 9 protrude rearward. The annular wire mesh 6 with the attached pressure ring 3 is placed in contact with the rear surface of the pressurizing ring 3, and the fixing part formwork 7 is disposed within the plurality of notches provided on the inner peripheral surface of the annular wire mesh 6. The front portions of the arc-shaped PC steel materials 8 are fitted into the recess 2, and the ends of the plurality of arc-shaped PC steel materials 8 placed on the rear surface of the annular wire mesh 6 are inserted through the side plates of the fixing part formwork 7, and the PC steel materials 8 are inserted into the annular shape. An annular reinforcing joining member installation process in which the annular reinforcing joining member is bound to a wire mesh 6 to form an annular reinforcing joining member 10, and between the existing concrete lining 11, the pressure ring 3, the anchoring part formwork 7, and the lining inner peripheral surface form 12. A step of pouring the ready-mixed concrete 13, a step of compressing the ready-mixed concrete 13 by extending the propulsion jack 5 and moving the shield machine 4 forward, and after the ready-mixed concrete 13 starts setting and stands on its own.
Place casting of a shield tunnel characterized by repeatedly performing the steps of shortening the propulsion jack 5 and moving the pressurizing ring 3 forward.
In the PC lining construction method.

〔Example〕

Next, the present invention will be explained in detail with reference to illustrated embodiments.

5 and 6 show a pressurizing ring 3 used in an embodiment of the present invention, in which a plurality of fixings (three in the case of illustration) are fixed to the rear part of the inner circumference of the steel annular body 1. Part formwork fitting recesses 2 are provided at equal intervals in the ring circumferential direction. Further, FIGS. 7 to 11 show an annular reinforcing joining member 10 installed at the rear of the pressure ring 3, and FIGS. 12 and 13 show the annular reinforcing joining member 10.

To explain an example in which the annular reinforcing joining member 10 is installed at the rear of the pressure ring 3, protrusions (not shown) are fixed in advance to the rear surface of the pressure ring 3 at a predetermined pitch. Further, on the inner and outer circumferential sides of the plurality of arc-shaped wire meshes constituting the annular wire mesh 6, a large number of recesses recessed backward are provided at intervals in the circumferential direction of the arc-shaped wire meshes, and the bottom of each recess has a front end. Anchor reinforcing bar 9 with engagement flange 19 fixed on the side
A washer 20 is fitted into the front end protrusion of the anchor reinforcing bar 9, and a fixing nut 21 is screwed together to form an arcuate wire mesh with an anchor reinforcing bar.

Next, the plurality of arc-shaped wire meshes are arranged in a circular manner and are brought into contact with the rear surface of the pressurizing ring 3, and the protrusions are inserted into the meshes of the wire meshes, and the intermediate part of the box-shaped steel fixing part formwork 7 is inserted. is fitted into a U-shaped notch provided on the circumferential side of the annular wire mesh 6, and the opening of the anchoring portion formwork 7 is opened inside the annular wire mesh 6, and the front portion of the anchoring portion formwork 7 is Pressure ring recess 2
As shown in FIG. 11, a pin 27 fixed in advance to the pressurizing ring 3 is fitted into the fixing part formwork 7 which is fitted into the pressurizing ring 3 and installed above the pressurizing ring 3.

Next, multiple arc-shaped PCs (three in the case of illustration)
The steel materials 8 are arranged at intervals in the circumferential direction of the annular wire mesh on the rear surface of the annular wire mesh 6, and the ends of each PC steel material 8 are inserted into the side plates of the anchoring part formwork 7 in the circumferential direction of the annular wire mesh. are bound to the annular wire mesh 6 with a binding wire 18.

As for the PC steel material, it is preferable to use an unbonded PC steel material that is filled with grease between a synthetic resin sheath and a PC steel rod inserted into it, but it is preferable to use a PC steel material that is inserted into the sheath pipe. You may. When using unbonded PC steel, it is desirable to bend the unbonded PC steel into a predetermined arc shape in advance at a factory.

When carrying out this invention to construct a cast-in-place PC lining for a shield tunnel, as shown in FIG. 1 and FIGS. The rear end of each propulsion jack 5 in the shield machine 4 is fixed to the front part of the pressure ring 3 with bolts, etc., and the annular reinforcing joint member 10 is attached to the rear part of the pressure ring 3 as described above. Set up.

Next, as shown in FIG. 2, the inside of the area to be concreted is covered with a lining inner peripheral surface form 12, and an injection hose is connected to the injection port 23 of the lining inner peripheral surface form 12 via an on-off valve 24. After connecting, the front end of the existing concrete lining 11, the pressurizing ring 3 and the anchoring part formwork 7,
Fresh concrete 13 is poured into the annular space surrounded by the lining inner circumferential formwork 12, the exposed part of the ground, and the shield tail part 22 through the injection hose, the on-off valve 24, and the injection port 23, and after the injection is finished, , closes the on-off valve 24.

