JPH02128098A - Method of shield lining construction - Google Patents

Abstract

PURPOSE:To reduce the term of works and the cost of construction, and to prevent the displacement of a ring by filling the air gap of the outer circumference of a precast concrete block unified with a reinforcing bar with cast-in-place concrete and supporting the reinforcing ring to the inside of the air gap. CONSTITUTION:An air gap 3 is assembled to the tail section of a shield body 1 to a ring shape at a required clearance. Reinforcing bars 4 are unified with precast concrete blocks 2, and dowel reinforcements 5 are projected at regular intervals. A plurality of the reinforcing rings 6 of semicircular arc members, one ends of which are connected rotatably by hinges 8 and to the other ends of which expansion jacks 9 are installed and in which two rings are paired, are mounted on the inner circumferential surface sides of the concrete blocks 2. Concrete 13 is placed and filled into the air gap 3 from a placing hole 12, and pressed by a press ring 11 by operating a press jack 10. Accordingly, the concrete blocks 2 are assembled to a ring shape in place of forms, thus improving the finish of the internal surface of a tunnel.

Description

[Detailed Description of the Invention] "Field of Application of the Invention" This invention involves assembling a precast concrete slab in a ring shape behind it while excavating with a shield machine, and pouring concrete into the outer circumferential space of the ring to integrate it. This relates to a shielded lining method that performs lining by doing this.

``Prior art and problems to be solved by the invention'' Conventionally, the shield lining method using the segment method has been known.
Since segments with high strength that can withstand external pressure are used, there is a problem in that the cost is inevitably high.

Therefore, in order to reduce costs, a shield lining method using directly cast concrete is known, but it requires a lot of time and effort in processes such as assembling, dismantling and moving the inner formwork, and assembling reinforcing bars. However, there were problems such as a long construction period and high equipment costs.

In particular, when lining small and medium-sized shields, the work space is narrow, so the arrangement of reinforcing bars and the assembly, disassembly, and internal formwork are difficult.
There were problems such as the extremely narrow working space required for movement, which made work extremely difficult.

"Means for Solving the Problems" In order to solve the above-mentioned conventional problems, the present invention uses a precast concrete slab instead of a formwork and integrates it with cast-in-place concrete that fills the outer peripheral void. , there is no need to assemble, dismantle, or move the inner formwork (even for tunnels with medium and small diameter cross sections, the construction period is shortened with a simple process).
In addition to reducing construction costs and making construction easier, by integrating reinforcing bars into the precast concrete slab in advance, the assembly process of reinforcing bars can be omitted, further reducing construction time.
This makes it possible to reduce construction costs, and by supporting the inside of the precast concrete slab with a reinforcing ring that can be expanded and contracted, it prevents the precast concrete slab from shifting due to unbalanced loads, and makes it easier to install and move the reinforcing ring. This paper proposes a shield covering method.

"Embodiments" Below, embodiments of the present invention shown in the drawings will be described.
While joining a plurality of arc-shaped precast concrete slabs 2 to each other in the ring direction at the tail portion of the shield body 1, a required interval is maintained so as to form a ring-sized gap 3 at the tail portion of the shield body 1. Assemble into a ring.

This precast concrete version 2 is integrated with required reinforcing bars 4 braided in an arc shape along its outer peripheral surface.
Furthermore, a plurality of dowel reinforcements 5 are integrally protruded at predetermined positions at predetermined intervals, so that the arrangement of reinforcing bars in the gap 3 is completed at the same time as the assembly of the ring.

In this case, if there is no need to place reinforcement in the gap 3, place the dowel reinforcement 5.
It may be only.

A plurality of perfect circular reinforcing rings 6 are installed at predetermined intervals on the inner circumferential surface side of the precast concrete slab 2 assembled in a ring shape, and a plurality of guides arranged extending long into the tunnel direction are installed inside the reinforcing rings 6 at predetermined intervals. It is removably fastened to the rod 7 via a grip mechanism such as a clamp fitting.

