JP2008274705A - Tunnel construction method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently construct a branch/merging section of a large-scale tunnel. <P>SOLUTION: When the branch/merging section of a plurality of shield tunnels is constructed, the construction area is surrounded by a shield roof forepoling 3 comprising a number of roof shield tunnels 6 and an improvement zone (a freezing zone 8), and a lining wall 4 of the branch/merging section is constructed on the inside. When the lining wall is constructed, an impermeable membrane wall 11 is formed between the roof shield tunnels 6, the roof shield tunnels 6 are filled with a concrete 21, the roof shield tunnels 6 adjacent to each other are connected to each other by a connecting beam 22, a primary lining wall 24 is formed by a sprayed concrete 23, and a second lining wall 26 integrated with the primary lining wall and each of the roof shield tunnels is constructed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a tunnel construction method, and more particularly to a tunnel construction method capable of efficiently constructing a branching / merging portion when, for example, a road tunnel having a large depth and a large cross section is provided in an urban area.

  As is well known, NATM (New Austrian Tunneling Method) or shield construction method is typical as a tunnel construction method for constructing a tunnel with a large depth and a large cross section. Adopting shield construction method because high support performance for ground is required to avoid adverse effects on existing underground structures, and water stoppage performance and groundwater conservation performance during construction and after completion are highly required. Is the most common.

By the way, when constructing a road tunnel by the shield method, it is necessary to install a ramp tunnel in addition to the main tunnel, and join both tunnels at important points to construct a branch junction. Construction of the part is not always easy.
In other words, the main tunnel and the ramp tunnel can be constructed without hindrance while maintaining stable ground and securing water sealing by the conventional shield method, but both shield tunnels are gradually changed in cross section at the branch junction. Since it is necessary to join each other, the conventional shield method cannot be applied as it is in the construction of the branch junction.

For this reason, it is indispensable to employ some kind of auxiliary construction method when constructing the branching junction. For example, a construction method as disclosed in Patent Document 1 has been proposed.
This is a construction of a shield roof tip receiving work with a large number of small-section roof shield tunnels so as to surround the construction area of the branch and merge section, and an improved zone by injecting a chemical solution between the roof shield tunnels and at the end of the construction area. In addition, a freezing zone is formed by the freezing method, and then the main tunnel or ramp tunnel is widened to construct a branching junction.
JP 2006-70530 A

According to the tunnel construction method disclosed in Patent Document 1, it is considered that a large-scale branch and junction can be safely and efficiently constructed. However, since a large number of roof shield tunnels are provided as temporary receivers, considerable cost is required. Therefore, it is considered that a sufficient cost reduction is necessary to make this truly effective.
Also, when excavating inside the shield roof tip construction, it is necessary to ensure sufficient support performance and water shielding performance by the improved zone, especially when the improved zone is a freezing zone by the freezing method. It is said that there is a need to further improve its reliability, and there is room for improvement in that respect.

  In view of the above circumstances, the present invention further improves the tunneling method disclosed in Patent Document 1, and is an effective and appropriate tunneling method that can further improve cost reduction and construction safety when constructing a large-scale branch junction. The purpose is to provide.

  The tunnel construction method of the present invention is basically similar to the tunnel construction method disclosed in Patent Document 1, and when constructing a branching junction between a plurality of shield tunnels, a roof shield machine is started from one of the shield tunnels. Shield roof tip receiving work that surrounds the branch junction by constructing a plurality of roof shield tunnels along the extension direction outside the branch junction to be constructed in a state of being arranged at predetermined intervals along the outline of the branch junction And improving the surrounding ground from the inside of the roof shield tunnel to form an improved zone between the roof shield tunnels, and then the shield tunnel inside the space surrounded by the shield roof prior construction and the improved zone A tunnel that constructs a merging wall by widening the bridge and constructing a lining wall for the merging branch Before constructing the lining wall of the branching junction, the ground shield between adjacent roof shield tunnels is cut from the inside of the roof shield tunnel to form a water shielding film wall, and in the roof shield tunnel. When building the lining wall with concrete filling, excavate between adjacent roof shield tunnels on the inner side of the water shielding film wall, construct a connecting beam to connect the roof shield tunnels, and primary cover with sprayed concrete Forming a work wall and constructing a cover wall of a branching junction by forming a secondary cover wall integrally with the primary cover wall and each roof shield tunnel inside the primary cover wall It is a feature.

