Tunnel lining construction method

Abstract

To provide a tunnel lining construction method that can suppress construction errors in connecting parts when assembling multiple PCa panels, and deformation due to self-weight or pressure during backfilling.SOLUTION: A tunnel lining construction method includes a first assembly step in which a plurality of PCa plates 12 are assembled along the circumferential direction of a tunnel while being supported by a PCa plate support device 3, a shape-retaining bolt installation step in which the plurality of PCa plates assembled along the circumferential direction of the tunnel and supported by the PCa plate support device are held in the correct position with shape-retaining bolts and support by the PCa plate support device is released, and a second assembly step in which a plurality of PCa plates are newly assembled along the circumferential direction of the tunnel while being supported by the PCa plate support device next to the plurality of PCa plates that have already been assembled along the circumferential direction of the tunnel and held in the correct position by the shape-retaining bolts, and the second assembly step and the shape-retaining bolt installation step are repeatedly performed.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a tunnel lining construction method. [Background technology]

[0002] Conventionally, known tunnel lining construction methods include constructing a tunnel lining by installing a center (movable formwork) and pouring lining concrete into it, and constructing a tunnel lining by assembling multiple arc-shaped precast concrete plates (PCa plates) in an arch or ring shape along the circumferential direction of the tunnel (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-123997 Summary of the Invention [Problem to be solved by the invention]

[0004] The method of constructing a tunnel lining by pouring lining concrete is prone to variations in quality due to a shortage of skilled workers and differences in skill level. In addition, the lining concrete requires a curing period, which limits how quickly the construction period can be shortened. Furthermore, constructing a tunnel lining by assembling multiple PCa plates is advantageous in shortening the construction period as it does not require a curing period for the lining concrete, but there is a risk of some looseness occurring at the joints between the PCa plates, which could result in construction errors.In particular, when the tunnel diameter is large, the number of PCa plates arranged circumferentially around the tunnel increases, and if construction errors occur, there is a risk that the PCa plates, when assembled into an arch or ring shape, will deform due to their own weight or the pressure during backfilling.

[0005] Therefore, the present invention aims to provide a tunnel lining construction method that can suppress construction errors in the connecting parts when assembling multiple PCa panels, and deformation due to self-weight or pressure during backfilling. [Means for solving the problem]

[0006] In order to achieve the above object, the present invention provides a tunnel lining construction method for constructing a tunnel lining by arranging and assembling a plurality of PCa plates along the circumferential direction of the tunnel on the inner periphery of sprayed concrete for a tunnel that has been applied to the excavation surface of the natural ground, and assembling a plurality of new PCa plates next to the new PCa plates along the circumferential direction of the tunnel while connecting them to the already assembled PCa plates, the method comprising: a first assembly step of assembling the plurality of PCa plates along the circumferential direction of the tunnel while supported by a PCa plate support device; a shape-retaining bolt installation step of holding the plurality of PCa plates assembled along the circumferential direction of the tunnel and supported by the PCa plate support device in correct positions with shape-retaining bolts and releasing the support by the PCa plate support device; and a second assembly step of assembling a plurality of new PCa plates along the circumferential direction of the tunnel while supported by the PCa plate support device next to the plurality of PCa plates that have already been assembled along the circumferential direction of the tunnel and held in correct positions by the shape-retaining bolts, and a plurality of PCa plate support parts attached to the frame and pressing the plurality of PCa plates assembled along the circumferential direction of the tunnel from the inside to the outside in the radial direction of the tunnel, each of the PCa plate support parts corresponding to one PCa plate, and having at least one pressing part that contacts the one PCa plate and presses the one PCa plate, and an arm attached to the frame and supporting the pressing part movably in the axial direction of the tunnel and the radial direction of the tunnel, the plurality of PCa plate support parts are arranged in a row in the circumferential direction of the tunnel, and have running parts attached to the frame and capable of running along rails installed in the roadbed of the tunnel, the shape-retaining bolts are screwed into screw holes that penetrate the PCa plates, one end side protrudes outward from the PCa plates, and the protruding dimension can be adjusted to be pressed against the inner circumferential surface of the sprayed concrete, and the second assembly process and the shape-retaining bolt installation process are repeatedly performed.

