JPH028494A - Arrival recovery of shield - Google Patents

Abstract

PURPOSE:To reduce the cost of construction without the needs for ground improvement by a method in which a shield-receiving container is set in an arrival vertical pit, a shield is penetrated into the container, the pit wall is connected with segments, and the shield is recovered. CONSTITUTION:A shield-receiving container 22 is set on a shield-receiving opening 20 in an arrival vertical pit H, and a shield 10 is housed in the container 22 through the pit H. The shield 10 is advanced in the container 22, the pit wall 14 is connected with segments 12 to prevent the intrusion of soil and groundwater, and the shield 10 is recovered.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a closed shield construction method, and more particularly to a shield arrival and recovery method that allows the shield to be suitably brought into the arrival shaft and recovered.

[Prior Art] Most of the ground on which the closed shield construction method is constructed is soft and weak due to standing water, and is not self-supporting.

Therefore, when constructing the conventional sealed shield method, it is necessary to improve the ground in the area around the reaching shaft in order to prevent groundwater and earth from flowing in through the shield receiving opening provided in the wall of the reaching shaft. was there.

Typical examples of such ground improvement methods include chemical injection method, deep mixing method, freezing method, and method of constructing a double cofferdam or excavating the inside of the cofferdam to lower the groundwater level.

[Problems to be Solved by the Invention] However, in the chemical injection construction method, since the construction is performed from above ground, the depth of the underground water of the shield increases and reliability decreases. In addition, the degree to which the ground is improved is unstable because it depends on the soil quality of the ground. There was also the problem of increased construction costs.

The deep mixing agitation method is more reliable than the chemical injection method, but it has the problem of being much more expensive and causing the construction cost to soar.

The freezing method is more reliable than the chemical injection method and the deep mixing method, but it is expensive and requires a long period of time. Furthermore, depending on the type of ground, there is a problem in that when frozen ground thaws, ground subsidence occurs, resulting in an unfavorable situation in terms of environmental conservation.

The method of constructing a double cofferdam requires a wide area on the ground, and in addition, it requires the use of an auxiliary construction method for water shutoff, resulting in high costs.

The present invention has been proposed in view of the problems of the conventional technology described above, and makes it possible to reach and recover the shield while maintaining the stability of the back ground without the need to construct ground improvement around the reaching shaft. The purpose is to provide a method for reaching and recovering the shield.

[Means for Solving the Problems] The shield arrival and recovery method of the present invention includes installing a shield receiving can in the reaching shaft at the shield receiving opening of the reaching shaft wall, and storing the shield in the can. The shield is then penetrated into the reaching shaft, the shield is advanced within the can body, the wall of the reaching shaft and the segment are connected to prevent earth and sand and groundwater from flowing into the reaching shaft, and the shield is recovered.

Here, in order to form a shield receiving opening in the reaching shaft wall, we formed a soil mortar column column wall without inserting H steel or sheet pile as a core material, and after installing the shield receiving can body, It is preferable to pull out the material. If a frame is not constructed in the arrival shaft, it is preferable to perform ground stabilization treatment to the extent that the ground around the shield receiving opening does not collapse, that is, stabilization treatment that is normally performed in the starting shaft when the shield is launched.

Further, it is preferable that the inside of the shield receiving can be filled with earth and sand. In that case, it is preferable that the filling material is strong enough to prevent the back ground from flowing into the can body even after the core material of the earth retaining wall (soil mortar column row wall) is pulled out.

Furthermore, it is preferable that a sealing mechanism is provided in the body portion of the can body, and the sealing mechanism is activated when the skin plate of the shield is positioned. A rubber tube is preferable as such a sealing mechanism, and if the water pressure is high, it is preferable to equip a rubber gasket between the rubber tube and the reaching shaft wall. On the other hand, if the diameter of the reaching shaft is sufficient and the length of the can can be made longer than the length of the shield, a sealing mechanism such as a rubber tube is not necessary.

In carrying out the present invention, it is preferable to use bagging segments as the segments of the frame of the vertical shaft that improve sealing performance.

[Operation] According to the shield reaching and recovering method of the present invention having the above-described configuration, the shield that has advanced underground or while being excavated passes through the wall of the reaching shaft, and is placed in a shield receiving can inside the shaft. Penetrates and is stored inside the body. The shield receiving opening portion of the wall of the shaft is connected to the segment following the shield in such a manner that a sufficient seal is formed to prevent earth, sand, groundwater, etc. from flowing into the reaching shaft. At the same time, the can body is disassembled and the shield is recovered.

Therefore, earth and sand and groundwater will not flow into the reaching shaft when the shield is reached, and there is no need to perform ground improvement treatment that is required in conventional closed shield construction methods.
Reliability regarding construction is improved, and construction cost and construction period are reduced. As a result, some of the problems of the prior art are solved.

[Embodiments] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Note that the same reference numerals indicate the same members in the accompanying drawings.

1A to 1E are process diagrams of an embodiment of the present invention.

