JPS6217072B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an area for expansion of a normal diameter tunnel.
The present invention relates to a circumferential expansion shield excavation method in which an expansion shield machine is propelled in the circumferential direction of the normal diameter tunnel to expand a part of the normal diameter tunnel into an annular shape, and particularly relates to an excavation method that requires fewer work steps. .

In general, the shield method is often used as an excellent construction method for tunnel excavation for subway construction and underground cable burying work, but it is often used when constructing subway stations or establishing underground cable connection work sites. It will be necessary to enlarge part of the tunnel.

The conventional method for carrying out this expansion work is to dig a vertical shaft from the ground in the area where the tunnel is planned to be expanded, which was generally constructed using the shield method.
This shaft was used to construct an expanded tunnel.

However, the method of installing vertical shafts is becoming increasingly difficult to implement in view of the fact that in recent years tunnel construction routes have become deeper underground in urban areas due to restrictions from various aboveground and underground obstacles.
In addition, there was also a problem in terms of cost, as the shaft that had been painstakingly excavated had to be backfilled, except for a portion, after the expansion work.

Therefore, in several previous applications including Japanese Patent Application No. 56-153966 (Japanese Unexamined Patent Publication No. 58-98595), the applicant proposed a tunnel expansion excavation method that improves the conventional expansion method.

According to this proposed construction method, an expansion excavation section is established at the starting end of the area scheduled for expansion in a normal diameter tunnel where the primary segment is installed, and the expansion shield machine is installed there. The expansion shield machine is propelled along the longitudinal direction of the normal diameter tunnel to excavate around the primary segment in the area scheduled for expansion, and while the primary segments of the expanded excavation area are sequentially removed, secondary excavation is carried out around the expanded excavation area. Attach the segments one after another.

By using this expansion excavation method, it becomes possible to expand the tunnel efficiently and economically.

In addition, in this already proposed enlarged excavation construction method, a construction method for providing an enlarged excavation section that serves as a starting base for the enlarged shield machine has been similarly proposed in a previous application by the present applicant.

This already proposed expansion excavation method for starting bases involves propelling a circumferential shield machine in the direction of the circumference of the normal diameter tunnel in the area where the primary segment is attached to the normal diameter tunnel, and excavating a part of the normal diameter tunnel. This is an excavation method that expands in a circular shape (circumferential expansion shield excavation method).

An outline of this previously proposed circumferential expansion shield excavation method will be explained based on FIGS. 1 to 2 A to F.

FIG. 1 shows a normal diameter tunnel T ₁ in which a primary segment 1 is installed and a planned enlargement area T ₂ represented by phantom lines. First, this expansion area T ₂
At the lower part of the primary segment 1, a required range is removed as shown by the broken line, and the end surface 1a of the primary segment 1 is exposed.

Next, as shown in Figure 2A, the normal diameter tunnel T ₁
Place the earth retaining steel box 2 over the removal range of the primary segment 1, and place the jack 3 as shown in Figure B.
The steel box 2 is pushed into the ground 4 using a screwdriver and buried. In addition, when it is desired to increase the burial depth, the steel boxes 2 are stacked in two or more stages as shown in the figure.

Next, as shown in FIG. 2C, after the earth 4 within the steel box 2 is excavated and removed by hand digging or the like, a circumferential shield machine 5 is installed inside the steel box 2. The circumferential shield machine 5 is equipped with a propulsion jack 6, and the propulsion jack 6 is initially attached to the reaction force receiver 2 of the steel box 2.
A reaction force is obtained from a, and then a reaction force is obtained from the secondary segment 7 to propel the circumferential shield machine, for example, counterclockwise in the figure. Furthermore, among the steel boxes 2,
The side wall 2b on the advancing side of the circumferential shield machine 5 is removed.
Further, when the soil quality of the ground 4 is good, the steel box 2 itself may be omitted.

In addition, the circumferential shield machine 5 has a normal diameter tunnel.
It is attached to a guide ring 8 installed on the primary segment 1 along the circumferential direction of T ₁ and is propelled along this guide ring 8 in a substantially circumferential direction. Furthermore, the secondary segments 7 are attached to the guide ring 8 in a hole surrounded by the steel box 2, and as the circumferential shield machine 5 advances, the number of secondary segments 7 is added to the circumferential shield machine 5. Pushed to the 5th side.

