JPS5933753B2 - Underground cutting and expansion type shield construction method - Google Patents

Description

[Detailed Description of the Invention] This invention involves excavating a tunnel (using the shield method) in relatively hard ground such as the 4th layer, and easily cutting and widening the tunnel cross section at any point along the way to construct a widening section. This is related to the underground cutting and expansion type shield construction method that can be used.

Traditionally, the space for cable joints in shield tunnels where power cables, communication cables, etc. are laid was secured by vertical shafts, but in recent years, in the case of tunnels in cities, it has become difficult to install vertical shafts due to environmental conditions. It's coming.

For this reason, it is necessary to cut and widen the tunnel underground and construct a widening section.

Conventionally, as underground cutting and expansion construction methods for shield tunnels, freezing construction method, chemical injection construction method, spectacle shield construction method, etc. are known, but these construction methods have the following drawbacks.

(1) Freezing construction method: A construction method that creates a structure that can secure the required space by freezing the ground that includes the area to be expanded, increasing the strength of the rock, and creating a structure that can secure the required space. However, depending on the geology, the phenomenon of ground heaving during freezing and sinking of the ground when thawing occurs, and the construction cost is high.

(2) Chemical injection method: This is a construction method that increases the strength of the ground by injecting and solidifying the ground that includes the area to be widened, thereby creating a structure that can secure the required space. However, due to its lack of reliability, it is difficult to measure ground stability using the chemical injection method alone, and the construction cost is high.

(3) Glasses shield method: A construction method in which two shield tunnels are excavated in parallel, a vibratory roof etc. is inserted from inside the tunnel between them to press down the ground, and then the earth and sand between the tunnels is excavated to secure the required space. Yes, in the case of a subway tunnel, single-track shield tunnels can be paralleled to form a double track, and the widened area can be used as a station area, but in the case of a tunnel for electric power cables or communication cables, parallel shield tunnels must be dug at the same time. Since there is no such area, it is difficult to implement, and has the drawback of requiring a large amount of land.

On the other hand, when building a tunnel, its cross-sectional shape may be circular, oval, horseshoe, rectangular, etc. From the viewpoint of the structure and safety, it may be constructed of curved lines such as circular, oval, horseshoe, etc. A cross-section which is closed at the same time is advantageous.

That is, it is important to configure the stress state in the vicinity of the open surface of the ground by a compression zone, and to avoid as much as possible a shape with a straight line that is likely to generate tensile force, since the ground is extremely weak against tensile force.

The present invention eliminates the above-mentioned drawbacks, and makes it possible to easily, safely, and economically construct a widening section having a curved contour or a similar contour that is advantageous in terms of the structure of the tunnel at any position during tunnel excavation. The purpose is to provide an underground cut-off type shield construction method.

Next, the present invention will be explained in detail using illustrated examples.

FIGS. 1 to 6 show an example of a shield machine used in the present invention, and the shield machine has an angle of approximately 120° above the lower semicircular section 7 extending in the front-rear direction, having a common center line therewith. An upper circular arc tube part 8 of ~130° is arranged,
A lateral extension plate 9 that protrudes outward along the vicinity of the horizontal center line 2 of the shield machine body is connected to the left and right upper ends of the lower semi-cylindrical part, and the outer end of the lateral extension plate 9 and the upper part Arc cylinder part 8
is connected to the lower end portion of the lateral projection portion 3 through an arc-shaped lateral projection portion 3 whose projection amount from a circle including the upper arcuate cylinder portion 8 gradually increases from the lower end portion toward the horizontal center line 2; The lateral protrusion 3 has a smaller curvature (larger radius) than the upper arcuate cylinder part 8, and the lower radius cylinder part 7. Upper arc cylinder part 8. The lateral extension plate 9 and the lateral protrusion 3 constitute a shield machine tail.

An excavation cutter 11 rotated by a drive device 10 is provided at the front of the shield machine main body 1, and a cutting surface U is provided inside the rear of the shield machine main body 1, that is, within the shield tail.
A letter-shaped rubber tail backing 12 is fitted, and an outer peripheral portion 13 of the tail backing 12 is fixed to the shield machine tail 14 with bolts 15 and band-shaped washers 16.

When the circular segment ring 4 is disposed within the shield machine tail, the gap between the inner circumferential surface of the shield machine tail and the outer circumferential surface of the segment ring 4 expands into a wedge shape at the side protrusion 30 portion.

For this purpose, the cross-sectional width of the tail backing 12 is changed into a wedge shape that matches the wedge-shaped gap, and the inner circumferential surface of the tail backing 12 is made circular so that it is in close contact with the segment ring 4 over its entire circumference.

As a means for excavating the ground in front of the side protrusion 3, a slope is provided inside the side protrusion 3 from the front to the rear and deviates toward the center of the shield machine body. A means for crushing or scraping the ground in the front part (by a wedge action) may be adopted, and when the tip of the telescopic excavation blade is rotated to a position opposite to the lateral protrusion 3, the telescopic excavation occurs. A type of excavation cutter (known as a copy cutter) whose blade is extended by cam action may also be used.

A shield jack 18 and other devices are provided inside the shield machine main body 1, but since these are the same as in the case of a conventional shield machine, a description thereof will be omitted.

A tunnel is excavated using the shield machine configured as described above, and the segment lining is constructed by sequentially assembling and adding circular segment rings 4 in the tail of the shield machine as shown in Fig. 7. go.

When cutting and widening the tunnel during tunnel excavation to construct the widening section 6, first, as shown in FIG. The navigation part upper segment 5 is connected to the existing segment ring 4, and as shown in FIG. 9, the widened part upper segment 5 is supported by an anchor member 19 such as an anchor bolt inserted into the ground. This prevents the flight part upper segment 5 from falling off when the lower half segment of the segment ring 4 is removed.

