JP7811191B2 - Construction method for invert structure in mountain tunnel - Google Patents

Description

The present invention relates to a construction method for invert structures in mountain tunnels.

Mountain tunnels are tunnels formed by excavating free-standing, relatively stable ground, such as bedrock. The excavated interior walls are covered with primary and secondary linings made of concrete or mortar. Specifically, after the tunnel is excavated using methods such as blasting, a protective layer is formed on the interior walls of a mountain tunnel, preferably by spraying mortar or concrete onto them. Then, a known tunnel lining formwork, for example, is installed inside the protective layer formed by the primary lining. A concrete lining of a predetermined thickness is then formed as a secondary lining, extending from the side walls of the tunnel to the upper arch-shaped section. Furthermore, a bottom invert lining of a predetermined thickness is integrally formed across the tunnel between the lower support sections of the pair of side walls of the previously formed lining extending from both side walls to the upper arch-shaped section. This results in a continuous secondary lining covering the entire interior wall of the mountain tunnel.

Mountain tunnels are formed by excavating relatively stable ground, so some tunnels constructed more than several decades ago, for example, omit the invert lining and only form a lining in the area from the tunnel's side wall to the upper arch-shaped section, forming a secondary lining. For such mountain tunnels that omit the invert lining, consideration is being given to forming a new invert lining to prevent future effects such as swelling of the base slab.

Conventionally, the most common method for forming an invert lining at the bottom of a tunnel, connecting it to the lining that was previously installed from the tunnel's side walls to the arch-shaped upper section, has been to use cast-in-place concrete (see, for example, Patent Document 1). However, finishing the top surface of the invert lining to create a curved shape requires a high level of skill. Furthermore, when using cast-in-place concrete, the poured concrete takes a considerable amount of time to harden and then undergo the required curing period. Therefore, particularly when forming a new invert lining on the lining from the side walls to the arch-shaped upper section, omitting the invert lining, traffic through the tunnel will be blocked for an extended period of time, so it is desirable to complete the construction as quickly as possible.

For these reasons, consideration has been given to shortening construction time by forming the invert lining using precast concrete members manufactured in advance in a factory or the like (see, for example, Patent Document 2 and Patent Document 3). Furthermore, when forming a new invert lining using precast concrete members (blocks) for an existing mountain tunnel constructed several decades ago, for example, it is desirable to be able to carry out construction work while maintaining access to the passageway without completely blocking traffic through the tunnel. Therefore, technology has been developed that allows the invert lining of a mountain tunnel to be constructed in sections on each side of the tunnel in the transverse direction (see, for example, Patent Document 4).

Japanese Patent Application Laid-Open No. 2020-159060 JP 2013-28898 A Japanese Patent Application Laid-Open No. 2018-123528 Japanese Patent Application Laid-Open No. 2000-145390

In the method of forming an invert in a mountain tunnel described in Patent Document 1, the access road and the ground below one side of the tunnel are excavated to form an excavation trench while maintaining access to the access road on the other side of the tunnel. Then, multiple blocks that make up the invert are lined up at the bottom of the excavation trench. The side of the ground below the access road in the other side of the tunnel where access is maintained is retained by the rising portions of the blocks placed adjacent to that other side of the tunnel. However, the task of precisely lining up multiple blocks at the bottom of the excavation trench formed in one side of the tunnel requires a lot of time and effort. Furthermore, because the side of the ground below the access road remains open and unretained until the blocks with rising portions are placed adjacent to the ground in the other side of the tunnel where access is maintained, it is believed to be difficult to maintain the access road and the ground below it in a stable state.

The present invention aims to provide a construction method for invert structures in mountain tunnels that, when constructing invert structures using PCa concrete blocks that make up the invert lining in existing mountain tunnels, can be constructed in one side area in the transverse direction of the tunnel while maintaining the passageway and the ground below it in a stable state in the other side area with a simple configuration.

This invention is a construction method for mountain tunnel invert structures. The invert structure, which uses PCa concrete blocks and is installed across the entire transverse area of the invert section of a mountain tunnel to form the invert lining, is constructed in two separate areas on either side of the transverse center, allowing one side to be constructed in each side area while ensuring passage in the other side area. In the transverse center of the tunnel in the invert section, a plurality of H-shaped steel beams are installed at predetermined intervals in the axial direction of the tunnel by being cast into the ground of the invert section with their flanges aligned in the axial direction of the tunnel, supporting earth retaining plate members. By supporting the H-shaped steel beams on the flanges on one side area or the other side area, the other can be constructed. The above objectives have been achieved by providing a construction method for invert structures in mountain tunnels that includes the steps of: forming one invert structure in one of the two areas using PCa concrete blocks up to the flange on one side of the tunnel, while ensuring passage in the other area; and restoring the passage in the other area by supporting an earth retaining plate member on the H-shaped steel and backfilling the upper part of the invert structure formed in one of the two areas, thereby restoring the passage in the other area; and, while ensuring passage in the restored passage, forming the remaining invert structure in the other area using PCa concrete blocks.

In the construction method for invert structures in mountain tunnels of the present invention, in the process of forming one side of the invert structure using PCa concrete blocks in one side region up to the portion beyond the flange portion on one side region, it is preferable that a sparser member be interposed between the inner surface of the flange portion on one side region of the H-shaped steel, so that the retaining plate member is supported by the flange portion on one side region while being biased toward the other side region.

The construction method for mountain tunnel invert structures of the present invention preferably involves installing multiple PC concrete blocks in the invert sections of one side region and the other side region, each of which is constructed by arranging them in series across the tunnel, while maintaining gaps between the blocks and the support bases at the lower ends of adjacent side wall linings and between adjacent PC concrete blocks, and also in the axial direction of the tunnel, while maintaining gaps between adjacent PC concrete blocks. The blocks thus formed are then integrated via the hardened solidifying material by filling the gaps between adjacent support bases and between adjacent PC concrete blocks with a solidifying agent and allowing it to harden.

The construction method for mountain tunnel invert structures of the present invention allows for the construction of invert structures using PCa concrete blocks that form the invert lining in existing mountain tunnels, in each of the transversely extending areas of the tunnel, in one of the areas, while maintaining the passageway and the ground below it in a stable state in the other area using a simple structure.

This is a simplified cross-sectional view illustrating a mountain tunnel in which invert structures are formed on both sides of the invert in the transverse direction of the tunnel using a construction method for invert structures according to a preferred embodiment of the present invention. This is a schematic top view of Figure 1 viewed from the A-A direction, illustrating the state in which the invert section structure is formed on both sides over the entire area of the invert section in the transverse direction of the tunnel. 1 is a schematic cross-sectional view of a mountain tunnel illustrating a construction method for an invert structure according to a preferred embodiment of the present invention. FIG. 4A to 4F are schematic top views of the main part of part B in FIG. 3, illustrating a construction method for an invert structure according to a preferred embodiment of the present invention. This is a schematic top view of an invert section structure provided in one side region of the invert section in the transverse direction of the tunnel. 4 is a schematic cross-sectional view taken along the line CC in FIG. 3 before the filling solidification material is filled. FIG. This is an oblique view of the PCa concrete block that constitutes the invert structure. (a) is a top view of the PCa concrete block that constitutes the invert section structure, (b) is a transverse side view of (a) viewed from the right side, and (c) is an axial side view of (a) viewed from the front side. 1 is a schematic cross-sectional view of a PCa concrete block taken along a portion where a bolt insertion hole is formed, illustrating the bolt insertion hole. FIG. FIG. 10 is a perspective view illustrating a ground adjuster attached to the lower end of a height adjustment bolt. This is a simplified cross-sectional view illustrating the state in which filling solidification material has been filled into the gaps between the receiving base, the gaps between adjacent PCa concrete blocks, and the gaps below the bottom surface of the hexahedron shape. 1 is a schematic cross-sectional view of a PCa concrete block in the transverse direction along the portion where a filler injection hole is formed, illustrating the filler injection hole and the opening and closing valve. FIG. This is a schematic top view of the invert structure explaining the injection status of the filling solidification material. 1 is an explanatory diagram of the unevenness formed on the surface of the central portion of a PCa concrete block. FIG.