Figures D to E show the state in which the circumferential shield machine 5 is propelled and the primary segments 1 are removed one by one, and Figure F shows the state in which the expanded excavation has been completed and the secondary segments 7 have been removed throughout the area to be expanded _T2 . The state shown is that it is attached to the circumference.

The enlarged excavation section completed in the planned expansion area T ₂ as described above will be used as a starting base for an enlarging excavator (not shown) that propels the normal diameter tunnel T ₁ in the longitudinal direction, and will also be used as a tunnel enlargement section as it is. Sometimes used.

According to the previously proposed circumferential expansion shield excavation method described above, it becomes easy to set up a starting base for the expansion shield machine that advances in the longitudinal direction of a normal diameter tunnel, and it has the advantage of streamlining tunnel expansion work. The advantage is that excavation of extensions in small areas is safe and economical.

The purpose of the present invention is to further improve the previously proposed circumferential expansion shield drilling method, thereby eliminating the need for burying a steel box or pre-drilling a hole for installing a circumferential shield machine, thereby reducing the number of work steps. An object of the present invention is to provide a circumference expanding shield excavation method that requires less.

In accordance with this objective, the gist of the present invention is to install a guide ring along the circumferential direction of the normal diameter tunnel, the starting end of which protrudes into the internal space of the normal diameter tunnel, and whose intermediate and terminal ends contact the primary segment;
The purpose is to propel a circumferential shield machine guided by this guide ring from the starting end of the guide ring, and to cut into the exposed ground by removing a required range of the primary segment.

The present invention will be explained below based on the embodiments shown in FIGS. 3 to 12. Note that parts that are the same as or correspond to those shown in FIGS. 1 and 2 will be described using the same reference numerals.

3 to 10 show a first embodiment of the invention, according to which the expansion shield machine 5 is guided in the area T ₂ to be expanded in the normal diameter tunnel T ₁ in which the primary segment 1 is installed. A guide ring 18 is attached to the primary segment 1 along the circumference of the normal diameter tunnel _T1 . This guide ring 18 consists of an arc-shaped starting end 19 that projects into the internal space of the primary segment 1, an intermediate part 20 that contacts the primary segment 1, and a terminal end 21. As shown in FIGS. 6 to 8, the starting end portion 19 is made of, for example, I-shaped steel, and the intermediate portion 20 and the terminal end portion 21 are made of, for example, H-shaped steel. Further, the starting end 19 is held at a predetermined position within the primary segment 1 by a fixing member 23 .

On the other hand, as shown in FIGS. 6 and 10, the circumferential shielding machine 5 has a substantially U-shaped cross section and a substantially fan-shaped side plate portion 5a and a bottom plate portion 5b.
A flange portion 5c extending outward is formed at the free end portion of a, and each flange portion 5c is provided with, for example, two protruding guides 5d. As shown in FIGS. 6 to 8, the protruding guide 5d slides in the groove of the I-shaped steel that becomes the starting end 19, and the flange 5c is formed at the lower part of the H-shaped steel that becomes the intermediate section 20 to the terminal end 21. It slides on the horizontal ridge 24. In addition, since each starting end part 19 is connected to the outside of the intermediate part 20, the protruding guide 5d of the circumferential shielding machine 5 protrudes outward from the intermediate part 20, and the circumferential shielding machine 5 is connected to the outside of the intermediate part 20. When the part 20 is reached, the protruding guide 5d becomes an obstacle, so cut it off. Incidentally, reference numeral 25 in FIG. 9 indicates a connecting fitting between the starting end portion 19 and the intermediate portion 20. Further, as shown by the broken line in FIG. 5, the terminal end portion 21 is detachable so as not to interfere with sliding at the starting end portion 19 of the circumferential shield machine 5.

It goes without saying that the circumferential shield machine 5 has a digging blade or a skin plate (not shown) on the advancing side and a propulsion jack 6. In addition, the circumferential shield machine 5 is connected to the primary segment 1
Of course, at the point where the first cut is made into the ground 4 on the outer periphery, the primary segment 1 is removed in advance over a required range. The removal range of the primary segment 1 is usually set at the lower part of the primary segment 1, but this primary segment 1 removal work may be performed before or after the installation of the guide ring 18. However, it is desirable to remove a predetermined area of the primary segment 1 before installing the guide ring 18, and to fix the middle part 20 of the guide ring 18 to the end face 1a thereof.
In this case, the intermediate portion 20 may be made replenishable, and as the removal range of the primary segment 1 widens, the intermediate portion 20 may be sequentially extended.