[0007] In this invention, multiple PCa plates are assembled while being supported by the PCa plate support device, and once assembly is complete, the multiple PCa plates are held in place by shape-retaining bolts, and the support of the multiple PCa plates by the PCa plate support device is released. This allows the same PCa plate support device to be used when assembling new PCa plates adjacent to PCa plates that have already been assembled along the circumferential direction of the tunnel. Furthermore, when assembling the PCa plates, even if the already assembled PCa plates are not supported by the PCa plate support device, they are held in the correct position by the shape-retaining bolts. This reduces construction errors at the joints between the PCa plates, and accurately converts vertical forces caused by the weight and pressure during backfilling into circumferential compressive forces on the tunnel lining, ensuring a reliable arch action effect and suppressing deformation. Furthermore, the retaining members that hold down the PCa plates are supported so that they can move in both the circumferential and axial directions of the tunnel, allowing the PCa plates to be supported in the desired positions. This allows the PCa plates to be supported in positions that are stable when connecting them, such as near the connecting parts between the PCa plates, and reduces construction errors at the connecting parts and deformation due to their own weight. In addition, the clamping sections that hold down multiple PCa panels are arranged in a single row in the circumferential direction of the tunnel, making it possible to achieve a simpler structure than a PCa panel support device in which multiple PCa panel support sections (clamping sections) are arranged in multiple rows. Furthermore, because it has a running section, the PCa plate support device can move along rails extending in the axial direction of the tunnel, so once one row of PCa plates has been assembled and support by the PCa plate support device is no longer required, the PCa plate support device can be easily moved to a position where it can support the newly assembled PCa plate.

[0008] In addition, in the tunnel lining construction method of the present invention, the shape-retaining bolt has a bolt that is inserted into the screw hole and a plate that is connected to the end of the bolt and pressed against the inner surface of the sprayed concrete, the bolt and the plate are configured to be detachable, and the method includes a backfilling filling process in which grout material is filled between the tunnel lining constructed from the plurality of PCa plates assembled along the circumferential direction of the tunnel and the sprayed concrete, and in the backfilling filling process, grout material is filled between the tunnel lining and the sprayed concrete while the plurality of PCa plates are held in the correct position by the shape-retaining bolt, and after the grout material has hardened, the bolt is removed from the plate and also from the PCa plates. By adopting such a configuration, the bolt can be reused. [Effects of the Invention]

[0009] According to the present invention, it is possible to suppress construction errors in the connecting parts when assembling multiple PCa panels, and deformation due to their own weight or pressure during backfilling. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a front view showing a PCa support device according to an embodiment of the present invention. [Figure 2] 1 is a plan view showing a PCa support device according to an embodiment of the present invention. [Figure 3] 1 is a front view showing a state in which support for a PCa board of a PCa support device according to an embodiment of the present invention is released. [Figure 4] FIG. [Figure 5] FIG. 1 is a diagram showing a tunnel lining construction method. [Figure 6] FIG. 1 is a diagram showing a tunnel lining construction method. [Figure 7] FIG. 1 is a diagram showing a tunnel lining construction method. [Figure 8] FIG. 1 is a diagram showing a tunnel lining construction method. [Figure 9]FIG. 1 is a diagram showing a tunnel lining construction method. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, a PCa plate support device and a tunnel lining construction method according to an embodiment of the present invention will be described with reference to Figs. As shown in FIG. 1, a tunnel lining 11 according to this embodiment is constructed by assembling a plurality of arc-shaped PCa plates 12 (precast concrete plates). The direction in which the tunnel extends is defined as the tunnel axis direction (the direction of arrow A in the figure), and the direction around the tunnel axis along the inner circumferential surface of the tunnel is defined as the tunnel circumferential direction. The direction extending perpendicular to the tunnel axis direction from the tunnel axis is defined as the tunnel radial direction. Within the tunnel radial direction, the side away from the tunnel axis is defined as the outer side, and the side approaching the tunnel axis is defined as the inner side. The horizontal direction in a plane perpendicular to the tunnel axis is defined as the tunnel width direction (the direction of arrow B in the figure).

