JP6687800B2 - Outer shell body and outer shell construction method - Google Patents

Description

  The present invention relates to an outer frame structure of an underground structure and an outer frame structure construction method for constructing an outer frame structure of an underground structure.

  Patent Documents 1 and 2 describe a method of constructing a large cross-section tunnel in a confluence region between a main line shield tunnel and a branch line shield tunnel. This method first constructs a leading shield tunnel, and then constructs a trailing shield tunnel while cutting a part of the leading shield tunnel. Next, an outer frame body is constructed by connecting the leading shield tunnel and the trailing shield tunnel. In the construction of the outer frame, concrete is placed in the leading shield tunnel before the trailing shield tunnel is constructed, and concrete is placed in the trailing shield tunnel after the trailing shield tunnel is constructed. Thus, the concrete cast in the leading shield tunnel and the concrete cast in the trailing shield tunnel are connected to each other to form an outer frame. Then, the inner peripheral region of the outer frame is excavated to form an underground cavity.

JP, 2005-105513, A JP, 2016-153601, A

  In the methods described in Patent Documents 1 and 2, since the concrete to be placed in the leading shield tunnel and the concrete to be placed in the trailing shield tunnel are placed at different timings, the leading shield tunnel and the trailing shield tunnel are A concrete joint (interface) is formed between the shield tunnel and the shield tunnel. Since the seam tends to become a passage for groundwater and the like and becomes a factor of reducing durability, it is necessary to perform a treatment for improving watertightness and durability on the seam. Therefore, there is a problem that the number of man-hours and the manufacturing cost increase as the number of joints increases.

  Therefore, an object of the present invention is to provide a strong outer shell and a method for constructing an outer shell that can construct a strong outer shell.

  An outer shell structure building method according to the present invention is an outer shell structure building method for building an outer shell structure of an underground structure, wherein a leading shield tunnel building step of building a leading shield tunnel having a leading outer shell, and a leading shield tunnel A trailing shield tunnel construction process for constructing a trailing shield tunnel having a trailing outer shell while cutting a part, and an outer frame for constructing an outer frame formed by placing concrete on the leading shield tunnel and the trailing shield tunnel. In the preceding shield tunnel construction process, in the preceding shield tunnel construction process, the outer shell skeleton planned area is cut in the trailing shield tunnel construction process in the outer shell skeleton planned region in which concrete is placed in the outer shell skeleton construction process in the preceding outer shell. A partition that divides into a side portion including a planned cutting area and a central portion that does not include a planned cutting area, and a pillar that supports the partition wall, In addition to the installation, a machinable filling material that can be cut in the trailing shield tunnel construction process is placed in the region on the planned cutting region side divided by the partition wall in the outer shell structure planned region, and in the trailing shield tunnel construction process. , Cutting the leading outer shell and the machinable filler of the leading shield tunnel to construct a trailing shield tunnel, and in the process of constructing the outer shell, part of the trailing outer shell of the trailing shield tunnel, cutting inside the leading shield tunnel The possible filling material and the partition wall are removed, and concrete is cast into the outer frame structure area of the leading shield tunnel and the trailing shield tunnel to integrate them.

  In this outer shell structure building method, when a part of the trailing outer shell, the machinable filler, and the partition wall are removed in the outer shell building step, the leading shield tunnel and the trailing shield tunnel that are adjacent to each other communicate with each other. Concrete can be cast and integrated into the tunnel and the trailing shield tunnel. As a result, the number of joints formed in the outer shell can be reduced as compared to the case where concrete is placed in each shield tunnel to construct the outer shell, so that the number of steps and the cost can be reduced.

  The strut may support the leading outer shell from the inner peripheral side. In this outer shell structure building method, in the process of constructing the leading shield tunnel, columns for supporting the leading outer shell from the inner peripheral side are installed in the leading outer shell of the leading shield tunnel, so that the leading outer shell is constructed in the trailing shield tunnel building process. It is possible to prevent the preceding outer shell from being deformed even when cutting.

  In the preceding shield tunnel construction step, concrete may be poured in a region between one end of the column and the preceding outer shell in the leading outer shell. In this outer shell structure building method, concrete is placed in the region between one end of the pillar and the leading shell in the leading shield tunnel building step, so while increasing the rigidity of the leading shield tunnel, the leading outer shell is constructed by the pillar. It can be efficiently supported.

  In the trailing shield tunnel construction step, the trailing shield tunnel may be constructed while cutting a part of the leading shield tunnel on both sides of the leading shield tunnel. In this outer frame building method, in order to build a trailing shield tunnel while cutting a part of the preceding shield tunnel on both sides of the leading shield tunnel, in the outer frame building process, concrete and its placed in the leading shield tunnel It is possible to integrate the concrete that is placed in the trailing shield tunnels that are placed on both sides. As a result, the number of joints formed on the outer frame can be further reduced.

  In the preceding shield tunnel construction step, as partition walls, a first partition wall for partitioning a side portion including one planned cutting region and a second partition wall for partitioning a side portion including the other planned cutting region are installed as pillars. The first support pillar that supports the first partition wall and the second support pillar that supports the second partition wall may be installed. In this outer shell structure building method, in the preceding shield tunnel building step, since a cavity is formed between the first partition wall supported by the first support pillar and the second partition wall supported by the second support pillar, the outer shell structure construction step is performed. By removing a part of the trailing outer shell, the machinable filler, and the partition wall, the leading shield tunnel and the trailing shield tunnels arranged on both sides thereof can be communicated with each other. In addition, it is possible to reduce the amount of concrete and machinable filler to be placed in the preceding shield tunnel construction process.

  The trailing outer shell has a main girder that extends in the circumferential direction of the trailing shield tunnel and a skin plate that is supported by the main girder and separates the inside and the outside of the trailing outer shell. May be removed to connect the planned outer frame body region in the leading shield tunnel and the trailing shield tunnel. In this method for constructing the outer frame, the skin plate of the trailing outer shell can be removed to form an opening that communicates the planned outer shell body region in the leading shield tunnel with the trailing shield tunnel. The concrete cast in the shield tunnel and the concrete cast in the trailing shield tunnel can be integrated.

  An outer frame body according to the present invention is an outer frame body of an underground structure, a leading shield tunnel having a leading outer shell, a trailing shield tunnel having a trailing outer shell overlapping with the leading shield tunnel, and a leading shield tunnel and It is equipped with concrete that has been cast into the trailing shield tunnel and integrated, and the trailing shield tunnel is stacked on the leading shield tunnel with the leading outer shell of the leading shield tunnel being cut. The installed concrete and the concrete placed in the trailing shield tunnel are integrated through an opening formed in a part of the trailing outer shell of the trailing shield tunnel. In this outer frame, the concrete placed in the leading shield tunnel and the trailing shield tunnel that are stacked on top of each other are integrated through the opening formed in a part of the trailing shell of the trailing shield tunnel, It is possible to reduce the number of joints formed in the outer frame body as compared with the outer frame body in which concrete is placed in each shield tunnel. As a result, the man-hours and the construction cost for constructing the outer shell can be reduced. Moreover, a strong outer frame body having excellent integration can be constructed.

  According to the present invention, a strong outer shell can be constructed.