Next, as shown in FIG. 3, the shield machine 4 is propelled toward the forward face 25 by extending the propulsion jack 5. In this way, the propulsion reaction force is transmitted to the existing concrete lining 11 via the annular reinforcing joint member 10 and the ready-mixed concrete 13, and the ready-mixed concrete 13 receives compressive force.

After the fresh concrete 13 starts to set and becomes self-supporting, the propulsion jack 5 is shortened to leave the annular reinforcing joint member 10 at the front end of the concrete lining 11 as shown in FIG. The pressure ring 3 is moved forward together with the piston rod of the propulsion jack 5.

Next, as described above, the process of installing the annular reinforcing joint member 10 on the rear part of the pressurizing ring 3, the process of installing the lining inner circumferential surface form 12, the process of pouring ready-mixed concrete 13, and the process of Repeating the steps of extending the propulsion jack 5 and shortening the propulsion jack 5,
Concrete lining will be added and constructed in stages.

After the concrete lining has undergone a curing period, the lining inner peripheral surface formwork 12 is removed from the mold, and then prestress is introduced into each PC steel material 8.
The fixing part formwork 7 is filled with mortar.

To explain an example of introducing prestress into the PC steel material 8, as shown in FIG. While screwing together, one end of the frame-shaped joint fitting 30 is inserted, and the male threaded portion 28 is inserted into the frame-shaped joint fitting 30.
Screw the fixing nut 31 onto the other PC steel material 8.
An engaging nut 33 and a nut 34 at the other end of the frame-shaped joint fitting 30 are screwed into the male threaded portion 32 at the end. In addition, in FIG. 14, 35 is a sheath.

Next, as shown in FIGS. 15 and 16, a pair of tension members 3 whose intermediate portions are pivotally connected by a support shaft 36
7, 38, and a hydraulic tensioning jack 40 pivotally connected to the proximal end of each tensioning member 37, 38 by a pin 39.
A tensioning member 37 in a tensioning device 41 consisting of
38 is engaged with each engagement nut 29, 33, and then the tensioning jack 41 is extended to tension the PC steel material 8 to introduce prestress, and then as shown in FIG. The fixing nut 31 is tightened and engaged inside one end of the frame-shaped joint fitting 30, and then the tensioning device 41 is removed, and each of the engagement nuts 29 and 33 is tightened and engaged with the frame-shaped joint fitting 30. do.

When carrying out this invention, the front end portion of the anchor reinforcing bar 9 may be fixed to the annular wire mesh 6 by welding. Further, with compressive prestress applied to each arc-shaped PC steel material 8, the ends of adjacent PC steel materials 8 may be connected using a known compression-resistant connecting fitting.

An anchor reinforcing bar fixed to the wire mesh is made to protrude forward from the wire mesh without providing a protrusion on the rear surface of the pressure ring 3 for passing through the mesh of the wire mesh, and the protruding end is provided at the rear of the pressure ring. The wire mesh may be locked to the pressurizing ring by fitting it into the fitting hole.

〔Effect of the invention〕

According to this invention, there is no need to install annular segments for accommodating the prestressing steel material at intervals in the longitudinal direction of the tunnel, so the cast-in-place PC of the shield tunnel can be evaluated as an integrated PC structure.
Lining can be easily and economically constructed, and a circular wire mesh 6 is used at the boundary of concrete pouring.
is interposed, so that stress can be reliably transmitted.Furthermore, the fixing part formwork 7 is fitted into the notch provided in the annular wire mesh 6, and the arc-shaped PC tied to the annular wire mesh 6 The end of the steel material 8 is inserted through the side plate of the anchoring part formwork 7, and the front end of the anchor reinforcing bar 9 is fixed to the annular wire mesh 6, thereby forming an annular reinforcing joining member 10.
Since the annular wire mesh 6 at 0 is in contact with the rear surface of the pressure ring 3 and the front part of the fixing part formwork 7 is fitted into the recess 2 of the pressure ring 3, the extension action of the propulsion jack 5 causes Fresh concrete 13
Even if the arc-shaped PC steel material 8 moves, it is possible to hold it in an accurate position so that it does not shift, and since the annular wire mesh 6 is placed between the rear surface of the pressurizing ring 3 and the concrete, Pressure ring 3
When the pressurizing ring 3 is moved forward, the edge of the pressurizing ring 3 and the concrete can be smoothly cut, and the possibility of disturbing the concrete surface can be eliminated. Furthermore, since the arc-shaped prestressed steel material 8 can be placed and bound at any position on the annular wire mesh 6, the prestressed steel material 8 can be placed in a position that cancels out the bending moment (especially the bending moment on the tension side) that occurs in the lining concrete. The prestressing steel material 8 can be tied and fixed, and the prestressing steel material 8 can also be arranged eccentrically according to changes in the cross-sectional force generated in the lining concrete, so the arrangement can be made to correspond to changes in the soil water pressure acting on the lining concrete. Furthermore, the anchor reinforcing bars 9 can be made to play the role of distribution bars.