[0012] The tunnel lining 11 is constructed from one side to the other in the tunnel axial direction. One side in the tunnel axial direction is the rear side, and the other side is the front side. The tunnel lining 11 is constructed sequentially from the rear side to the front side. On the outside of the tunnel lining 11 in the radial direction of the tunnel, sprayed concrete 14 is applied to the excavation surface 13 of the natural ground, and grout material 15 is filled between the sprayed concrete 14 and the PCa plate 12 of the tunnel lining 11.

[0013] The multiple PCa plates 12 are arranged in the tunnel circumferential and axial directions. Adjacent PCa plates 12 in the tunnel circumferential direction and adjacent PCa plates 12 in the tunnel axial direction are connected to each other. The multiple PCa plates 12 of the tunnel lining 11 are arranged in an arch shape along the tunnel circumferential direction when viewed from the tunnel axial direction. Hereinafter, "arch shape along the tunnel circumferential direction" will be referred to as "arch shape." In the tunnel lining construction method according to this embodiment, first, a plurality of PCa plates 12 are sequentially arranged along the tunnel circumferential direction and assembled into a row to form a row of arches made up of the plurality of PCa plates 12. Then, a plurality of new PCa plates 12 are sequentially arranged in front of this arch along the tunnel circumferential direction and assembled into a row to form a row of arches made up of the plurality of PCa plates 12. Then, a row of arches is sequentially formed toward the front. Each time a PCa plate 12 is placed at its installation position, it is connected to the PCa plate 12 adjacent to it in the tunnel circumferential direction and the PCa plate 12 adjacent to it in the tunnel axial direction.

[0014] When constructing the tunnel lining 11, a construction device 2 (see Figures 4 and 5) is used to place the PCa plates 12 in the installation position and connect them to adjacent PCa plates 12. In addition, a PCa plate support device 3 and shape-retaining bolts 4 (see Figure 3) are used to support or hold the PCa plates 12 in the correct position so that they do not shift out of position. The PCa plate support device 3 is configured to support the PCa plate 12 once the PCa plate 12 is placed at the installation position when the erection device 2 assembles the plurality of PCa plates 12 into an arch shape. The shape-retaining bolts 4 are configured to hold the multiple PCa plates 12 in their correct positions and maintain the multiple PCa plates 12 in an arch-like shape after the multiple PCa plates 12 assembled in an arch shape are connected to adjacent PCa plates 12 in the circumferential direction of the tunnel and adjacent PCa plates 12 in the axial direction of the tunnel. That is, when assembling the multiple PCa plates 12 into an arch shape, the PCa plate support device 3 supports the multiple PCa plates 12 arranged at the installation position. After assembling the multiple PCa plates 12 into an arch shape and connecting them to the adjacent PCa plate 12 on the rear side in the tunnel axial direction, the shape-retaining bolts 4 hold the multiple PCa plates 12 in the arch shape. Details of the shape-retaining bolts 4 will be described later.

[0015] The PCa plate support device 3 is positioned behind the erection device 2. A pair of rails 17 extending in the tunnel axis direction are provided on the tunnel roadbed 16. The PCa plate support device 3 and the erection device 2 are configured to be able to travel along the rails 17 in the tunnel axis direction.

[0016] As shown in FIGS. 1 and 2, the PCa plate support device 3 has a frame 31, a plurality of PCa plate support units 32 attached to the frame 31, a running unit 33 attached to the frame 31, and a scaffolding 34 attached to the frame 31. The PCa plate support units 32 are configured to press the plurality of PCa plates 12 assembled in an arch shape from the inside to the outside in the radial direction of the tunnel. The running units 33 are configured to be able to run along rails 17 installed on the roadbed 16 of the tunnel. The running units 33 have a carriage unit 35 that can run along the rails 17, and a platform unit 36 ​​that is attached on the carriage unit 35 and supported by the carriage unit 35. The PCa plate support device 3, which can move along the rails 17, is configured to be able to stop at a predetermined position.