It is a perspective view showing a schematic structure of an underground structure concerning an embodiment. It is sectional drawing in the II-II line shown in FIG. It is sectional drawing in the III-III line shown in FIG. It is a figure which shows the structure of the outer shell of a shield tunnel. It is sectional drawing in the VV line shown in FIG. It is sectional drawing which shows the structure of the part which overlaps with the trailing shield tunnel of a front shell. It is sectional drawing which shows a part of outer frame body. It is a schematic diagram for demonstrating a starting base construction process. FIG. 9 is a sectional view taken along line IX-IX shown in FIG. 8. It is a schematic diagram for demonstrating a precedent shield tunnel extending process. FIG. 11 is a sectional view taken along line XI-XI shown in FIG. 10. It is sectional drawing in the XII-XII line shown in FIG. It is sectional drawing for demonstrating the area | region in a front shield tunnel. It is sectional drawing for demonstrating the front shield tunnel filling process. It is sectional drawing which shows the internal structure of a front shield tunnel. It is a perspective view showing a support unit. FIG. 17 is a sectional view taken along line XVII-XVII shown in FIG. 16. It is sectional drawing in the XVIII-XVIII line shown in FIG. It is sectional drawing for demonstrating arrangement | positioning of a support unit. Sectional drawing which shows the internal structure of the cut | disconnected leading shield tunnel. It is a schematic diagram for demonstrating a trailing shield tunnel construction process. FIG. 22 is a sectional view taken along line XXII-XXII shown in FIG. 21. It is sectional drawing in the XXII-XXIII line shown in FIG. It is sectional drawing for demonstrating an outer frame body construction process. It is sectional drawing for demonstrating an outer frame body construction process. It is sectional drawing which shows the state which removed the partition of the support unit. It is sectional drawing for demonstrating an outer frame body construction process. It is sectional drawing for demonstrating an outer frame body construction process. It is a schematic diagram for demonstrating a case wall construction process. It is a schematic diagram for demonstrating an excavation process.

  Hereinafter, preferred embodiments of an outer shell structure building method and an outer shell structure will be described in detail with reference to the drawings. In the present embodiment, in order to join the newly installed branch line shield tunnel to the existing main line shield tunnel, the outer frame structure building method according to the present invention is designed so that the main line shield tunnel and the branch line shield tunnel are provided in the joining area of the main line shield tunnel and the branch line shield tunnel. It is applied to a method of constructing a large cross-section tunnel that surrounds both sides of the tunnel. In addition, the outer frame body according to the present embodiment is an outer frame body of a large-section tunnel constructed by such a method. However, the method for constructing an outer frame and the outer frame of the present invention are not limited to the method for constructing such a large-section tunnel and the method applied to such a large-section tunnel. In all the drawings, the same or corresponding parts are designated by the same reference numerals.

  First, the underground structure will be described. As shown in FIGS. 1 to 3, the underground structure 1 according to the present embodiment has both the main line shield tunnel 2 and the branch line shield tunnel 3 that are constructed in a confluence region of the main line shield tunnel 2 and the branch line shield tunnel 3. It is a large-section tunnel that surrounds. An underground cavity 4 extending in the axial direction of the underground structure 1 is formed inside the underground structure 1, and the underground structure 1 has an outer frame body 12 of the underground cavity 4 formed by connecting a plurality of shield tunnels 11. Is equipped with.

  The shield tunnel 11 is a tunnel constructed by a known shield excavation method or shield propulsion method. That is, the shield tunnel 11 digs into the ground with a shield machine and assembles a segment which becomes the wall surface of the tunnel behind the shield machine, and excavates the shield machine with thrust from a propulsion tube. It is a tunnel constructed by assembling a propulsion pipe. That is, the shield tunnel 11 is extended by constructing a tunnel lining body or a tunnel skeleton by the segment assembled by excavating the shield machine and the propulsion pipe assembled by the excavation. The segment assembled by excavating the shield machine and the propulsion pipe assembled by the excavation serve as the outer shell 11A of the shield tunnel 11. The underground structure 1 is axially stretched between one end 1a (upper right end in FIG. 1) and the other end 1b (lower left end in FIG. 1) of the underground structure 1. A plurality of shield tunnels 11 are arranged in the circumferential direction so as to surround both the main line shield tunnel 2 and the branch line shield tunnel 3.

  As shown in FIG. 4 and FIG. 5, the outer shell 11A is constructed by a plurality of segment rings, which are assembled by assembling a plurality of segments 30 in a ring shape in the circumferential direction, and are connected in the tunnel axial direction. The segment 30 constituting the outer shell 11A includes a main girder 31, a joint plate 32, and a skin plate 33. The main girder 31 is a member that extends in the circumferential direction of the shield tunnel 11, and has a predetermined length in the axial direction of the shield tunnel 11. The main girder 31 is made of, for example, a steel material such as a shaped steel, and functions as a structure of the outer shell 11A. The joint plate 32 is a member that extends in the axial direction of the shield tunnel 11, and has a predetermined length in the axial direction of the shield tunnel 11. The joint plates 32 of the adjacent segments 30 can be connected to each other, and a plurality of segments 30 are connected in the circumferential direction to form a ring-shaped segment ring closed in the circumferential direction. The joint plate 32 is made of, for example, a plate-shaped steel material. Between the joint plates 32, one or a plurality of ribs extending parallel to the joint plates are provided. The skin plate 33 is a member forming the outer peripheral surface of the shield tunnel 11. The skin plate 33 is connected to the outer peripheral side of the main girder 31 and separates the inner side of the shield tunnel 11 from the ground. The main girders 31 of the segment rings and the main girders 31 of the adjacent segment rings can be connected to each other, and a plurality of segment rings are connected in the tunnel axis direction to form the shield tunnel 11. The main girders 31 adjacent to the main girders 31 and the joint plate 32 adjacent to the joint girders 32 can be connected by, for example, bolting. The skin plate 33 is made of, for example, a curved plate-shaped steel material having an arc-shaped cross section, and functions as a partition wall that separates the outer shell 11A and the ground.

  As shown in FIGS. 1 to 3, the plurality of shield tunnels 11 include a leading shield tunnel 13 that is a part of the plurality of shield tunnels 11 and the remaining shield tunnels of the plurality of shield tunnels 11. And a trailing shield tunnel 14 which is the tunnel 11. The outer shell 11A of the leading shield tunnel 13 is called the leading outer shell 13A, and the outer shell 11A of the trailing shield tunnel 14 is called the trailing outer shell 14A. The leading outer shell 13A and the trailing outer shell 14A are constructed by a plurality of segments 30, as shown in FIGS. 4 and 5.

  The leading shield tunnel 13 extends from one end 1a to the other end 1b. The trailing shield tunnel 14 extends from one end 1a to the other end 1b. That is, both ends of the leading shield tunnel 13 and the trailing shield tunnel 14 reach the one end 1a and the other end 1b. The trailing shield tunnel 14 is a shield tunnel that is stretched after the leading shield tunnel 13 is stretched. The trailing shield tunnel 14 is arranged between adjacent leading shield tunnels 13, and the trailing shield tunnel 14 is superposed on the leading shield tunnel 13 in a state where the leading outer shell 13A of the leading shield tunnel 13 is cut. ing. The leading shield tunnel 13 and the trailing shield tunnel 14 that are adjacent to each other overlap each other in the entire region from the one end 1a to the other end 1b. In the portion where the leading shield tunnel 13 and the trailing shield tunnel 14 overlap, the leading outer shell 13A of the leading shield tunnel 13 is scraped off, and the trailing outer shell 14A of the trailing shield tunnel 14 is as shown in FIG. The joint plate 32, the ribs and the skin plate 33 are removed from the main girder 31 to form an opening 34.

