JP4824653B2 - Tunnel junction and method of constructing tunnel junction - Google Patents

Description

The present invention relates to a tunnel merging section provided by expanding a tunnel and a method for constructing a tunnel merging section.

Conventionally, in order to establish a junction of tunnels, etc., as a method of connecting a ramp tunnel to a main tunnel, a vertical shaft is provided from the ground to the tunnel, and the tunnels are connected to each other by the vertical shaft. However, in this method, it is good if the work base can be installed on the ground of the junction, but if there are structures or the like on the ground, the junction of the tunnel cannot be constructed.

In addition, since it takes a lot of time to construct a tunnel junction, the installation of a work base on the ground has a great impact on traffic around the work base. For this reason, a method of constructing a tunnel junction where a ramp tunnel is provided alongside the main tunnel and the two tunnels communicate with each other underground is adopted.

FIG. 10 is a diagram illustrating a state in which a lamp shield tunnel 43 is provided alongside the main line shield tunnel 41 and the junction 45 is provided by connecting the main line shield tunnel 41 and the lamp shield tunnel 43. The main shield tunnel 41 and the lamp shield tunnel 43 are joined by injecting chemicals to stop the water at the joints of both tunnels, excavating and retaining the mountain from each tunnel, and placing concrete, etc. Done in

As a method of constructing such a tunnel junction part underground, for example, a pipe roof is formed by installing a plurality of pipes that penetrate the main line tunnel and the ramp part tunnel, and the ground surrounded by the pipe roof is excavated. There is a method for constructing a tunnel junction where a tunnel junction is constructed by lining the inside of a pipe roof (Patent Document 1).

In addition, there is a tunnel construction method in which a plurality of roof shields are started from the lamp shield, a roof shield tunnel is provided so as to surround the junction, the surrounding ground is improved from the inside of the roof shield, and the junction is constructed (Patent Document) 2).
JP 2004-353264 A JP 2006-70530 A

However, in the method for constructing the merge portion according to Patent Document 1, an extra excavation portion 47 as shown in FIG. 10 is formed, so that it is necessary to purchase an extra site in addition to the site necessary for the original merge portion. There's a problem. Moreover, since it is necessary to construct a pipe roof between the main tunnel and the ramp tunnel over the entire length of the junction, there is a problem that the number of pipes is large and construction takes time.

In the tunnel construction method of Patent Document 2, the roof shield is started from the outer periphery of the lamp shield in a direction perpendicular to the lamp shield, and the roof shield tunnel is constructed while bending the route of the roof shield in the direction of the lamp shield axis. Since there is a limit to the radius, a roof shield tunnel with a larger range than necessary will be constructed. Further, since the overexcavated portion 47 as described above is formed, the site exceeding the site necessary for the merged portion is exceeded. There is a problem that an acquisition is necessary. Moreover, there is a problem that it is difficult to accurately and accurately control the turning of the plurality of roof shields.

The present invention has been made in view of such problems, and when the main tunnel and the ramp tunnel are communicated at the tunnel junction or the like, the tunnel junction is constructed within the minimum site required for the tunnel junction. An object of the present invention is to provide a tunnel merging section and a method for constructing the tunnel merging section that can be performed and have excellent workability.

In order to achieve the above-described object, the first invention provides a first tunnel, a widened portion provided in the first tunnel and provided in a stepped shape so that the amount of widening gradually increases, and the widening. A pipe roof provided in a divergent shape from the portion toward the substantially axial direction of the first tunnel, a housing provided in a region surrounded by the pipe roof and connected to the widened portion, and connected to the housing And a second tunnel provided alongside the first tunnel.

According to the first aspect of the present invention, the range in which the widening amount is small directly widens the tunnel in a staircase shape, and the range in which the widening amount is large is obtained by starting the pipe roof from the widened portion in the substantially axial direction of the tunnel. Therefore, it is possible to provide a tunnel junction that can be constructed within the minimum site required for the tunnel junction.

The second invention includes a step (a) of providing a first tunnel, a step (b) of providing a widened portion in the first tunnel, and a pipe extending from the widened portion in a substantially axial direction of the first tunnel. A step (c) of providing a roof, a step (d) of forming a water stop in a surrounding ground by the pipe roof, and a step (e) of providing a casing in a water stop region surrounded by the water stop. And a step (f) of connecting a second tunnel to the housing, and a method for constructing a tunnel junction.

In the step (c), the pipe roof is provided in a divergent shape from the widened portion, and in the step (b), widening is performed so that the amount of widening gradually increases with respect to the adjacent widened portion. The widened portion may be provided in a step shape.