In the tunnel construction method of the present invention, when forming the water-shielding film wall between the roof shield tunnels, a slit is formed by cutting the improved zone formed between the roof shield tunnels with a wire saw from inside the roof shield tunnel. On the other hand, it is preferable to form a water shielding film wall by drawing a water shielding film into the slit. In that case, it is preferable that a cutting portion that can be cut with a wire saw is provided in advance in the segment of the roof shield tunnel, and the slit is formed by cutting the improved zone while cutting the cutting portion with the wire saw.
In addition, when the improvement zone formed between the roof shield tunnels is formed as a freezing zone by the freezing method, a water-insulating film wall is formed by a flat bag-shaped water-insulating film and the inside has a heat insulating property. Is preferably filled.

  Furthermore, the segment forming the roof shield tunnel includes a reinforcing material such as a reinforcing bar embedded in concrete filled in the roof shield tunnel, a connecting beam for connecting the roof shield tunnels, and a primary lining. A joint for connecting reinforcing members such as reinforcing bars embedded in the wall and the secondary lining wall to the segments may be provided in advance.

According to the present invention, since the shield roof tip receiving work and the improvement zone are formed so as to surround the planned position at the time of the construction of the branch joint part, when the branch tunnel part is widened to construct the branch joint part, It is possible to safely and efficiently construct branch junctions while ensuring sufficient support performance and water stoppage performance for natural ground, and prevent subsidence to the ground surface or existing structures in the ground and conserve surrounding groundwater Can be achieved.
In particular, since the construction of the shield roof tip receiving construction is performed by arranging a plurality of roof shield tunnels at predetermined intervals, the shield roof tip receiving construction can be made sufficiently rigid, and the construction is performed by the conventional shield construction method. It can be constructed easily and accurately, and an optimum shield roof tip construction can be constructed by setting the number and arrangement of roof shield tunnels according to the form and scale of the branching junction to be constructed.

In addition, the present invention does not simply provide the shield roof tip construction as a temporary construction, but uses it as a part of the lining wall of the construction, and each roof shield tunnel is filled with concrete and adjacent to it. The matching roof shield tunnels are connected by connecting beams, and the primary and secondary lining walls are integrally formed inside the shield roof tip receiving work, making them robust and structural safety as a whole. Thus, it is possible to construct an excellent lining wall, and it is possible to reduce costs and improve workability as compared with a case where a temporary shield roof tip receiving work and a permanent lining wall are provided separately.
In addition, prior to the construction of the lining wall, a water shielding film wall is first formed between the roof shield tunnels, so that sufficient water shielding performance can be ensured. Since the primary lining wall is formed, the creep of the improved zone can be reduced and sufficient supporting performance can be ensured.

In addition, when constructing a water barrier film, the improvement zone is cut from the inside of the roof shield tunnel with a wire saw and the slits are cut and the water barrier film is pulled in. By providing the cutting part in advance, it is possible to efficiently construct the water-impervious wall film only by work from inside the roof shield tunnel.
In addition, when the improved zone is formed as a freezing zone by the freezing method, sprayed concrete as the primary lining wall to be applied afterwards by filling the inside with a heat-insulating material by forming a water-shielding membrane wall into a bag shape. Can be thermally insulated from the freezing zone, and workability and construction quality can be improved.