A preferred embodiment of the present invention relates to a construction method for an invert structure in a mountain tunnel. This construction method is used to form a new invert lining 32 on the base 30a of an existing mountain tunnel 30 shown in Figure 1, in continuation with the lining 31 previously formed to cover the inner wall surface of the tunnel, extending from both side wall portions 31a to the upper arch-shaped portion 31b. The new invert lining 32 is then formed on both the left and right sides of the tunnel's transverse centerline C.

In this embodiment, the mountain tunnel 30 is a tunnel constructed, for example, several decades ago, and the ground to be excavated was stable. Therefore, at the time of construction, the lining 31 covering the tunnel inner wall surface was formed only from the side wall portions 31a on both sides to the upper arch-shaped portion 31b. However, over the years, concerns have arisen about the impact of swelling of the base portion 30a, so as shown in Figure 2, a new invert lining 32 is formed using invert structures 10 on both the left and right sides.

Furthermore, when forming a new invert lining 32 in an existing mountain tunnel 30, it is desirable to be able to carry out construction work while ensuring access to the passageway without completely blocking traffic through the tunnel. Therefore, in this embodiment, as shown in Figure 3, the steps of forming the invert structure 10 are carried out in one side area of the tunnel while ensuring access to the passageway 60 in the other side area in the transverse direction. The construction method for invert structures in mountain tunnels in this embodiment allows for efficient formation of the invert structure 10 in one side area while maintaining the passageway 60 and the underlying ground 61 in the other side area in a stable state using a simple configuration when constructing the invert structure 10 in each side area in the transverse direction of the tunnel.

The construction method for the invert section structure of this embodiment is a construction method for a mountain tunnel in which the invert section structure 10, which uses PCa concrete blocks 20 and is installed across the entire transverse area of the invert section 33 of the mountain tunnel 30 to form the invert section lining 32, is constructed in two separate areas on either side of the transverse center, allowing one side to be formed in each side area while ensuring passage in the other side area (see Figure 3).In the transverse center of the tunnel in the invert section 33, multiple H-shaped steel beams 35 that support retaining plate members are installed upright at a predetermined interval in the axial direction of the tunnel by being cast into the ground of the invert section 33 with the flange portions 35a aligned in the axial direction of the tunnel (see Figures 2 and 5). As shown in Figures 4(a) to (f), by supporting the flange portion 35a on one side region 55A of the H-shaped steel 35 or the flange portion 35a on the other side region 55B, the ground 61 of the passageway 60 in the other side region 55B is retained, thereby ensuring passage in the other side region 55B (see Figure 3), and in one side region 55A, a process of forming one side of the invert structure 10 using PCa concrete blocks 20 up to a portion beyond the flange portion 35a on the one side region 55A (see Figures 4(a) and (b)); By supporting the retaining plate member 57 on the retaining plate 35, the upper portion of the invert structure 10 on one side formed in one side region 55A is backfilled to form ground 61' (see Figures 4(d) and (e)), which is then retained to restore a passage 60' (see Figures 4(d) and (e)) in the one side region 55A, and with access to the restored passage 60' secured, the remaining invert structure 10 on the other side region 55B is formed using PCa concrete blocks 20 (see Figures 4(d) to (f)).

Furthermore, according to this embodiment, in the process of forming one side of the invert structure 10 in one side region 55A using PCa concrete blocks 20 up to the portion beyond the flange portion 35a on one side region 55A, a sparser member 56 is preferably interposed between the H-shaped steel 35 and the inner surface of the flange portion 35a on one side region 55A, so that the retaining plate member 57 is supported by the flange portion 35a on the one side region 55A while being biased toward the other side region 55B (see Figures 4(a) and (b)).

In this embodiment, the invert structure 10 formed in one side region 55A and the other side region 55B is preferably formed by arranging a plurality of PCa concrete blocks 20 in series across the tunnel and in the invert section 33, as shown in FIGS. 1 and 2, with gaps 21a and 21b maintained between the blocks and the receiving bases 31c at the lower ends of adjacent side wall lining bodies 31a and between adjacent PCa concrete blocks 20, and by arranging the blocks in series across the tunnel and in the invert section 33, with gaps 21b maintained between the blocks and adjacent PCa concrete blocks 20, and by arranging the blocks in series across the tunnel and in the invert section 33 with gaps 21b maintained between the blocks and adjacent PCa concrete blocks 20, and by filling the gaps 21a between the blocks and adjacent receiving bases 31c and the gaps 21b between the blocks and adjacent PCa concrete blocks 20 with a filling solidification material 22 and allowing it to harden (see FIG. 11), thereby integrating the blocks 20X and 10Y via the hardened filling solidification material 22.

That is, in this embodiment, as shown in Figures 5 and 6, the invert section structure 10 is a structure of the invert section 33 using PCa concrete blocks 20 that is provided in at least one side region of the invert section 33 of a mountain tunnel 30 in the transverse direction of the tunnel and constitutes the invert section lining 32. As shown in Figures 7 and 8(a) to 8(c), the PCa concrete blocks 20 are each formed as a hexahedral block having a curved upper surface 20a and a curved lower surface 20b so as to have a curved shape that follows the cross-sectional shape of the invert section lining 32. These multiple PCa concrete blocks 20 are arranged in series in the transverse direction of the tunnel and installed in the invert section 33, with gaps 21a, 21b maintained between the receiving base portions 31c at the lower ends of adjacent side wall linings 31a and between adjacent PCa concrete blocks 20. They are also arranged in series in the axial direction of the tunnel and installed in the invert section 33, with gaps 21b maintained between adjacent PCa concrete blocks. As shown in Figures 1, 2, and 11, these multiple PCa concrete blocks 20 arranged in a row and column are integrated via filling and solidifying material 22 that has been filled and hardened in the gaps 21a between adjacent support portions 31c, the gaps 21b between adjacent PCa concrete blocks 20, and the gaps 21c below the hexahedral underside that communicate with these gaps 21a and 21b, and form at least a part of the invert section lining body 32, forming one side of the invert section lining body 32.

In this embodiment, the multiple PCa concrete blocks 20 are preferably formed to have similar hexahedral shapes with the same width x in the transverse direction of the tunnel, the same vertical width y in the axial direction of the tunnel, and the same height z (see Figures 7 and 8(a)-(c)). The multiple PCa concrete blocks 20 are arranged in a row and column, and are installed in the invert section 33 so that the gaps 21b, which are filled with filling solidification material 22 and extend axially between adjacent PCa concrete blocks 20 in the transverse direction of the tunnel, and the gaps 21b, which extend transversely between adjacent PCa concrete blocks in the axial direction of the tunnel, are preferably arranged in a potato-like pattern that is linearly continuous (see Figures 2 and 5). The gaps 21a between adjacent receiving sections 31c and the gaps 21b between adjacent PC concrete blocks, which are filled with filling solidification material 22, are preferably spaced approximately 15 to 30 mm apart.

In this embodiment, the multiple PCa concrete blocks 20 constituting the invert structure 10 are arranged in a row in the transverse direction of the tunnel, with gaps 21a, 21b filled with filling solidification material 22 between the receiving bases 31c at the lower ends of adjacent side wall linings 31a and between adjacent PCa concrete blocks 20, as described above. They are also arranged in a row in the axial direction of the tunnel, with gaps 21b filled with filling solidification material 22 between adjacent PCa concrete blocks, and are installed in the invert section 33 in a row in both the vertical and horizontal directions. Furthermore, as shown in Figures 7 and 8(a)-(c), the PCa concrete blocks 20 are formed as hexahedral blocks with curved upper and lower surfaces 20a, 20b that are curved to follow the cross-sectional shape of the invert section lining 32, and have a pair of flat axially opposing surfaces 20c at the front and rear and a pair of flat laterally opposing surfaces 20d at the left and right.