[0017] The frame 31 is formed in a gate shape that is symmetrical in the width direction, and has a front frame 311 located on the front side, a rear frame 312 located on the rear side, and a construction member 313 installed between the front frame 311 and the rear frame 312. The front frame 311 and the rear frame 312 are arranged with a gap in the front-to-rear direction. The front frame 311 and the rear frame 312 are formed in approximately the same shape. The front frame 311 and the rear frame 312 each have a first pillar portion 314 located at one end in the width direction, a second pillar portion 315 located at the other end in the width direction, and a beam portion 37 installed between the upper end portion of the first pillar portion 314 and the upper end portion of the second pillar portion 315. The first pillar portion 314 of the rear frame 312 is arranged at a distance behind the first pillar portion 314 of the front frame 311, the second pillar portion 315 of the rear frame 312 is arranged at a distance behind the second pillar portion 315 of the front frame 311, and the beam portion 37 of the rear frame 312 is arranged at a distance behind the beam portion 37 of the front frame 311. The first column portion 314, the second column portion 315, and the beam portion 37 are each made of steel frame material. The erection member 313 is made of steel material such as steel plate or steel frame material.

[0018] The first pillar portion 314 and the second pillar portion 315 extend vertically. The first pillar portion 314 and the second pillar portion 315 are erected on the base portion 36 of the running portion 33. The lower ends of the first pillar portion 314 and the second pillar portion 315 are joined to the base portion 36. The beam portion 37 is formed in a mountain shape that is symmetrical in the width direction, with the center in the width direction being higher than both ends in the width direction. 1, the beam portion 37 has a first beam portion 371, a second beam portion 372, a third beam portion 373, and a fourth beam portion 374. The first beam portion 371, the second beam portion 372, the third beam portion 373, and the fourth beam portion 374 are arranged in this order from one side to the other side in the width direction.

[0019] The first beam portion 371 is joined to the upper end of the first column portion 314 and extends obliquely upward toward the other widthwise side. The second beam portion 372 is joined to the other widthwise end of the first beam portion 371 and extends obliquely upward from one widthwise side to the other widthwise side at a gentler gradient than the first beam portion 371. The third beam portion 373 is joined to the other widthwise end of the second beam portion 372 and extends obliquely downward from one widthwise side to the other widthwise side. The fourth beam portion 374 is joined to the other widthwise end of the third beam portion 373 and extends obliquely downward from one widthwise side to the other widthwise side at a steeper gradient than the third beam portion 373. The other widthwise end of the fourth beam portion 374 is joined to the upper end of the second column portion 315. The first beam portion 371 and the fourth beam portion 374 are symmetrical in the width direction, and the second beam portion 372 and the fourth beam portion 374 are symmetrical in the width direction.

[0020] As shown in Figures 1 and 2, the PCa plate support portion 32 has a pressing portion 321 that contacts the PCa plate 12 and presses it down, and an arm 322 that is attached to the frame 31 and supports the pressing portion 321 so that it can move in the tunnel axial direction and the tunnel radial direction.

[0021] 2, the arm 322 has a first arm 323 joined to the beam portion 37 and extending in the tunnel axis direction, and a second arm 324 joined to the tip of the first arm 323 and extending in the tunnel radial direction. The first arm 323 and the second arm 324 are arranged so as to be perpendicular to each other. The first arm 323 is configured to be extendable and retractable in the tunnel axial direction. The second arm 324 is configured to be extendable and retractable in the tunnel radial direction. The first arm 323 and the second arm 324 are configured, for example, by hydraulic cylinders.

