JP2007303195A - Construction method for shield tunnel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a construction method for a shield tunnel for constructing a tunnel provided with a branch line tunnel branched from a main line tunnel by a shield machine in only a construction process. <P>SOLUTION: A main line lined body 10a and a branched/joined lined body 10c are constructed in a general part 12aa and a branching/joining part 12ab of the main line tunnel 12a, respectively, while excavating the natural ground by a main line shield machine in this construction method. The inside of a pit in a scope equivalent to the branching/joining part 12ab is blocked by filler 14. The filler 14 is digged while converting the direction of a branch line shield machine 1b arranged at a predetermined position in the vicinity of the scope equivalent to the branching/joining part 12ab in the pit of the main line tunnel 12a toward a construction scheduled position of the branch line tunnel 12b by using the branch line shield machine 1b. After cutting the branched/joined lined body 10c by a cutter, the natural ground is excavated from the branching/joining part 12ab, and the branching/joining part 12ab and a branch line lined body 10b of the branch line tunnel 12b are constructed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a construction method for a shield tunnel.

Conventionally, when a tunnel having a branch tunnel branched from a main tunnel is constructed by a shield construction method, a method of constructing a branching / merging portion connecting both by an open-cut construction method from the ground is generally used.
However, it is difficult to secure construction space on the ground, and it is often difficult to understand the surrounding residents due to traffic obstacles due to work zones and noise during construction. It has become.

Under such circumstances, as shown in Patent Document 1, after constructing the main tunnel, excavated natural ground so as to gradually approach the main tunnel from a position separated from the main tunnel, and attached the branch tunnel to the main tunnel. A construction method for a shield tunnel has been devised that connects and connects the main and branch tunnels that have been constructed and removed.
JP 2000-257370 A (see FIG. 1)

 However, the construction method of the shield tunnel described above is a process of constructing a main line tunnel and a branch line tunnel with a shield excavator, then disassembling the wall portion between the two, building a temporary support column and applying a secondary lining to connect the two In addition to the construction process of the main tunnel and the branch tunnel by the shield method, the main tunnel and the branch line need to be improved. A branching / merging part construction process for connecting the tunnels is generated, and the work is complicated, the construction period is likely to be prolonged, and the construction cost is likely to increase.

 In view of the above circumstances, an object of the present invention is to provide a shield tunnel construction method capable of constructing a tunnel including a branch tunnel that branches off from a main tunnel only by a construction process using a shield excavator.

 The shield tunnel construction method according to claim 1 is to construct a main line tunnel using a main line shield excavator and to construct a branch line tunnel using a branch line shield excavator having a smaller cross-sectional diameter than the main line shield excavator. Shield tunnel construction method, constructing a main line lining body in the general part of the main line tunnel while excavating the ground with the main line shield excavator, and branch line shield excavation at the branch / junction with the branch line tunnel A first step of constructing a branching / merging lining body having segments that can be cut by a machine, a second step of closing a mine in a range corresponding to a branching / merging portion of the main tunnel with a filler, After excavating the filler from the inside of the main tunnel with a branch shield excavator and cutting the branch / merge lining body, excavate ground from the branch / merge part of the main tunnel. It is characterized by consisting of a third step of building a branch lining of branching and merging portion and branch tunnels.

 In the construction method of the shield tunnel according to claim 2, the branch shield excavator is built in the main shield excavator, and after the first step is finished, the branch shield excavator is separated and branched / joined. The second step includes carrying out retreating to a predetermined position near the rear end in the tunnel excavation direction in a range corresponding to the part.

 The construction method of the shield tunnel according to claim 3 corresponds to the branching / merging part by carrying the branch shield excavator from the shaft after the first step is completed, wherein the main tunnel is provided with a shaft. It is characterized by including the second step to arrange at a predetermined position in the vicinity of the range.

 According to the construction method of the shield tunnel according to claims 1 to 3, after constructing the main tunnel while excavating the ground with the main shield excavator, the branch shield excavator is started from the inside of the main tunnel. Compared to the conventional construction where the branch and junction between the main tunnel and the branch tunnel were constructed by the open-cut method because the branch tunnel of the shield tunnel was constructed, the construction space on the ground and the traffic obstacles and construction due to the work zone Since there is no need to consider the noise inside, it is possible to construct a shield tunnel having a branch tunnel in the main tunnel without causing a load on the surrounding residents.