Furthermore, each of these PCa concrete blocks 20 has bolt boxes 23 or female thread anchors 24 embedded and fixed to the four sides of the hexahedral top surface for connecting adjacent PCa concrete blocks 20 using bolt members (not shown). The bolt boxes 23 open to the top surface 20a of the PCa concrete block 20, and the female thread anchors 24 open to the upper ends of the axially facing surfaces 20c and the transversely facing surfaces 20d of the side surfaces. As shown in Figure 7, each PCa concrete block 20 has three bolt insertion holes 25 that penetrate the hexahedron in the vertical direction, located at each corner of an isosceles triangle (see Figure 8(a)). A female thread member 25a, into which a height adjustment bolt 26 is threaded, is fixed to each bolt insertion hole 25 below the vertical middle. A large trumpet-shaped recess 25b is formed from the portion where the female screw member 25a of each bolt insertion hole 25 is fixed, expanding in diameter upward and opening onto the upper surface 20a of the PCa concrete block 20, and a small trumpet-shaped recess 25c is formed from the portion where the female screw member 25a is fixed, expanding in diameter downward and opening onto the lower surface 20b of the PCa concrete block 20. Height adjustment bolts 26 are inserted into these bolt insertion holes 25 and screwed into the female screw members 25a, so that the height adjustment bolts 26 are attached with their lower ends 26a protruding movably from the lower surface 20b of the PCa concrete block 20. Furthermore, because the large trumpet-shaped recess 25b and the small trumpet-shaped recess 25c have a trumpet shape that tapers toward the upper and lower openings, the box punching members attached to the box-shaped formwork for pouring concrete to form these trumpet-shaped recesses 25b, 25c can be smoothly removed after the concrete has hardened.

As shown in Figure 8(a), the three bolt insertion and threaded holes 25 are formed on the top surface 20a of the PCa concrete block 20, preferably at each corner of an isosceles triangle (see dashed line) with the base positioned parallel to one axially opposing surface 20c and the apex positioned on the other axially opposing surface 20c.

Furthermore, as shown in FIGS. 11 and 12, some of these PCa concrete blocks 20, specifically the PCa concrete blocks 20', have filler injection holes 27 that penetrate the hexahedron in the vertical direction. A female threaded member 27a is fixed to the vertical middle of each filler injection hole 27, and the male threaded portion of an on-off valve 28 is threadedly engaged with the female threaded member 27a. An upper horn-shaped recess 27b is formed, expanding in diameter upward from the portion where the female threaded member 27a is fixed, and opening onto the upper surface 20a of the PCa concrete block 20'. Also, a lower horn-shaped recess 27c is formed, expanding in diameter downward from the portion where the female threaded member 27a is fixed, and opening onto the lower surface 20b of the PCa concrete block 20'. The male threads of the on-off valve 28 are threaded into the female threads 27a of these filler injection holes 27, and the handle 28a is positioned above the upper surface 20a of the PCa concrete block 20'. This allows the on-off valve 28 to be detachably attached to the PCa concrete block 20', with the handle 28a being able to be opened and closed by working on the upper surface 20a of the PCa concrete block 20'. Furthermore, the upper and lower trumpet-shaped recesses 27b and 27c have a trumpet shape that tapers toward the upper and lower openings. This allows the box punching members attached to the box-shaped formwork for concrete pouring to form these trumpet-shaped recesses 27b and 27c to be smoothly removed after the concrete has hardened.

In this embodiment, the filler injection holes 27 that penetrate the hexahedral PCa concrete block 20' in the vertical direction can be preferably formed in the center of the top surface 20a of the PCa concrete block 20' (see Figure 8(a)).

In addition, in this embodiment, spacer jigs 29a, 29b can be attached to each of the pair of flat axially opposing surfaces 20c and the pair of flat transversely opposing surfaces 20d, preferably of a hexahedral shape, of the PCa concrete blocks 20 (20'), to maintain a predetermined gap 21b between the opposing surfaces 20c, 20d (see Figures 5, 6(b), and (c)). Preferably, multiple lifting jigs 29c are embedded and fixed in the hexahedral upper surface 20a, to be used when lifting each PCa concrete block 20 (see Figure 8(a)).

In this embodiment, these PCa concrete blocks 20 are formed, for example, at a manufacturing factory, by pouring concrete into a box-shaped formwork assembled to conform to the above-mentioned predetermined hexahedron shape, allowing it to harden, and then demolding after a predetermined curing period. The resulting blocks are then formed into a hexahedron shape with a curved upper surface 20a and lower surface 20b, preferably measuring approximately 1,385 to 1,435 mm in width x, approximately 730 mm in length y, and approximately 500 mm in height z, and weighing approximately 1,300 kg. For example, by placing and supporting reinforcement bars inside the box-shaped formwork, the above-mentioned bolt boxes 23, female thread anchors 24, and box-punching members for the bolt insertion and threading holes 25 and filler injection holes 27 can be attached and embedded in the PCa concrete block 20 or temporarily fixed thereto. In this embodiment, the size, shape, weight, etc. of the PCa concrete blocks 20 used as invert blocks can be designed appropriately according to the capacity of the lifting equipment or other equipment that can be used in the work yard 71 of one side area 55A without affecting vehicle traffic in the other side area 55B. For example, the weight of the PCa concrete blocks 20 can preferably be 1,000 to 1,500 kg.

In addition, in this embodiment, the multiple PCa concrete blocks 20 are formed to have similar hexahedral shapes, which limits the type of box-shaped formwork used and allows for efficient production. Furthermore, because the blocks are of similar weight, workability during lifting and transportation is improved, and they can be handled in the same way when lifting or installing. This makes it easy to precisely install each PCa concrete block 20 in a predetermined position, for example, in a potato-like arrangement. This also makes it possible to reduce manufacturing costs.

In this embodiment, as described above, the invert structure 10 is constructed in each of the pair of half regions 55A, 55B, with the regions on either side of the tunnel's transverse center being treated as a pair of half regions (see Figures 1 and 2). As described above, in the center of the tunnel's transverse direction in the invert section 33, multiple H-shaped steel beams 35 supporting retaining plate members 57 can be installed at a predetermined interval in the tunnel axial direction by driving them into the ground of the invert section 33 with the flange portions 35a aligned in the tunnel axial direction, to support the retaining plate members 57 that prevent the other half region from being affected when the invert structure 10 is constructed in each of the half regions 55A, 55B. For this reason, at the position where these H-shaped steel beams 35 are installed, a pair of PCa concrete blocks (central blocks) 20B adjacent in the axial direction of the tunnel at the center of the tunnel's transverse direction can have notched recesses 20e with rectangular cross-sections formed in the corners on both sides of the gap 21b between them (see Figure 5). These notched recesses 20e in the corners on both sides can provide a flange mounting recess 10a for mounting one flange of the H-shaped steel beam 35 on the end face (central end face) 10B of each invert structure 10 on the central side of the tunnel's transverse direction, at the portion where the H-shaped steel beam 35 is installed.

That is, in the block groups 20X, 20Y (see FIG. 1) made up of a plurality of PCa concrete blocks 20 constituting the invert structure 10 of each one side region 55A, 55B, the PCa concrete block 20 (central side block 20B) arranged in the portion where the H-shaped steel 35 is erected has a curved upper surface portion 20a and a lower surface portion 20b having a curved shape that follows the cross-sectional shape of the invert section covering body 32, and is formed as a hexahedral block having a pair of flat axial opposing surfaces 20c at the front and rear and a pair of flat transverse opposing surfaces 20d at the left and right (see FIGS. 8(a) to (c)), and at the corner portion between the axial opposing surfaces 20c and the transverse opposing surfaces 20d at any one location, as shown in FIG. 5, for example, a notched recess 20e having a rectangular cross-sectional shape cut out so as to have a side portion with a width of 1/2 or more of the width of the flange portion 35a of the H-shaped steel 35 is provided continuously from the upper surface portion 20a to the lower surface portion 20b. As a result, at the central ends of a pair of central blocks 20B that are adjacent in the axial direction of the tunnel at the section where the H-shaped steel 35 is erected, these cutout recesses 20e form flange mounting recesses 10a that can accommodate the flange portions of the H-shaped steel 35.