[0022] The pressing portion 321 is connected to the tip of the second arm 324 . The holding part 321 moves in the tunnel axial direction as the first arm 323 expands and contracts, and moves in the tunnel radial direction as the second arm 324 expands and contracts. The PCa plate support part 32 can position the holding part 321 at any position by adjusting the expansion and contraction of the first arm 323 and the second arm 324. The position of the pressing portion 321 is adjusted so that the outer surface in the tunnel radial direction comes into surface contact with the inner surface in the tunnel radial direction of the arched PCa plate 12 to press the PCa plate 12. The outer surface in the tunnel radial direction of the pressing portion 321 is referred to as pressing surface 321a. FIG. 3 shows a state in which the pressing portion 321 is separated from the inner surface of the PCa plate 12 in the tunnel radial direction.

[0023] In this embodiment, four PCa plate supporting portions 32 are provided in one PCa plate supporting device 3. The four PCa plate supporting portions 32 are arranged in the circumferential direction of the tunnel. The four PCa plate support portions 32 are a first PCa plate support portion 326, a second PCa plate support portion 327, a third PCa plate support portion 328, and a fourth PCa plate support portion 329. The first PCa plate support portion 326 is joined to a first beam portion 371 of the front frame 311 and the rear frame 312. The second PCa plate support portion 327 is joined to a second beam portion 372 of the front frame 311 and the rear frame 312. The third PCa plate support portion 328 is joined to a third beam portion 373 of the front frame 311 and the rear frame 312. The fourth PCa plate support portion 329 is joined to a fourth beam portion 374 of the front frame 311 and the rear frame 312. The first to fourth PCa plate support portions 329 have the same configuration, but are installed in different positions and facing different directions. The direction in which the second arm 324 of each PCa plate support portion 32 (first to fourth PCa plate support portions 329) extends and the direction in which the pressing surface 321a faces are perpendicular to the beam portion 37 (first to fourth beam portions 374) to which each PCa plate support portion 32 is joined.

[0024] By providing four PCa plate support portions 32, each of the four PCa plates 12 arranged in the circumferential direction of the tunnel can be supported by a PCa plate support portion 32. The extension and contraction of the first arms 323 and second arms 324 of the four PCa board supports 32 may be operable to operate collectively or individually. Also, the arms may be configured to be switchable between operating collectively and operating individually.

[0025] The scaffolding 34 is attached to the front side of the front frame 311 and to the erection section between the front frame 311 and the rear frame 312. The scaffolding 34 is formed in a shape that follows the gate shape of the frame 31. The scaffolding 34 is used for operating the PCa plate support section 32, checking the support state of the PCa plate support section 32, and for maintenance and inspection.

[0026] As shown in Figure 4, the construction device 2 has a guide unit 21, a PCa board holding unit 22 attached to the guide unit 21, and a running unit 23 attached to the guide unit 21. The running unit 23 has a carriage unit 24 that can run along the rails 17, and a platform unit 25 that is attached to the carriage unit 24 and supported by the carriage unit 24. The construction device 2 that can move along the rails 17 is configured to be able to stop at a predetermined position. The guide section 21 is formed in an arch shape. The guide section 21 is installed on the mounting section 25. The construction device 2 is arranged so that the arch of the guide section 21 is oriented along the circumferential direction of the tunnel. The PCa plate holding portion 22 is configured so that the PCa plate 12 can be attached and detached, and can move in the circumferential direction of the tunnel along the guide portion 21 with one PCa plate 12 attached.

[0027] The construction device 2 is configured to hold the PCa plate 12 with the PCa plate holding section 22, move in the circumferential direction of the tunnel, place the held PCa plate 12 at the mounting position, and connect it to an already installed PCa plate 12 adjacent to the circumferential direction of the tunnel or the axial direction of the tunnel.