 In addition, since the main line tunnel, the branch line tunnel, and all the junctions and junctions that connect both can be mechanically constructed by the main line shield excavator and the branch line shield excavator, both the main line tunnel and the branch line tunnel are constructed separately. This eliminates the need for a branching / merging section construction process as in the conventional construction method in which the lining body is destroyed and communicated, and the workability can be greatly improved.

 Furthermore, since it can be mechanically constructed by the main shield excavator and the branch shield excavator, there is little impact on the natural ground. It is possible to construct a branch / junction part mechanically in various procedures, and it is not necessary to carry out extensive ground improvement, and it is possible to construct a safe and high-quality shield tunnel with a branch tunnel in the main tunnel. It becomes possible.

 In addition, since the branch shield excavator is started from inside the tunnel of the main tunnel to construct the branch tunnel of the shield tunnel, either the branch shield excavator is built in the main shield excavator in advance, or the start vertical shaft, the reaching vertical shaft or the middle Since the branch shield excavator can be carried into the tunnel of the main tunnel using a vertical shaft, it is not necessary to newly secure a site for constructing a start shaft for the branch shield excavator. Construction can be carried out smoothly, and construction costs can be greatly reduced.

 1 to 9 show an embodiment of a shield tunnel construction method according to the present invention. The present invention is a method of constructing a shield tunnel having a branch tunnel branched from a main tunnel, and when constructing a main tunnel and a branch tunnel using the main shield excavator and the branch shield excavator, the main shield excavator is used. After constructing the main line tunnel, the branch shield excavator is started from the inside of the main line tunnel to construct the branch / merging part and the branch tunnel.

(First embodiment)
In the first embodiment, a construction method of a shield tunnel in which a main line tunnel and a branch line tunnel are constructed using a main line shield excavator with a built-in branch line shield excavator will be described.

 A main shield excavator 1a shown in FIG. 1 (a) is an apparatus for constructing a main tunnel 12a among shield tunnels 12 as shown in FIG. 2, and a branch line for constructing a branch tunnel 12b branched from the main tunnel 12a. The shield excavator 1b is built in, and the branch shield excavator 1b is configured to be detachable from the main shield excavator 1a.

As shown in FIG. 1B, the branch shield excavator 1b includes a skin plate 2b and a cutter 3b.
The skin plate 2b is a cylindrical body that forms the outer shell of the branch shield excavator 1b, and the cross section thereof has a shape corresponding to the branch tunnel 12b. The cutter 3b for excavating the natural ground 13 is provided in front of the skin plate 2b, and the natural ground 13 is excavated by rotating the cutter bit 3c installed in the front.

 Further, the branch shield excavator 1b includes a chamber 4b for taking excavated soil into the back surface of the cutter 3b inward of the skin plate 2b, and a soil removal device 5 for expelling the excavated soil from the chamber 4b. On the inner wall of the plate 2b, there is provided a branch lining body 10b which is arranged at a predetermined spacing in the circumferential direction and extends in the digging direction and assembled in a ring shape behind the skin plate 2b, such as a ring girder. A shield jack 7b that presses and advances the branch shield excavator 1b is provided.

 Further, the inner wall behind the skin plate 2b is provided with a tail packing 6b in contact with the outer peripheral surface of the branch line covering body 10b. The tail packing 6b uses a structure in which wire brushes are attached in multiples, but can prevent the phenomenon that earth and sand or groundwater flows into the skin plate 2b from the gap between the skin plate 2b and the branch line covering body 10b. Any one can be used.

On the other hand, the main line shield excavator 1a incorporating the above-described branch shield excavator 1b includes a skin plate 2a and a cutter 3a as shown in FIG.
The skin plate 2a is a cylindrical body that forms the outer shell of the main shield excavator 1a, and has a cross section corresponding to the main tunnel 12a. The cutter 3a for excavating the natural ground 13 is provided in front of the skin plate 2a. As shown in FIG. 1 (b), the outer diameter of the cutter 3b constituting the branch shield excavator 1b at the center portion is provided. A similar cutter fitting hole 9 is formed.