In this embodiment, as shown in Figures 5 and 6, the multiple PCa concrete blocks 20 that make up the invert section structure 10 have multiple transverse block rows 20D that include a base side block 20A arranged adjacent to the base portion 31c at the lower end of the side wall lining body 31a, a central side block 20B arranged on the transverse central side of the invert section, and one or more intermediate blocks 20C (in this embodiment, one intermediate block 20C) arranged between them. These PCa concrete blocks 20A, 20B, 20C are arranged in a row in the transverse direction of the tunnel, with gaps 21a, 21b maintained between adjacent base portions 31c and between adjacent PCa concrete blocks 20A, 20B, 20C, and also in the axial direction of the tunnel, with gaps 21b maintained between adjacent PCa concrete blocks 20A, 20B, 20C (transverse block rows 20D), and are installed in rows vertically and horizontally on the invert section 33. The multiple PCa concrete blocks 20A, 20B, and 20C used when constructing the invert structure 10 can be installed using the following method for installing PCa blocks in the invert section.

In other words, in this embodiment, the multiple PCa concrete blocks 20A, 20B, 20C of each transverse block row 20D arranged in succession in the transverse direction of the tunnel are installed in the invert section 33 by installing the base-side block 20A adjacent to the base section 31c and temporarily fixing it using the temporary fixing means 36, as shown in Figure 6, and then installing the intermediate block 20C and the central block 20B adjacent to the temporarily fixed base-side block 20A.

Also, for example, the base section side block 20A is installed adjacent to the base section 31c and temporarily fixed using the temporary fixing means 36, and then the intermediate section block 20C is installed adjacent to the temporarily fixed base section side block 20A, and at the adjacent location between the installed intermediate section block 20C and the base section side block 20A, they are temporarily fixed using bolt members (not shown) via a bolt box 23 arranged on the upper surface 20a of at least one of the PCa concrete blocks 20A, 20C that is close to the transverse opposing surface 20d, and the height and position of each PCa concrete block 20A, 20C are then adjusted, and the bolt members are then fully tightened. Next, the central block 20B is installed adjacent to the intermediate block 20C, and at the adjacent location between the installed central block 20B and the intermediate block 20C, they are temporarily fixed with bolts via a bolt box 23 arranged on the upper surface 20a of at least one of the PCa concrete blocks 20C, 20B that is close to the transverse opposing surface 20d. After adjusting the height and position of the central block 20B, the bolts are finally tightened, thereby installing the multiple PCa concrete blocks 20A, 20B, 20C of each transverse block row 20D connected in the transverse direction of the tunnel into the invert section 33.

In this embodiment, the temporary fixing means 36 that temporarily fixes the pedestal-side block 20A adjacent to the pedestal 31c preferably comprises a wire, chain, or other such cable 36b, both ends of which are secured to a locking member attached to a hole-in anchor 36a embedded in the pedestal 31c and to a locking member attached to a bolt box 23 or a lifting jig 29c provided on the pedestal-side block 20A. The wire, chain, or other such cable 36b may be provided with an extension/retraction adjustment means 36c, such as a turnbuckle, that adjusts the length between the locked ends. This makes it possible to adjust the width of the gap 21a maintained between the pedestal 31c and the adjacent pedestal-side block 20A.

In addition, in this embodiment, the height of each of the PCa concrete blocks 20A, 20B, and 20C can be adjusted using three height adjustment bolts 26 threaded into the bolt insertion holes 25 formed in the three locations described above, as shown in Figures 8(a) and 9. That is, each of the PCa concrete blocks 20A, 20B, and 20C has three bolt insertion holes 25 formed in the vertical direction, and a height adjustment bolt 26 is attached to each bolt insertion hole 25 in a manner that allows the lower end 26a to protrude downward from the underside 20b of the PCa concrete block 20A, 20B, and 20C. Prior to the process of filling the gaps 21a between adjacent receiving portions 31c of multiple PCa concrete blocks 20A, 20B, 20C arranged vertically and horizontally with filling solidifying material 22, the gaps 21b between adjacent PCa concrete blocks 20A, 20B, 20C, and the gaps 21c below the hexahedral undersides 20b that communicate with these gaps 21a, 21b (see Figure 11), the PCa concrete blocks 20A, 20B, 20C are rotated from above to change the length by which the three height adjustment bolts 26 in each PCa concrete block 20A, 20B, 20C protrude from the underside 20b of the PCa concrete block 20A, 20B, 20C, thereby adjusting the height and inclination of each PCa concrete block 20A, 20B, 20C.

As described above, in this embodiment, a nut member, preferably a female thread member 25a, is fixed to each bolt insertion hole 25 below the vertical middle. The height adjustment bolts 26 are threadedly attached to these nuts 25a, allowing the lower ends 26a of the height adjustment bolts 26 to protrude downward from the undersides 20b of the PCa concrete blocks 20A, 20B, and 20C. A tiltable ground adjuster 26b can be attached to the lower ends 26a of the height adjustment bolts 26. This allows the lower ends 26a of the height adjustment bolts 26 to be stably grounded on the ground, i.e., the filling bottom surface 26c, below the undersides 20b. The ground adjuster 26b can also be shaped so that when the height adjustment bolt 26 is retracted upward, the opening periphery of the bolt insertion hole 25 can be tapered to fit into the small trumpet-shaped recess 25c, which widens downward and is formed in the underside 20b of the PCa concrete blocks 20A, 20B, and 20C.

In this embodiment, the upper end 26d of the height adjustment bolt 26 is preferably formed to have a rectangular cross section. By engaging a rotation tool, such as an insert extension bar, with this upper end 26d and rotating the height adjustment bolt 26, the length of protrusion of the lower end 26a of the height adjustment bolt 26 from the lower surface 20b of the PCa concrete block 20A, 20B, or 20C can be easily adjusted by working above the upper surface 20a of the PCa concrete block 20A, 20B, or 20C. As described above, the bolt insertion hole 25 has a large trumpet-shaped recess 25b that expands upward from the portion where the nut member 25a, which is a female thread member, is secured, and opens to the upper surface 20a of the PCa concrete block 20A, 20B, or 20C. If the upper end 26d of the height adjustment bolt 26 protrudes from or is close to the upper surface 20a of the PCa concrete block 20A, 20B, or 20C after the lower end 26a is adjusted to contact the filling bottom surface 26c, preventing sufficient cover thickness from being secured above the upper end 26d when the large trumpet-shaped recess 25b is filled with finishing filler, the upper end 26d of the height adjustment bolt 26 can be cut to the required length in the large trumpet-shaped recess 25b. This ensures the desired cover thickness of the finishing filler, such as mortar, filled in the bolt insertion hole 25, preventing corrosion of the height adjustment bolt 26. The work of cutting the upper end 26d of the height adjustment bolt 26 can be performed smoothly because the large trumpet-shaped recess 25b, which expands in diameter, provides ample working space.

Furthermore, in this embodiment, in the invert section structure 10 using the above-mentioned PCa concrete blocks 20A, 20B, and 20C, the following PCa block connection structure 37 in the invert section structure can be adopted as the connection structure for connecting and arranging multiple PCa concrete blocks 20A, 20B, and 20C vertically and horizontally and installing them as a single unit on the invert section 33 while maintaining gaps 21b of a predetermined spacing width between adjacent PCa concrete blocks 20A, 20B, and 20C.