The reinforcing ring 6 has two semi-circular arc members rotatably connected to each other by a hinge 8 or the like at one end, and a hinge 8 at the other end.
An expansion/contraction jack 9 is installed that automatically expands and contracts in the radial direction using the expansion/contraction jack 9 as a fulcrum.By extending this expansion/contraction jack 9, the precast concrete slab 2 is pressed from inside and supported, and the expansion/contraction jack 9 is also contracted. As a result, the precast concrete slab 2 is also released and can be easily moved forward along the guide rod 7.

On the other hand, the front surface of the gap 3 is closed by a press ring 11 which is moved horizontally forward and backward by a press jack 10.

Concrete 13 is cast and filled into the void 3 thus formed through the pouring hole 12 provided in the precast concrete slab 2 or the press ring 11, and after the filling is completed, the shield body 1 is advanced by a propulsion jack, and
The press jack 10 is operated to pressurize the concrete 13 with the press ring 11.

At this time, the reinforcing ring 6 serves to evenly support the precast concrete slab 2 against uneven loads due to concrete placement pressure and earth pressure when the tail of the shield body l is pulled out, and to prevent deviation of the ring. Become.

In this way, the concrete 13 is densely filled into the voids 3 and tail voids in a moderately compacted state until it comes into contact with other peaks, and then the concrete 13 is cured for a predetermined period of time.

After curing the concrete 13, with the precast concrete slab 2 and the concrete 13 integrated by the reinforcing bars 4 and dowel bars 5, loosen the widening jacks 8 of the reinforcing ring 6 and insert the reinforcing ring 6 along the guide rod 7. Move forward and continue the same steps as above.

"Effects of the Invention" As described above, according to the present invention, a plurality of arc-shaped precast concrete slabs are assembled into a ring shape in place of formwork in the tail portion of the shield body, and this and the concrete filled in the gap around the outer periphery are integrated. This makes it possible to simplify the complex and dangerous work of dismantling and moving formwork, and to reduce construction time and costs with a simple and safe process even for small and medium diameter tunnels, as well as to reduce the need for secondary lining, etc. It is possible to improve the finish of the tunnel inner surface without requiring any process.

In addition, since reinforcing bars or dowel bars are integrated in advance on the outer circumferential surface of the precast concrete slab, the reinforcement can be completed at the same time as the precast concrete slab is assembled, eliminating the need for reinforcing reinforcement work on site and reducing construction time and costs. In addition to making it possible to reduce the amount of waste, it is also possible to ensure the integration of the precast concrete slab and cast-in-place concrete.

Furthermore, since the inner side of the ring of the precast concrete slab is supported by a reinforcing ring that can be expanded and contracted in the radial direction, the precast concrete slab is evenly supported against the unbalanced load caused by the concrete placement pressure and the soil ridge when the tail of the shield body is pulled out. , the deviation of the ring can be prevented.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional side view showing a construction state according to the present invention, and FIG. 2 is a longitudinal sectional front view thereof. 1...Shield body, 2...Precast concrete plate, 3...Gap, 4...Reinforcement bar, 5...Giver bar, 6...
Reinforcement ring, 7. Guide pipe, 8. Hinge, 9. Expansion/contraction jack, 10. Press jack 11.
Press ring, 12...Pour hole, 13...Cast-in-place concrete.

Claims (1)

[Claims] 1) A plurality of arc-shaped precast concrete slabs are assembled into a ring shape with a required gap around the outer periphery in the tail portion of the shield body, and this gap is filled with cast-in-place concrete to produce a precast concrete slab. A shield lining method that is characterized by integrating cast-in-place concrete with cast-in-place concrete. 2) The shield lining method according to claim 1, wherein reinforcing bars are integrated in advance on the outer peripheral surface of the precast concrete slab. 3) The shield lining method according to claim 1 or 2, characterized in that dowel reinforcements are integrally provided on the outer peripheral surface of the precast concrete slab in advance. 4) Claim 1 characterized in that the inner side of the precast concrete slab assembled in a ring shape is supported by a reinforcing ring that can be expanded and contracted in the radial direction, and after the cast-in-place concrete is cured, the reinforcing ring is contracted and moved forward. , the shield lining method described in 2 or 3.