In the step (c), the distance between the pipes at the upper end of the pipe roof may be smaller than the distance between the pipes at the lower end of the pipe roof. In the step (b), a pillar for partitioning the widened portion may be provided in the first tunnel. Further, in the step (e), a temporary wall is provided at a terminal portion of the housing. May be.

According to the second aspect of the invention, the range in which the widening amount is small widens the tunnel directly in a staircase shape, and the range in which the widening amount is large is obtained by starting the pipe roof from the widened portion in the substantially axial direction of the tunnel, Since it is provided in a divergent shape along the shape of the section, it can be constructed within the minimum site required for the tunnel junction, and the upper pipe interval is narrower than the lower pipe interval, A pipe roof that can withstand the earth pressure is provided, and a pillar that divides the widened section is provided, and the tunnel on the merging side is connected after the pipe roof is constructed. It is possible to provide a method for constructing a tunnel junction that can use the main tunnel even during construction of the tunnel junction.

According to the present invention, when connecting a main tunnel and a ramp tunnel at a tunnel junction or the like, the tunnel junction can be constructed within the minimum site required for the tunnel junction, and the workability is excellent. A tunnel junction and a method for constructing a tunnel junction can be provided.

Hereinafter, embodiments of the present invention will be described in detail. FIG. 1 to FIG. 9 are diagrams showing steps for constructing a tunnel junction according to the present embodiment.

First, as shown in FIG. 1, the main line shield tunnel 1 is provided with a widened portion 7a. 1A is a plan view showing a state in which the widened portion 7a is provided in the main shield tunnel 1, FIG. 1B is a cross-sectional view taken along the line AA in FIG. 1A, and FIG. It is BB sectional drawing of 1 (a). As shown in FIG. 1 (b), the main shield tunnel 1 is constructed by a shield machine (not shown).

The method of providing the widened portion 7a in the main line shield tunnel 1 is as follows. First, the water stop part 9a is given to the area | region which widens from the inside of the main line shield tunnel 1, and a ground is excavated. The water stop part 9a can be provided by chemical | medical solution injection | pouring, a freezing pipe | tube, etc., for example. Next, the widened portion segment 5a corresponding to the widened portion 7a is moved in the widening direction. As shown in FIG.1 (c), the widening segment 3a which has the width | variety corresponding to the moving amount | distance of the wide part segment 5a is installed between the main line shield tunnel 1 and the wide part segment 5a.

Note that the widened portion segment 5a may be newly installed with a segment for the widened portion 7a, instead of moving and using the segment used in the main line shield tunnel 1. Further, during the movement of the widened portion segment 5a, a support or jack (not shown) is provided in the main line shield tunnel 1 as necessary. Further, for example, the widened portion 7a may be provided by using a tunnel construction method disclosed in JP-A-2006-348678.

Next, as shown in FIG. 2, the widening work is repeated, and the widening amount is increased stepwise, thereby providing the widened portion 7 e. 2A is a plan view of the main shield 1 in a state where the widened portion 7e is provided in a stepped shape, FIG. 2B is a cross-sectional view taken along the line C-C in FIG. 2A, and FIG. It is DD sectional drawing of Fig.2 (a).

A method of providing the widened portion 7e from the widened portion 7a in a stepped manner is as follows. First, from the widened portion 7a constructed by the widened portion segment 5a, a water stop portion (not shown) is provided in the widened portion 7b planned construction portion, and the ground is excavated. Next, the widened portion segment 5b is moved to the excavation portion, the widened segment 3b corresponding to the amount of movement is installed, and the widened portion 7b is provided.

The above operations are repeated to provide the widened portions 7c and 7d while increasing the movement amount of the widened portion segment 5, that is, the widening amount. When the widened portion 7d is constructed as shown in FIG. 2B, the water stop portion 9b is provided from the widened portion 7d, and after the widened portion segment 5e is moved in the widening direction, the widened segment 3e is installed and widened. A portion 7e is provided.

The widened portion 7e serves as a pipe roof start base 11 described later. Further, a middle pillar 15 is provided so as to partition the pipe roof start base 11 and the main shield tunnel 1. Since the pipe roof start base 11 and the inside of the main shield tunnel 1 are partitioned by the middle pillar 15, in the subsequent construction, it is possible to carry out another construction at the same time in the main shield tunnel 1, It is also possible to start traffic of vehicles and the like.