  Then, the distance between the central axis of the adjacent shield tunnel 13 and the central axis of the trailing shield tunnel 14 which are adjacent to each other becomes narrower from one end portion 1a to the other end portion 1b, so that the underground cavity 4 becomes the main shield tunnel 2 and The cross-sectional area of the underground cavity 4 is reduced from one end portion 1a toward the other end portion 1b so as to follow the outer shape of the branch line shield tunnel 3. Further, the degree of overlap between the adjoining leading shield tunnel 13 and trailing shield tunnel 14 is large so that the cross-sectional area of the underground cavity 4 becomes smaller from the one end 1a to the other end 1b.

  The trailing shield tunnel 14 includes a first trailing shield tunnel 141 extending toward the other end 1b, and a second trailing tunnel extending between the tip of the first trailing shield tunnel 141 and the other end 1b. And a row shield tunnel 142. The first trailing shield tunnel 141 is a shield tunnel having the same diameter as the leading shield tunnel 13, and the second trailing shield tunnel 142 is a shield tunnel having a smaller diameter than the first trailing shield tunnel 141. The first trailing shield tunnel 141 extends from the one end 1a to the other end 1b, and the second trailing shield tunnel 142 extends from the tip of the first trailing shield tunnel 141 to the other end 1b. It has been stretched. Therefore, of the one trailing shield tunnel 14, the portion on the one end 1a side is the large-diameter first trailing shield tunnel 141, and the portion on the other end 1b side is the second trailing shield tunnel having the small diameter. 142.

  As described above, the interval between the adjacent leading shield tunnels 13 is narrower on the side of the other end 1b than on the side of the one end 1a, so that the trailing shield is provided in the entire region from the one end 1a to the other end 1b. If the tunnels 14 have the same diameter, the amount of overlap between the leading shield tunnel 13 and the trailing shield tunnel 14 becomes excessive. Therefore, on the one end 1a side, the trailing shield tunnel 14 is a large-diameter first trailing shield tunnel 141, and on the other end 1b side, the trailing shield tunnel 14 is a small-diameter second trailing shield tunnel 142. Then, the overlapping amount of the leading shield tunnel 13 and the trailing shield tunnel 14 is reduced to reduce the cutting amount of the leading shield tunnel 13 when the trailing shield tunnel 14 is constructed.

  To be more specific, the shield tunnel 11 is composed of 18 leading shield tunnels 13 and 18 trailing shield tunnels 36 in total. That is, the number of leading shield tunnels 13 and the number of trailing shield tunnels 14 are the same. The underground structure 1 is divided into two regions, a first region A1 and a second region A2, from one end 1a of the underground structure 1 toward the other end 1b. The leading shield tunnel 13 has the same diameter in the first area A1 and the second area A2. The trailing shield tunnel 14 is a large-diameter first trailing shield tunnel 141 in the first area A1, and is a small-diameter second trailing shield tunnel 142 in the second area A2. The leading shield tunnels 13 and the trailing shield tunnels 14 are alternately arranged, and the trailing shield tunnels 14 are arranged between the leading shield tunnels 13 adjacent to each other.

  As shown in FIGS. 1 to 3 and 7, the outer frame body 12 is a substantially arcuate frame body forming the outer frame of the underground cavity 4. The outer frame body 12 is formed by connecting adjacent shield tunnels 11. Specifically, the outer frame body 12 is made of reinforced concrete that is placed in the adjacent leading shield tunnel 13 and trailing shield tunnel 14. Then, the reinforced concrete cast in the leading shield tunnel 13 and the reinforced concrete cast in the trailing shield tunnel 14 have an opening 34 (FIG. 6) formed in a part of the trailing outer shell 14A of the trailing shield tunnel 14. Integrated).

  As shown in FIGS. 1 to 3, at one end 1a of the underground structure 1, a one-sided casing wall 15 that seals (stops water) one side surface of the outer shell 12 is constructed. On the other end 1b of 1, the other side wall 16 that seals (stops water) the other side surface of the outer shell 12 is constructed.

  Then, by excavating and removing a part or all of the earth and sand in the inner peripheral side region of the outer shell body 12 sandwiched between the one side wall 15 and the other side wall 16, the underground cavity 4 is formed inside the underground structure 1. Are formed.

  Next, a method of constructing the above-mentioned underground structure 1 will be described. The method for constructing an underground structure according to the present embodiment includes a starting base building step (S1), a leading shield tunnel building step (S2) for building a leading shield tunnel 13 having a leading outer shell 13A, and a leading shield tunnel 13. While cutting a part, the trailing shield tunnel construction step (S3) of constructing the trailing shield tunnel 14 having the trailing outer shell 14A, and placing concrete in the leading shield tunnel 13 and the trailing shield tunnel 14 are performed. An outer shell body building step (S4) of building the outer shell body 12 is formed, a case wall building step (S5), and an excavation step (S6).

  In the starting base construction step (S1), as shown in FIGS. 8 and 9, the starting base 21 for extending the shield tunnel 11 is built. The starting base 21 extends circumferentially from the starting tunnel 22 so as to surround both the main tunnel tunnel 2 and the branch shield tunnel 3 and the starting tunnel entrance 22 extending from the branch shield tunnel 3 to the radially outer side of the branch shield tunnel 3. And a circumferential shield tunnel 23. The starting hole 22 can be constructed by a known shield machine, and the circumferential shield tunnel 23 can be constructed by a known shield machine.

  In the preceding shield tunnel building step (S2), as shown in FIGS. 1 and 10, one end portion 1a and the other end portion 1b of the underground structure planned area (not shown), which is a planned construction area of the underground structure 1, are provided. In between, a plurality of preceding shield tunnels 13 extending in the axial direction are constructed in the circumferential direction. The one end 1a and the other end 1b of the planned underground structure area are the same as the one end 1a and the other end 1b of the underground structure 1, respectively.

  If the adjacent leading shield tunnels 13 are constructed, the trailing shield tunnel construction step (S3) is started before the extension of all the leading shield tunnels 13 is completed, and the adjacent leading shield tunnels are constructed. The trailing shield tunnel 14 may be extended between the tunnels 13.

  In the preceding shield tunnel construction step (S2), the preceding shield tunnel drawing step (S21) and the preceding shield tunnel filling step (S22) are performed.

  In the leading shield tunnel stretching step (S21), as shown in FIGS. 10 to 12, the leading shield tunnel 13 is stretched from the starting base 21 constructed at the one end 1a to the other end 1b. Specifically, in the leading shield tunnel stretching step (S21), 18 leading shield tunnels 13 are stretched from the starting base 21 constructed on the one end 1a to the other end 1b. At this time, without extending the adjacent leading shield tunnels 13 at the same time, one of the adjacent leading shield tunnels 13 is first extended and then the other leading shield tunnel 13 is trailing. Stretching is preferred. Further, it is preferable to use two or more shield excavators for excavation of the leading shield tunnel 13. By using two or more shield machines, a plurality of leading shield tunnels 13 can be extended in parallel.

  Further, in the leading shield tunnel stretching step (S21), the plurality of leading shield tunnels 13 are stretched so that the central axes of the neighboring leading shield tunnels 13 approach each other from the one end 1a toward the other end 1b. To do.