[0028] The shape-retaining bolt 4 shown in Fig. 3 has a bolt 41 inserted into a screw hole 121 formed in the PCa plate 12, and a plate 42 detachably attached to the tip of the bolt 41 on the outside of the PCa plate 12. The surface of the plate 42 is in contact with the shotcrete 14. By screwing the bolt 41 into the screw hole 121 and causing it to protrude outside the PCa plate 12, the plate 42 attached to the tip of the bolt 41 is pressed against the shotcrete 14. This fixes the position of the bolt 41 relative to the shotcrete 14, and maintains the arch-like shape formed by the multiple PCa plates 12.

[0029] Next, the construction method for tunnel lining will be explained. Before constructing the tunnel lining 11, shotcrete 14 is applied to the excavation surface 13 of the excavated natural ground, and one or both of H-shaped steel supports (not shown) and rock bolts (not shown) are installed. If necessary, a waterproof sheet (not shown) is installed on the inner surface of the shotcrete. In Figures 5 to 9, which explain the tunnel lining construction method, the shotcrete 14 and natural ground on the outside of the PCa plate 12 are omitted.

[0030] When constructing the tunnel lining 11, a plurality of PCa plates 12 are assembled in an arch shape from the rear side to the front side of the tunnel lining 11 in the tunnel axis direction. First, a first assembly step is carried out in which a plurality of PCa plates 12 located on the rear side are assembled into a single arch shape. First, the erection device 2 and the PCa plate support device 3 are moved on the rails 17 to a position where the PCa plates 12 are assembled into an arch shape. Next, as shown in FIG. 5, the PCa plate 12 is held by the installation device 2, and as shown in FIG. 6, the PCa plate 12 held by the installation device 2 is placed at the installation position. Once the PCa plate 12 has been placed in the installation position, as shown in Fig. 3, the PCa plate 12 is supported by the PCa plate support part 32 of the PCa plate support device 3. The arm 322 (see Figs. 1 and 2) of the PCa plate support part 32 is extended or retracted to adjust the position of the pressing part 321, and the pressing surface 321a of the pressing part 321 is brought into contact with the PCa plate 12 to support the PCa plate 12. Similarly, as shown in Figure 8, in the same way, multiple PCa plates 12 forming a row of arches are sequentially placed at the installation positions, supported by PCa plate support parts 32, and then connected to adjacent PCa plates 12 in the tunnel circumferential direction and tunnel axial direction. The PCa plate support device 3 of this embodiment has four PCa plate support portions 32 arranged in the circumferential direction of the tunnel, and is therefore able to individually support four PCa plates 12 arranged in the circumferential direction of the tunnel.

[0031] Next, as shown in Figure 9, a shape-retaining bolt installation process is carried out in which multiple PCa plates 12 assembled in an arch shape and supported by a PCa plate support device 3 are held in the correct position with shape-retaining bolts 4, and the support by the PCa plate support device 3 is released. In the shape-retaining bolt installation process, the bolt 41 of the shape-retaining bolt 4 is screwed into the screw hole 121 to protrude outside the PCa plate 12, and as shown in FIG. 3, the plate 42 attached to the tip of the bolt 41 is pressed against the shotcrete 14. This fixes the position of the bolt 41 relative to the shotcrete 14. As a result, the multiple PCa plates 12 are held in the correct position, and the arch-like shape formed by the multiple PCa plates 12 is maintained. Once the PCa plate 12 is held in the correct position by the shape-retaining bolts 4, the arm 322 (see Figure 3) of the PCa plate support device 3 is contracted to move the pressing portion 321 away from the PCa plate 12, and support by the PCa plate support device 3 is released.

[0032] Next, a second assembly process is carried out in which a row of new PCa plates 12 are assembled in an arch shape using a construction device 2 while being supported by a PCa plate support device 3 next to a plurality of PCa plates 12 that have already been assembled in an arch shape and held in the correct position by shape-retaining bolts 4. The second assembly process is carried out in the same manner as the first assembly process, and when connecting the PCa plates 12, the PCa plates 12 adjacent in the tunnel circumferential direction and the PCa plates 12 adjacent in the tunnel axial direction are connected to each other.