In this manner, the widened portion 7a to the widened portion 7e are constructed while increasing the amount of widening stepwise. In such a widening method, there is a limit to the amount of widening. Therefore, the main shield tunnel 1 cannot be widened by repeating the above method over the entire length of the tunnel junction.

When the pipe roof start base 11 is provided by the above-described widening method, the pipe roof 13 is then provided from the pipe roof start base 11. FIG. 3 is a view showing a state where the pipe roof 13 is provided from the pipe roof start base 11, FIG. 3 (a) is a plan view of the main line shield 1, and FIG. 3 (b) is a view of FIG. 3 (a). EE sectional drawing and FIG.3 (c) are F direction arrow directional views of Fig.3 (a). Here, the pipe roof 13 is composed of a plurality of pipes 17 and the entire pipes 17 arranged side by side.

The pipe roof start base 11 starts the pipe roof 13 toward the substantially axial direction of the main line shield tunnel 1. As shown in FIG. 3B, the ends of the plurality of pipes 17 constituting the pipe roof 13 in the pipe roof start base 11 are arranged at substantially equal intervals along the inner peripheral surface of the widened portion segment 5e. . As shown in FIG. 3C, the pipes 17 started from the pipe roof starting base 11 in the substantially axial direction of the main shield tunnel 1 are provided so that the intervals between the pipes 17 are widened, that is, in a divergent shape. As a result, the pipe roof 13 is constructed. That is, the distance between the pipes 17 at the pipe roof end portion 23 is substantially larger than the distance between the pipes 17 at the pipe roof start base 11.

The intervals between the pipes 17 in the pipe roof end portion 23 are not equal intervals. That is, the distance 19 between the upper pipes located at the upper part of the pipe roof 13 is smaller than the distance 21 between the lower pipes located at the lower part of the pipe roof 13. This is because a large earth pressure from the upper part is applied above the pipe roof 13, so that the strength enough to counter the earth pressure is necessary.

A region surrounded by the pipe roof 13 in the pipe roof end portion 23 is determined by the size of the lamp shield tunnel 35 described later. That is, it is necessary to determine the shape of the pipe roof 13 that is widened so that the region surrounded by the pipe roof 13 can be joined to the lamp shield tunnel 35.

Next, as shown in FIG. 4, a water stop portion 9 c is provided on the surrounding ground from the pipe roof 13, and water stop portions 9 d, 9 e, 9 f are provided from inside the main line shield tunnel 1. 4A is a plan view of the main shield tunnel 1, and FIG. 4B is a cross-sectional view taken along the line GG of FIG. 4A.

The water stop part 9c is provided by chemical | medical solution injection | pouring etc. with respect to the surrounding ground from the inside of each pipe 17 which comprises the pipe roof 13. FIG. Further, water stop portions 9d and 9e are provided above and below the main line shield tunnel 1 from the inside of the main line shield tunnel 1. Further, the pipe roof end portion 23 is provided with a water stop portion 9 f from the main line shield tunnel 1. Accordingly, water does not enter the water stop region 25 surrounded by the water stop portions 9c, 9d, 9e, and 9f from the external ground.

Here, although the water stop part 9c provided in the circumference | surroundings of the pipe roof 13 is provided by chemical | medical solution injection | pouring etc. from each pipe 17, the water stop part 9c provided by each pipe 17 needs to be provided seamlessly. That is, when a gap having no water stop effect is generated in the water stop portion 9c, water enters from there and hinders subsequent construction. Accordingly, the interval between the pipes 17 must be determined so as to secure a junction region with the lamp shield tunnel 35 and to prevent the water stop portion 9c from becoming discontinuous.

For example, when the water stop effect of the chemical injection performed from the pipe 17 extends to a range of 2 m in diameter from the pipe 17, the center distance between the adjacent pipes 17 must be within 2 m. That is, when the center distance between the pipes 17 exceeds 2 m, a portion having no water stop effect occurs between the adjacent pipes 17. Therefore, the distance between the pipes 17 constituting the pipe roof 13 needs to ensure that the distance between the pipes 17 is sufficient to secure at least a joining region with the lamp shield tunnel 35 by making the pipe roof 13 widen at the end. It is necessary to set the distance between the pipes 17 within a range where the water stop portion 9c can be obtained.

In addition, when performing chemical | medical solution injection | pouring from the pipe 17, the hole for performing chemical | medical solution injection | pouring to a ground is normally provided in the pipe 17. FIG. FIG. 5 is an enlarged view of the N portion in FIG. 4A and shows the hole 24 provided in the pipe 17. As described above, since the pipes 17 are provided so as to spread toward each other and the distance between the pipes is increased at the pipe end portion 23, the pitch of the holes 24 for injecting the chemical liquid is surely obtained in order to obtain a water stop effect. It becomes narrower as it goes to the pipe roof end 23.

