JPS6343557B2 - - Google Patents

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a circumferential shield segment that is installed on the inner circumferential surface of the enlarged excavated portion by enlarging and excavating the outer circumference of an existing tunnel constructed using the shield method. It is.

(Prior art) A conventional shield segment is a ring-shaped assembly of plate-shaped segment pieces each having an arcuate surface that fits the inner peripheral surface of a tunnel excavated by a shield machine that is propelled along the axial direction of the tunnel. It was something to wear.

(Background of the Invention) When constructing a subway station or connecting underground cables, it becomes necessary to enlarge a portion of a tunnel.

The conventional method for carrying out the above expansion work is as follows:
A shaft was dug from the ground in the area where the existing tunnel was to be expanded using the shield method, and this shaft was used to construct the expanded tunnel.

However, in recent years, in view of the fact that tunnel construction routes have become deeper underground due to the restrictions of various aboveground and underground obstacles in urban areas, it has become increasingly difficult to implement this method, and the shafts that have been excavated have also been expanded. There was also a cost problem as all but the rear part had to be backfilled.

Therefore, the applicant of the present application previously proposed a tunnel expansion excavation method that improves these conventional methods in Japanese Patent Application No. 153966/1983. This new construction method involves creating an expanded excavation section for the shielding machine's launch base at one end of the area scheduled for expansion within the tunnel where primary shielding has been performed.
Here, an expanding shield machine that propels in the axial direction along the outer periphery of the primary shield segment is installed, and the expanding shield machine is propelled to perform expanding excavation, and the primary shield segment of the expanded excavation area is sequentially removed while expanding into the expanded excavation area. It is designed to provide a secondary shield.

For this purpose, it is necessary to carry out an enlarged excavation with a relatively short length in the axial direction, such as the enlarged part for the starting base of the enlarged shield machine that is propelled in the axial direction in the tunnel enlargement method, and also to A special circumferential shield segment is also required which is attached to the inner circumferential surface of the tunnel and is connected to the primary shield segment applied to the existing tunnel.

(Problems to be Solved by the Invention) The circumferential shield segment described above requires a face plate to cover the donut-shaped gap that occurs between the circumferential shield segment and the primary shield segment installed in the existing small-diameter tunnel. The conventional shield segment structure cannot be used as is.

Therefore, an object of the present invention is to provide a circumferential shield segment that can be adapted to an enlarged excavation section where the length in the axial direction of the tunnel is relatively short, such as the starting base of the above-mentioned enlarged tunnel.

(Means for Solving Problems) The gist of the present invention is to remove a primary shield segment installed in an existing tunnel, enlarge its outer periphery, excavate it, and attach it to the inner circumferential surface of the enlarged excavated portion. The segments are donut-shaped when assembled, and the segments are constructed between fan-shaped ridge-fastening plates arranged oppositely at intervals and the wide ends of the ridge-fastening plates. This is a circumferential shield segment formed by an outer peripheral plate that connects the plates.

(Example) Examples of the present invention will be described below with reference to the drawings together with the state of use thereof.

FIGS. 1A to 1F are explanatory diagrams showing the construction work process of the enlarged excavation section.

First, as shown in FIG. 1A process diagram and FIG. Remove it from the inside of the tunnel in a direct line along the
Of the divisible guide rings 5 previously installed between the segment 3 within the planned expansion area and the adjacent segment 4 outside the planned expansion area, the guide ring piece 5a installed on the segment 3a to be removed is removed.

In order to facilitate removal, it is desirable that the segments 3 in the area to be expanded be arranged in advance in the form of a base plate, or that the joint surfaces of the segments be inclined inward.

A steel box 6 is installed at the position of the removed segment 3a. This steel box 6 is a rectangular cylindrical frame body, and at least the plate material in the direction perpendicular to the axis of the tunnel is removably tensioned with screw means. A reception area is provided.

Next, as shown in step B in FIG. 1, a jack 7 is installed between the jack holder of the steel box 6 and the upper primary shield segment, and the steel box 6 is pushed into the ground 8 by the extension of the jack. It is press-fitted, and the inside is excavated by hand digging or other excavation means. After one rod of the previously installed steel box 6 has been sunk, similar steel boxes are stacked, the jack is extended again and the box is sunk into the ground 8, and the process of excavating the inside of the box is repeated until it is sunk to a predetermined depth. and perform internal excavation.

