JP2630600B2 - Ground excavation method using two-stage shield device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a shield method which is a kind of a tunnel method.

<Prior Art> Generally, a conventional shield device has a cylindrical shape entirely covered with a skin plate 11, as shown in FIG.
A hood portion 12 for excavating the ground at the front, a tail portion 13 for assembling the segment 7 at the rear portion, and a ring gutter portion 14 which connects the middle thereof to support and reinforce the entire structure of the siled device. Consists of two parts.

Then, while excavating the ground in the hood portion 12, the tunnel is constructed by moving forward in the ground by the propulsive force of the shield jack 15 installed inside.

Also, as shown in Japanese Utility Model Application Laid-Open No. 59-13693, a shield device that excavates the ground while suppressing the looseness of the ground near the face by making the inner cutter head protrude from the front surface of the outer cutter head of the shield device. It has been known.

<Problems to be Solved by the Present Invention> The shield method is generally a tunnel construction method for soft ground.

Therefore, the soft ground is easily collapsed, so how to perform safe and quick excavation is a major proposition.

 Therefore, a chemical solution injection method has been conventionally used.

This chemical injection method injects the chemical into the ground to be excavated,
The excavation is carried out in such a manner that the soft ground is hardened to some extent in advance and the collapse of the ground is prevented.

However, in the case of the conventional shield device, since the chemical is injected from the hood 12 on the front surface described above, the chemical is injected in a fan shape, and the chemical is injected only into a very small area immediately before the hood 12. Can not do.

That is, as shown in FIG. 5, the chemical solution can be injected only into the area A surrounded by the fan-shaped wavy line, and the chemical solution cannot be injected into the surrounding areas B and C also surrounded by the wavy line. is there.

Therefore, it is not possible to excavate a wide area of the ground at once, and it is necessary to repeatedly excavate the ground and inject the chemical solution.

 Therefore, it is difficult to perform the excavation work efficiently.

In addition, since it is difficult to inject a chemical solution into a range B surrounded by a wavy line at an obliquely upper part of the shield device, the upper ground may collapse, which is dangerous.

<Object of the present invention> The present invention has been made in order to solve the above-described problems, and a two-stage method capable of injecting a chemical solution at an earlier stage and capable of freely and reliably selecting an injection position. It is an object of the present invention to provide a ground excavation method using a shield device.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

The excavation means used in the ground excavation method using the two-stage shield device of the present invention includes a large-diameter shield device 1 and a small-diameter shield device 5.

<B> Large Diameter Shield Device (FIGS. 1 to 3) As the large diameter shield device 1, a known shield device provided with a reaction wall 41 inside a known shield device is used.

(1) Cutter head As shown in FIG. 2, the cutter head 2 has a drill bit 21 disposed on a disk, and a sediment intake 22 provided therebetween.

A central hole 26 having a diameter substantially equal to the diameter of the small-diameter shield device 5 is opened in the central portion in parallel with the axial direction of the tunnel, and a seal member 23 is attached to the inner periphery thereof.

(2) Rotary motor As shown in FIG. 3, the cutter head 2 is connected to a ring-shaped gear member 25 via a large and small donut-shaped support member 24 that supports the cutter head 2.

Gears of the plurality of rotary motors 3 are meshed with the gear member 25, and the cutter head 2 can be rotated by driving the rotary motor 3.

The support member 24, as shown in FIG.
Is slidably fitted with a wall body 31 fixed to the inner periphery of
The rotating motor 3 is also fixed to the wall 31.

(3) Reaction Wall The reaction wall 41 is a wall provided on the reinforcing column 4 fixed inside the large-diameter shield device 1 as shown in FIG.

The reaction wall 41 is located at the rear end of the small-diameter shield device 5 and takes a reaction force for the small-diameter shield device 5 to propell.

A window is provided in the center of the reaction wall 41 to carry excavated earth and sand.

<B> Small Diameter Shield Device As the small diameter shield device 5, a known shield device including a cutter head 51, a shield jack for excavation, an earth discharging means, an erector device, and the like is used.

In the present embodiment, a description will be given of a case where a rotary cutting shield device for mechanical excavation is used.

The diameter of the small-diameter shield device 5 is formed substantially equal to the central hole 26 of the cutter head 2 of the large-diameter shield device 1, and the small-diameter shield device 5 is housed in the large-diameter shield device 1 from the central hole 26. .

At this time, the cutter head 51 of the small-diameter shield device 5 is used.
However, it is positioned so as to be flush with the cutter head 2 of the large-diameter shield device 1, and the rear end thereof is stored in contact with the reaction wall 41.

Inside the small-diameter shield device 5, there is a case where a chemical injector 52 for injecting a chemical into the surrounding ground is mounted at an arbitrary position.

<Soil excavation method using two-stage shield device> (Fig. 4) <a> Projection of small-diameter shield device While drilling the ground by rotating the cutter head 51 of the small-diameter shield device 5, a small segment 53 is provided at the rear. And the small-diameter shield device 5 is protruded into the ground by the propulsive force of the jack.

At this time, the reaction force for propelling the small-diameter shield device 5 is secured by the reaction wall 41, so that the small-diameter shield device 5 can be reliably protruded.