In the main shield excavator 1a, the cutter 3b of the branch shield excavator 1b is fitted into a cutter fitting hole 9 provided in the cutter 3a, so that the cutter 3a and the cutter 3b are flush with each other as shown in FIG. And excavating the natural ground 13 by rotating the cutter bit 3c installed in front of both.
In this case, a plurality of convex portions (not shown) that can be protruded and projected from the outer peripheral surface of the cutter 3b at an equal pitch, and a concave portion (not shown) that can be fitted to the convex portion on the inner peripheral surface of the cutter 3a. (Not shown) is provided, and the projections and the recesses are fitted to rotate the cutter 3a and the cutter 3b together. If it does in this way, it will become unnecessary to provide the cutter rotation drive device of a main line shield excavator.

 Further, the main line shield excavator 1a has a chamber 4a for taking excavated earth and sand to the back of the cutter 3a inside the skin plate 2a, but is configured to communicate with the chamber 4b of the branch shield excavator 1b. By using the earth removal device 5 provided in the branch shield excavator 1b in common, the excavated earth and sand collected in the chambers 4a and 4b are discharged. Note that the chamber 4b of the branch shield excavator 1b, which is configured to communicate with the chamber 4a of the main shield excavator 1a, is used when the branch tunnel 12b is constructed as shown by a broken line in FIG. The communication part is covered and closed.

 Further, on the inner wall of the skin plate 2a, like the branch shield excavator 1b, it is arranged with a predetermined spacing in the circumferential direction and extends in the excavation direction so as to form a ring shape behind the thrust receiving member 11a or the skin plate 2a. A shield jack 7a for pressing the main line lining body 10a to be assembled to the main line shield excavator 1a is provided.

Further, the inner wall behind the skin plate 2a is provided with a tail packing 6a in contact with the outer peripheral surface of the main line lining body 10a. The tail packing 6a is the same as the branch shield excavator 1b, and uses a configuration in which wire brushes are attached in multiple layers. However, earth and sand and groundwater are exposed to the skin plate 2a from the gap between the skin plate 2a and the main line lining body 10a. Any of them may be used as long as it can prevent the phenomenon flowing inward.
Then, in the above, the branch shield excavator 1b is built in the main shield excavator 1a, and both the branch shield excavator 1b and the main shield excavator 1a include the skin plate 2 and the shield jack 7. For the branch shield excavator 1b, it is not necessary to provide the skin plate 2b and the shield jack 7b from the beginning. After the main line shield excavator 1a reaches the shaft 16, the main body of the branch shield excavator 1b is moved backward to the vicinity of the rear end of the branching / merging portion 12ab, and then the skin plate 2b is attached to the main body of the branch shield excavator 1b. At the same time, the main line shield jack 7a may be diverted and attached as the shield jack 7b.

 A construction method of the shield tunnel 12 using both the main shield excavator 1a having the above-described configuration and the branch shield excavator 1b incorporated therein will be described below with reference to FIGS. 4 and 5 show horizontal sections of the main shield excavator 1a, the branch shield excavator 1b, and the shield tunnel 12. FIG.

(First step)
As shown in FIG. 4 (a), the mainline lining body 10a is constructed in the general part 12aa of the mainline tunnel 12a while excavating the natural ground 13 with the mainline shield excavator 1a. At the branching / merging portion 12ab of the main tunnel 12a and the branch tunnel 12b, a branching / merging lining structure 10c provided with a segment 15b (described later) that can be cut by the branch shield excavator 1b as the ground 13 is excavated. Will continue to build. After passing the branching / merging portion 12ab and entering the general portion 12aa again, the main line lining body 10a is constructed up to the reaching shaft 16, and the main shield excavator 1a is made to reach the reaching shaft 16.