Next, as shown in step C in FIG. 1, a bottom plate 6a is attached to the bottom surface of the steel box 6 that was first sunk.
This steel box 6 is for earth retention and is provided to prevent the collapse of the ground 8 in the excavated portion, but it may be omitted depending on the soil quality.

3 and 4, the guide ring 5 is returned to its original annular shape with the removed guide ring piece 5a fitted into the circumferential shield machine 9, and the steel box 6 is Then, the guide ring pieces 5a are tightly tied to the segments 4 outside the expansion area adjacent to both sides of the area 2 to be expanded. The circumferential shielding machine 9, like a general shielding machine, is equipped with a skin plate 9a having a cutting edge formed at the tip on the outer circumferential side, and a shield jack 9b mounted within the skin plate. The base of this shield jack 9b is pivotally attached to the inside of the hood, and the cylinder protrudes rearward.

The circumferential shielding machine 9 has a skin plate 9a formed in an arc shape that matches the circumference to be expanded and excavated, and an inner diameter portion of which is formed into an arc shape that is approximately equal to the outer diameter of the primary shield segments 3 and 4, and a tip side of the inner diameter portion. is provided with a cutting edge 9c similar to the skin plate, and a leg 9d having an L-shaped cross section protrudes from the inner diameter portion for fitting into the guide ring 5. On the other hand, the guide ring 5 is an annular assembly of guide ring pieces 5a which are divided into the same number of primary shield segments in the circumferential direction, and its cross-sectional shape is similar to that of the circumferential shield machine 9, as shown in FIG. It is formed into a groove shape into which the leg piece 9d can be fitted.

Therefore, the shielding machine 9 can freely slide along the guide ring 5, and in this case, although not shown in the drawings, in order to improve the slidability between the leg piece 9d and the guide ring 5, as necessary. A sliding member such as a roller or a sliding plate can be attached.

In the above embodiment, in order to facilitate the fitting of the circumferential shield machine 9 onto the guide ring 5, the guide ring is made separable, and some of the guide ring pieces 5a are removed before fitting the circumferential shield machine. Although the guide ring 5 and the shape of the leg 9d of the circumferential shield machine may have a structure in which it is not necessarily necessary to separate or remove the shield, the guide ring 5 and the circumferential shield leg 9d may be of different shapes.

Further, the configuration in which the guide ring 5 is installed in advance between the primary shield segments 3 and 4 inside and outside the planned expansion area 2 can also be configured such that the guide ring 5 is installed along the inner periphery of the primary shield segment 4 adjacent to the planned expansion area. There is no need to install it in advance.

Continuing to explain the step C in FIG. 1, a reaction force receiver 10 is attached to the inner surface of the sunken steel box 6 opposite to the direction in which the circumferential shield machine 9 is propelled, and this reaction force receiver 10 and the circumference A circumferential shield segment 11 having the configuration shown in FIG. 5 is installed between the shield machine 9 and the base thereof is attached to the guide ring 5 as shown in FIG. Fix it.

This circumferential shield segment 11 has a slightly different shape depending on the mounting angle position like a normal shield segment, and there are various types of segment pieces such as A type, B type, K type, etc., but basically the shape shown in Fig. 5 is as follows. As shown in the figure, the top and both sides of the reinforcing frame made of channel steel are surrounded by a top plate having an arcuate surface and trapezoidal side plates made of steel plates to form a U-shaped cross section. A mounting hole 11a is provided for mounting on the guide ring 5, and mounting holes 11b are provided at the edges of the open front and rear surfaces for connecting adjacent circumferential shield segments with each other by screw means.

Although not shown, reaction force receivers for the shield jack 9b are provided on the inner surfaces of both end plates of the circumferential shield segment 11.

Next, as shown in step D in FIG. 1, the circumferential shield machine 9 is
Remove the front side plate 6b on the side that propels the machine, extend the shield jack 9b using the circumferential shield segment 11 whose base is attached to the guide ring 5 as a reaction force receiver, and move the circumferential shield machine 9 along the circumferential direction. While propelling it into the ground in front of it, the ground inside the circumferential shield machine is enlarged and excavated by hand or by excavating means such as an earth auger (not shown) attached to the center of the circumferential shield machine.

In this case, the reaction force of the circumferential shield machine 9 is transmitted from the pressed circumferential shield segment 11 to the ground via the reaction force receiver 10 attached to the rear side plate 6c of the steel box 6.