That is, as shown in FIG. 5, the end hole pitch 26 that is the pitch of the holes 24 of the pipe 17 in the pipe roof end portion 23 is based on the root hole pitch 28 that is the pitch of the holes 24 on the pipe roof start base 11 side. Is set too narrow. Therefore, in the pipe roof end portion 23 where the distance between the pipes 17 becomes large, the pitch of the holes 24 becomes narrow, so that the chemical solution can be reliably injected, and the distance between the pipes 17 is near the pipe roof start base 11. Since it is small, a sufficient water stop effect can be obtained even if the pitch of the holes 24 for injecting the chemical solution is increased.

Next, as shown in FIG. 6, a tunnel housing 29 is provided in the water stop region 25. 6A and 6B are views showing a state in which the tunnel housing 29 is provided in the water stop region 25. FIG. 6A is a plan view of the main shield tunnel 1, and FIG. 6B is a cross-sectional view taken along line H-H in FIG. It is sectional drawing. FIG. 6A is a perspective view of the pipe roof 13.

As described above, the water stop region 25 surrounded by the water stop portions 9c, 9d, 9e, and 9f does not enter water from an external ground. Therefore, the ground in the water stop area 25 is excavated from the inside of the main line shield tunnel 1, and the tunnel housing 29 is provided in a C shape along the pipe roof 13 on the outer periphery of the water stop area 25. The tunnel housing 29 can be formed by, for example, a NATM (New Australian Tunneling Method) method. The ends of the tunnel housing 29 are joined to the upper and lower sides of the main shield tunnel 1.

When the tunnel housing 29 is constructed and the tunnel housing 29 and the main shield shield 1 are joined, the removal segment 27 facing the water stop region 25 is removed. That is, the main line shield tunnel 1 and the space formed by the tunnel housing 29 are connected. The end portion of the tunnel housing 29 at the pipe roof end portion 23 is stopped by the water stop portion 9f.

The other end of the tunnel housing 29 is connected to the widened portion segment 5e in the pipe roof start base 11. That is, the tunnel housing 29 is connected so as to widen the main shield tunnel 1 from the side of the main shield tunnel 1, and the end is joined to the widened portion 7 e of the main shield tunnel 1. Here, since the pipe roof 13 is provided in a divergent shape, the tunnel housing 29 is also provided in a divergent shape along the pipe roof 13.

Next, as shown in FIG. 7, a temporary wall 31 is provided at the pipe roof end portion 23. 7 is a view showing a state in which the temporary wall 31 is provided. FIG. 7A is a plan view of the main shield tunnel 1, and FIG. 7B is a cross-sectional view taken along the line II of FIG. 7A. In addition, illustration of the pipe roof 13 and the water stop part 9 was abbreviate | omitted in Fig.7 (a).

The temporary wall 31 is a temporary wall provided to prevent water and earth and sand from entering the tunnel housing 29 until a lamp shield tunnel 35 described later arrives. The temporary wall 31 is provided in a crescent shape so as to cover the end of the concrete housing 19 on the pipe roof end portion 23 side. That is, the temporary wall 31 is joined to the end portion of the tunnel housing 29 and further joined to the outer peripheral surface of the main shield tunnel 1 at the pipe roof end portion 23.

The temporary wall 31 can be made of, for example, concrete, mortar, or fiber reinforced board. Further, when the lamp shield tunnel 35 is constructed to the nearest place, or when the water is reliably stopped by the water stop portion 9 and there is no intrusion of earth and sand, the temporary wall 31 may not be provided.

Next, as shown in FIG. 8, the lamp shield tunnel 35 is provided by the shield machine 33. FIG. 8 is a view showing a state in which the main shield shield 1 is provided with a lamp shield tunnel 35. FIG. 8 (a) is a plan view of the main shield shield 1, and FIG. 8 (b) is a cross-sectional view of FIG. It is J sectional drawing. In addition, illustration of the pipe roof 13 and the water stop part 9 was abbreviate | omitted in Fig.8 (a), and illustration of the temporary wall 31 was abbreviate | omitted in FIG.8 (b).