[0033] The above-mentioned shape-retaining bolt installation process and the second assembly process are performed alternately to assemble the PCa plates 12 in an arch shape over the entire tunnel axial direction, thereby constructing the tunnel lining 11.

[0034] A backfilling step is carried out in which grout material 15 (see FIG. 3) is filled between the tunnel lining 11 constructed by a plurality of PCa plates 12 assembled in an arch shape and the sprayed concrete 14. In the backfilling process, grout material 15 is filled between the tunnel lining 11 and the sprayed concrete 14 while the multiple PCa plates 12 are held in an arch shape by the shape-retaining bolts 4. After the grout material 15 has hardened, the bolts 41 are removed from the plate 42 and also from the PCa plate 12. The plate 42 together with the grout material 15 is left between the shotcrete 14 and the PCa plate 12.

[0035] Next, the functions and effects of the PCa plate support device 3 and tunnel lining construction method according to the present embodiment will be described. According to the present embodiment, the retaining portion 321 that holds down the PCa plate 12 is supported so as to be movable in the tunnel circumferential direction and the tunnel axial direction, thereby enabling the PCa plate 12 to be supported at a desired position. This allows the PCa plate 12 to be supported at a position that is stable when connecting the PCa plates 12, such as a position close to the connecting portion between the PCa plates 12, and suppresses construction errors at the connecting portion and deformation due to its own weight or pressure during backfilling. Furthermore, the holding portions 321 that hold down the multiple PCa plates 12 are arranged in the circumferential direction of the tunnel, and therefore can support each of the multiple PCa plates 12 that are arranged in the circumferential direction of the tunnel. Furthermore, since the holding portions 321 that hold down the multiple PCa plates 12 in this embodiment are arranged in a row in the circumferential direction of the tunnel, the structure can be simpler than that of the PCa plate support device 3 in which the multiple PCa plate support portions 32 are arranged in multiple rows.

[0036] Moreover, the PCa plate support device 3 according to this embodiment has a running part 33 to which the frame 31 is attached and which can run along a rail 17 installed on the roadbed 16 of the tunnel. With this configuration, the PCa plate support device 3 can move along the rails 17 extending in the tunnel axis direction, so that once one row of PCa plates 12 has been assembled and support by the PCa plate support device 3 is no longer required, the PCa plate support device 3 can be easily moved to a position where it can support the newly assembled PCa plate 12.

[0037] Furthermore, in the tunnel lining construction method according to this embodiment, a plurality of PCa plates 12 are assembled while being supported by the PCa plate support device 3, and once assembly is complete, the arch-shaped shape formed by the plurality of PCa plates 12 is maintained by the shape-retaining bolts 4, and support of the plurality of PCa plates 12 by the PCa plate support device 3 is released. This allows the same PCa plate support device 3 to be used when assembling new PCa plates 12 adjacent to PCa plates 12 that have already been assembled in an arch shape. Furthermore, when assembling the PCa plate 12, even if the already assembled PCa plate 12 is not supported by the PCa plate support device 3, it is held in the correct position by the shape-retaining bolts 4, so construction errors in the connecting parts can be reduced and deformation due to its own weight or pressure during backfilling can also be reduced.

[0038] Furthermore, in the tunnel lining construction method according to this embodiment, in the backfilling process, grout material 15 is filled between the tunnel lining 11 and the sprayed concrete 14 while the multiple PCa plates 12 are held in an arch-like shape by the shape-retaining bolts 4, and after the grout material 15 has hardened, the bolts 41 are removed from the plates 42 and also from the PCa plates 12. With this configuration, the bolt 41 can be reused.