In other words, in this embodiment, as shown in Figures 5, 6, and 8(a) to (c), the PCa block connection structure 37 has transverse spacer jigs 29a (see Figure 8(b)) fixed to one of the transversely opposing surfaces 20d of adjacent PCa concrete blocks 20A, 20B, 20C in the transverse direction of the tunnel, preferably at least three of which are interposed between the opposing transverse surfaces 20d. The transversely opposing surfaces 20d are connected by the fastening force of bolt members (not shown) fastened in bolt boxes 23 arranged on the upper surface 20a of at least one of the PCa concrete blocks 20A, 20B, 20C that is adjacent to the transversely opposing surfaces 20d, while maintaining a gap 21b of a predetermined spacing width between the transversely opposing surfaces 20d. Additionally, between each pair of axially opposing surfaces 20c of adjacent PCa concrete blocks 20A, 20B, and 20C in the tunnel axis direction, axial spacer jigs 29b (see Figure 8(c)) are fixed to one of the axially opposing surfaces 20c, preferably at least three locations. The bolt boxes 23 are located on the upper surface 20a of at least one of the PCa concrete blocks 20A, 20B, and 20C adjacent to the axially opposing surfaces 20c. The fastening force of bolts (not shown) fastened by bolts is used to connect each pair of adjacent PCa concrete blocks 20A, 20B, and 20C in the tunnel axis direction, maintaining a predetermined gap 21b between the axially opposing surfaces 20c. The transverse spacer jigs 29a and axial spacer jigs 29b can also be attached to the transversely opposing surfaces 20d and axially opposing surfaces 20c at the locations where the bolt boxes 23 are installed.

In this embodiment, the transverse spacer jigs 29a and/or the axial spacer jigs 29b may be made of mortar blocks, preferably attached and fixed to one of the opposing surfaces 20c, 20d. The mortar block spacer jigs 29a, 29b may be removably attached to the opposing surfaces 20c, 20d and removed after the PCa concrete blocks 20A, 20B, 20C are fully tightened and connected. The transverse spacer jigs 29a and/or the axial spacer jigs 29b may also be made of male threaded members, preferably threaded into female threaded inserts embedded in one of the opposing surfaces 10c, 10d, so that the protruding length can be adjusted.

The transverse spacer jigs 29a and axial spacer jigs 29b, preferably arranged in at least three locations and secured to either one of the transverse opposing surfaces 20d or the axial opposing surface 20c, are preferably secured to at least two locations in the area below the center of gravity of the PCa concrete blocks 20A, 20B, and 20C. This makes it possible to stably and accurately form gaps 21a and 21b of the specified spacing in the area below the center of gravity, where it is difficult to confirm that the gaps 21a and 21b have been formed accurately, without using special equipment when installing the PCa concrete blocks 20A, 20B, and 20C.

The bolt members fastened in the bolt boxes 23 arranged on the upper surface 20a of at least one of the PCa concrete blocks 20A, 20B, 20C adjacent to the transverse opposing surface 20d, or the bolt members fastened in the bolt boxes 23 arranged on the upper surface 20a of at least one of the PCa concrete blocks 20A, 20B, 20C adjacent to the axial opposing surface 20c, may preferably be fastened across the bolt box 23 arranged on the upper surface 20a adjacent to the axial opposing surface 20c or transverse opposing surface 20d of one of the PCa concrete blocks 20A, 20B, 20C, and a female thread anchor 24 embedded in the axial opposing surface 20c or transverse opposing surface 20d of the other PCa concrete block 20A, 20B, 20C. Preferably, the bolt box 23 may be fastened across the bolt box 23 arranged on the top surface 20a adjacent to the axially opposing surface 20c or the transversely opposing surface 20d of one PCa concrete block 20A, 20B, 20C, and the bolt box 23 arranged on the top surface 20a adjacent to the axially opposing surface 20c or the transversely opposing surface 20d of the other PCa concrete block 20A, 20B, 20C.

In this embodiment, as shown in FIG. 11, the multiple PCa concrete blocks 20A, 20B, and 20C arranged in a row and column are integrated via the filling solidification material 22 that is filled and hardened in the gaps 21a between adjacent receiving portions 31c, the gaps 21b between adjacent PCa concrete blocks 20A, 20B, and 20C, and the gaps 21c below the hexahedral undersides that communicate with these gaps, thereby constituting at least a portion of the invert section covering body 32. In this embodiment, the filling solidification material 22 is filled in the gaps 21a between adjacent receiving portions 31c, the gaps 21b between adjacent PCa concrete blocks 20A, 20B, and 20C, and the gaps 21c below the hexahedral undersides that communicate with these gaps 21a and 21b, using the following construction method.

In other words, in this embodiment, in order to fill the gaps 21a between adjacent receiving portions 31c of multiple PCa concrete blocks 20A, 20B, and 20C arranged in a row vertically and horizontally, the gaps 21b between adjacent PCa concrete blocks 20A, 20B, and 20C, and the gaps 21c below the hexahedral lower surface portions that communicate with these gaps 21a and 21b, the opening portions of the gaps 21a and 21b that open on the upper surface portions 20a, gable end surface portions 10A (see Figures 5 and 11), and center end surface portions 10B (see Figures 5 and 11) of multiple PCa concrete blocks 20A, 20B, and 20C arranged in a row vertically and horizontally, are closed. 11 to 13, the filling material 22 is sequentially injected into the gaps 21a and 21b through the center-side filler injection holes 27d provided vertically through one or more of the plurality of center-side blocks 20B arranged in the axial direction of the tunnel, and through the pedestal-side filler injection holes 27e provided vertically through one or more of the plurality of pedestal-side blocks 20A arranged in the axial direction of the tunnel. Preferably, as shown in FIG. 13, the filling material 22 is first injected through the center-side filler injection holes 27d, then switched to the pedestal-side filler injection holes 27e, and further injected through the pedestal-side filler injection holes 27e. After that, the filling material 22 is confirmed to flow out of the opening of the gap 21a between the pedestal 31c and the upper surface 20a of the pedestal-side block 20A, and the filling of the filling material 22 is completed. It is also possible to inject the filling solidification material 22 using only the filling material injection hole 27d of the center side block 20B, without using the filling material injection hole 27e of the base side block 20A, and to finish filling the filling solidification material 22 once it has been confirmed that the filling solidification material 22 is flowing out from the opening of the gap 21a between the base 31c held by the upper surface 20a of the base side block 20A.

In this embodiment, the multiple PCa concrete blocks 20A, 20B, and 20C arranged in a row and column are preferably adjacent to the tunnel axial direction of the previously constructed existing invert structure 40 (see Figures 5 and 13). With the gaps 21d between the upper surface 20a and the central end surface 10B of the multiple PCa concrete blocks 20A, 20B, and 20C arranged in a row and column closed, the filling and solidifying material 22 is injected, preferably by switching from the central filler injection hole 27d located on the existing invert structure 40 side to the central filler injection hole 27d located on the gable side, as shown in Figure 13. At the same time, the filling and solidifying material 22 is injected by switching from the base-side filler injection hole 27e located on the existing invert structure 50 side to the base-side filler injection hole 27e located on the gable side. It is also possible to switch from the filler injection hole 27d of the central block 20B on the existing invert structure 50 side to the filler injection hole 27d of the central block 20B on the gable side and inject the filling solidification material 22 partway, and then switch again from the filler injection hole 27e of the base block 20A on the existing invert structure 50 side to the filler injection hole 27e of the base block 20A on the gable side and inject the filling solidification material 22.

Furthermore, in this embodiment, strip-shaped formwork 41a is attached by overlapping and fixing to the upper surface 20a of multiple PCa concrete blocks 20A, 20B, and 20C, preferably arranged vertically and horizontally, so as to cover the openings of gaps 21b in the upper surface 20a, thereby blocking the openings of the upper surface 20a (see Figure 11). At the gable end 10A, strip-shaped formwork is attached by overlapping and fixing to the gable end 10A, preferably covering the openings of gaps 21a, 21b, and 21c, thereby blocking the openings of the gable end 10A (not shown). At the center end 10B, strip-shaped formwork 41b is attached by overlapping and fixing to the center end 10B, preferably covering the openings of gaps 21b, 21c, and 21d, thereby blocking the openings of the center end 10B (see Figure 11).

It is also preferable to form these strip-shaped formwork using transparent plate-shaped members. This makes it possible to visually observe the filling status of the solidifying material 22 into each of the gaps 21a, 21b, 21c, and 21d through these transparent strip-shaped formworks.

