JPH0574679B2 - - Google Patents

Description

[Detailed Description of the Invention] "Field of Application of the Invention" This invention relates to a cast-in-place lining method in which concrete is placed around a lining formwork installed behind it while excavating with a shield machine. This relates to the shield lining method.

``Prior art and problems to be solved by the invention'' The conventional cast-in-place shield lining construction method involves assembling reinforcing bars and an inner formwork at the tail of the shield body after excavation is completed, and attaching a press ring to the front of this inner formwork. After installing the concrete and pouring concrete into the inner formwork,
A method is known in which concrete is pressurized at high pressure by a required number of press jacks provided on a press ring, and a shield machine is propelled by using the concrete as an inner formwork to absorb the reaction force of the propulsion jacks.

However, in the conventional construction method described above, a press jack is incorporated into the press ring in addition to the propulsion jack, resulting in a complex structure that is difficult to maintain and manage.In addition, the amount of concrete pushed in by the press jack (covering yield) differs each time the construction is carried out, and the concrete There were drawbacks such as the quality and filling management being difficult.

"Means for Solving the Problems" In order to solve the above-mentioned conventional problems, the present invention has the following features:
The inner formwork is assembled into a ring shape at the tail part of the shield body, a press ring is installed in front of this inner formwork, and between the front side of the inner formwork and the press ring,
Annular expansion and contraction bodies that can be expanded and contracted in the front and back directions are installed tightly in the expanded state, and cast-in-place concrete is filled into the inner formwork, and in this state, a shield machine is created by a propulsion jack that takes a reaction force against the press ring. By propelling the shield machine and pressurizing the filled concrete while gradually contracting the expansion and contraction body by the propelling reaction force, the reaction force of the shield machine is transferred to the concrete or inner formwork through the press ring without using a press jack etc. can be taken,
The structure of the press ring can be simplified, and the expansion and contraction body can be contracted to stop the retreat of the press ring in front of the inner formwork, making it possible to keep the lining finished form constant. This paper proposes a cast-in-place shield lining method that makes it possible to secure the amount of concrete extruded through the contraction of the expansion/contraction body commensurate with the tail voids that occur, thereby making it easier to manage concrete filling.

"Embodiment" Below, an embodiment of the present invention shown in the drawings will be described. An inner formwork 2 is installed in the tail part of the shield body 1, and a reinforcing bar is placed in the ring-shaped gap 3 between the inner formwork 2 and the tail part. Install 4.

Next, an annular expansion and contraction body 5 that can be expanded and contracted in the front and rear directions is attached to the front surface of the inner formwork 2 in an expanded state.
A gap 3' is formed between the outer periphery and the inner circumferential surface of the shield body 1, which communicates with the gap 3 of the inner formwork.

This expansion/contraction body 5 is, for example, as shown in FIG.
Bellows plates 5b and 5b' made of an elastic material such as rubber or soft elastic synthetic resin are provided between the front and rear annular plates 5a and 5a', and air or liquid is put inside the bellows plates 5b and 5b' to expand as the fluid enters and exits. Use something that can be contracted, or something that can be expanded and contracted by a spring placed inside.

Further, in front of the expansion and contraction body 5, an annular press ring 6 is installed to be able to slide freely along the inner circumferential surface of the shield body 1, thereby closing the front surface of the gap 3'.

The opposite surface of the air gap 3' in the press ring 6 is
The press ring 6 is provided with a flange portion 6' that protrudes slightly so as to be located at the end of the inner formwork when the expansion and contraction body 5 is at its maximum contraction, and that protrudes from the inner periphery of the expansion and contraction body 5. .

Cast-in-place concrete 8 is injected into the spaces 3 and 3' thus formed through either or both of the injection holes 7 provided in the inner formwork 2 or the press ring 6.

After filling the concrete 8, the propulsion jack 9 whose rear end is attached to the press ring 6 is extended and the shield machine is propelled by applying a reaction force to the inner formwork 2 through the filling concrete 8 and the expansion/contraction body 5. The reaction force causes the press ring 6 to move backward, and accordingly, the expansion and contraction body 5 gradually contracts while uniformly pressurizing the concrete 8, which sequentially fills the tail voids formed at the rear of the shield body 1.

The concrete 8 filled in the void 3' in this way is gradually extruded, and the void 3 and the tail void are densely filled with appropriately compacted concrete 8 until it comes into contact with the ground, and the expansion and contraction body 5 The concrete 8 is cured for a predetermined period of time in a state in which the press ring 6 is completely contracted and the press ring 6 is locked to the inner formwork 2.

After the concrete 8 hardens, the press ring 6 and the expansion/contraction body 5 are removed, and the inner formwork 2 is further dismantled and moved forward, and the same steps as described above are successively performed.

"Effects of the Invention" As described above, according to the present invention, the inner formwork is assembled into a ring shape at the tail part of the shield main body, the press ring is installed in front of this inner formwork, and the front side of the inner formwork and the press ring are assembled. An annular expansion and contraction body that can be expanded and contracted in the front and back direction was installed tightly between the press ring and the press ring in an expanded state, and the inner formwork was filled with cast-in-place concrete, and in this state, a reaction force was applied to the press ring. The shield machine is propelled by the propulsion jack, and the filling concrete is pressurized while gradually contracting the expansion and contraction body due to the reaction force of the propulsion, so the reaction force of the shield machine can be used to fill the concrete through the press ring without using a press jack, etc. It can be used in concrete or internal formwork, simplifying the structure of the press ring, and pressurizing the filled concrete while gradually contracting the expansion and contraction body, so it can be applied evenly without overpressuring the concrete. Can be compacted.

In addition, the retreat of the press ring can be stopped at the front of the inner formwork to maintain a constant lining shape.
Furthermore, by adjusting the amount of contraction of the expansion/contraction body, it is possible to appropriately secure the amount of concrete extruded in proportion to the tail voids generated by the propulsion of the shield machine, thereby making it easier to manage the filling of concrete. can.

[Brief explanation of drawings]

1 and 2 are vertical sectional side views showing the construction state according to the present invention, and FIG. 3 is a partial vertical sectional side view showing an example of the expandable body according to the present invention. 1...Shield body, 2...Inner formwork, 3, 3'
... air gap, 4 ... reinforcing bar, 5 ... expansion and contraction body, 6 ... press ring, 6' ... flange part, 7 ... injection hole,
8...Concrete, 9...Propulsion jack.

Claims (1)

[Claims] 1. An inner formwork is assembled into a ring shape in the tail part of the shield body, a press ring is installed in front of the inner formwork, and a press ring is provided between the front surface of the inner formwork and the press ring so that the inner formwork can be expanded and contracted in the front and rear direction. The annular expansion and contraction body is densely installed in an expanded state, and the inner formwork is filled with cast-in-place concrete, and in this state, the shield machine is propelled by a propulsion jack by applying a reaction force to the press ring, and The filling concrete is pressurized while gradually contracting the expansion and contraction body by the propulsion reaction force, and after curing for a predetermined period of time, the press ring and expansion and contraction body are removed and moved;
A cast-in-place shield lining construction method characterized by continuing the above steps.