 Here, as shown in FIG. 3A, the main line lining body 10a has sufficient strength against earth pressure from the natural ground 13, and the main line shield excavator 1a and the branch line shield excavator 1b. It is formed by assembling a general reinforced concrete or steel segment 15a having a rigidity that cannot be cut by the cutters 3a and 3b into a ring shape.

On the other hand, as shown in FIG. 3 (b), the branch / merging lining body 10c uses a segment 15a having the same form as that used in the main line lining body 10a. Although the portion surrounded by the branch line covering body 10b has the resistance against the earth pressure of the natural ground 13, the segment 15b formed to such an extent that it can be cut by the cutter 3b of the branch line shield excavator 1b is adopted. It is assembled in a ring shape.
As the segment 15b, for example, a concrete segment using a fiber reinforcement impregnated with a resin as a reinforcing material in place of a normal reinforcing bar of a segment, or a segment filled with concrete with a segment outer shell made of FRP is conceivable. . The bolts connecting the segments 15b are preferably plastic bolts that can be cut.

(Second step)
As shown in FIG. 4 (b), when the reaching shaft 16 is reached, the main shield excavator 1a is left as it is, and the branch shield excavator 1b built in the main shield excavator 1a is removed from the main shield excavator 1a. If separated and the starting side in the direction of digging of the main shield excavator 1a is set to the rear, a predetermined position of the general portion 12aa in the vicinity of the rear end of the branching / merging portion 12ab (the construction of the partition body 20 described later and the filling of the filler 14) Move backward to a position where there is no hindrance to the work.

Next, as shown in FIG. 4 (c), the inside of the branching / merging portion 12 ab of the main tunnel 12 a is closed with the filler 14. In closing, first, the partition 20 is constructed at both ends of the branch / merging portion 12ab in the tunnel axis direction. The partition 20 may be constructed by assembling a formwork on the entire cross section in the tunnel and placing the concrete in the same manner as in the ordinary concrete frame construction. However, a precast product such as a steel member or concrete is placed in the tunnel. It may be assembled according to the cross section.
Note that the partition 20 on the side where the branch shield excavator 1b starts is applied when at least a portion through which the branch shield excavator 1b passes is filled with a material that can be cut by the branch shield excavator 1b, for example, the filler 14. It is preferable to make unreinforced concrete strong enough to withstand the pressure. After the partition body 20 is constructed, the tunnel mine closed by the partition body 20 is filled with a filler 14 such as fluidized soil or soil cement. Moreover, the entrance packing 8 is installed in the outer side of the partition 20 at the start side of the branch shield excavator 1b.
Further, when the branch shield excavator 1b starts, as shown in FIG. 4 (c), the reaction force receiving body 21 of the branch shield excavator 1b is installed on the inner surface of the main line lining body 10a behind it.

(Third process)
As shown in FIG. 4 (c), a segment 15a is inserted between the reaction force receiving member 21 and the shield jack 7b of the branch shield excavator 1b and assembled in a ring shape. It can be transmitted to the reaction force receiver 21 via 15a. Then, the cutter 3 b of the branch shield excavator 1 b is made to face the entrance packing 8.
The cutter 3b of the branch shield excavator 1b is rotated to cut and dig the partition 20 and the filler 14 of the branch / merging portion 12ab of the main tunnel 12a as shown in FIG. The segment 15a is assembled on the rear side, and the branch line covering body 10b is constructed.

Further, the branch shield excavator 1b is turned in the direction of excavation to match the planned construction position of the branch tunnel 12b, the segment 15b of the branching / merging lining body 10c is cut, and the branch shield excavator 1b is placed in the ground 13 Proceed to Thereafter, the natural ground 13 is dug along the planned construction position of the branch line tunnel 12b, and the branch line covering body 10b of the branch line tunnel 12b is constructed.
Thereafter, as shown in FIG. 5 (b), the branch line covering body 10b assembled in the tunnel of the main tunnel 12a is disassembled, and the filler 14, the partition body 20, and the reaction force receiving body 21 are removed. .