Furthermore, it is preferable to attach air vent hoses 42 (see Figure 11) extending from appropriate positions to the band-shaped formwork 41a attached to cover the openings of the gaps 21a, 21b, and 21d on the upper surfaces 20a of multiple PCa concrete blocks 20A, 20B, and 20C arranged vertically and horizontally. These hoses 42 communicate with the gaps 21a, 21b, and 21d on the upper surfaces 20a. This allows air to be effectively vented from the gaps 21a, 21b, and 21d via the air vent hoses 42 when the filling solidification material 22 is being filled, and the flow of the filling solidification material 22 from these air vent hoses 42 makes it possible to confirm that the filling solidification material 22 has been filled.

In this embodiment, in order to fill the gaps 21a between adjacent receiving portions 31c of the multiple PCa concrete blocks 20A, 20B, 20C arranged in a row vertically and horizontally, the gaps 21b between adjacent PCa concrete blocks 20A, 20B, 20C, and the gaps 21c below the hexahedral bottom surfaces that communicate with these gaps 21a and 21b, the upper surfaces 20a of the multiple PCa concrete blocks 20A, 20B, 20C arranged in a row vertically and horizontally, With the openings of gaps 21a, 21b, 21c at end face 10A and center face 10B closed, filling solidification material 22 is sequentially injected through center-side filler injection holes 27d provided vertically penetrating one or more of the center-side blocks 20B connected together in the axial direction of the tunnel, and through base-side filler injection holes 27e provided vertically penetrating one or more of the base-side blocks 20A connected together in the axial direction of the tunnel. Open/close valves 28 are attached to center-side filler injection holes 27d and base-side filler injection holes 27e, respectively. When the filling solidification material 22 is filled by sequentially connecting the injection hose to the valves 28 of the selected center-side filler injection holes 27d or pedestal-side filler injection holes 27e, the valves 28 of the center-side filler injection holes 27d or pedestal-side filler injection holes 27e are closed after filling is completed. The valves 28 of the unused center-side filler injection holes 27d or pedestal-side filler injection holes 27e are left open and can be used as air vents. As described above, in the process of filling the filling solidification material 22, the filling solidification material 22 can be injected only through the filler injection hole 27d of the center-side block 20B, without using the filler injection hole 27e of the pedestal-side block 20A, and the filling of the filling solidification material 22 can be completed by confirming that the filling solidification material 22 flows out of the opening of the gap 21a between the pedestal-side block 31c held by the upper surface 20a of the pedestal-side block 20A. By filling the filling solidification material 22 through the filling material injection hole 27d on the central side, air can be smoothly removed from the gap 21a between the receiving portion 31c held on the upper surface 20a of the receiving portion side block 20A, effectively preventing air from collecting in the filled filling solidification material 22.

In addition, in this embodiment, the multiple PCa concrete blocks 20A, 20B, and 20C arranged in a row and column are preferably arranged adjacent to each other in the axial direction of the tunnel of the previously formed existing invert structure 40, as described above. With the openings of the gaps 21d between the upper surface 20a and the central end surface 10B of the multiple PCa concrete blocks 20A, 20B, and 20C arranged in a row and column closed, the filling solidification material 22 is injected by switching from the opening/closing valve 28 of the central filler injection hole 27d located on the existing invert structure 40 side to the opening/closing valve 28 of the central filler injection hole 27d located on the gable side. At the same time, the filling solidification material 22 is injected by switching from the opening/closing valve 28 of the filler injection hole 27e on the receiving base side located on the existing invert structure 40 side to the opening/closing valve 28 of the filler injection hole 27e on the receiving base side located on the gable side. As described above, it is also possible to switch from the filler injection hole 27d of the central block 20B on the existing invert structure 50 side to the filler injection hole 27d of the central block 20B on the gable side and inject the filling solidification material 22 partway, and then switch again from the filler injection hole 27e of the base block 20A on the existing invert structure 50 side to the filler injection hole 27e of the base block 20A on the gable side and inject the filling solidification material 22.

For each of the central filler injection holes 27d and base-side filler injection holes 27e, the open/close valves 28 can be attached by threading the male threads 28b into the female threaded members 27a fixed to the middle of the central filler injection holes 27d or base-side filler injection holes 27e in the penetration direction, as described above, so that they protrude upward from the top surfaces of multiple PCa concrete blocks 20A, 20B arranged vertically and horizontally. This makes it easy to detachably connect the injection hoses by working on the top surfaces 20a of the PCa concrete blocks 20A, 20B, 20C.

The construction method for invert structures in mountain tunnels in this embodiment allows for the above-described invert lining 10 to be constructed in each of the transversely extending side regions 55A and 55B of the tunnel, and for example, allows for the steps of forming the invert structure 10 to be carried out in one side region 55A while ensuring passage on the passageway 60 in the other side region 55B, as shown in Figures 3 and 4(a) to (f).

In other words, in this embodiment, as described above, in the center of the tunnel in the transverse direction of the invert section 33, multiple H-shaped steel beams 35 that support the retaining plate members 57 are installed upright at a predetermined interval in the axial direction of the tunnel by being driven into the ground of the invert section 33 with the flange portions 35a aligned in the axial direction of the tunnel (see Figures 2 and 5). As shown in Figures 4(a) to (f), the construction method of the invert structure of this embodiment is preferably to interpose a sparser member 56 between the inner surface of the flange portion 35a on one side region 55A of the H-shaped steel 35, and support the retaining plate member 57 on the flange portion 35a on one side region 55A while shifting it toward the other side region 55B. By retaining the ground 61 of the passageway 60 in the other side region 55B, the invert structure 10 on one side is installed in one side region 55A so as to extend beyond the flange portion 35a on the one side region 55A while ensuring passage in the other side region 55B (see Figure 3). The process includes a step of forming the inverted structure 10 on one side of the one-side region 55B (see Figures 4(a) and (b)), and a step of supporting an earth retaining plate member 57 on the flange portion 35a of one side region 55A of the H-shaped steel 35 to backfill the upper portion of the inverted structure 10 on one side of the one-side region 55A and creating ground 61' (see Figures 4(d) and (e)) by retaining the earth retaining plate member 57, thereby restoring a passage 60' (see Figures 4(d) and (e)) in the one-side region 55A, and then forming the remaining inverted structure 10 on the other side of the other region 55B with the passage on the restored passage 60' secured (see Figures 4(d) to (f)).

In this embodiment, in the process of forming one side of the invert structure 10 on one side of the side region 55A, first, the ground 61 below the passage 60 in the other side region 55B is retained, and then the passage 60 and the ground 61 below it on one side region 55A are excavated down to the base portion 30a of the mountain tunnel 30. As shown in Figure 4(a), the ground 61 below the passageway 60 in the other half region 55B is secured by attaching both ends of a known earth retaining plate member 57, which has a length spanning the flange portions 35a of each pair of adjacent H-shaped steel beams 35 spaced a predetermined distance apart, to the inner surfaces of the flange portions 35a of one half region 55A of the H-shaped steel beams 35. Sparser members 56 are interposed between the end portions and the inner surfaces of the retaining plate member 57, which is attached in a biased position toward the other half region 55B. This allows the flange portions 35a of one half region 55A to support the earth pressure from the other half region 55B, thereby enabling simple and stable earth retaining.

As a result, as shown in Figure 4(a), the invert structure 10 on one side region 55A can be formed by arranging the flange portion 35a of the H-shaped steel 35 on one side region 55A in the flange arrangement recess 10a formed by the notched recess 20e of a pair of PCa concrete blocks (center-side blocks) 20B adjacent in the axial direction of the tunnel, on the central side of the tunnel in the transverse direction of the invert structure 10 on that side region 55A. This also makes it possible to form the invert structure 10 on one side region 55A in such a way that the end face, excluding the notched recess 20e, formed by the transversely opposing surface 20d of the center-side block 20B protrudes beyond the flange portion 35a of the one side region 55A, while still ensuring passage through the passageway 60 in the other side region 55B (see Figure 3).

In this way, the invert structure 10 in one side region 55A is formed to extend beyond the flange portion 35a on one side region 55A of the H-shaped steel 35. This makes it possible to easily fill and harden the gap 51 (see Figures 1 and 2) between the one-side block group 20X and the other-side block group 20Y in the process of forming the invert structure 10 on the other side region 55B, which will be described later.