The shield machine 33 advances in the direction of arrow K while constructing the lamp shield tunnel 35 in parallel to the main shield tunnel 1, and the lamp shield tunnel 35 is constructed toward the temporary wall 31 provided in the tunnel housing 29. The As described above, the tunnel housing 29 provided in a divergent shape forms the largest cross-sectional shape at the pipe roof end portion 23. Therefore, as shown in FIG. 8B, the end portion of the tunnel housing 29 at the pipe roof end portion 23 has a region that can be joined to the lamp shield tunnel 35.

9A and 9B are diagrams showing a state in which the lamp shield tunnel 35 is connected to the tunnel housing 29. FIG. 9A is a plan view of the main shield 1 and FIG. 9B is an LL line in FIG. 9A. FIG. 9C is a cross-sectional view taken along line MM in FIG. 9A. In addition, illustration of the pipe roof 13 was abbreviate | omitted in Fig.9 (a).

The lamp shield tunnel 35 is connected to the tunnel housing 29 through the temporary wall 31 by the shield machine 33. That is, the lamp shield tunnel 35 is connected to the main shield tunnel 1 through the tunnel housing 29.

As shown in FIG. 9B, the lamp shield tunnel 35 and the main shield tunnel 1 are independent tunnels on the front side of the junction with the tunnel housing 29, and roads and the like that are not shown in the figure are inside each tunnel. It is constructed. At the junction between the lamp shield tunnel 35 and the tunnel housing 29, the lamp shield tunnel 35 and the main line shield tunnel 1 are spatially connected. In the tunnel housing 29, the lamp shield tunnel 35 does not exist in a tunnel shape, and the tunnel housing 29 and the main shield tunnel 1 are connected as shown in FIG.

That is, the tunnel junction according to the present embodiment is configured as follows. Each of the tunnels is configured separately, and the lamp shield tunnel 35 and the main line shield tunnel 1 provided together are connected in the vicinity of the end portion 23 of the pipe roof via a tunnel housing 29. The width of the tunnel housing 29 is gradually reduced from the joint with the lamp shield tunnel 35 toward the joint with the widened portion 7e (pipe roof start base 11).

Furthermore, the width of the main shield tunnel 1 is narrowed in a stepped manner from the widened portion 7e to the widened portion 7a, and becomes the original width of the main shield shield 1. Therefore, a vehicle or the like passing through the lamp shield tunnel 35 can gradually merge with the main shield tunnel 1 at the tunnel housing 29 and the widened portion 7.

As described above, according to the method for constructing a tunnel junction according to the present embodiment, since the tunnel junction can be constructed in the ground, the tunnel junction is not affected by structures on the ground. Can be built. Moreover, since the tunnel junction part can be constructed in a shape along the inclination of the tunnel junction part by the widened part 7 provided in the stepped shape and the tunnel housing 29 provided in the end-expanding shape, an extra range of Since excavation is not necessary and there is no need to purchase extra land, efficiency is high.

Further, the distance between the pipes 17 at the pipe roof end portion 23 is such that the distance 19 between the upper pipes at the upper part of the pipe roof 13 is smaller than the distance 21 between the lower pipes at the lower part of the pipe roof 13. It can perform strength and water stop enough to resist intrusion and has good workability.

Since the pipe roof 13 is started from the widened portion 7 provided in the main shield tunnel 1 toward the substantially axial direction of the main shield tunnel 1, there is no need to bend the pipe roof 13, and the workability is excellent. Compared with the case where the pipe roof 13 is started perpendicularly to the main shield tunnel 1, there is no increase in the construction area due to the turning radius of the pipe roof 13, so that the tunnel junction can be constructed with a minimum construction range. .

In addition, since the pipe roof start base 11 and the main shield tunnel 1 are partitioned by the middle pillar 15, another construction can be performed in parallel in the main shield tunnel 1 even when the tunnel housing 29 is constructed. The main line shield tunnel 1 can be opened, and the passage of vehicles and the like can be started.

Furthermore, since it is possible to simultaneously construct the junction without waiting for the lamp shield tunnel 35 to be constructed, there is no need to wait for the lamp shield tunnel 35 to be constructed, and the provisional wall 31 is provided. There is no intrusion of earth and sand or water in the tunnel housing 29 until it reaches. Since the temporary wall 31 can be easily penetrated by the shield machine 33, it is not necessary to remove it. Therefore, it is possible to obtain a method for constructing a tunnel junction where the workability is excellent and the construction period can be shortened.

As mentioned above, although embodiment of this invention was described referring an accompanying drawing, the technical scope of this invention is not influenced by embodiment mentioned above. It is obvious for those skilled in the art that various modifications or modifications can be conceived within the scope of the technical idea described in the claims, and these are naturally within the technical scope of the present invention. It is understood that it belongs.