As described above, the shield tunnel 12 can be constructed without constructing the branching / merging portion 12ab between the main tunnel 12a and the branch tunnel 12b by the open-cut method.
Further, when the branch / merging portion 12ab is constructed, the main tunnel 12a and the branch tunnel 12b, which have been conventionally used, are constructed after the construction process of the main tunnel 12a and the branch tunnel 12b by the main shield excavator 1a and the branch shield excavator 1b. There is no need to perform a branching / merging part construction process for connection, and the main line tunnel 12a, the branch line tunnel 12b, and the branching / merging part 12ab are all mechanically using the main line shield excavator 1a and the branch line shield excavator 1b. It can be constructed.
Incidentally, the main line shield excavator 1a is then disassembled leaving the skin plate 2a at the end of the reaching shaft 16, and the main line lining body 10a is constructed by assembling the segment 15a inside the skin plate 2a. Alternatively, the main shield excavator 1 a may be completely penetrated into the reaching shaft 16 and the main shield excavator 1 a may be carried out from the reaching shaft 16 as it is. When carrying out the main line shield excavator 1a as it is, the main line shield excavator 1a is completely penetrated into the shaft 16 while constructing the main line lining body 10a, and then the branch shield excavator 1b is removed from the main line shield excavator 1a. It is preferable to separate and move backward in the vicinity of the rear end of the branching / merging portion 12ab.

(Second Embodiment)
In the first embodiment described above, the case where the main shield excavator 1a including the branch shield excavator 1b is used for the construction method of the shield tunnel for constructing the main tunnel 12a and the branch tunnel 12b is shown. The main construction method is not necessarily limited to this, and the main shield excavator 1a and the branch shield excavator 1b may be separate.

 When these separate main shield excavators 1a and branch shield excavators 1b are used, as shown in FIG. 6, when constructing the main tunnel 12a, the main shield excavator 1a is carried and penetrated into the ground. For this purpose, the branch shield excavator 1b is carried into the main tunnel 12a. Below, the construction method of the shield tunnel using two shield excavators, the main line shield excavator 1a and the branch shield excavator 1b, is shown.

 The main line shield excavator 1a and the branch line shield excavator 1b used here are formed in the same sectional diameter as the main line shield excavator 1a in the main line tunnel 12a and the branch line shield excavator 1b in the same manner as the branch line tunnel 12b. The other configuration is the same as that of the branch shield excavator 1b shown in the first embodiment. That is, as shown in FIG. 1 (c), the skin plate 2, the cutter 3 provided with the cutter bit 3c, the chamber 4 positioned on the back surface of the cutter 3, the soil removal device 5 for conveying the excavated sediment in the chamber 4, and the tail packing 6. It has a shield jack 7 and a thrust receiving member 11 for applying thrust to the main line shield excavator 1a and the branch shield excavator 1b.

(First step)
As shown in FIG. 7 (a), while digging the natural ground 13 with the main line shield excavator 1a, the main line lining body 10a is constructed in the general part 12aa of the main line tunnel 12a and the branch line tunnel 12b is branched. The main line shield excavator 1a is made to reach the reaching shaft 16 while the branching / merging lining body 10c having a part of the segment 15b that can be cut by the branch shield excavator 1b at the junction 12ab is constructed.
The main line lining body 10a and the branching / merging lining body 10c are the same as those shown in the first embodiment.

(Second step)
As shown in FIG. 7B, the inside of the branch / merging portion 12ab of the main tunnel 12a is closed with the filler 14. In this closing, the partition 20 is first constructed at both ends of the branch / merging portion 12ab in the tunnel axis direction, and then the filler 14 is filled into the tunnel closed by the partition 20. The construction of the partition 20 and the filling method of the filler 14 are the same as those in the first embodiment. And the entrance packing 8 is installed in the outer side of the partition 20 by the side of the start of the branch shield excavator 1b.
Next, if the branch shield excavator 1b is carried from the start shaft 17 and the starting side is set to the rear in the direction of the main shield excavator 1a, it moves to a predetermined position of the general portion 12aa near the rear end of the branch / merging portion 12ab. Let
Then, when the branch shield excavator 1b starts, as shown in FIG. 7C, the reaction force receiving body 21 of the branch shield excavator 1b is installed on the inner surface of the main line lining body 10a behind it.

