JPS6342075B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an expansion shield excavation method for expanding and excavating the circumference of an existing tunnel provided with a primary shield segment using a circumferential shield machine.

(Prior Art) The present applicant proposed the following method as the expansion shield excavation method (Japanese Patent Application Laid-open No. 106695-1983).
method).

The primary shield segments of the planned expansion area of the existing tunnel where the primary shield segments have been applied are removed in series along the axial direction of the tunnel, the ground in the removed area is enlarged and excavated, and the shield excavation machine for outer circumference excavation is carried out. A guide ring having an annular groove opening on the inner circumferential surface along the circumferential direction is installed at both ends of the area to be expanded, and a guide ring is installed in the annular groove between the two guide rings on both sides of the shield excavator. The shield tunneling machine is fitted by engaging the respective T-shaped ears formed in the shield tunneling machine, and the T-shaped ears are engaged with the guide grooves and fitted between the guide rings at the rear of the shield tunneling machine. The circumferential segment is fixed in the installed state, and the area to be expanded is expanded by alternately performing excavation with a shield excavator by pressurizing the circumferential segment with a shovel and removing the primary shield segment. .

(Problems to be Solved by the Invention) The construction method does not require the creation and backfilling of vertical shafts, unlike the construction method in which vertical shafts are excavated from the ground surface in each area scheduled for expansion and large-diameter tunnels are added. In addition, when the shield machine reaches the area to be expanded, a special enlarging blade is attached to the cutter head of the shield machine, and the diameter of the tunnel created is expanded by the operation of the blade. There are no structural defects that would make it impossible to resist earth pressure from the circumferential surface at diameters greater than or equal to All of the steps can be done in the same place, which improves work efficiency, but work efficiency is poor because the shield tunneling machine excavates and the circumferential segment assembly and segment removal are performed alternately. Since the existing tunnels and circumferential segments in the planned area will be in a missing circle, they will not have sufficient resistance to the surrounding earth pressure, and therefore reinforcement work will be necessary if the earth pressure is large.

It is an object of the present invention to provide an expanded shield excavation method that eliminates such inconveniences.

(Means for Solving the Problems) The present invention provides a means for expanding the area to be expanded in an existing tunnel in which a primary shield segment is provided and guide rings are installed in advance at both ends of the area to be expanded. The primary shield segments are removed in series along the axis of the tunnel, the ground in this removed area is excavated, a shield excavator for outer circumference excavation is installed here, and the shield excavator is slid onto both guide rings. Attach it freely,
Further, the circumferential segments are sequentially fixed in a state in which they are slidably attached to both guide rings at the rear of the shield tunneling machine in the propulsion direction, and the shield tunneling machine is sequentially fixed by applying pressure to the circumferential segment at the rearmost end. In the expansion shield excavation method, which excavates in the circumferential direction of the existing tunnel along a guide ring and seals the rear of the excavating shield excavator by continuously fixing the circumferential segments to expand and create the area to be expanded, The guide ring has an annular groove opening on the outer circumferential surface, and the shield tunneling machine and the circumferential segments sequentially fixed to the rear thereof are engaged with the groove of the guide ring, and the primary shield segment is not removed. After the shield excavator is excavated in the circumferential direction of the existing tunnel along the guide ring and the area to be expanded is expanded, all the primary shield segments in the area to be expanded are removed. Features.

(Example) Embodiments of the invention will be described with reference to the drawings.

At the time of constructing the existing tunnel 2 with the primary shield segment 1 into the ground 3, the segment 1 ₁ existing outside the planned expansion area 4 and the area 4
At the boundary with the segment 1 ₂ existing within the tunnel, there is a guide annular groove 5 which is formed of a plurality of ring segments and opens on the outer peripheral surface along the circumference of the existing tunnel 2.
A guide ring 6 having a diameter is provided. To excavate the planned expansion area 4, first, after constructing the existing tunnel 2, remove the lower segment ₁₂ ' of the segments ₁₂ in the area 4 in series along the axial direction of the tunnel, and Of the ring segments 7 that make up the ring 6, the lower ring segment _7a is also removed, and as shown in FIG. A steel box 8, which is a removable frame that communicates with the direction, is installed,
As shown in FIG. 4b, the steel box 8 is pressed into the ground 3 by extending the jack 9, the earth and sand inside the steel box 8 is discharged, and the steel boxes 8 are stacked, and the jack 9 is pressed into place. After the tip steel box 8 reaches a predetermined depth of the ground, the earth and sand are discharged to complete the construction of the forward base cavity 10. At this time, a bottom plate 8a for earth retaining is attached to the bottom of the steel box 8 that was first sunk, and a side plate 8 of the steel box 8 on the side in the propulsion direction of the shield excavator 11 is attached.
Remove b.