  Here, the leading shield tunnel 13 needs to include a portion that can be cut by a shield machine or the like that extends the trailing shield tunnel 14. Therefore, at least the segment or the propulsion pipe of the leading outer shell 13A of the leading shield tunnel 13 that is cut by the extension of the trailing shield tunnel 14 is cuttable. As the machinable segment or the propulsion pipe, for example, a fibrous reinforced resin machinable segment or a machinable propulsion pipe as described in Patent Document 1, Patent Document 2, Patent No. 4851133, Patent No. 4939803, etc. To use.

  In the leading shield tunnel filling step (S22), the inside of the leading shield tunnel 13 is filled so that the shield machine that extends the trailing shield tunnel 14 can proceed while overlapping the leading shield tunnel 13.

  Here, as shown in FIG. 13, regions of the leading shield tunnel 13 that are to be cut in the trailing shield tunnel building step (S3) are a planned cutting region 13E and a planned cutting region 13F. The planned cutting area 13E and the planned cutting area 13F are formed on both sides of the leading shield tunnel 13. Of the regions in the preceding outer shell 13A, the region where concrete is placed in the outer shell structure building step (S4) is referred to as the outer shell structure planned region 13B. One end of the outer shell structure planned region 13B overlaps with the planned cutting region 13E, and the other end of the outer shell structure planned region 13B overlaps with the planned cutting region 13F. Out of the region in the preceding outer shell 13A, the region other than the planned cutting region 13E, the planned cutting region 13E, and the planned outer frame body region 13B is located on the inner peripheral side of the outer frame body 12 with respect to the outer frame body planned region 13B. The area is defined as the inner peripheral area 13C. Further, among the regions in the preceding outer shell 13A, the regions other than the planned cutting region 13E, the planned cutting region 13E and the planned outer frame body region 13B are located on the outer peripheral side of the outer frame body 12 with respect to the outer frame body planned region 13B. The area to be formed is the outer peripheral side area 13D.

  As shown in FIGS. 13 to 15, in the preceding shield tunnel filling step (S22), as the filling inside the preceding shield tunnel 13, the support unit 40 is arranged, and concrete and a machinable filling material are placed (filling). To do.

  The support unit 40 is arranged in the outer shell structure planned region 13B at the radial center of the leading shield tunnel. The configuration of the support unit 40 will be described later.

  Concrete is placed in the concrete placing area 50A and the concrete placing area 50B. The concrete pouring area 50A is an area within the inner peripheral side area 13C, and is an area excluding the planned cutting area 13E, the planned cutting area 13E and the planned outer shell structure area 13B. The concrete placing area 50B is an area within the outer peripheral side area 13D, and is an area excluding the planned cutting area 13E, the planned cutting area 13E and the planned outer shell structure area 13B. The concrete placing areas 50A and 50B are set by excluding the vicinity of the planned cutting areas 13E and 13F so that the concrete is not cut during the excavation of the trailing shield tunnel 14 (the trailing outer shell 14A). That is, concrete is not placed near the planned cutting regions 13E and 13F.

  The machinable filler material is placed in the machinable filler material area 51A and the machinable filler material area 51B. The machinable filler material region 51A is a region including the planned cutting region 13E, and is a region surrounded by the preceding outer shell 13A, the support unit 40, and the concrete placing regions 50A and 50B. The machinable filler material region 51B is a region including the planned cutting region 13F and is a region surrounded by the leading outer shell 13A, the support unit 40, and the concrete placing regions 50A and 50B. The machinable filler material regions 51A and 51B are planned cutting regions 13E which are regions to be excavated (cut) in order to allow an excavation error during excavation of the trailing shield tunnel 14 (the trailing outer shell 14A). , Slightly larger than 13F.

  By the way, as shown in FIG. 20, when the leading shield tunnel 13 is cut in the subsequent shield tunnel building step (S3) in the subsequent step, the main girder 31 supporting the leading outer shell 13A (see FIGS. 4 and 5). The leading outer shell 13A is also cut to separate the first leading outer shell portion 13AA and the second leading outer shell portion 13AB. Further, no concrete is placed in the planned outer skeleton region 13B. Therefore, the main girder 31 cannot support the earth pressure acting in the opposing direction of the first leading outer shell portion 13AA and the second leading outer shell portion 13AB. Therefore, by arranging the support unit 40 in the outer skeleton planned region 13B, when the leading shield tunnel 13 is cut in the subsequent shield tunnel construction step (S3) in the subsequent step, the load due to earth pressure or impact during cutting is applied. Thus, the deformation of the leading shield tunnel 13 is suppressed.

  As shown in FIGS. 15 to 19, the support unit 40 includes a first partition wall 41A and a second partition wall 41B, a first support column 42A and a second support column 42B, an inner circumference side support girder 43A and an outer circumference side support girder 43B. An inner peripheral side shield plate 44A and an outer peripheral side shield plate 44B.

  The first partition wall 41A divides the outer shell structure region 13B into a side part 13G including the planned cutting region 13E and a central part 13J not including the planned cutting region 13E. The second partition wall 41B divides the outer skeleton planned region 13B into a side part 13H including the planned cutting region 13F and a central part 13J not including the planned cutting region 13F. The side portion 13G divided by the first partition wall 41A is a region of the first partition wall 41A opposite to the second partition wall 41B. The side portion 13H divided by the second partition wall 41B is a region of the second partition wall 41B opposite to the first partition wall 41A. The central portion 13J divided by the first partition wall 41A and the second partition wall 41B is a region located at the radial center part of the leading shield tunnel 13, and is a region between the first partition wall 41A and the second partition wall 41B. is there.

  Specifically, the first partition wall 41A and the second partition wall 41B are composed of a flat iron plate, and the first partition wall 41A and the second partition wall 41B are arranged so as to face each other in the circumferential direction of the outer shell structure planned region 13B. To be installed. Then, a plurality of first partition walls 41A and second partition walls 41B are arranged along the axial direction of the leading shield tunnel 13.

  The first support column 42A supports the first partition wall 41A and also supports the leading outer shell 13A from the inner peripheral side. The second support column 42B supports the second partition wall 41B and also supports the leading outer shell 13A from the inner peripheral side.

  Specifically, the first support column 42A and the second support column 42B are each made of a steel material such as H-shaped steel, and the first support column 42A and the second support column 42B are arranged side by side in the circumferential direction of the outer frame structure scheduled region 13B. It is arranged as follows. 42 A of 1st support | pillars and 42 B of 2nd support | pillars are the opposing direction (concrete pouring area 50A) of the 1st front outer shell part 13AA and the 2nd front outer shell part scheduled part which are isolate | separated by the trailing shield tunnel construction process (S3). And the concrete pouring area 50B).

  Further, the first partition 41A is detachably connected to the first support 42A, and the second partition 41B is detachably connected to the second support 42B. The first partition wall 41A and the second partition wall 41B can be connected to the first support pillar 42A and the second support pillar 42B by, for example, bolting or welding. Then, the plurality of first support columns 42A and the second support columns 42B are arranged along the axial direction of the leading shield tunnel 13.

  The inner peripheral side support girder 43A supports the tips of the first support columns 42A and the second support columns 42B on the concrete placing region 50A side, and the outer peripheral side support girders 43B are the concrete placing regions of the first support column 42A and the second support column 42B. Support the tip on the 50B side.