Furthermore, depending on the condition of the ground, the strength of the ground may be increased and the water stopped by chemical injection 20 or the like, and in areas where there is a particular concern about spring water, the water level may be lowered by well points 21 or the like.

Note that a vibrating roof 22 may be provided for safety in a ground that is likely to collapse when the widening portion 6 is excavated.

As mentioned above, after taking the necessary preliminary measures to excavate the widened portion 6, the widened portion 6 is excavated and formed, and the wire mesh 23 is brought into contact with the ground in the widened portion 6. Fixed with anchor bolt 24 and confirmed! J-) 25 is sprayed to maintain the ground surface of the widened section while digging through the widened section of a predetermined cross section.

As shown in FIG. 10, in the widened part 6, the thickness of the lower part is gradually increased outward so as to form a substantially uniform gap with the inner surface of the upper half of the tail of the shield aircraft. A prefabricated permanent structure, that is, a lining, is assembled and constructed using the upper segment 5 and the specially shaped lower flight section 26 having a continuous curve below it.

Next, after constructing a widened portion of the required length, a tunnel with a circular cross section is dug again using the circular segment ring 4 as described above.

A secondary concrete lining may be applied to the inside of the segments of the circular cross section and the widening section, and the permanent structure in the lower half of the widening section may be constructed of reinforced concrete without using segments. You can.

It is preferable that the lateral protrusion 3 has an arc shape,
It may be linear.

Further, in the case of the above embodiment, the side protrusions 3 extend over the entire length of the shield machine body 1, but if the ground is relatively soft, the side protrusions 3 of the shape shown in the figure may be attached only to the tail of the shield machine. A lateral protrusion is provided, and the amount of protrusion of the lateral protrusion is gradually reduced toward the front of the shield machine body, so that the lateral protrusion disappears at the front end of the shield machine body or at a portion closer to the front end of the shield machine body. Good too.

According to this invention, a shield machine is constructed by providing lateral protrusions 3 on both left and right sides of the upper half of a circular shield machine main body 1, the lateral protrusions 3 gradually increasing in the amount of protrusion from the circular shape toward the horizontal center line 2. When it becomes necessary to cut and widen the widened portion 6 because a tunnel is excavated by using the widening portion 6, the widened portion upper segment 5 whose lower outer surface protrudes laterally in the same way as the lateral protruding portion 3 is used. The widened portion 6 is cut and expanded while supporting the ground in the upper half of the tunnel cross section, and the lower widened portion segment 26 or the lower reinforced concrete lining is continuous to the lower end of the upper widened portion segment 5. It is better to provide
It is possible to easily construct a widened section lining having a lining whose entire or almost entire cross section is curved, so that the section of the widened section lining can be made relatively thin and economically constructed. At the same time, it is possible to select the most stable cross section for excavation, temporary construction, and lining of the widening section, and it is also possible to construct the widening section at the necessary location and length.

In addition, ordinary segments can be used in areas other than the widening area, making it less general, and most of the conventional shield construction techniques can be used, making it easy to universalize. In some cases, the ground near and above the horizontal center line of the shield machine body is supported by existing segments, which prevents ground collapse such as cave-ins and skin drops, ensuring worker safety. Effects such as being able to do this can be obtained.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIGS. 1 to 6 show an example of a shield machine used in the invention, with FIG. 1 being a vertical sectional side view and FIG. Its front view, Fig. 3 is an enlarged longitudinal sectional front view showing the vicinity of the side protrusion of the shield machine, Fig. 4 is a sectional view taken along line A-A in Fig. 3, and Fig. 5 is taken along line B-B in Fig. 3. The cross-sectional view, FIG. 6, is a cross-sectional view taken along the line C--C in FIG. 3. Figure 7 is a longitudinal front view showing the state in which a circular tunnel is being excavated, Figure 8 is a longitudinal front view showing the state in which the upper segment of the widening part is connected to the segment ring in the tail of the shield machine, and Figure 9 is an enlarged view. A vertical sectional front view showing the state where the width part is excavated,
Fig. 10 is a longitudinal sectional front view showing the state in which the widening section has been constructed, Fig. 11 is a longitudinal sectional side view of the tunnel with the widening section, and Fig. 12
The figure is a sectional view taken along line D-D, and Figure 13 is E-E in Figure 11.
14 is a sectional view taken along line FF in FIG. 11. In the figure, 1 is the circular shield machine body, 2 is the horizontal center line,
3 is a lateral protrusion, 4 is a circular segment ring, 5 is an upper segment of the widening part, 6 is a widening part, 7 is a lower semi-cylindrical part,
8 is an upper circular cylinder part, 9 is a horizontal plate, 11 is an excavation cutter,
12 is a rubber tail backing, 19 is an anchor part,
23 is a wire mesh, 24 is an anchor bolt, 25 is concrete, and 26 is a lower segment of the widened portion.

Claims (1)

[Claims] 1. Using a shield machine configured by providing lateral protrusions 3 on both left and right sides of the upper half of the circular shield machine main body 1, the amount of protrusion from the circular shape gradually increasing toward the horizontal center line 2,
The circular segment ring 4 is assembled in the tail of the shield machine to excavate a circular tunnel, and when the area where the width needs to be widened is reached, the upper part of the widening part whose lower parts on both left and right sides protrude in the same way as the lateral projecting parts 3. After the segments 5 are connected to the existing circular segment ring 4, the widening section 6 is excavated to construct a lower widening section lining that is continuous with the lower portions of both left and right sides of the upper widening section segment 5. Underground cutting and expanding shield construction method.