Note that the branch shield excavator 1b is not necessarily carried in the main tunnel 12a in the above-described order, and may be carried before or during the work of filling the filler 14.
Moreover, it may replace with carrying in the branch shield excavator 1b from the starting shaft 17 as mentioned above, and you may make it carry in from there provided the small shaft intermediate shaft 18 as shown in FIG. Of course, when the intermediate shaft through which the main shield excavator 1a passes is provided in the middle of the main tunnel 12a, the nearest shaft 18 for carrying the branch shield excavator 1b is not provided. The branch shield excavator 1b may be carried in from the intermediate shaft.

(Third process)
The subsequent steps are the same as those in the first embodiment. Therefore, detailed description is omitted.

  Incidentally, the main shield excavator 1a after reaching the reaching shaft 16 in the present embodiment, but when the main tunnel 12a is further extended, the main shaft shield excavator 1a is set as the starting shaft 16a. As it is, it may be allowed to advance the digging toward the reaching shaft 16 in the next section, or the main shield excavator 1a may be disassembled while leaving only the skin plate 2 at the end of the reaching shaft 16, Alternatively, the main shield excavator 1a may be carried out from the reaching shaft 16 as it is.

(Modification of the second embodiment)
In the second embodiment described above, the excavation direction of the main shield excavator 1a and the initial excavation direction of the branch shield excavator 1b are substantially the same. In this modification, as shown in FIG. 9, the main shield excavation is performed. That is, the excavation direction of the machine 1a is opposite to the initial excavation direction of the branch shield excavator 1b.

(First step)
Similarly to the second embodiment, the main shield excavator 1a is made to reach the reaching shaft 16. Thereafter, the main shield shield excavator 1a is disassembled, or the excavation is proceeded toward the arrival shaft 16 in the next section as it is to secure the space of the arrival shaft 16.
(Second step)
Similarly to FIG. 7B of the second embodiment, the inside of the branch / merging portion 12ab of the main tunnel 12a is closed with the filler 14. In this closing, first, the partition 20 is constructed at both ends in the tunnel axis direction of the branching / merging portion 12ab, and then the filler 14 is filled into the tunnel closed by the partition 20. The construction of the partition 20 and the filling method of the filler 14 are the same as those in the first embodiment. And the entrance packing 8 is installed in the partition 20 on the start side of the branch shield excavator 1b (in this embodiment, the partition 20 on the reach shaft 16 side).
Next, if the branch shield excavator 1b is carried into the main tunnel 12a from the arrival shaft 16 (or the intermediate shaft 18 instead), and the end side is set forward in the direction of the main shield excavator 1a, the branch / merging portion 12ab It is moved to a predetermined position of the general part 12aa in the vicinity of the front end.
Then, when the branch shield excavator 1b starts, the reaction force receiver 21 of the branch shield excavator 1b is installed on the inner surface of the main line lining body 10a behind the branch shield excavator 1b.
(Third process)
Since the subsequent steps are the same as those of the first and second embodiments except that the direction of the branch shield excavator 1b is opposite, the detailed description is omitted.

 As explained above, according to the construction method of the shield tunnel 12 of the present invention, the main tunnel 12a is constructed while excavating the ground 13 with the main shield excavator 1a, and then the branch line is formed from the inside of the main tunnel 12a. Since the shield excavator 1b is started to construct the branch tunnel 12b of the shield tunnel 12, compared to the conventional construction in which the branch / merging portion 12ab between the main tunnel 12a and the branch tunnel 12b is constructed by the open-cut method, Therefore, it is not necessary to take into consideration the construction space, traffic obstacles due to work zones, noise during construction, and the like, so that the shield tunnel 12 can be constructed without causing a load on the surrounding residents.

 Further, since the main line tunnel 12a, the branch line tunnel 12b, and all of the branching / merging portions 12ab connected to each other can be mechanically constructed by the main line shield excavator 1a and the branch line shield excavator 1b, the main line tunnel 12a and the branch line tunnel 12b. Thus, it is not necessary to construct a branching / merging part construction process as in the conventional construction method in which the two lining bodies are destroyed and then communicated with each other after the construction is individually constructed, and the workability can be greatly improved.