  Specifically, the inner peripheral side support girder 43A and the outer peripheral side support girder 43B are each made of a steel material such as H-shaped steel, and the inner peripheral side support girder 43A and the outer peripheral side support girder 43B are connected to the first support column 42A. And the second support columns 42B are arranged so as to be parallel to each other in the circumferential direction of the outer frame structure planned region 13B. The inner peripheral side support girder 43A is bridged over the first support column 42A and the second support column 42B along the circumferential direction of the outer shell structure planned region 13B, and the concrete placing region 50A side of the first support column 42A and the second support column 42B. To the tip of the. The outer peripheral side support girder 43B is bridged over the first support column 42A and the second support column 42B along the circumferential direction of the outer shell structure planned region 13B, and the concrete support region 50B side of the first support column 42A and the second support column 42B. Attach to the tip.

  The inner peripheral side shield plate 44A shields the concrete placing area 50A side of the support unit 40. The outer peripheral side shield plate 44B shields the concrete pouring region 50B side of the support unit 40.

  Specifically, the inner peripheral side shield plate 44A and the outer peripheral side shield plate 44B are made of a flat iron plate, and the inner peripheral side shield plate 44A and the outer peripheral side shield plate 44B are connected to each other in the outer skeleton scheduled region 13B. They are arranged so as to face each other in the radial direction. The inner peripheral side shield plate 44A is bridged over a plurality of inner peripheral side support girders 43A along the axial direction of the outer shell structure planned region 13B, and is joined to the tip of the inner peripheral side support girder 43A on the concrete placing region 50A side. . The outer peripheral side shielding plate 44B is bridged over a plurality of outer peripheral side support girders 43B along the axial direction of the outer shell structure planned region 13B, and is joined to the tip of the outer peripheral side support girder 43B on the concrete placing region 50B side. Then, a plurality of inner peripheral side shield plates 44A and outer peripheral side shield plates 44B are arranged along the axial direction of the preceding shield tunnel 13.

  In the support unit 40 configured in this way, the first support column 42A and the second support column 42B, the inner peripheral side support girder 43A, and the outer peripheral side support girder 43B form a double girder-shaped frame. Then, inside the support unit 40, an internal space 45 surrounded by the first partition wall 41A, the second partition wall 41B, the inner peripheral side shield plate 44A, and the outer peripheral side shield plate 44B is formed. The internal space 45 is the same as the central portion 13J divided by the first partition 41A and the second partition 41B. Then, the first partition wall 41A, the second partition wall 41B, the inner peripheral side shield plate 44A, and the outer peripheral side shield plate 44B serve as partition walls of the internal space 45 and surround the internal space 45, so that they are placed inside the preceding shield tunnel 13. The concrete and the machinable filler to be filled do not enter the inner space 45. Therefore, the internal space 45 is hollow.

  Further, the concrete is cast in the concrete casting region 50A between the first strut 42A and one end of the second strut 42B and the first preceding shell 13AA in the leading shell 13A, and It is placed in the concrete placing area 50B between the other ends of the columns 42A and the second columns 42B and the second preceding outer shell portion 13AB. Then, the tips of the first strut 42A and the second strut 42B on the concrete pouring region 50A side pass through the inner peripheral side support girder 43A and the inner peripheral side shield plate 44A, and the concrete pouring region 50A of the inner peripheral side region 13C. Is connected to the concrete to be cast into, and the tips of the first strut 42A and the second strut 42B on the concrete casting region 50B side are connected to the outer circumferential side region 13D via the outer circumferential side support girder 43B and the outer circumferential side shield plate 44B. It is connected to the concrete to be placed in the concrete placing area 50B. As a result, the first support column 42A and the second support column 42B support the first partition wall 41A and the second partition wall 41B, and the first leading outer shell portion 13AA and the second leading outer shell portion 13AB of the leading outer shell 13A are provided inside. Support from the circumference side.

  The filling of the inside of the leading shield tunnel 13 can be performed as follows, for example. When the extension of the leading shield tunnel 13 is completed, the remains of the shield machine are left at the tip of the leading shield tunnel 13, and the collected materials of the shield machine are collected from the leading shield tunnel 13 to the starting base 21 of the one end 1a. To do. The collected items of the shield excavator correspond to, for example, a cutter motor, a shield jack, electric components, and the like. A part of the shield machine, which has a function of preventing the inflow of earth and sand by forming an outer shell of the shield machine, such as a cutter portion and a peripheral steel shell portion, is left as a remnant in the ground. At that time, the inside of the leading shield tunnel 13 is sequentially filled from the tip of the leading shield tunnel 13 toward the one end 1a. The filling of the inside of the leading shield tunnel 13 divides the leading shield tunnel 13 into a plurality of spans, and constructs a partition wall on the side of one end 1a of the span to be filled. Then, the support unit 40 is placed, and concrete and a machinable filler are placed on the span.

  The arrangement of the support unit 40, the order of placing the concrete and the machinable filler, the order of assembling the support unit 40, and the like are not particularly limited, and are appropriately set from the viewpoint of workability and the like. Moreover, you may perform a part of these processes simultaneously. In order to place the concrete and the machinable filler in the concrete placing areas 50A and 50B and the machinable filler areas 51A and 51B, a formwork is appropriately arranged between the support unit 40 and the preceding outer shell 13A. Set up.

  In the trailing shield tunnel construction step (S3), as shown in FIGS. 1 and 20 to 23, extending the trailing shield tunnel 14 from the starting base 21 constructed at one end 1a to the other end 1b. Then, between the one end portion 1a and the other end portion 1b of the planned underground structure area (not shown) which is the planned construction area of the underground structure 1, the plurality of trailing shield tunnels 14 extending in the axial direction are encircled. Build in the direction. Specifically, in the trailing shield tunnel construction step (S3), 18 trailing shield tunnels 14 are extended from the starting base 21 constructed at one end 1a to the other end 1b in the outer shell structure planned region. To do. At this time, since the earth and sand on the upper part of the shield tunnel tends to loosen, it is preferable to extend from the trailing shield tunnel 14 arranged below so that the upper part is extended by the shield tunnel later. Further, like the extension of the leading shield tunnel 13, it is preferable to use two or more shield excavators for excavating the trailing shield tunnel 14. By using two or more shield excavators, a plurality of trailing shield tunnels 14 can be extended in parallel.

  In the trailing shield tunnel construction step (S3), the central axes of the trailing shield tunnels 14 adjacent to each other approach each other from one end 1a to the other end 1b, and the leading shield tunnels 13 adjacent to each other move. The plurality of trailing shield tunnels 14 are extended so that the central axis and the central axis of the trailing shield tunnel 14 approach each other. Thereby, the cross-sectional area of the underground cavity can be reduced from the one end 1a to the other end 1b. In the trailing shield tunnel construction step (S3), one of the leading shield tunnels 13 is arranged so that the leading shield tunnel 13 and the trailing shield tunnel 14 which are adjacent to each other overlap each other in the entire area from the one end 1a to the other end 1b. The portion is cut and the trailing shield tunnel 14 is extended.

  Here, when a part of the leading shield tunnel 13 is cut, the main girder 31 (see FIGS. 4 and 5) that supports the leading outer shell 13A is also cut, and the leading outer shell 13A becomes the first leading outer shell portion 13AA. It is separated into a second preceding outer shell portion 13AB. However, the first support column 42A and the second support column 42B of the support unit 40 arranged between the first leading outer shell portion 13AA and the second leading outer shell portion 13AB are the inner support girder 43A and the outer support girder. 43B, the inner peripheral side shield plate 44A and the outer peripheral side shield plate 44B, and the concrete placed in the concrete placing areas 50A and 50B, and the first leading outer shell portion 13AA and the second leading outer shell portion 13AB. Is supported from the inner circumference side. Therefore, even if a part of the leading shield tunnel 13 is cut in the trailing shield tunnel building step (S3), the leading shield tunnel 13 does not collapse.

