JPS6217071B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an enlarged tunnel excavation method, and particularly to an enlarged tunnel excavation method in which an enlarged tunnel is excavated in the middle of a normal tunnel. In this type of conventional expansion excavation method, it is common to widen a normal diameter tunnel by excavating a vertical hole from the ground in the area planned for expansion, which has been excavated by a primary shield excavation machine with a normal diameter. Ta.

However, the above construction method has disadvantages such as the difficulty of securing a place to excavate a vertical hole in the recent overcrowded ground conditions, and the need to backfill the excavated vertical hole after the widening work is completed. Improvement was desired.

Therefore, the applicant first excavated a normal-diameter tunnel with a primary shield excavator, then partially enlarged and excavated one end of the planned expansion area of the tunnel to establish a starting base, and expanded the shield excavation at this starting base. The machine is assembled and installed, and the expansion shield excavation machine is propelled to carry out expansion excavation while sequentially removing the primary segments that have already been installed throughout the area to be expanded, and at the same time, the secondary segments are applied to the inner surface of the widening area. We proposed a construction method for constructing an expanded tunnel. The purpose of this application is to further improve this construction method, and its gist is that when a primary shield excavator is used to excavate a normal-diameter tunnel and the area to be expanded is reached, a starting base is placed behind the primary segment constructed in the normal-diameter tunnel. An enlarged section is provided, and the enlarged shield tunneling machine is assembled in the enlarged section and engaged in a pressable manner with the rear end of the primary segment, and the jacks of the primary shield tunneling machine are first extended to remove the primary shield tunneling machine. An expanding shield excavator that is propelled to excavate a normal diameter, then shortens the jack of the extended primary shield excavator, and extends the jack of the expanded shield excavator, and is propelled while pressing the rear end of the primary segment. Excavation with an enlarged diameter is carried out at the same time, and then the jack of the expanding shield excavator is reduced to form a secondary segment on the inner surface of the widening section, and then the primary shield excavating machine and the expanding shield excavating machine are alternately propelled in the same manner as described above. This construction method involves excavating an expansion tunnel in the area scheduled for expansion.

This improves the previously proposed construction method, which required constructing a single primary segment over the entire area planned for expansion and then removing it again during widening work, shortening the construction period and making it more economical. This will further improve the effectiveness of the project.

Embodiments of the present invention will be described below with reference to the drawings. First, as shown in FIG. A diameter tunnel 2 is excavated to one end of the area 3 to be expanded, and a primary segment 4 is applied to the inner surface of the normal diameter tunnel 2. The primary shield excavator 1 is propelled by extending the jack 1a using the already tensioned primary segment 4 as a reaction force receiver, and after excavating the face, the jack 1a is retracted and the erector device is attached to the inner surface of the tunnel. This is similar to the conventional shield construction method, in which a new primary segment is connected to an already tensioned primary segment for tensioning.

Next, several rings of the primary segment 4 stretched at one end of the area to be expanded 3 behind the primary shield excavator 1 are removed from the inside of the tunnel, and the inner end of the removed ring is marked as shown in FIG. 1B. The guide ring 5 is attached, and the inner shield excavator 7 is installed in a steel box 6 buried in the lower part of the inner periphery, and while the jack 7a of the excavator is extended, the guide ring 5 is installed, and the inner circumferential shield excavator 7 is Perform excavation and build launch base 8. On the inner surface of this starting base 8, circumferential segments 9 made of steel and having an inward letter shape are installed in succession each time circumferential excavation is performed to prevent the collapse of the ground.
Depending on the soil quality, ground improvement by chemical injection or the like may be performed in the area 10 around the base indicated by diagonal lines.

Next, inside the starting base 8, the
As shown in FIG.
Assemble and install 1.

Next, the front plate 9a of the circumferential segment 9 is removed, and as shown in FIG. Expanding shield excavator 11 while extending the jack 13 by the length of one segment as a reaction force receiver.
As shown in FIG.
4 in sequence. This initial propulsion is carried out until just before the sliding contact between the tail seal of the expanding shield tunneling machine 11 and the circumferential segment 9 is released, and then the initial propulsion jack 13 and the temporarily assembled segment 1
Remove 4. Then, as shown in FIG. 5, a secondary segment 14 is integrally stretched on the inner surface of the circumferential segment 9, and
b is the skin plate 1c of the primary shield excavator 1
When overlapped with the rear end portion, the enlarged shield excavator 11 is engaged and connected to the primary segment 4 of several rings remaining at the rear of the primary shield excavator 1 so that it can be pressed.