 Further, since it can be mechanically constructed by the main shield excavator 1a and the branch shield excavator 1b, it has little influence on the natural ground 13, so that the natural ground conditions around the branching / merging portion 12ab are changed. However, the branching / merging part 12ab can be mechanically constructed in a uniform procedure, and there is no need to carry out extensive improvement of the ground (even if implemented, the branching / merging lining body 10c and the branch line) Therefore, it is possible to construct the safe and high-quality shield tunnel 12 having the branch tunnel 12b in the main tunnel 12a.

 Moreover, since the branch line shield excavator 1b is started from the inside of the main tunnel 12a to construct the branch tunnel 12b, either the branch shield excavator 1b is built in the main line shield excavator 1a in advance or the start vertical shaft 17 or the arrival Since the branch shield excavator 1b can be carried into the main tunnel 12a using the vertical shaft 16 or the intermediate shaft 18, it is not necessary to newly secure a site for constructing the start shaft 17 for the branch shield excavator 1b. Therefore, it is easy to get the understanding to the residents in the surrounding area, and it is possible to carry out the construction smoothly and to significantly reduce the construction cost.

It is a figure which shows the main line shield excavator and branch line shield excavator used for the construction method of the tunnel which concerns on this invention. It is a figure which shows the construction planned position of the main line tunnel and branch line tunnel which concern on this invention. It is a figure which shows sectional drawing of the main line tunnel which concerns on this invention. It is a figure which shows the 1st-2nd process in the construction method of the main line tunnel and branch line tunnel of 1st Embodiment concerning this invention. It is a figure which shows the 3rd process in the construction method of the main line tunnel and branch line tunnel of 1st Embodiment which concerns on this invention. It is a figure which shows the construction method of the main line tunnel and branch line tunnel of 2nd Embodiment concerning this invention. It is a figure which shows the 1st-2nd process in the construction method of the main line tunnel and branch line tunnel of 2nd Embodiment which concerns on this invention. It is a figure which shows the other construction method of the main line tunnel and branch line tunnel of 2nd Embodiment which concerns on this invention. It is a figure which shows the further another construction method of the main line tunnel and branch line tunnel of 2nd Embodiment which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Shield excavator 2 Skin plate 3 Cutter 4 Chamber 5 Earth removal apparatus 6 Tail packing 7 Shield jack 8 Entrance packing 9 Cutter fitting hole 10a Main line covering body 10b Branch line covering body 10c Branching / merging covering body 11 Thrust receiving member 12 shield tunnel 12a main tunnel 12b branch tunnel 13 ground 14 filler 15 segment 16 reaching shaft 17 starting shaft 18 intermediate shaft 20 partitioning body 21 reaction force receiver

Claims (3)

A tunnel construction method for constructing a main line tunnel using a main line shield excavator, and constructing a branch line tunnel using a branch line shield excavator having a smaller cross-sectional diameter than the main line shield excavator,
While digging the ground with the main line shield excavator, the main line lining body is constructed in the general part of the main line tunnel, and the branch / junction with the branch line tunnel is provided with a segment that can be cut with the branch line shield excavator. A first step of constructing a confluence lining body;
A second step of closing a mine in a range corresponding to a branching / merging portion of the main tunnel with a filler;
After excavating the filler from the inside of the main tunnel with a branch shield excavator and cutting the branch / merging lining body, excavating the ground from the branch / merging part of the main tunnel, branching / merging part and branch line A method for constructing a shield tunnel, comprising a third step of constructing a tunnel branch lining body. In the construction method of the shield tunnel according to claim 1,
The branch shield excavator is built in the main shield excavator;
After the first step is completed, the branch shield excavator is separated and moved back to a predetermined position near the rear end in the tunnel excavation direction in a range corresponding to the branching / merging portion. Construction method of shield tunnel characterized by this. In the construction method of the shield tunnel according to claim 1,
The main tunnel is equipped with a shaft,
After the first step, the second step includes carrying out the branch shield excavator from the vertical shaft and placing it at a predetermined position in the vicinity of the range corresponding to the branching / merging portion. Construction method for shield tunnels.

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