  Then, in the trailing shield tunnel building step (S3), as the trailing shield tunnel 14 of the first area A1, the first trailing shield tunnel building step of extending the first trailing shield tunnel 141 toward the other end 1b. (S31), and as the trailing shield tunnel 14 of the second area A2, a second rear portion having a diameter smaller than that of the first trailing shield tunnel 141 is provided between the tip of the first trailing shield tunnel 141 and the other end portion 1b. A second trailing shield tunnel construction step (S32) of extending the row shield tunnel 142 is performed. In the first trailing shield tunnel construction step (S31), the first trailing shield tunnel 141 is extended from the one end 1a, and in the second trailing shield tunnel construction step (S32), the first trailing shield tunnel 141 The second trailing shield tunnel 142 extends from the tip to the other end 1b. Thereby, one trailing shield tunnel 14 extending from the one end 1a to the other end 1b is extended.

  The extension of the first trailing shield tunnel 141 and the second trailing shield tunnel 142 is described in, for example, JP2005-194752A, JP10-153083A, and JP10-096392A. This can be easily done by using a machine (parent-child shield machine). That is, in the first trailing shield tunnel construction step (S31), the parent shield machine of the parent-child shield machine extends the first trailing shield tunnel 141, and thereafter, the child shield machine is started from the parent-child shield machine, and the child shield machine is started. The machine extends the second trailing shield tunnel 142 from the tip of the first trailing shield tunnel 141.

  In the present embodiment, the arrival base (internal cavity) corresponding to the starting base 21 of the one end 1a is not constructed in the other end 1b, but the starting base 21 of the one end 1a is formed in the other end 1b. When the corresponding reaching base is constructed, the shield machine having reached the other end 1b may be dug from the other end 1b toward the one end 1a. In this case, it is not necessary to move the shield machine from the other end 1b to the one end 1a. Moreover, when the arrival base corresponding to the starting base 21 of the one end 1a is constructed in the other end 1b, in the second trailing shield tunnel construction step (S32), the arrival base of the other end 1b is The second trailing shield tunnel 142 may be extended toward the tip of the one trailing shield tunnel 141. In this case, the extension of the second trailing shield tunnel 142 can be started before the extension of the first trailing shield tunnel 141 is completed.

  By the way, as shown in FIG. 24, due to the construction of the leading shield tunnel 13, the support unit 40 is disposed in the outer shell structure region 13B inside the leading shield tunnel 13, and the machinable filler is cast. Has been done. Further, due to the construction of the trailing shield tunnel 14, the leading shield tunnel 13 and the trailing shield tunnel 14 which are adjacent to each other overlap each other. At this overlapping portion, the trailing outer shell 14A of the trailing shield tunnel 14 is connected to the leading shield tunnel 14A. The tunnel 13 and the trailing shield tunnel 14 are separated from each other.

  In the outer shell structure building step (S4), first, as shown in FIG. 25, a part of the trailing outer shell 14A of the trailing shield tunnel 14 is removed to connect the leading shield tunnel 13 and the trailing shield tunnel 14 to each other. Let Specifically, as shown in FIGS. 5 and 6, in the portion of the trailing outer shell 14A of the trailing shield tunnel 14 that overlaps with the leading shield tunnel 13, the main girder 31 is left and the joint plate 32 is left. , The rib and the skin plate 33 are removed. The joint plate 32, the ribs, and the skin plate 33 are removed from the trailing shield tunnel 14 side. Thereby, the opening 34 that connects the leading shield tunnel 13 and the trailing shield tunnel 14 is formed. In this embodiment, the main girder 31 is left and the joint plate 32 and the rib are removed. However, the main girder 31 may be removed and removed, or the joint plate 32 and the rib may be left. In order to integrate the leading outer shell 13A and the trailing outer shell 14A, the skin plate 33 is preferably removed and removed.

  In the outer shell building process (S4), next, the machinable filler placed in the machinable filler regions 51A and 51B inside the preceding shield tunnel 13 is removed. Removal of the machinable filler is performed, for example, by cutting the machinable filler in a portion corresponding to the opening 34 with a cutter of a shield machine. This cutting waste is discharged from the preceding shield tunnel 13 together with the soil remaining after excavation by the shield machine.

  In the outer shell structure building step (S4), next, as shown in FIGS. 25 and 26, the first partition 41A and the second partition 41B of the support unit 40 are removed. The removal of the first partition 41A and the second partition 41B can be performed by removing the first partition 41A and the second partition 41B from the opening 34 side from the first support 42A and the second support 42B. Since the internal space 45 of the support unit 40 is hollow, by removing the first partition wall 41A and the second partition wall 41B, the outer shell structure planned region 13B of the leading shield tunnel 13 is formed in the adjacent trailing shield tunnel 14. It is in communication with the internal space. Even at this time, the first support columns 42A and the second support columns 42B are not removed. Since the first support columns 42A and the second support columns 42B of the support unit 40 support the first leading outer shell portion 13AA and the second leading outer shell portion 13AB from the inner peripheral side, the deformation of the leading shield tunnel 13 can be prevented.

  In the outer shell structure building step (S4), next, as shown in FIGS. 27 and 28, concrete 62 is poured into the leading shield tunnel 13 and the trailing shield tunnel 14 to be integrated. Specifically, the leading shield tunnel 13 and the trailing shield tunnel 14 are provided with a reinforcing bar 61 that passes through the opening 34 and bridges the leading shield tunnel 13 and the trailing shield tunnel (see FIG. 27). Then, concrete 62 is placed in the leading shield tunnel 13 and the trailing shield tunnel 14 (see FIG. 28). Note that, in FIG. 28, in order to make it easier to understand how to cast the concrete 62, the illustration of the concrete cast in the concrete placing areas 50A and 50B is omitted. As a result, the concrete 62 cast in the leading shield tunnel 13 and the concrete 62 cast in the trailing shield tunnel 14 are directly integrated through the opening 34 and are also laid through the opening 34. By winding the passed reinforcing bar 61, it is integrated and a strong outer frame body is constructed.

  Then, the outer frame body 12 is formed by driving the concrete 62 (reinforced concrete) thus integrated into all the shield tunnels 11. At this time, it is preferable to cast concrete 62 into all the shield tunnels 11 all at once to integrate them, because no joints are formed in the circumferential direction of the outer shell 12. However, considering the transportability of the concrete material, the workability of placing, etc., all the shield tunnels 11 are divided into a plurality of groups, and the concrete 62 is placed and integrated into each of the divided groups. As a result, it is possible to construct the outer skeleton body 12 with few joints of concrete.

  In the outer frame building process (S4), frozen soil is applied around the leading shield tunnel 13 and the trailing shield tunnel 14 by a freezing method or the like so that groundwater or the like does not enter the leading shield tunnel 13 and the trailing shield tunnel 14. It is preferable to create and to freeze and stop water around the leading shield tunnel 13 and the trailing shield tunnel 14.