For example, the widened portion 7 has five levels from 7a to 7e, but is not limited to five levels.

It is a figure which shows the state which provided the wide part 7a in the main line shield tunnel 1, (a) is a top view of the main line shield tunnel 1, (b) is AA sectional drawing of (a), (c) is (a). BB sectional drawing of. It is a figure which shows the state which provided the wide part 7a to the wide part 7e in the main line shield tunnel 1 stepwise, (a) is a top view of the main line shield tunnel 1, (b) is CC sectional drawing of (a), (C) is DD sectional drawing of (a). It is a figure which shows the state which provided the pipe roof 13 from the pipe roof start base 11, (a) is a top view of the main line shield tunnel 1, (b) is EE sectional drawing of (a), (c) is (a) ) F direction arrow view of. It is a figure which shows the state which provided the water stop part 9 from the pipe roof 13 and the main line shield tunnel 1, (a) is a top view of the main line shield tunnel 1, (b) is GG sectional drawing of (a). FIG. 4A is an enlarged view of the N portion, and shows the end portion hole pitch 26 and the root portion hole pitch 28 of the pipe 17. It is a figure which shows the state which provided the tunnel housing | casing 29 in the water stop area | region 25, (a) is a top view of the main line shield tunnel 1, (b) is HH sectional drawing of (a). It is a figure which shows the state which provided the temporary wall 31 in the pipe roof terminal part 23, (a) is a top view of the main line shield tunnel 1, (b) is II sectional drawing of (a). It is a figure which shows the state which constructed | assembled the lamp shield tunnel 35 with the shield machine 33, (a) is a top view of the main line shield tunnel 1, (b) is JJ sectional drawing of (a). It is a figure which shows the state with which the lamp shield tunnel 35 and the tunnel housing | casing 29 were connected, (a) is a top view of the main line shield tunnel 1, (b) is LL sectional drawing of (a), (c) is (a) MM sectional drawing of). The figure which shows the conventional tunnel junction part.

Explanation of symbols

1 ......... Main shield tunnel 3 ......... Wide segment 5 ......... Wide portion segment 7 ......... Wide portion 9 ......... Water stop 11 ... …… Pipe roof start base 13 ... …… Pipe roof 15 ... ... Middle column 17 ... Pipe 19 ... ... Upper pipe distance 21 ... ... Lower pipe distance 23 ... ... Pipe roof end 24 ... ... Hole 25 ... ... Water stop area 26 ... ... End Hole pitch 27 ......... Removed segment 28 ......... Root hole pitch 29 ......... Tunnel housing 31 ......... Temporary wall 33 ......... Shield machine 35 ......... Ramp shield tunnel 41 ......... Main shield tunnel 43 ... …… Lamp shield tunnel 45 ……… Merging part 47 ……… Excavation part

Claims (7)

The first tunnel,
A widening portion provided in the first tunnel and provided in a stepped manner so that the amount of widening gradually increases;
A pipe roof provided in a divergent shape from the widened portion toward the substantially axial direction of the first tunnel;
A housing provided in a region surrounded by the pipe roof and connected to the widened portion;
A second tunnel connected to the housing and attached to the first tunnel;
The tunnel junction part characterized by comprising. Providing a first tunnel (a);
Providing the widened portion in the first tunnel (b);
A step (c) of providing a pipe roof in the substantially axial direction of the first tunnel from the widened portion;
A step (d) of forming a water stop portion in a surrounding ground with the pipe roof;
A step (e) of providing a housing in a water stop region surrounded by the water stop portion;
Connecting a second tunnel to the housing (f);
A method for constructing a tunnel junction. 3. The method for constructing a tunnel junction according to claim 2, wherein, in the step (c), the pipe roof is provided so as to be wider from the widened portion. In the step (b), the widening operation is repeated so that the amount of widening gradually increases with respect to the adjacent widened portions, and the widened portions are provided in a step shape. The method for constructing the tunnel junction. The distance between pipes at the upper end of the pipe roof is smaller than the distance between pipes at the lower end of the pipe roof in the step (c). The method for constructing the tunnel junction. 6. The method for constructing a tunnel junction part according to claim 2, wherein in the step (b), a pillar for partitioning the widened part is provided in the first tunnel. The tunnel junction construction method according to any one of claims 2 to 6, wherein, in the step (e), a temporary wall is provided at an end portion of the housing.

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