In FIG. 1A, a shield 10 is being excavated in the ground A toward a reaching shaft H, and a plurality of segments 12, 12... are successively forming a tunnel behind the shield 10. .

The wall portion of the reaching shaft H includes a shaft main body wall 14 and a soil mortar column row wall 16, and the soil mortar column row wall 1
6 has a core material 18 made of H steel. A shield receiving opening 20 is formed at a predetermined position in the shaft main body wall 14 and the soil mortar column row wall 16, and a shield receiving can body 22 is provided in the shield receiving opening 20. The lid portion 2 is attached to the shield receiving can body 22.
4 are provided.

In the state shown in FIG. 1A, the shield receiving can 2
2 is filled with earth and sand 26. A ring-shaped rubber tube 28 as shown in FIG. 1C is inserted into the body portion of the can body 22 in a contracted state.

Soil mortar column row wall 16 of shaft H reached by shield 10
When reaching this point, the core material 18 is pulled out in the direction of arrow 30, as shown in FIG. 1B. When the shield 10 is moved to the left in FIG. 1B, the shield 10 cuts and penetrates the shield receiving opening 20 of the soil mortar column wall 16 and partially penetrates into the can body 22. .

The shield 10 is further advanced from the state shown in FIG. 1B, and when the skin plate 32 of the shield 10 reaches the position where the rubber tube 28 is provided in the can body 22, as shown in FIG. 1C, the shield 10 is stopped. do.

Then, as shown by the arrow 33, air is injected to expand the rubber tube 28, and the skin plate 32 and the can body 2 are
2, and the lid portion 24 side of the can body 22 is sealed against earth and sand and groundwater.

Here, if the earth and sand pressure or water pressure is high, rubber tube 2
8 and the shaft body wall 14, a rubber packing 36 is provided as an auxiliary means to reduce the pressure acting on the rubber tube 28.

After inflating the rubber tube 28, the front surface 3 of the shield 10
After confirming that earth pressure and water pressure no longer act on the can body 8, the lid portion 24 of the can body 22 is removed.

The shield 10 is further advanced, and as shown in FIG. 1D, bagging segments 40, 40, . Then, the shaft body wall 14 and the fill mortar column column wall 16 are sealed 44 (see FIG. 1E) with the segments 40, 40, . . . . And back ground A
After confirming that the earth pressure and water pressure are cut off, the seal 36 is recovered, the rubber tube 28 is contracted, and the shield 10 is recovered. Next, the remaining body portion 34 of the can body 22 is disassembled, and the shaft body wall 14 is removed as shown in FIG. 1E.
and the segment 42 are rigidly connected 44. This completes the work using the shield arrival and recovery method.

In the embodiment shown in FIG. 2, the length g of the shield receiving can 22 is longer than the length of the shield 10, and the first
The sealing mechanism, such as the rubber tube, used in the embodiments of Figures A through 1E is no longer necessary.

FIGS. 3A and 3B show still another form of the shield receiving can 22, which minimizes the amount of earth and sand 26 (FIG. 1A) to be filled inside the can 22 and prevents the shield from penetrating. The body of the shield-receiving can is expandable and retractable in order to allow the shield to be propelled after the shield is moved. The body portion 50 shown in FIG. 3A is constructed in a three-stage nesting type, while the bellows type body portion 52 is shown in FIG. 3B.

In addition, FIG. 4 shows the shield 10 or the shield receiving can body 22.
It shows in detail the state in which it cannot be contained.

[Effects of the Invention] According to the shield arrival and recovery method of the present invention, (1) ground improvement becomes unnecessary;

(2) Reaching the shield while maintaining the stability of the back ground,
Can be collected.

(3) pi@Eco cost is reduced, construction period is slightly shortened.

(4) It is unnecessary to occupy the area around the reaching shaft above ground.

(5) The construction depth (the depth at which the excavation progresses to the shield or the reaching shaft) does not affect the reliability of construction.

(6) The shield receiving can body can be reused.

It has excellent effects such as:

[Brief explanation of the drawing]

Figures 1A to 1E are cross-sectional views showing the steps of an embodiment of the closed shield construction method of the present invention, and Figure 2 shows a shield receiving can used in the second embodiment of the present invention. FIGS. 3A and 3B are sectional views showing other modified examples of the shield-receiving can body, and FIG. 4 shows details of the shield and shield-receiving can body used in the present invention. FIG. 10...Shield 12.40.42...Segment 14...Shaft body wall 16...Soil mortar column row wall 18...Core material 20...Shield receiving opening 22...Shield receiving can body A...Ground H...Target shaft Patent applicant Chubu Electric Power Co., Ltd. Kajima Corporation Kuha

Claims (1)

[Claims] installing a shield receiving can in the reaching shaft at a shield receiving opening of the reaching shaft wall, penetrating the shield into the reaching shaft so as to be received in the can, and advancing the shield within the can; A method for reaching and recovering a shield, characterized in that the wall of the reaching shaft and the segment are connected to each other so that earth and sand and groundwater do not flow into the reaching shaft, and the shield is recovered.