In the method of the present invention, the circumferential shield machine 5 is propelled from the starting end 19 of the guide ring 18 arranged as described above. As shown in FIG. 3, the circumferential shield machine 5 rotates around the center of curvature O of the starting end 19, and its four corners a, b, c, and d are located in the area T to be expanded as shown in the figure. It gradually intrudes into the ground 4 in ₂ in an arc. At this time, the terminal end 21 of the guide ring 18 is removed in advance. Until the circumferential shielding machine 5 reaches the intermediate part 20, the excavation depth changes from shallow to deep, so the dimensions of the secondary segments 7a to 7d attached to the enlarged excavation part are adjusted accordingly. Try to gradually increase the size. Note that the secondary segments 7a to 7
d can be attached using the terminal end 21 of the guide ring 18. After the circumferential shield machine 5 reaches the intermediate portion 20, excavation is sequentially performed using the secondary segments 7 of a predetermined size. Note that this secondary segment 7 can be attached using the intermediate portion 20 of the guide ring 18. Next, when the circumferential shielding machine 5 approaches almost one circumference, as shown in FIG.
e are successively removed, the circumferential shielding machine 5 is further advanced to perform excavation to the full depth, and finally the entire enlarged excavation is shielded with a secondary segment 7 of a predetermined size. During the above work, guide ring 1
The starting end of 8 is removed after passing the circumferential shielding machine 5, and the circumferential shielding machine 5 may be buried at the end of the work.

11-12 show a second embodiment of the present invention,
The rotation center O until the circumferential shield machine 5 cuts into the ground 4 is set on the primary segment 1,
There is an advantage that the guide ring 18 can be shortened and the number of small-sized secondary segments 7a to 7b can be reduced.

As explained above, according to the present invention, the circumferential shielding machine gradually cuts into the ground around the outer periphery of the primary segment from the internal space of the primary segment along the guide ring, so the circumferential shielding machine is installed outside the primary segment. There is no need to dig a hole in advance for the purpose of excavation, and the effect is that the enlarged excavation work becomes extremely efficient.

[Brief explanation of the drawing]

Figure 1 is a schematic vertical cross-sectional view of a normal diameter tunnel to show the previously proposed circumference-expanding shield excavation method, and Figure 2 is a cross-sectional view taken along the line -A in Figure 1.
~F is a process diagram of the previously proposed circumference-expanding shield excavation method, FIGS. 3 and 4 are process diagrams of the circumference-expanding shield excavation method according to the first embodiment of the present invention, respectively, and FIG. 3 is a detailed explanatory diagram of the main parts of FIG. 3, FIG. 6 is a plan view of FIG. 5, FIG. 7 is a sectional view taken along the line - - of FIG. FIG. 5 is an enlarged view of the main part, FIG. 10 is a perspective view of the circumferential shield machine of FIG. It is a process explanatory diagram. T ₁ …Normal diameter tunnel, T ₂ …Expansion planned area, 1
...Primary segment, 4...Mound, 5...Circumferential shield machine, 5c...Flange part, 5d...Protrusion guide, 6...
Propulsion jack, 7...Secondary segment, 18...Guide ring, 19...Starting end, 20...Intermediate portion, 21...
Termination portion, 23...fixing material, 24...horizontal flange, 25...
Connection fittings.

Claims (1)

[Claims] 1. An excavation method in which a circumferential shield machine is propelled in the circumferential direction of the normal diameter tunnel in a planned expansion area of the normal diameter tunnel where the primary segment is installed, and a part of the normal diameter tunnel is expanded into an annular shape,
A circumferential shield is provided along the circumferential direction of the normal diameter tunnel, and is guided by the guide ring, the guide ring having a starting end protruding into the normal diameter tunnel interior space and an intermediate part and a terminal end touching the primary segment. Propelling the machine from the starting end of the guide ring, cutting into the exposed ground by removing a required range of the primary segment, and sequentially propelling the circumferential shield machine along the guide ring. A circumferential expansion shield excavation method characterized by expanding and excavating the outer periphery of the primary segment.