After the invert structure 10 on one side region 55A is formed, in this embodiment, as shown in FIG. 4(c), the lower end portion of the retaining plate member 57 is removed from the H-beam 35 together with the sparser member 56, and the portion between the lower end portion and the ground 61 on the other side region 55B is backfilled up to the height of the top surface of the formed invert structure 10 (see dotted portion). Then, as shown in FIG. 4(d), the portion of the retaining plate member 57 above the invert structure 10 on one side region 55A is removed from the H-beam 35 together with the sparser member 56. The removed retaining plate member 57 is then repositioned, with both ends of the retaining plate member 57 abutting against the inner surface of the flange portion 35a on the other side region 55B of the H-beam 35 via the sparser member 56, and the retaining plate member 57 is reattached in a biased position toward the one side region 55A. The resulting gap between the retaining plate member 57 and the ground 61 below the passageway 60 in the other side area 55A is then backfilled, and the retaining plate member 57 is secured to the inner surface of the flange portion 35a on one side area 55A of the H-shaped steel 35.

Continuing from this state, as shown in Figure 4(e), in one side region 55A, the upper portion of the formed invert structure 10 is backfilled up to the height of the passageway 60 in the other side region 55B, creating a paving base 61', and the upper surface of the created base 61' is paved to restore the passageway 60' in one side region 55A. After restoring the passageway 60' in one side region 55A, while ensuring access to the restored passageway 60', in the other side region 55B, the passageway 60 and the underlying ground 61 are excavated down to the base 30a of the mountain tunnel 30, in the same manner as described above, with the other side region 55B designated as the new side region where the invert structure 10 will be formed. Additionally, by engaging both ends of the retaining plate member 57 with the inner surface of the flange portion 35a on the other side region 55A of the H-shaped steel 35 using a sparser member 56, the earth pressure from one side region 55A can be supported by the retaining plate member 57, allowing for simple and stable retaining while also forming the invert structure 10 in the other side region 55B.

That is, in the process of forming the remaining invert structure 10 in the other half region 55B, as shown in Figures 4(d) to (f), preferably, a retaining plate member 57 is supported via a sparser member 56 on the flange portion 35a of the H-shaped steel 35 on the other half region 55B side. This retains the ground 61' created by backfilling the upper portion of the invert structure 10 formed in one half region 55A, thereby restoring the access path 60' in that half region 55A. Then, with access to the restored access path 60' secured, the remaining invert structure 10 is formed in the other half region 55B.

Furthermore, in the process of forming the remaining invert structure 10 in the other half-side region 55B, as described below, the gap 51 between the one-side block group 20X formed in one half-side region 55A and the other-side block group 20Y formed in the other half-side region 55B can also be filled and solidified with the filling solidification material 22.

In this embodiment, after the remaining invert structure 10 is formed in the other side region 55B, the retaining plate member 57 and the sparser member 56 are removed, and the upper part of the invert structure 10 formed in the other side region 55B is backfilled up to the height position of the passage 61 ' in the one side region 55A, thereby reconstructing the ground for paving and paving the upper surface of the constructed ground, thereby restoring the passage (not shown) in the other side region 55B as well.

In this embodiment, the invert section structures 10 formed in one side region 55A and the other side region 55B are integrated to form the invert section structure 50 across the entire transverse area, constituting the invert section covering body 32, as shown in Figures 1 and 2.

In other words, the invert section structure 50 covering the entire transverse area is a structure using PCa concrete blocks 20A, 20B, and 20C that is provided throughout the entire transverse area of the tunnel in the invert section 33 of the mountain tunnel and constitutes the invert section lining body 32, and each of the PCa concrete blocks 20A, 20B, and 20C is formed as a hexahedral block having curved upper surface 20a and lower surface 20b so as to have a curved shape that follows the cross-sectional shape of the invert section lining body 32, as described above. 1 and 2, in each of the tunnel's transverse side regions 55A and 55B, a plurality of PCa concrete blocks 20A, 20B, and 20C are arranged in series in the transverse direction of the tunnel and installed in the invert section 33, with gaps 21a and 21b maintained between the receiving bases 31c at the lower ends of adjacent side wall lining bodies 31a and between adjacent PCa concrete blocks. Also, in the axial direction of the tunnel, adjacent PCa concrete blocks 20A, 20B, and 20C are arranged in series in the invert section 33, with gaps 21b maintained between them. This forms a first-side block group 20X and an second-side block group 20Y. Furthermore, a gap 51 is maintained between the first-side block group 20X and the second-side block group 20Y in the central portion of the tunnel's transverse direction. The multiple PCa concrete blocks 20A, 20B, 20C arranged vertically and horizontally in the one-side block group 20X and the other-side block group 20Y are integrated to form the invert section covering body 32 via the filling solidification material 22 that has been filled and hardened in the gaps 21a between adjacent receiving portions 31c, the gaps 21b between adjacent PCa concrete blocks 20A, 20B, 20C, the gaps 51 between the one-side block group 20X and the other-side block group 20Y, and the gaps 21c below the hexahedral underside that communicate with these gaps 21a, 21b and gaps 51.

In addition, in this embodiment, the gaps 21a between adjacent receiving base portions 31c filled with filling solidification material 22 and the gaps 21b between adjacent PCa concrete blocks 20A, 20B, and 20C preferably have a spacing width of 15 to 30 mm, and the gap portion 51 between one side block group 20X and the other side block group 20Y preferably has a spacing width of 100 to 130 mm.

Furthermore, in this embodiment, the multiple PCa concrete blocks 20A, 20B, 20C arranged in a row vertically and horizontally in the one-side block group 20X and the other-side block group 20Y are installed in the invert section 33 in a potato-like arrangement, with the gaps 21b extending axially between adjacent PCa concrete blocks in the transverse direction of the tunnel and the gaps extending transversely between adjacent PCa concrete blocks in the axial direction of the tunnel filled with filling solidification material 22, preferably both arranged linearly and continuously.

Furthermore, in this embodiment, it is preferable that the central side surface of the PCa concrete block (central side block) 20B located closest to the center of one side block group 20X, which faces the gap portion 51, and the central side surface of the PCa concrete block (central side block) 20B located closest to the center of the other side block group, are formed with irregularities 52 to improve adhesion with the filling solidification material 22, as shown in Figure 14, for example.

The unevenness 52 that improves adhesion with the filling solidification material 22 can also be formed on the lateral opposing surfaces 20d across the maintained gaps 21a, 21b of each PCa concrete block 20 that are arranged in series across the tunnel and installed in the invert section 33, preferably with gaps 21a, 21b maintained between the receiving base portions 31c at the lower ends of adjacent side wall lining bodies 31a and adjacent PCa concrete blocks 20. The unevenness 52 that improves adhesion with the filling solidification material 22 can also be formed on the axial opposing surfaces 20c across the maintained gaps 21b of each PCa concrete block 20 that are arranged in series across the tunnel and installed in the invert section 33, preferably with gaps 21b maintained between the PCa concrete blocks 20.

In addition, in this embodiment, it is preferable that the PCa concrete block (central block) 20B located most centrally of the one-side block group 20X and the PCa concrete block (central block) 20B located most centrally of the other-side block group 20Y are connected via long bolt members (not shown). This makes it possible to ensure the installation accuracy of the one-side block group 20X and the other-side block group 20Y, as well as to ensure the shear strength of the portion between these block groups 20X and 20Y.