[0039] The above describes an embodiment of the PCa plate support device 3 and tunnel lining construction method according to the present invention, but the present invention is not limited to the above embodiment and can be modified as appropriate within the scope of its intent. For example, in the above embodiment, the PCa plate support device 3 has a running part 33 to which a frame 31 is attached and which can run along a rail 17 installed on the roadbed 16 of the tunnel, but the mechanism for moving the PCa plate support device 3 may be other than the above. Furthermore, in the above embodiment, the shape-retaining bolt 4 has a bolt 41 that is inserted into the screw hole 121 and a plate 42 that is connected to the end of the bolt 41 and pressed against the inner surface of the sprayed concrete 14, and the bolt 41 and the plate 42 are configured to be detachable, but the shape-retaining bolt 4 may be configured in a manner other than the above as long as it is capable of being pressed against the inner surface of the sprayed concrete 14. Furthermore, in the present invention, "plural PCa plate support parts are arranged in a row in the circumferential direction of the tunnel" does not necessarily mean that the plural PCa plate support parts are lined up on the same line, and depending on the arrangement of the plural PCa plates, adjacent plural PCa plate support parts may be slightly misaligned from the same line. For example, the plural PCa plate support parts may be arranged along the circumferential direction of the tunnel so that they are alternately positioned in a zigzag pattern on both sides of a straight line extending in the circumferential direction of the tunnel. [Explanation of symbols]

[0040] 3 PCa board support device 4 Shape-retaining bolts 11 Tunnel lining 12 PCa board 13 Excavation surface 14 Shotcrete 15 Grout material 16 Roadbed 17 Rail 23 Running part 31 frames 32 PCa board support part 33 Running part 41 volts 42 Plates 121 screw hole 321 Clamp 321a Pressing surface 322 Arm

Claims

[Claim 1] A tunnel lining construction method in which a plurality of PCa plates are arranged and assembled along the circumferential direction of the tunnel on the inner periphery of the sprayed concrete of a tunnel that has been constructed on the excavation surface of the natural ground, and a plurality of new PCa plates are assembled next to them along the circumferential direction of the tunnel while connecting them to the already assembled PCa plates, thereby constructing a tunnel lining, a first assembly process in which the plurality of PCa plates are assembled along the circumferential direction of the tunnel while being supported by a PCa plate support device; A shape-retaining bolt installation process in which the plurality of PCa plates assembled along the circumferential direction of the tunnel and supported by the PCa plate support device are held in position with shape-retaining bolts and the support by the PCa plate support device is released; a second assembly process in which a plurality of PCa plates are newly assembled along the circumferential direction of the tunnel while being supported by the PCa plate support device next to the plurality of PCa plates that have already been assembled along the circumferential direction of the tunnel and held in place by the shape-retaining bolts; The PCa plate support device is The frame and A plurality of PCa plate support parts that are attached to the frame and press the plurality of PCa plates assembled along the circumferential direction of the tunnel from the inside to the outside in the radial direction of the tunnel, The PCa plate support parts are each At least one pressing portion corresponding to one PCa board and contacting the one PCa board to press the one PCa board; an arm attached to the frame and supporting the pressing portion movably in the axial direction of the tunnel and the radial direction of the tunnel; The plurality of PCa plate support portions are arranged in a row in the circumferential direction of the tunnel, A running part is attached to the frame and is capable of running along a rail installed on the roadbed of the tunnel, The shape-retaining bolt is screwed into a screw hole that penetrates the PCa plate, and one end side protrudes outward from the PCa plate. By adjusting the protruding dimension, the shape-retaining bolt is pressed against the inner circumferential surface of the sprayed concrete. The second assembly step and the shape-retaining bolt installation step are repeated, The shape-retaining bolt has a bolt inserted into the screw hole and a plate connected to an end of the bolt and pressed against the inner circumferential surface of the sprayed concrete, The bolt and the plate are configured to be detachable, A backfilling step is included in which grout material is filled between the tunnel lining constructed by the plurality of PCa plates assembled along the circumferential direction of the tunnel and the sprayed concrete, In the backfilling process, grout material is filled between the tunnel lining and the sprayed concrete while the plurality of PCa plates are held in the correct position by the shape-retaining bolts, and after the grout material has hardened, the bolts are removed from the plates and also from the PCa plates. This is a tunnel lining construction method characterized by the above.

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