The shield tunneling machine 11, as shown in FIG.
As shown in FIG. 6, the shield excavator 1
It is a U-shaped frame body that is roughly similar to the main body part 13 of No. 1, and has T-shaped ears 15 and 16 at both upper ends of the frame body. shield tunneling machine 1
1 and the circumferential segment 14 are sequentially fitted between the guide rings 6, 6, and a propulsive force is applied to these to create the area 4 to be expanded. That is, the shield excavator 1 is inserted into the grooves 5 formed in both the guide rings 6, 6 with the lower ring segments 7a, 7a removed.
The shield tunneling machine 11 is mounted by engaging the T-shaped ears 15 formed on both sides of the shield tunneling machine 11 (see Figs.
Figure c), further behind this shield excavator 11,
Similarly, T-shaped ears 16 are provided on both guide rings 6, 6.
are engaged with the grooves 5 of the guide rings 6, 6 to attach the circumferential segment 14, and the joining edge 17 of this circumferential segment 14 is fixed to the joining edge 18 of the shield tunneling machine 11 by fastening bolts or the like (the first 4d), the shield excavator 11 is then propelled in the direction of the arrow by expansion and pressure by the jack 19 of this circumferential segment 14, and while the shield excavator 11 is plunged into the ground 3 in front, the inside of the shield excavator 11 is The ground 3 is excavated by hand or by an appropriate excavation means such as an earth auger attached to the center of a shield excavator 11 (not shown), and further,
At the rear of the circumferential segment 14 there is a guide ring 6,6
Then, each T-shaped ear piece 16 is engaged with the groove 5 of the guide ring 16, and the other circumferential segments 14, 14, etc. are sequentially attached, and the shield excavator 11 is moved by pressing the last circumferential segment 14 with the jack 19. The shield excavator 11 is sealed at the rear by digging and connecting the joining edges 17 between the circumferential segments 14 (Fig. 4e),
The shield excavator 11 excavates in the direction of the arrow and the earth and sand are discharged to expand the planned expansion area 4. Finally, the bottom plate 8a of the steel box 8
The side plate 8c is removed, and the shield tunneling machine 11 is returned to the cavity 10 and removed from the guide rings 6, 6. Then, the circumferential segment 14 and the reverse taper circumferential segment 14' for the key segment are attached to the removed portion of the ring segment 7a. is bolted to the adjacent segment 1 ₁ and then all segments 1 ₂ within the area to be enlarged 4 are removed. The circumferential segment 14 that engages the guide ring 6 is then fixed to the guide ring 6, for example by welding. Thus both guide rings 6,
The enlarged tunnel 20, which is composed of the circumferential segments 14 fixedly connected to each other on the entire circumference of the tunnel 6, is completed, and the enlargement construction work is completed (FIG. 4f).

In the embodiment described above, in order to facilitate the installation of the shield tunneling machine 11 and the circumferential segment 14 between the guide rings 6, 6, each guide ring 6 is divided into two parts. Before installing the ring segments 7a, some of the ring segments 7a were removed and then reinstalled after installing them.
Depending on the shape, it is possible to adopt a configuration that does not necessarily require division or removal.

(Effects of the Invention) The present invention is an enlarged shield excavation method in which the outer circumference of a primary shield segment is enlarged and excavated while a shield excavator is sequentially excavated along a guide ring, in which the guide ring is opened on the outer circumferential surface along the circumferential direction. Using a device having a groove, the shield excavator and the circumferential segments to which it is fixed in sequence to the rear are engaged with the grooves of the guide ring, and the shield excavator excavates in the circumferential direction of the existing tunnel along the guide ring. However, after the area of the tunnel planned for expansion is expanded, all the primary segments of the area planned for expansion are removed, so the workability is better than the construction method previously proposed by the applicant. Additionally, during the expansion, the existing tunnel in the area scheduled for expansion will maintain its circular shape, so it will have a large resistance to the surrounding earth pressure, and will therefore have the effect of not requiring any reinforcement work.

[Brief explanation of the drawing]

Fig. 1 is a schematic partial perspective view of the existing tunnel provided with primary shield segments, Fig. 2 is a longitudinal sectional view of the existing tunnel in Fig. 1, Fig. 3 is an enlarged view of part A in Fig. 2, and Fig. 4 Figures a to f are cross-sectional views taken along lines in Figure 2 showing the steps of the excavation method according to the present invention, Figure 5 is a perspective view of a shield excavator, and Figure 6 is a perspective view of a circumferential segment. 1... Primary shield segment, 2... Existing tunnel, 4... Expansion planned area, 5... Annular groove, 6... Guide ring, 7... Ring segment, 9... Jacket, 1
0... Cavity for forward base, 11... Shield excavator, 1
4... Circumferential segment, 19... Jacket, 20... Expanding tunnel.

Claims (1)

[Claims] 1. In an existing tunnel in which a primary shield segment has been applied and guide rings have been installed in advance along the circumferential direction at both ends of the area to be expanded, the primary shield segments in the area to be expanded are arranged in series along the axis of the tunnel. remove the ground, excavate the ground in this removed area, install a shield excavator for outer circumference excavation here, attach the shield excavator to both of the guide rings in a slidable manner, and further move the shield excavator in the direction of propulsion. The circumferential segments are sequentially fixed while being slidably attached to both guide rings at the rear, and by applying pressure to the circumferential segment at the rearmost end, the shield excavator is sequentially moved along the guide rings into the existing tunnel. In the expansion shield excavation method, in which the area to be expanded is expanded by sealing the rear of the shield excavator by continuously fixing the circumferential segments, an opening is formed on the outer circumferential surface as the guide ring. The shield tunneling machine and the circumferential segments successively fixed to the rear thereof are engaged with the grooves of the guide ring, and the shield tunneling machine is inserted into the guide ring without removing the primary shield segment. An expansion shield excavation method comprising: excavating in the circumferential direction of an existing tunnel along the tunnel, expanding a planned expansion area of the tunnel, and then removing all primary shield segments within the expansion planned area.