Then, a new circumferential shield segment 11 is disposed adjacent to the previously installed circumferential shield segment in the enlarged excavation part, and the base part is connected to the mounting hole 11a.
The opening edge is fixed to the guide ring 5 through the mounting hole 11b, and the opening edge is fixed to the previously provided circumferential shield segment through the mounting hole 11b.

Thereafter, in the same process, enlarging excavation is carried out while the circumferential shielding machine 9 is sequentially propelled along the guide ring 5, and circumferential shielding segments are sequentially attached to the removed primary shielding segments shown in process E in FIG. The process is repeated until the primary shield segment 3b is located adjacent to the primary shield segment 3a.
In this case, the circumferential shield machine 9 is propelled while the cylinder tip of the shield jack 9b is sequentially moved so as to collide with the reaction force receiver of the circumferential shield segment adjacent to the rear of the shield machine. At this point, if the collapse of the ground from above becomes a problem, use the mounting hole 11b of the last installed circumferential shield segment to install the circumferential shield machine 9.
Close the openable and closable retaining plate 12 (see Fig. 4) attached to the blade opening, perform ground improvement as necessary to prevent the face from collapsing, and remove the primary shield segment 3b.

Then, in the same way as in the above process, enlarging excavation is carried out while propelling the circumferential shield machine 9, and the work of sequentially attaching the circumferential shield segments 11 is carried out at a position slightly in front of the steel box 6 shown in process F in FIG. Then, remove the side plate 6c of the steel box 6 and excavate until just before the box. After that, the front end side of the circumferential shield machine 9 is attached to the circumferential shield segment in the first installed steel box, and the rear end side of the circumferential shield machine is attached to the last attached circumferential shield segment, and then the circumferential shield The base side of the machine is integrally joined to the guide ring 5 by screw means, and after removing the shield jack 9b, reaction force receiver 10, etc. of the circumferential shield machine, a K-shaped circumference is attached to the inside of the circumferential shield machine 9. Install shield segment 13. As a result, expanded excavation will be carried out across the entire outer periphery of the planned expansion area 2,
The outside of the enlarged excavation section is surrounded by a circumferential shield segment 11 and a K-shaped circumferential shield segment 13 in a donut shape, thereby making it possible to obtain an enlarged tunnel in which collapse of the ground is prevented. This expanding tunnel is constructed by assembling and installing another expanding shield machine inside which propels the tunnel in the axial direction, as shown by the imaginary line in Figure 6, and by removing the front plate of the circumferential shield segment in the traveling direction. This will serve as a starting base for the expanding shield machine, and it will be possible to create a long expanded excavation section along the axial direction of the tunnel. In addition to the above starting base,
It can also be used in a variety of applications requiring the creation of relatively short extensions within the tunnel.

(Effects of the Invention) As is clear from the embodiments described above, the circumferential shield segment of the present invention covers the inner circumferential surface of an enlarged tunnel in which the outer circumference of an existing tunnel is enlarged, and at the same time protects the inner peripheral surface of the enlarged tunnel by enlarging the outer circumference of the existing tunnel. It also covers the donut-shaped gap that occurs at the joint,
It is possible to prevent the collapse of the ground.

[Brief explanation of the drawing]

Figures 1 A to F are process diagrams of the excavation method in which the circumferential shield segment of the present application is used, Figure 2 is a perspective view showing the planned expansion area in the tunnel in the same method, and Figure 3 is a guide ring with a circumferential Fig. 4 is a side view showing the propulsion state of the circumferential shield machine, Fig. 5 is a perspective view of the circumferential shield segment, and Fig. 6 is a circumferential shield attached to the guide ring. FIG. 3 is a front view showing a state in which segments are attached. Explanation of symbols, 1... Primary tunnel, 2... Area to be expanded, 3... Primary shield segment within the area to be expanded, 4... Primary shield segment outside the area to be expanded, 5... Guide ring, 6... Steel box, 7... Jyatsuki, 8... Rock, 9...
Circumferential shield machine, 10... Reaction force receiver, 11... Circumferential shield segment, 12... Earth retaining plate, 13...
K-shaped circumferential shield segment.

Claims (1)

[Claims] 1 The primary shield segment installed in the existing tunnel is removed and its outer periphery is enlarged and excavated, and the segment is attached to the inner circumferential surface of the enlarged excavated part and becomes donut-shaped when assembled, and the segments are separated at intervals. A circumferential shield segment formed of fan-shaped plate materials for cresting that are arranged in an opposing manner and an outer circumferential plate that is installed between the wide end portions of the plate materials for cresting and connecting the plate materials for cresting.