JPS6217068B2 - - 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 the gist is that when a tunnel of normal diameter is excavated with a primary shield excavator and the area to be expanded is reached,
An enlarged part serving as a starting base is provided at the rear of the primary segment made in the normal diameter tunnel, and an enlarged shield excavator is assembled in the enlarged part and pressably engaged with the rear end of the primary segment. While the jacking of the primary shield tunneling machine is stopped, the expanding shield tunneling machine is propelled by using the jacking of the expanding shield tunneling machine, and the primary segment whose rear end is pressed by the expansion shield machine drives the primary shield tunneling machine. This is an enlarged tunnel excavation method in which the outer circumference of a normal diameter tunnel is expanded and excavated simultaneously.

This improves the previously proposed construction method, which required constructing a single primary segment over the entire area planned for expansion and 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. A circumferential shield excavator 7 is installed in a steel box 6 buried at the bottom of the circumference, and a circumferential shield excavator 7 is installed along the guide ring 5 while extending the jack 7a of the excavator. 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, each divided unit is assembled and installed with a donut-shaped expansion shield excavator 11 using an erector device 12.

Next, the front plate 9a of the circumferential segment 9 is removed, and as shown in FIG. Expanding shield excavator 1 while extending the jack 13 as a reaction force receiver by the length of the primary segment.
1 is advanced one segment at a time, and the temporarily assembled segments 14 are successively installed in the gaps created by the advancement, as shown in FIG. This initial propulsion is carried out until just before the sliding contact between the tail seal of the enlarged shield tunneling machine 11 and the circumferential segment 9 is released, and then the initial propulsion jack 13 and the temporarily assembled segment 14 are removed.

As shown in FIG. 5, the secondary segment 14 is integrally stretched on the inner surface of the circumferential segment 9. At the point where the two rings are overlapped with each other, the enlarged shield tunneling machine 11 is engaged and connected to the primary segment 4 of the several rings remaining behind the primary shield tunneling machine 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, the jack 1a of the primary shield excavator 1 is kept in the retracted state, and the jack 11a of the expansion shield excavator 11 is extended, and the secondary segment 14, which has already been stretched, receives the reaction force. 1 segment.

As a result, the primary segment 4 connected via the connecting fitting 15 is propelled by one segment in the same manner as in the push pipe construction method, and the jack 1a in front of the primary segment 4 is pressed to push the primary shield excavator. 1 is also propelled by one segment.

Next, the jack 11a of the extended expanded shield tunneling machine 11 is retracted, and a new secondary segment is joined to the already tensioned secondary segment on the inner surface of the widened part, and the erector device 12 is
Tension it by.

Similarly, while the expansion shield excavation machine 11 and the primary shield excavation machine 1 are simultaneously advanced by the propulsion force of the jack 11a of the expansion shield excavation machine 11,
Expanding excavation will be carried out in the planned expansion area 3 and an expanded tunnel will be constructed.

When continuing to excavate a normal diameter tunnel after completion of widening, the enlarging shield excavator 11 is again removed from the primary segment 4, dismantled and removed, and the primary shield excavator 1 excavates.

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 the construction method 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.

[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, and FIGS. 5 and 6 are explanatory diagrams showing the engaged state of the primary shield excavation machine and the enlarged shield excavation machine. 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. Assemble the machine and pressably engage the rear end of the primary segment, and with the jack of the primary shield machine at rest, use the jack of the expanding shield machine to propel the expanding shield machine. An enlarged tunnel excavation method characterized in that a primary shield excavator is simultaneously propelled by a primary segment whose rear end is pressed by the enlarged shield machine to enlarge and excavate the outer periphery of a normal diameter tunnel.