  In the case wall construction step (S5), as shown in FIG. 29, one side case wall 15 that seals (stops water) one side surface of the outer shell 12 is formed on the one end 1a of the underground structure 1, On the other end 1b of the underground structure 1, the other side wall 16 that seals (stops water) the other side surface of the outer shell 12 is constructed. The one side wall 15 and the other side wall 16 are constructed, for example, by freeze-stopping the one end 1a and the other end 1b of the underground structure 1 to construct the one side wall 15 and the other side wall 16. Excavate the area to be filled and place reinforced concrete. Thereby, the one side wall 15 and the other side wall 16 can be constructed.

  In the excavation step (S6), as shown in FIG. 30, a part or all of the inner peripheral side region of the outer shell body 12 sandwiched between the one side wall 15 and the other side wall 16 is excavated to form the underground cavity 4. Form. That is, by excavating a part or all of the inner peripheral side region of the outer shell body 12 sandwiched between the one side wall 15 and the other side wall 16 and discharging the excavated soil, the inner wall side of the outer shell body 12 is discharged. An underground cavity 4 is formed in the. Then, the excavated earth and sand is discharged from the main line shield tunnel 2 and the branch line shield tunnel 3.

  As described above, in the present embodiment, in the leading shield tunnel building step (S2), the first support column 42A and the first supporting column 42A that support the leading outer shell 13A from the inner peripheral side in the leading outer shell 13A of the leading shield tunnel 13 are provided. Since the two columns 42B are installed, it is possible to suppress the deformation of the leading outer shell 13A even if the leading outer shell 13A is cut in the trailing shield tunnel building step (S3). Then, when the part of the trailing outer shell 14A, the machinable filler, and the first partition wall 41A and the second partition wall 41B are removed in the outer shell structure building step (S4), the adjoining leading shield tunnel 13 and trailing shield tunnel 13 are removed. Since it communicates with 14, it is possible to cast concrete into the leading shield tunnel 13 and the trailing shield tunnel 14 to integrate them. As a result, the number of joints formed in the outer frame body 12 can be reduced as compared with the case where concrete is placed in each shield tunnel to construct the outer frame body, and thus the number of steps and the cost can be reduced. Moreover, the strong outer frame body 12 excellent in unity can be constructed.

  In addition, in the preceding shield tunnel construction step, the concrete placing area 50A between the first strut 42A and one end of the second strut 42B and the first preceding outer shell portion 13AA, the first strut 42A, and the second strut 42B are Since concrete is placed in the concrete placing area 50B between the end portion and the second leading outer shell portion 13AB, the rigidity of the leading shield tunnel 13 is increased, and the first strut 42A and the second strut 42B are used to break the leading portion. The shell 13A can be efficiently supported. In addition, in this embodiment, although the 1st support | pillar 42A and the 2nd support | pillar 42B have supported the 1st preceding outer shell part 13AA and the 2nd preceding outer shell part 13AB via concrete, the 1st support | pillar 42A or The two columns 42B may directly support the first leading outer shell portion 13AA or the second leading outer shell portion 13AB without interposing concrete.

  Further, in order to construct the trailing shield tunnel 14 while cutting a part of the leading shield tunnel 13 on both sides of the leading shield tunnel 13, the concrete that is placed in the leading shield tunnel 13 in the outer frame building step (S4). It is possible to integrate 62 and the concrete 62 that is placed in the trailing shield tunnel 14 arranged on both sides thereof. This makes it possible to further reduce the number of joints formed on the outer frame body 12.

  In addition, in the preceding shield tunnel building step (S2), a cavity is formed in the internal space 45 between the first partition 41A supported by the first support 42A and the second partition 41B supported by the second support 42B. Therefore, by removing a part of the trailing outer shell 14A, the machinable filler, the first partition wall 41A and the second partition wall 41B in the outer shell structure building step (S4), the leading shield tunnel 13 and the front shield tunnel 13 are arranged on both sides thereof. It is possible to communicate with the trailing shield tunnel 14. Moreover, it is possible to reduce the amount of concrete and the machinable filler to be placed in the preceding shield tunnel construction step (S2).

  Further, since the skin plate 33 of the trailing outer shell 14A can be removed, the opening 34 for connecting the planned outer shell structure region 13B in the leading shield tunnel 13 and the trailing shield tunnel 14 can be formed. A reinforcing bar 61 is arranged so as to span between the leading shield tunnel 13 and the trailing shield tunnel 14. Thereby, the concrete 62 cast in the leading shield tunnel 13 and the concrete 62 cast in the trailing shield tunnel 14 can be integrated.

  Although the preferred embodiment of the present invention has been described above, the present invention is not limited to the above embodiment.

  For example, the trailing shield tunnel may be superposed only on one side of the leading shield tunnel. In this case, the concrete that is placed in the leading shield tunnel and the trailing shield tunnel that overlap each other and are adjacent to each other are integrated and the joining surface is not formed. The leading shield tunnel and the trailing shield tunnel that are adjacent to each other without overlapping each other, for example, build a connecting path between the leading shield tunnel and the trailing shield tunnel, and by placing reinforced concrete in this connecting path, It is possible to connect the concrete to be placed in the leading shield tunnel and the trailing shield tunnel.

  Further, the leading shield tunnel and the trailing shield tunnel do not have to overlap with each other in a part from one end to the other end. Also in this case, for example, by constructing a connecting path between the leading shield tunnel and the trailing shield tunnel and placing reinforced concrete in this connecting passage, the leading shield tunnel and the trailing shield tunnel are placed. Can be connected to concrete.

  In addition, the support unit does not necessarily have to include two partition walls and columns, but may include at least one partition wall and columns. In this case, an internal space is not formed in the support unit, but by removing the partition wall from the support pillar, it is possible to connect the outer shell structure planned region to each other, and by the support pillar, the first leading outer shell portion and the second leading outer shell portion can be connected. Can be supported.

  Further, the trailing outer shell of the trailing shield tunnel does not necessarily have to be composed of the main girder, the joint plate, the rib and the skin plate, and after the trailing shield tunnel is constructed, an opening communicating with the leading shield tunnel is formed. Any configuration is possible as long as it can be configured.

  Moreover, you may perform a part of each process in parallel. For example, the trailing shield tunnel building process may be started before the leading shield tunnel building process is completed. That is, the construction of the trailing shield tunnel may be started before the construction of all the leading shield tunnels is completed. Also, the second trailing shield tunnel building step may be started before the first trailing shield tunnel building step is completed. That is, the construction of the second trailing shield tunnel may be started before the construction of all the first trailing shield tunnels is completed. Further, the outer frame building process may be started before the shield tunnel building process is completed. That is, the construction of the outer frame may be started before the construction of all shield tunnels is completed. Further, the excavation process may be started before the outer frame building process is completed.

  Further, the outer frame body may be formed by concrete cast in the entire area of the trailing outer shell of the trailing shield tunnel, and the outer shell of the leading shield tunnel in the trailing outer shell of the trailing shield tunnel may be formed. It may be formed of concrete that is cast in a region formed by the inner peripheral surface and the outer peripheral surface of a substantially circumferential shape (substantially arcuate shape) that continues from the frame planned area. In this case, inside the trailing shell of the trailing shield tunnel, place a formwork in the area where concrete is placed, place a machinable filler material on the outside of the formwork, and place it inside the formwork. You may pour the concrete which becomes the outer frame.

  Further, the cross-sectional shape of the shield tunnel, the number of shield tunnels, the number of leading shield tunnels, and the number of trailing shield tunnels are not particularly limited.