Also, since the sealing material 23 is attached to the inner peripheral surface of the central hole 26 of the cutter head 2 of the large-diameter shield device 1,
The small-diameter shield device 5 can be smoothly projected and housed without the earth and sand being caught in the gap.

<B> Injection of Chemical Solution After protruding the small-diameter shield device 5 by a predetermined distance, the chemical solution 6 is injected from the chemical injector 52 into the ground.

At this time, since the liquid injector 52 can be attached to an arbitrary position, the injection position of the liquid 6 can be freely selected.

Therefore, as shown in FIG. 5, the chemical solution 6 is placed in the ranges B and C surrounded by the wavy line which could not be injected by the conventional shield device.
Can be injected.

<C> Storage of the small-diameter shield device After the injection of the chemical solution 6, the assembled small segment 53 is removed, and the large-diameter shield device 1 is excavated and propelled, so that the small-diameter shield device 5 naturally becomes a large-diameter shield device. It is stored in one.

In addition, when excavation is performed by the large-diameter shield device 1 in a state where the small-diameter shield device 5 is stored in the normal ground, temporary stress release occurs in the ground, which may cause deformation of the ground.

In this case, by holding the internal pressure of the small-diameter shield device 5 in the housed state high, the ground at the center portion on the face side can be supported, and the deformation of the ground can be reduced.

<Effects of the Present Invention> Since the present invention has been described above, the following effects can be expected.

<B> In the case of the conventional shield device, since the chemical is injected from the hood on the front surface, the chemical is injected in a fan shape, and the chemical can be injected only into a very small area immediately before the hood. .

For this reason, it is not possible to excavate a wide area of the ground at once, and it is necessary to frequently and repeatedly excavate the ground and inject the chemical solution, which makes it difficult to work efficiently.

However, in the case of the present invention, the small-diameter shield device protrudes into the ground in advance, and the chemical solution can be injected into a wide area in the front that could not be injected conventionally.

Therefore, a wide area of the ground can be excavated at once, and it is not necessary to frequently and repeatedly excavate the ground and inject the chemical solution, and the work can be performed efficiently.

<B> Conventionally, it is difficult to inject a chemical solution into the ground at an obliquely upper part in front of the shield device, so that the upper ground may be collapsed, which is dangerous.

However, according to the present invention, since the liquid injector can be attached to an arbitrary position of the small-diameter shield device, the injection position of the liquid medicine can be freely selected.

Therefore, it is possible to inject a chemical solution into the ground diagonally above the front of the shield device, which could not be injected by the conventional shield device.

Therefore, there is no possibility of causing collapse of the upper ground, and the work can be performed safely.

<C> The device of the present invention can freely select the injection position of the chemical solution.

For this reason, there is no longer any area on the ground around the shield device where the chemical solution cannot be injected.

Therefore, the chemical solution can be reliably injected into the ground to harden the soft ground, and the ground can be prevented from collapsing and excavation can be performed safely.

<D> In the conventional shield device in which the surface of the cutter head is integrally formed, since the peripheral speeds of the central portion and the peripheral portion of the cutter head are different, there is a possibility that uniform excavation of the ground may be hindered.

However, since the present invention includes the large-diameter shield device and the small-diameter shield device, the center portion and the peripheral edge portion of the cutter head can rotate independently.

Therefore, it is possible to eliminate the difference in the peripheral speed between the central portion and the peripheral portion of the cutter head, and to excavate the ground evenly.

<E> When excavating with a shield device from both sides of the excavation plan line, the shield device is removed at the underground junction and the tunnel is penetrated.

At this time, if the periphery of the junction is formed of soft ground, earth and sand may flow into the tunnel when the shield device is removed.

However, in the case of the present invention, it is possible to extend the small-diameter shield device, inject the chemical solution, and improve the ground around the junction reliably and without delay.

Therefore, when the shield device is removed, earth and sand do not flow into the tunnel, and the tunnel can be safely and quickly penetrated.

<F> When excavation is performed only by the conventional large-diameter shield device, temporary stress release occurs in the ground, which may cause deformation of the ground.

However, in the case of the present invention, by holding the internal pressure of the small-diameter shield device in the housed state high, the ground at the center portion on the face side can be supported, and the deformation of the ground can be reduced.

[Brief description of the drawings]

FIG. 1: Cross-sectional view of a two-stage shield device used in the method of the present invention FIG. 2: Front view of a two-stage shield device used in the method of the present invention FIG. Illustration of internal structure Fig. 4: Illustration showing chemical solution injection process Fig. 5: Illustration of shield device used in conventional shield method

Claims (1)

(57) [Claims] 1. A shield device which excavates the ground by an excavation portion located on the front surface of a cylindrical body and moves forward in the ground by a propulsion force of a jack while assembling a segment at a rear portion. A large-diameter shield device having a central hole parallel to the tunnel axis direction and having a reaction wall for small-diameter shield provided therein; and a small-diameter shield device housed in the central hole of the large-diameter shield device. The small-diameter shield device is configured to be able to start independently and independently of the large-diameter shield device by obtaining a reaction force on the reaction force wall of the segment and the large-diameter shield device assembled in the small-diameter shield device. A two-stage shield device.