  In addition, by providing joints for mechanically connecting reinforcing materials such as reinforcing bars to the inside and outside of the roof shield tunnel, it is possible to arrange reinforcing bars inside the roof shield tunnel or to the outside. Thus, the workability of the construction of the connecting beams and the reinforcement of the reinforcing bars can be improved, and the reinforcing material and the lining wall formed by the entire roof shield tunnel can be structurally integrated.

One embodiment when the tunnel construction method of the present invention is applied to construction of a road tunnel having a large depth and a large section in an urban area will be described with reference to FIGS.
In the present embodiment, as shown in FIG. 1, the main shield tunnel 1 and the lamp shield tunnel 2 are both constructed by the conventional shield method, and the outside of the planned construction position of the branch / merging portion is set in advance. The shield roof tip receiving work 3 is constructed, and on the inside, for example, a part of the wide side wall of the main line shield tunnel 1 is removed, and a backhoe or other excavating machine is carried from there, and the excavating machine is used to The widened portion is excavated from the upper side to the lower side, and unnecessary portions on the side walls of the main shield tunnel 1 are removed, and finally the oval lining wall 4 (see FIGS. 3 to 6) inside the shield roof tip receiving work. ) To complete the branching junction.
In the present embodiment, it is assumed that the main shield tunnel 1 has a diameter of about 17 m, for example, and the lamp shield tunnel 2 has a diameter of about 11 m, for example. Further, in this embodiment, as shown in FIG. 2, the main shield tunnel 1 is widened in three stages laterally at the branch and merge part, and finally each part of the branch and merge part as shown in FIGS. A horizontally long oval lining wall 4 whose cross-sectional shape is gradually reduced toward the front is formed.

Specifically, in this embodiment, the lamp shield tunnel 2 is advanced ahead of the main line shield tunnel 1, and the excavation is continued until the lamp shield tunnel 2 reaches at least the planned construction position of the branch junction as shown in FIG. Advance to stop. Then, a roof shield machine (not shown) is started from the side wall near the tip of the lamp shield tunnel 2, and a plurality (20 in the illustrated example) are placed outside the planned construction position of the branch / merging portion as shown in FIG. The roof shield tunnel 6 is constructed in a state of being arranged at a predetermined interval along the outline of the branching junction, and the shield roof tip receiver 3 is configured by the entirety of the plurality of roof shield tunnels 6.
In addition, the arrangement | sequence of the predetermined space | interval in the roof shield tunnel 6 is a space | interval of the grade which can show | play the effect as a support or water stop between the roof shield tunnel 6 which the improvement zone by the freezing or chemical | medical solution mentioned later adjoins. This is determined in consideration of the ground conditions and the like, but in this embodiment, the roof shield tunnels 6 are arranged sufficiently densely along the contour of the branching junction as shown in the figure.

  Each roof shield tunnel 6 starts a small-diameter (for example, about 3 m diameter) roof shield machine from the tunnel side wall near the tip of the lamp shield tunnel 2 as shown in FIG. Although it is constructed so as to extend along the extension direction (tunnel axis direction) of the branch and merge part, in this embodiment, the branch and merge part gradually decreases in cross-sectional shape toward the front as described above. As shown in FIGS. 3 to 5, the distance between the roof shield tunnels 6 is narrowed toward the front in accordance with the cross-sectional shape of the branching junction, and the positions thereof are changed as shown in FIGS. 4 to 5. It is shifted slightly in the radial direction, and the entire shape of the shield roof tip receiver 3 is tapered as a whole.

When constructing each roof shield tunnel 6, prepare one or several roof shield machines, start them sequentially from the lamp shield tunnel 2, and when they reach the tip of the branch junction, the skin plate and cutter The outer shell device such as the device is left and only the internal device is recovered, and the recovered internal device is assembled into a new outer shell device in the lamp shield tunnel 2 to assemble a new roof shield machine and start it again. Just do it. Of course, if possible, all the roof shield tunnels 6 may be constructed simultaneously by independent roof shield machines, or the roof shield machine that reaches the tip of the branching junction may be U-turned from there. It is also conceivable to continuously construct the roof shield tunnel 6 in the opposite direction.
Moreover, as a method for starting the roof shield machine from the side wall portion of the lamp shield tunnel 2, the start method of the shield machine from the side wall portion of the conventional shield tunnel, and the T-joining technology between the conventional shield tunnels Can be used as is.