As shown in FIGS. 6A and 6B, this connecting part has a connecting fitting 1 bolted to the rear end of the primary segment 4 on one side and an enlarged shield excavator 11 on the other side.
5, the two are integrally joined.

The primary shield excavator 1 and the enlarged shield excavator 11, which are thus engaged through the primary segment 4 of several rings, excavate an enlarged tunnel in the following manner.

First, as shown in Figure 6A, the primary shield excavator 1
When the jack 1a is extended, the primary segment 4 locked to the enlarged shield tunneling machine 11 is used as a reaction force to propel the primary shield tunneling machine 1 by one segment.

Next, as shown in FIG. 6B, while retracting the jack 1a of the extended primary shield excavator 1, the jack 11a of the expanded shield excavator 11 is extended using the already tensioned secondary segment 14 as a reaction force receiver. , the expansion shield excavator 11 is propelled by one segment.

Next, as shown in FIG. 6C, the jack 11a of the extended expanded shield excavator 11 is retracted, and a new secondary segment is joined to the already tensioned secondary segment on the inner surface of the widened part. It is stretched by the erector device 12. Similarly, the primary shield excavator 1 and the enlarged shield excavator 11
The enlarged tunnel is constructed by carrying out enlarged excavation in the planned expansion area 3 while alternately promoting the excavation. When continuing to excavate a normal diameter tunnel after the widening is completed, use the expanding shield excavator 1 again.
1 from the primary segment 4 and dismantle it.
This is done by the primary shield excavator 1.

In this way, the present construction method is not limited by ground conditions, unlike the conventional method of digging a vertical hole from the ground during widening work, and does not require backfilling of the vertical hole after widening work, and is similar to the method previously proposed by the applicant. Unlike construction methods in which a normal-diameter tunnel is first constructed and excavation is carried out by sequentially removing the primary segments that have been installed over the entire area scheduled for expansion during widening work, the primary segments are only installed locally. It is possible to further improve work efficiency by performing enlarged excavation.

Furthermore, by alternately propelling the primary shield tunneling machine and the expansion shield tunneling machine, a normal diameter tunnel is first excavated and then the area around it is widened, making it easier to excavate. It is something that plays.

[Brief explanation of the drawing]

The drawings all show embodiments of the present application, and FIG. 1 is an explanatory diagram showing the construction state of the expansion part for the launch base, FIG. 2 is an explanatory diagram showing the assembled state of the expansion shield excavator, and FIG. and Fig. 4 are explanatory diagrams showing the initial excavation state, Figs. 5 and 6 are explanatory diagrams showing the engaged state of the primary shield excavation machine and the enlarged shield excavation machine, and Fig. 7 is an explanatory diagram showing the same excavation state. It is a diagram. Explanation of symbols, 1...Primary shield tunneling machine, 2...Normal diameter tunnel, 3...Expansion planned area, 4...Primary segment, 5...Guide ring, 6...Steel box,
7... Circumferential shield excavator, 8... Starting base, 9... Circumferential segment, 10... Base surrounding area, 11... Expanding shield excavator, 12... Erector device, 13... Initial propulsion jack, 14... Temporary assembly segment, 15...
Connection fittings.

Claims (1)

[Claims] 1. When the area to be expanded is reached while excavating a normal-diameter tunnel with a primary shield excavator, an enlarged part that will serve as a starting base is provided behind the primary segment made in the normal-diameter tunnel, and the enlarged shield excavation is carried out in this enlarged part. The machine is assembled and pressably engaged with the rear end of the primary segment, and the jack of the primary shield excavator is first extended to propel the primary shield excavator to excavate a normal diameter. Reduce the jitter of the shield excavator and increase the jitter of the expanded shield excavator,
Excavation of an enlarged diameter is performed using an expanding shield excavator which is propelled while pressing the rear end of the primary segment, and then the jerk of the expanding shield excavator is reduced to form a secondary segment on the inner surface of the widened section, and the following steps are carried out as described above. Similarly, an expansion tunnel excavation method is characterized in that an expansion tunnel is excavated in an area to be expanded while alternately propelling a primary shield excavation machine and an expansion shield excavation machine.