[Brief explanation of the drawing]

1 to 17 show embodiments of the present invention, in which FIG. 1 is a longitudinal cross-sectional side view showing a state in which an annular reinforcing joint member is installed at the rear of a pressurizing ring, and FIG. 2 is a concrete A vertical side view showing a state in which the inside of the planned construction area is covered with a lining inner circumferential surface formwork and ready-mixed concrete is poured; FIG. FIG. 4 is a longitudinal sectional side view showing a state in which the pressurizing ring is moved forward after the concrete has hardened. FIG. 5 is a front view of the pressurizing ring, and FIG. 6 is an enlarged sectional view taken along the line A--A in FIG. 5. 7 to 11 show the state in which the annular reinforcing joining member is installed at the rear of the pressurizing ring, FIG. 7 is a front view, and FIG. 8 is a B--B in FIG.
FIG. 9 is an enlarged sectional view taken along the line C-C in FIG. 7, FIG. 10 is an enlarged plan view showing the vicinity of the lower anchoring part formwork, and FIG. 11 is an enlarged cross-sectional view of the upper anchoring part formwork. FIG. 3 is a longitudinal side view showing a supported state. Fig. 12 is a side view of the annular reinforcing joint member, Fig. 13 is an enlarged cross-sectional plan view showing a part of it, and Fig. 14 is a PC in the anchoring part formwork.
A plan view showing the state of the steel material before prestressing,
Fig. 15 is a front view of the tensioning device, Fig. 16 is a partially longitudinal side view showing the relationship between the tip of the tensioning device and the prestressing steel, and Fig. 17 is a connection by introducing prestress into adjacent prestressing steels. Plan view showing the state, No. 18
The figure is a vertical side view showing cast-in-place lining by a conventional construction method, and FIG. 19 is a vertical side view showing an enlarged part of FIG. 14. In the figure, 1 is a steel annular body, 2 is a recess for fitting the fixing part formwork, 3 is a pressurizing ring, 4 is a shield machine, 5 is a propulsion jack, 6 is a circular wire mesh, 7 is a fixing part formwork, 8 is an arc-shaped PC steel material, 9 is an anchor reinforcing bar, 10 is an annular reinforcing joint member, 11 is an existing concrete lining, 12 is a lining inner peripheral surface form, 13 is a ready-mixed concrete, 18 is a binding wire, 19
is an engagement flange, 21 is a fixing nut, 22 is a shield tail portion, 23 is an injection hole, 24 is an on-off valve,
26 is mortar.

Claims (1)

[Claims] 1. A pressurizing ring 3 configured by providing a plurality of recesses 2 for fitting the fixing part formwork on the inner peripheral side of the rear part of the steel annular body 1 is attached to the rear part of the propulsion jack 5 in the shielding machine 4, and then An annular wire mesh 6 to which a large number of anchor reinforcing bars 9 that protrude rearward are attached is brought into contact with the rear surface of the pressurizing ring 3, and a fixing part formwork 7 is placed within a plurality of notches provided on the inner circumferential side of the annular wire mesh 6. At the same time, the front part of the fixing part formwork 7 is fitted into the recess 2, and the ends of the plurality of arc-shaped PC steel members 8 arranged on the rear surface of the annular wire mesh 6 are inserted into the side plates of the fixing part formwork 7. At the same time, an annular reinforcing joining member installation step is performed in which the PC steel materials 8 are tied together in an annular wire mesh 6 to form an annular reinforcing joining member 10, and the existing concrete lining 11, the pressure ring 3, the anchoring part formwork 7, and the inside of the lining are A step of injecting the ready-mixed concrete 13 between the peripheral formwork 12, a step of compressing the ready-mixed concrete 13 by extending the propulsion jack 5 and moving the shield machine 4 forward, and a step of moving the ready-mixed concrete 13 forward. A method for constructing a cast-in-place PC lining for a shield tunnel, characterized in that the process of repeatedly moving the pressurizing ring 3 forward by shortening the propulsion jack 5 and moving the pressurizing ring 3 forward after it starts condensing and stands on its own.