The main shield tunnel 1 is dug separately from the construction of the shield roof tip receiver 3 as described above, and the main shield tunnel 1 is passed through the inside of the shield roof tip receiver 3. Further, by freezing (improving) the surrounding ground mountains by freezing pipes (improving means) 7 installed in each shield tunnel 6, they are frozen in a state where they are connected between the roof shield tunnels 6 as shown in FIG. A zone (improved zone) 8 is formed.
Then, as described above, the main junction tunnel 1 is widened laterally by the excavation method described above on the inner side thereof, and finally the branch merge section is constructed, and finally the tip of the lamp shield tunnel 2 with respect to the branch junction section Prior to this, a water shielding film wall 11 is first constructed between adjacent roof shield tunnels 6 as shown in FIG.

As shown in FIG. 13, the construction of the water shielding film wall 11 includes arranging a wire saw 12 and a winch carriage 14 for pulling the water shielding film 13 in the roof shield tunnel 6, and the winch carriage 14 is used to attach the wire saw 12. The freezing zone 8 that is towed and formed between the roof shield tunnels 6 is cut into a slit shape, followed by drawing the water shielding film 13 into the slit.
When the freezing zone 8 outside the roof shield tunnel 6 is cut with the wire saw 12, the segment of the roof shield tunnel 6 is also cut at the same time. The cutting part 15 (see FIG. 13) that can be cut is preferably formed in advance, and after cutting, a reinforcing joint 16 (see FIG. 6) may be attached inside the cutting part 15 for reinforcement.
Further, if the water shielding film 13 for forming the water shielding film wall 11 is formed into a thin bag shape and filled with a heat insulating filler, the primary covering formed inside the water shielding film wall 11 in the subsequent stage. The shotcrete 23 as the work wall 24 and the freezing zone 8 can be thermally insulated by the water shielding film wall 11, so that the workability of the shotcrete 23 can be improved and the construction quality can be ensured.

  As shown in FIGS. 14A and 14B, after the main shield tunnel 1 is dug while the above steps are performed and the main shield tunnel 1 passes through the inside of the shield roof tip receiving work 3. Next, the freezing pipe (improving means) 9 is inserted by boring from both ends of the roof shield tunnel 6 to the inner ground, and the freezing zone is also provided at the positions of both ends of the shield roof tip receiver 3 as shown in FIG. (Improved zone) 10 is formed.

As described above, the planned construction position of the branch and merge part is the shield roof tip receiving work 3 constituted by the roof shield tunnel 6 and the freezing zone 8, the water shielding film wall 11 constructed between the roof shield tunnel 6, and the end part. It is completely surrounded by the freezing zone 10 constructed in (Tsumabetsu) and isolated from the natural ground outside it.
Therefore, the lining wall 4 is constructed on the inner side, and each roof shield tunnel 6 forming the shield roof tip receiver 3 is also used as a part of the lining wall 4 in order to use the lining wall. 4 is performed according to the procedure shown in FIGS.