In this embodiment, the invert structure 50 for the entire transverse area of the tunnel described above is formed as follows. That is, in the invert structure 50 for the entire transverse area of the tunnel, a plurality of PCa concrete blocks 20A, 20B, 20C are arranged in series in the transverse direction of the tunnel in one side region 55A of the tunnel, with gaps 21a, 21b maintained between the receiving base 31c at the lower end of the adjacent side wall lining body 31a and between adjacent PCa concrete blocks 20A, 20B, 20C, and are installed in the invert section 33. Gaps 21b are also maintained between adjacent PCa concrete blocks 20A, 20B, 20C in the axial direction of the tunnel. and a step of filling and hardening a filling solidification material 22 into the gaps 21a between the adjacent receiving base portions 31c of the plurality of PCa concrete blocks 20A, 20B, 20C of the one side block group 20X arranged in a row and row, the gaps 21b between the adjacent PCa concrete blocks 20A, 20B, 20C, and the gaps 21c below the lower surface portions of the hexahedrons communicating with the gaps 21a, 21b, and 21c, respectively; and a step of filling and hardening a filling solidification material 22 into the gaps 21a between the adjacent receiving base portions 31c of the plurality of PCa concrete blocks 20A, 20B, 20C of the one side block group 20X arranged in a row and row, and the gaps 21b between the adjacent PCa concrete blocks 20A, 20B, 20C, and the gaps 21c below the lower surface portions of the hexahedrons communicating with the gaps 21a, 21b, and 21c, respectively, of the plurality of PCa concrete blocks 20A, 20B, 20C in the other side region 55B in the transverse direction of the tunnel. A step of forming the other side block group 20Y by arranging the PCa concrete blocks 20A, 20B, 20C in a row in the transverse direction of the tunnel and installing them in the invert section 33 while maintaining gaps 21a, 21b between them and the receiving base section 31c at the lower end of the adjacent side wall lining body 31a and between them and the adjacent PCa concrete blocks 20A, 20B, 20C, and also by arranging the PCa concrete blocks 20A, 20B, 20C in a row in the axial direction of the tunnel and installing them in the invert section 33 while maintaining gaps 21b between them and the adjacent PCa concrete blocks 20A, 20B, 20C, The process includes a step of filling and hardening filling solidification material 22 into the gaps 21a between adjacent support portions 31c of multiple PCa concrete blocks 20A, 20B, 20C, the gaps 21b between adjacent PCa concrete blocks 20A, 20B, 20C, and the gaps 21c below the hexahedral undersides that communicate with these, as well as into the gaps 51 between one side block group 20X and the other side block group 20Y. This makes it easy to form the invert structure 50 that is provided across the entire transverse area of the tunnel and that constitutes the invert lining 32.

The construction method for invert structures in mountain tunnels of the present invention, which has the above-mentioned configuration, enables the invert structures 10 that make up the invert lining 32 to be constructed in each of the side regions 55A, 55B in the transverse direction of the tunnel in an existing mountain tunnel 30. This makes it possible to form the invert structures in one side region 55A while maintaining the passageway 60 and the underlying ground 61 in the other side region 55B in a stable state using a simple configuration.

The present invention is not limited to the above-described embodiment, and various modifications are possible. For example, the invert section structure of the present invention is not limited to construction work to add a lining to the invert section of a mountain tunnel where the lining covering the tunnel's inner wall surface is formed only in the area from both side walls to the upper arch-shaped section, and is not formed in the invert section. It can also be used in construction work to repair the invert section lining already installed in a mountain tunnel and reinstall a new invert section lining.

In addition, in the process of forming the remaining invert structure on one side, by supporting the retaining plate member 57 on the flange portion of the other side area of the H-shaped steel via a sparser member, it is not necessarily necessary to retain the ground created in one side area.For example, by engaging both ends of the retaining plate member with the surface of one side area of the flange portion of one side area of the H-shaped steel, the retaining plate member can be supported by the H-shaped steel, thereby retaining the ground created by backfilling in one side area.

Furthermore, in the process of forming one side of the invert structure using PCa concrete blocks up to the portion beyond the flange portion on one side of the invert structure, the H-beam can be supported by the H-beam, for example, by engaging both ends of the retaining plate member with the surface of the flange portion on the other side of the H-beam. The PCa concrete blocks are not limited to those in the above embodiment, and various other shapes and weights can be used.

10 Invert portion structure 10a Flange arrangement recess 10A Gable side end surface portion 10B Central side end surface portion 20, 20' PCa concrete block 20a Upper surface portion 20b Lower surface portion 20c Axial opposing surface 20d Transverse opposing surface 20e Notched recess 20f, 20g Axial connecting portion 20A Receiving base side block 20B Central side block 20C Intermediate block 20D Transverse direction block row 20E Outer PCa concrete block 20F Inner PCa concrete block 20X One side block group 20Y Other side block group 21a Gap 21b between the receiving base portion Gap 21c between adjacent PCa concrete blocks Gap 21d below the lower surface portion Gap 21d between existing invert portion structure 22 Filling solidification material 23 Bolt box 24 Female thread anchor 25 Bolt insertion screw hole 25a Female thread member (nut member)
25b Large trumpet-shaped recess 25c Small trumpet-shaped recess 26 Height adjustment bolt 26a Lower end 26b Grounding adjuster 26c Filling bottom surface portion 26d Upper end 27 Filler material injection hole 27a Female thread member 27b Upper trumpet-shaped recess 27c Lower trumpet-shaped recess 27d Center side filler material injection hole 27e Receiving base side filler material injection hole 28 Opening and closing valve 28a Handle portion 29a Transverse direction spacer jig 29b Axial direction spacer jig 29c Lifting jig 30 Mountain tunnel 30a Base portion 31 Lining 31a Side wall portion (side wall lining body)
31b Arch-shaped portion 31c Support portion 32 Invert portion lining body 33 Invert portion 35 H-shaped steel 35a Flange portion 36 Temporary fixing means 36a Hole-in anchor 36b Cable member 36c Expansion adjustment means 37 PCa block connection structure 40 Existing invert portion structure 41a Upper surface band plate-shaped formwork 41b Gable portion band plate-shaped formwork 41c Central side band plate-shaped formwork 42 Air vent hose 50 Invert portion structure 51 throughout the transverse direction of the tunnel Gap portion 55A between one side block group and the other side block group One side region 55B Other side region 56 Sparser member 57 Retaining plate member 60, 60' Passageway 61, 61' Ground below the passway b Gap below the underside

Claims (3)

A construction method for an invert section structure in a mountain tunnel, in which an invert section structure using PCa concrete blocks is installed in the entire transverse direction of the invert section of a mountain tunnel to constitute an invert section lining, and is constructed in two separate regions on either side of the center of the transverse direction, so that each side can be formed in one region while ensuring passage in the other region,
a step of installing H-shaped steel beams in the invert section, with flanges aligned in the axial direction of the tunnel, at predetermined intervals in the axial direction of the tunnel, so as to support earth retaining plate members, by installing them in the ground of the invert section;
a step of forming one side of the invert structure in one of the half-side areas using PCa concrete blocks up to the part beyond the flange portion on one half-side area, while ensuring passage in the other half-side area by supporting the flange portion on one half-side area or the flange portion on the other half-side area of the H-shaped steel cast in the H-shaped steel casting step and thereby retaining the ground of the passage in the other half-side area;
A construction method for invert structures in mountain tunnels , comprising the steps of: supporting an earth retaining plate member on the H-shaped steel cast in the H-shaped steel casting step ; retaining the ground formed by backfilling the upper part of the invert structure on one side formed in one side area; thereby restoring a passage in the one side area; and, with passage on the restored passage secured, forming the remaining invert structure on the other side area using PCa concrete blocks. The construction method for an invert structure in a mountain tunnel described in claim 1, wherein in the process of forming one side of the invert structure using PCa concrete blocks in one side region up to a portion beyond the flange portion on one side region, a sparser member is interposed between the inner surface of the flange portion on one side region of the H-shaped steel, and the retaining plate member is supported by the flange portion on one side region while being biased toward the other side region. 3. The method for constructing an invert structure in a mountain tunnel as claimed in claim 1 or 2, wherein the invert structures formed in one side region and the other side region are each formed by arranging a plurality of PCa concrete blocks in a row in the transverse direction of the tunnel, while maintaining gaps between them and the support bases at the lower ends of adjacent side wall lining bodies and between adjacent PCa concrete blocks, and by installing the blocks in a row in the invert section, and also in the axial direction of the tunnel, while maintaining gaps between them and adjacent PCa concrete blocks. The blocks are then integrated via the hardened filling solidification material by filling the gaps between adjacent support bases and between adjacent PCa concrete blocks and allowing it to harden.