JPS6221120B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for closing a concrete placement area when tunnel concrete is placed inside a segment assembled at the rear of a shield that excavates underground.

When concrete is placed inside the segment at the rear of the shield in parallel with underground excavation by the shield, a central form is assembled inside the segment with the required concrete pouring area separated, and the concrete is poured. When press-fitting fresh concrete into a newly constructed section, the end of the concrete pouring section is closed, but the tunnel entrance side is closed by the end face of the concrete wall that was previously cast, and concrete leaks from there. Since there is no shield, the blockage is exclusively at the open end on the shield side.

Conventionally, the opening end was closed by inserting a wooden board. However, in order to fit a wooden board between a segment with a certain curvature and the central form, it is necessary to prepare and prepare a wooden board divided into quite fine pieces, and since the wooden board is solid, It is difficult to close the opening end without any gaps to prevent concrete from leaking or flowing out, so the gaps created there are usually filled with rags, etc., and they cannot be removed after use. There were drawbacks such as poor workability and time-consuming process.

This invention was devised in order to eliminate the drawbacks caused by the wooden board, and its purpose is to be able to adapt to the cross-sectional area and curvature of the opening end of the concrete pouring part, and to It is an object of the present invention to provide a closing method using an air bag that not only can close an open end without a gap due to its own elasticity, but also can be easily attached to and removed from the open end and has excellent workability.

The present invention will be explained in detail below using illustrated examples.

In the figure, 1 is the shield, 2 is the segment assembled at the rear of the shield, 3 is the central form installed inside the segment 2, and the concrete pouring part 4
It is assembled with a separation between the two.

Reference numeral 5 designates an air bag, as shown in the figure, it includes a bag body 6 formed by laminating a plurality of pieces of durable synthetic rubber cloth of a required length, which circumferentially closes the concrete casting part 4, and the bag body. 6 and reinforcing covers 7 and 8 made of rubberized cloth or the like applied to the outside thereof. In addition, on the side of the bag body 6 in contact with the segment 2, a required number of back plates 9, 9, etc. made of plywood or elastic cloth-filled synthetic rubber plates are attached in parallel with gaps. The reinforcing cover 8 is provided to cover the back plates 9, 9...
has been applied.

Further, between each of the backrest plates 9, 9..., a sealing material 10 made of synthetic rubber or the like and having a trapezoidal cross section is buried downward from above the reinforcing cover 8. The bag main body 6 can be curved according to the curvature of the opening end of the concrete placement part 4 formed thereon by the backing plates 9, 9..., and the back support by the sealing material 10 can be By complementing the gaps between the plates, even if the curvature changes to some extent, concrete can be prevented from leaking or flowing out through the gaps.

Reference numeral 11 denotes an air injection connection fitting, which is attached to the end of the bag body 6 on the side that comes into contact with the central form 3.

Next, the method of closing using the air bag will be explained.

First, the air bag 5 is inserted into the open end of the concrete casting section 4 in a flat state.
The example shown is a case where two airbags 5, 5 are used, and a backing plate 12 or the like is used on the central form 3 with the side on which the backing plates 9, 9... are provided facing the segment 2. The connecting fitting 11 for air injection is positioned from the central form 3 into the tunnel hole.

When the above preparations are completed, air is injected into the bag main body 6 through the air inlet, and the bag body 6 is inflated by air pressure and pressurized outward.
...and the sealing material 10 is brought into close contact with the segment 2, and the opposite side is brought into close contact with the central form 3. As a result, the open end of the concrete casting section 4 is closed without a gap by the expanded air bag 5, and the air bag itself is pressurized outward by the air pressure to withstand external pressure.

Therefore, even if fresh concrete is press-fitted into the concrete placement part 4, the air bag 5 will not be deformed by the pressure, completely preventing concrete from leaking or flowing out.

Further, after the fresh concrete has solidified, the air in the air bag 5 may be allowed to flow out to the outside, and the air bag 5 can be deflated and easily removed.

As described above, this invention provides a concrete placement portion 4 between the segment 2 and the central form 3.
The bag body 6 has the required length to circumferentially close the bag.
and reinforcing covers 7, 8 provided on the outside of the bag body 6, and a required number of back plates 9, 9... are arranged in parallel on the side in contact with the segment 2, and each intermittent back Since the air bag can be curved according to the curvature of the open end of the concrete placement part by the backing plate, the air bag can be adapted to the open end that should always be closed. Moreover, due to the elasticity of the air bag itself, the contact surfaces with the segments and the central form are watertightly closed, and not only leakage of concrete but also outflow can be completely prevented. Furthermore, it is easy to remove after use, as all you have to do is extract the air to the outside and deflate the air bag.It can be used repeatedly without being affected by the curvature, and is not only easy to work with but also economical. It has the following features.

[Brief explanation of the drawing]

The drawings show one embodiment of the air bag for shield construction according to the present invention, in which Fig. 1 is a schematic longitudinal sectional view showing the state of excavation by the shield, Fig. 2 is a cross-sectional front view of the air bag, and Fig. 3 is a vertical sectional view. Side view,
FIG. 4 is a longitudinal sectional side view of the concrete pouring part with the open end closed, and FIG. 5 is a front view of the same. 1... Shield, 2... Segment, 3... Central form, 4... Concrete placement part,
5... Air bag, 6... Bag body, 7,8
... Reinforcement cover, 9 ... Back plate.

Claims (1)

[Claims] 1. When closing the concrete placement area between the segment assembled at the rear of the shield and the central form provided inside the segment by using an air bag of the required length, the air bag is It has a structure in which a plurality of back plates are installed in parallel on one side of the bag and a reinforcing cover is provided, and the air bag is inserted into the concrete pouring area with the back plate placed on the segment side, and the air bag is inserted into the concrete pouring area by the expansion of the main body. A closure method in the shield construction method, characterized in that the back plate is press-fitted into segments.