First, as shown in FIG. 10, a reinforcing material 20 such as a reinforcing bar or a PC steel bar is arranged in the roof shield tunnel 6, and then the concrete 21 is filled in the roof shield tunnel 6. This process may be performed sequentially from the roof shield tunnel 6 where the construction of the water shielding film wall 11 is completed.
Next, the main line shield tunnel 1 (or the lamp shield tunnel 2) is started to cut and expand to the outside, and as shown in FIG. 11, the freezing zone inside the water shielding film wall 11 between the adjacent roof shield tunnels 6 8 is excavated, and a connecting beam 22 is constructed inside the water-impervious film wall 11 and a shotcrete 23 is formed, whereby an arch-shaped support work by the roof shield tunnel 6, the link beam 22 and the shotcrete 23 is formed. The primary lining wall 24 is constructed.
Thereby, loosening and creep deformation of the freezing zone 8 between the roof shield tunnels 6 are sufficiently suppressed. At this time, if the water-insulating film wall 11 sufficiently secures the water-insulating performance, and the water-insulating film wall 11 is filled with the heat insulating filler as described above, the shotcrete 23 Can be thermally insulated from the freezing zone 8 to ensure its workability and construction quality without any trouble. In any case, it is preferable to use the shotcrete 23 that exhibits high strength in a short time.

As described above, the inside of the shield roof tip receiver 3 is excavated while the primary lining wall 24 is sequentially formed between the roof shield tunnels 6, and the entire inside of the shield roof tip receiver 3 is excavated. After that, as shown in FIG. 12, a reinforcing material 25 such as a reinforcing bar or a PC steel bar is assembled inside the primary lining wall 24 and connected to the reinforcing material 20 arranged in the roof shield tunnel 6.
Then, by installing a centle (not shown) which is a movable mold apparatus and placing concrete to construct the secondary lining wall 26, the roof shield tunnel 6, the primary lining wall 24, and the secondary covering are performed. The lining wall 4 having a robust composite structure in which the entire construction wall 26 is integrated is constructed.
When constructing the lining wall 4, reinforcing members 20 and 25 such as reinforcing bars and PC steel bars are arranged inside and outside the roof shield tunnel 6 as described above, and the roof shield tunnel 6 is connected to the connecting beam 22. Therefore, it is advisable to provide joints for mechanically joining the reinforcing members 22 and 25 and the connecting beam 22 in advance in the segments of the roof shield tunnel 6, thereby improving the workability. Can be integrated structurally reliably.

According to the construction method described above, the shield roof tip receiving work 3 composed of a number of roof shield tunnels 6 is constructed on the outside of the branching and joining part, and the freezing zones 8 and 10 are formed on the periphery and on the inside of both ends, In addition, a water shielding film wall 11 is formed between the roof shield tunnels 6 and then the main shield tunnel 1 is widened on the inner side to construct a branching junction. In this case, the roof shield tunnels 6 are connected by the connecting beams 22. Since it is connected and the primary lining wall 24 is constructed there, it is possible to secure sufficient support performance and water stoppage performance for the ground in the construction of the branch junction, and to prevent the complete settlement of the ground surface or existing structures in the ground. It is possible to achieve thorough groundwater conservation.
Further, the high-strength shield roof tip receiving work 3 composed of a plurality of roof shield tunnels 6 is not simply provided as a temporary structure, but the concrete 21 is filled therein and the roof shield tunnels 6 are connected to each other by the connecting beams 22. In addition, since it is structurally integrated with the primary lining wall 24 and the secondary lining wall 26 provided on the inside, the roof shield tunnel 6 also functions effectively as a part of the lining wall 4 of the main installation. It is possible to construct a lining wall 4 that is robust and excellent in structural safety as a whole. Of course, as compared with the case where the shield roof tip receiving work 3 is simply provided as a temporary structure and the main lining wall 4 is provided independently, the overall cost can be reduced and the workability can be improved. is there.

  In addition, since the shield roof tip receiver 3 is constructed by closely arranging a plurality of roof shield tunnels 6, not only can it be made sufficiently rigid, but also the optimum cross-sectional shape corresponding to the shape of the branching junction The shield roof tip receiving work 3 can be freely and highly accurately constructed. If the roof shield tunnels 6 are arranged in an arch shape and the roof shield tunnels 6 are integrally connected by a freezing zone 8 formed between them as in the present embodiment, the shield roof tip receiving work is performed. 3 as a whole has a particularly high rigidity and an extremely stable cylindrical underground structure, and therefore a particularly excellent support effect can be obtained.