DESCRIPTION OF SYMBOLS 1 ... Underground structure, 1a ... One end part, 1b ... The other end part, 2 ... Main line shield tunnel, 3 ... Branch line shield tunnel, 4 ... Underground cavity, 11 ... Shield tunnel, 11A ... Outer shell, 12 ... Outer frame, Reference numeral 13 ... Leading shield tunnel, 13A ... Leading outer shell, 13AA ... First leading outer shell portion, 13AB ... Second leading outer shell portion, 13B ... Outer skeleton planned area, 13C ... Inner circumferential side area, 13D ... Outer circumferential side area, 13E ... Planned cutting region, 13F ... Planned cutting region, 13G ... Side part, 13H ... Side part, 13J ... Central part, 14 ... Trailing shield tunnel, 14A ... Trailing outer shell, 15 ... One side grave wall, 16 ... The other side wall, 21 ... Starting base, 22 ... Starting entrance, 23 ... Circumferential shield tunnel, 30 ... Segment, 31 ... Main girder, 32 ... Joint plate, 33 ... Skin plate, 34 ... Opening, 40 ... Support unit, 41A 1st partition wall, 41B ... 2nd partition wall, 42A ... 1st support | pillar, 42B ... 2nd support | pillar, 43A ... Inner peripheral side support girder, 43B ... Outer peripheral side support girder, 44A ... Inner peripheral side shield plate, 44B ... Outer peripheral side shield Plate, 45 ... Internal space, 50A ... Concrete placing area, 50B ... Concrete placing area, 51A ... Machinable filler area, 51B ... Machinable filler area, 61 ... Reinforcing bar, 62 ... Concrete, 141 ... First rear Row shield tunnel, 142 ... Second trailing shield tunnel, A1 ... first area, A2 ... second area.

Claims (6)

An outer frame of an underground structure,
A leading shield tunnel having a leading shell,
A trailing shield tunnel having a trailing outer shell, which is superposed on the leading shield tunnel in a state where the leading outer shell of the leading shield tunnel is cut,
A first concrete that is cast into the leading shield tunnel and the trailing shield tunnel and is integrated through an opening formed in a part of the trailing outer shell of the trailing shield tunnel,
A unit having a section steel installed in the preceding shield tunnel,
A second concrete disposed between the preceding outer shell and the first concrete ,
The unit has a shield plate that partitions the first concrete and the second concrete, and a support girder made of shaped steel arranged on the first concrete side of the shield plate,
Outer frame.   An outer frame of an underground structure,
  A leading shield tunnel having a leading shell,
  A trailing shield tunnel having a trailing outer shell, which is superposed on the leading shield tunnel in a state where the leading outer shell of the leading shield tunnel is cut,
  A first concrete that is cast into the leading shield tunnel and the trailing shield tunnel and is integrated through an opening formed in a part of the trailing outer shell of the trailing shield tunnel,
  A unit having a section steel installed in the preceding shield tunnel,
  A second concrete disposed between the preceding outer shell and the first concrete,
  The unit has a support girder disposed along the axial direction of the outer shell and supporting the leading outer shell in a state where the leading outer shell of the leading shield tunnel is cut.
Outer frame.   An outer frame of an underground structure,
  A leading shield tunnel having a leading shell,
  A trailing shield tunnel having a trailing outer shell, which is superposed on the leading shield tunnel in a state where the leading outer shell of the leading shield tunnel is cut,
  A first concrete that is cast into the leading shield tunnel and the trailing shield tunnel and is integrated through an opening formed in a part of the trailing outer shell of the trailing shield tunnel,
  A unit having a steel material such as H-shaped steel installed in the preceding shield tunnel;
  A second concrete disposed between the preceding outer shell and the first concrete,
  The unit is provided along a circumferential direction of the outer frame body, and has a pillar that supports the leading outer shell in a state in which the leading outer shell of the leading shield tunnel is cut.
Outer frame. A method for constructing an outer frame of an underground structure, comprising:
A leading shield tunnel construction step of constructing a leading shield tunnel having a leading outer shell;
A trailing shield tunnel building step of building a trailing shield tunnel having a trailing outer shell while cutting a part of the leading shield tunnel.
An outer shell structure building step of building the outer shell structure by placing a first concrete in the leading shield tunnel and the trailing shield tunnel,
In the preceding shield tunnel construction step, in the preceding outer shell, in the outer skeleton planned region where concrete is placed in the outer skeleton building step, a unit having a shape steel is installed, and the preceding outer shell and the outer skeleton are planned. Place the second concrete in the area between the area,
In the trailing shield tunnel construction step, the trailing shield tunnel is constructed by cutting the leading outer shell of the leading shield tunnel,
In the outer shell structure building step, a part of the trailing outer shell of the trailing shield tunnel is removed, and the first concrete is cast into the outer shell body planned region of the leading shield tunnel and the trailing shield tunnel. Set up and integrate ,
The unit has a shield plate that partitions the first concrete and the second concrete, and a support girder made of shaped steel arranged on the first concrete side of the shield plate,
Construction method of outer frame.   A method for constructing an outer frame of an underground structure, comprising:
  A leading shield tunnel construction step of constructing a leading shield tunnel having a leading outer shell;
  A trailing shield tunnel building step of building a trailing shield tunnel having a trailing outer shell while cutting a part of the leading shield tunnel.
  An outer shell structure building step of building the outer shell structure by placing a first concrete in the leading shield tunnel and the trailing shield tunnel,
  In the preceding shield tunnel construction step, in the preceding outer shell, in the outer skeleton planned region where concrete is placed in the outer skeleton building step, a unit having a shape steel is installed, and the preceding outer shell and the outer skeleton are planned. Place the second concrete in the area between the area,
  In the trailing shield tunnel construction step, the trailing shield tunnel is constructed by cutting the leading outer shell of the leading shield tunnel,
  In the outer shell structure building step, a part of the trailing outer shell of the trailing shield tunnel is removed, and the first concrete is cast into the outer shell body planned region of the leading shield tunnel and the trailing shield tunnel. Set up and integrate,
  The unit has a support girder disposed along the axial direction of the outer shell and supporting the leading outer shell in a state where the leading outer shell of the leading shield tunnel is cut.
Construction method of outer frame.   A method for constructing an outer frame of an underground structure, comprising:
  A leading shield tunnel construction step of constructing a leading shield tunnel having a leading outer shell;
  A trailing shield tunnel building step of building a trailing shield tunnel having a trailing outer shell while cutting a part of the leading shield tunnel.
  An outer shell structure building step of building the outer shell structure by placing a first concrete in the leading shield tunnel and the trailing shield tunnel,
  In the preceding shield tunnel construction step, a unit having a steel material such as H-shaped steel is installed in the outer shell structure planned region in which the concrete is placed in the outer shell structure building step in the leading outer shell, and the preceding outer shell and In the area between the outer frame structure planned area, pour the second concrete,
  In the trailing shield tunnel construction step, the trailing shield tunnel is constructed by cutting the leading outer shell of the leading shield tunnel,
  In the outer shell structure building step, a part of the trailing outer shell of the trailing shield tunnel is removed, and the first concrete is cast into the outer shell body planned region of the leading shield tunnel and the trailing shield tunnel. Set up and integrate,
  The unit is provided along a circumferential direction of the outer frame body, and has a pillar that supports the leading outer shell in a state in which the leading outer shell of the leading shield tunnel is cut.
Construction method of outer frame.