In addition, by setting the lamp shield tunnel 2 ahead of the main shield tunnel 1 as in the present embodiment, when the lamp shield tunnel 2 reaches the planned construction position of the branch junction, Since the main line shield tunnel 1 can be excavated by parallel work with it, it is possible to start early, and particularly efficient construction is possible, and the entire construction period can be sufficiently shortened.
Furthermore, since the construction method of this embodiment is basically an organic combination of the conventional shield construction method, freezing construction method, and excavation construction method with many proven results, it is not only excellent in safety and reliability. Therefore, it can be constructed at a relatively low cost, and it can be said that it is an optimum construction method especially when constructing road tunnels with large depths and large sections in urban areas.

  Although the embodiment of the present invention has been described above, the above embodiment is merely a preferred example, and the present invention is not limited to the above embodiment. For example, the above embodiment is an application example to a road tunnel having a large depth and a large cross section in an urban area, but the present invention is generally applicable when constructing tunnels of various scales, uses, and forms as long as it has a branching junction. Various design changes are possible in accordance with the size and form of the branching junction in the tunnel to be constructed and considering various conditions such as the surrounding environment. For example, the number of roof shield tunnels 6 and the size and form of the shield roof tip receiving work 3 may be changed as appropriate within a range in which a desired receiving effect can be secured, and the freezing zones 8 and 10 formed around the roof shield tunnel 6 The range, the form of the lining wall 4 and its construction method, and other details of each process may be optimally designed without departing from the scope of the present invention, and an appropriate auxiliary construction method may be adopted as necessary. Of course it is good.

In the above embodiment, the improvement zones to be constructed between the roof shield tunnels 6 and inside the end of the shield roof tip receiver 3 are the freeze zones 8 and 10 by the freezing method, but when the groundwater pressure is not so much, etc. Then, this improvement zone may be improved by chemical injection, and the selection of this construction method is appropriately adopted depending on the ground conditions and the like.
Even in the improved zone (freezing zone 10 in the above embodiment) constructed on the inner side of the end portion of the shield roof tip receiving work 3, construction was performed on both ends in the above embodiment, but the end portion on the maximum widening section side. If only the improvement zone (the freezing zone 8 in the above embodiment) formed between the roof shield tunnels 6 can be combined with the end side of the minimum widening section, the end side of the minimum widening section is small. There is no need to separately improve the end.
In the above embodiment, the freezing zone 10 inside the end portion of the shield roof tip receiver 3 is constructed from within the roof shield tunnel 6, but depending on the convenience of the whole process (for example, early in the roof shield tunnel 6). In the case of filling with concrete 21), the construction may be performed by another method.

  Furthermore, in the said embodiment, although the roof shield machine for constructing the roof shield tunnel 6 started from the lamp shield tunnel 2, you may make it start from the main line shield tunnel 1. FIG. In this case, when the main shield tunnel 1 reaches the vicinity of the branch and merge section widening section, the roof shield machine is started from the side wall portion of the main shield tunnel 1 behind the main shield tunnel 1 and the main shield tunnel 1 advances as it is. . Then, the shield roof tip receiver 3 is constructed, an improvement zone is formed between the roof shield tunnels 6 or inside the end portions of the shield roof tip receiver 3, and the shield machine of the lamp shield tunnel 2 arrives. Widen the branch junction. Of course, when it becomes necessary to construct a branch and junction part immediately in the construction period, the roof shield machine may be started from both the main shield tunnel 1 and the lamp shield tunnel 2.

It is a figure which shows the outline | summary of the tunnel construction method which is embodiment of this invention. It is a top view of a branch junction part. FIG. 3 is a cross-sectional view (taken along line III-III in FIG. 2) of the branch merge section. FIG. 4 is a cross-sectional view (taken along line IV-IV in FIG. 2) of the branch and merge portion. FIG. 5 is a cross-sectional view (taken along line V-V in FIG. 2) of the branch merge section. FIG. 4 is a partial cross-sectional view showing details of the lining wall (an enlarged view of a VI portion in FIG. 3). It is a figure which shows a construction procedure and is a figure which shows the state which constructed the shield roof tip receiving construction. It is a figure which shows the state which constructed the freezing zone (improvement zone). It is a figure which shows the state which constructed the water-impervious film wall similarly. It is a figure which shows the state which filled the roof shield tunnel with the concrete same as the above. It is a figure which shows the state which constructed the primary lining wall same as the above. It is a figure which shows the state which constructed the secondary lining wall same as the above. It is a figure which shows the state which is constructing the water-impervious film wall. It is a figure which shows the state which is constructing the freezing zone (improvement zone) in the both ends of a branch merge part similarly.

Explanation of symbols

1 Main Line Shield Tunnel 2 Lamp Shield Tunnel 3 Shield Roof Tip Reception 4 Clining Wall 6 Roof Shield Tunnel 7 Freezing Pipe (Improvement)
8 Freezing zone (improved zone)
9 Freezing tube (improving means)
10 Freezing zone (improved zone)
DESCRIPTION OF SYMBOLS 11 Water-blocking film wall 12 Wire saw 13 Water-blocking film 14 Winch cart 15 Cutting part 16 Reinforcement joint 20 Reinforcement material 21 Concrete 22 Connecting beam 23 Sprayed concrete 24 Primary lining wall 25 Reinforcement material 26 Secondary lining wall

Claims (4)

When constructing a branch junction between multiple shield tunnels, branch roof junction tunnels along the extension direction outside the branch junction where the roof shield machine should be started from one of the shield tunnels. By constructing in a state of being arranged at predetermined intervals along the contour of the roof, a shield roof tip receiving construction that surrounds the branching junction is constructed, and the surrounding ground is improved from the inside of the roof shield tunnel to between the roof shield tunnels After forming the improved zone, the tunnel which constructs the branching junction by widening the shield tunnel inside the space surrounded by the shield roof tip receiving construction and the improvement zone and constructing the lining wall of the branching junction Construction method,
Prior to the construction of the lining wall of the branch junction, the ground shield between adjacent roof shield tunnels was cut from the inside of the roof shield tunnel to form a water shielding film wall, and the roof shield tunnel was filled with concrete. ,
When constructing the lining wall, excavate between the adjacent roof shield tunnels inside the water-shielding film wall, construct a connecting beam that connects the roof shield tunnels, and form a primary lining wall by sprayed concrete. ,
A tunnel construction method characterized in that a lining wall of a branch junction is constructed by forming a secondary lining wall integrally with the primary lining wall and each roof shield tunnel inside the primary lining wall. The tunnel construction method according to claim 1,
In the segment that forms the roof shield tunnel, a cutting part that can be cut with a wire saw is provided in advance,
When forming a water-shielding film wall between the roof shield tunnels, a slit is formed by cutting an improved zone between the roof shield tunnels together with the cutting portion from the inside of the roof shield tunnels with a wire saw, and the shields are formed in the slits. A tunnel construction method that draws in a water film to form a water shielding film wall. The tunnel construction method according to claim 2,
The improved zone formed between the roof shield tunnels is formed as a freezing zone by the freezing method,
A tunnel construction method characterized in that a water barrier film wall formed between roof shield tunnels is formed by a flat bag-shaped water barrier film, and the bag-shaped water barrier film is filled with a heat insulating filler. . The tunnel construction method according to any one of claims 1 to 3,
The segment forming the roof shield tunnel includes a reinforcing material such as a reinforcing bar embedded in the concrete filled in the roof shield tunnel, a connecting beam connecting the roof shield tunnels, and a primary lining wall and A tunnel construction method characterized in that joints for connecting reinforcing members such as reinforcing bars embedded in the secondary lining wall to the segments are provided in advance.

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