Construction method for invert structure in mountain tunnel

Abstract

To provide a construction method for an invert structure which is capable of forming an invert structure constituting a lining body for the invert on each one side area in the transverse direction of the tunnel.SOLUTION: A construction method for an invert structure comprises a process of forming an invert structure 10 at one side in one side area 55A while ensuring passage through a traffic route 60 by retaining the ground 61 at the other side area 55B by supporting an earth retaining plate member 57 with an H-shaped steel 35, and a process of forming the invert structure 10 at the remaining side at the other side area 55B while ensuring the passage by restoring a traffic route 60' by retaining the ground created in the one side area 55A by replacing the earth retaining plate members 57 and supporting it with the H-shaped steel 35.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a construction method for an invert structure in a mountain tunnel. [Background technology]

[0002] A mountain tunnel is formed by excavating a free-standing, relatively stable foundation, such as bedrock. The excavated interior wall surface is covered with a primary lining and a secondary lining, typically made of concrete or mortar. Specifically, after excavating the tunnel using blasting or other methods, a protective layer is formed on the interior wall surface of the mountain tunnel, preferably by spraying mortar or concrete. Then, a known tunnel lining formwork is installed inside the protective layer formed by the primary lining, and a concrete lining of a predetermined thickness is formed as a secondary lining from the side walls to the arch-shaped upper portion of the tunnel. Furthermore, a bottom invert lining of a predetermined thickness is integrally formed in the transverse direction of the tunnel between the lower end supports of the pair of side walls of the previously formed lining extending from both side walls to the arch-shaped upper portion of the tunnel, thereby continuously covering the entire interior wall surface of the mountain tunnel with a secondary lining.

[0003] Furthermore, because mountain tunnels are formed by excavating relatively stable ground, some tunnels constructed more than several decades ago, for example, omit the invert lining and form a secondary lining only in the area from the tunnel's side wall to the upper arch-shaped part. For such mountain tunnels that omit the invert lining, it is being considered to form a new invert lining to prevent future effects such as swelling of the base of the tunnel.

[0004] Cast-in-place concrete has traditionally been used as a method for forming an invert lining at the bottom of a tunnel, connecting it to a lining that has been installed earlier from the side walls to the upper arch-shaped section of the tunnel (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 a predetermined curing period. Therefore, particularly when forming a new invert lining on the lining from the side walls to the upper arch-shaped section, which omits the invert lining, traffic inside the tunnel will be blocked for a long period of time, so it is desirable to complete the construction as quickly as possible.

[0005] For this reason, it has been considered to shorten the construction period 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). Also, when forming a new invert lining using precast concrete members (blocks) for an existing mountain tunnel that was built several decades ago, for example, it is desirable to be able to carry out construction work while ensuring passage on the passageway without completely blocking traffic through the tunnel, and therefore a technology has been developed that enables the construction of the invert lining of a mountain tunnel in each area on one side in the transverse direction of the tunnel (see, for example, Patent Document 4). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2020-159060 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-28898 [Patent Document 3] Japanese Patent Application Publication No. 2018-123528 [Patent Document 4] Japanese Patent Application Laid-Open No. 2000-145390 Summary of the Invention [Problem to be solved by the invention]

[0007] In the method of forming an invert in a mountain tunnel described in Patent Document 1, the access road and the ground below it in one side area are excavated to form an excavation trench while ensuring passage on the access road in the other side area in the transverse direction of the tunnel, and then multiple blocks that make up the invert are lined up at the bottom of the excavation trench that has been formed.The side of the ground below the access road in the other side area where passage is ensured is retained by the rising parts of the blocks that are placed adjacent to the other side area.However, the work of precisely lining up multiple blocks at the bottom of the excavation trench formed in one side area requires a lot of time and effort, and the side of the ground below the access road remains open and not retained until the blocks with rising parts are placed adjacent to the ground in the other side area where passage is ensured, making it difficult to maintain the access road and the ground below it in a stable state.

[0008] The present invention aims to provide a construction method for invert structures in mountain tunnels, which, when constructing invert structures using PCa concrete blocks that form the lining of the invert section in existing mountain tunnels, can be formed in one side area while maintaining the passageway and the ground below it in a stable state in the other side area with a simple configuration when constructing the invert structures using PCa concrete blocks in each side area in the transverse direction of the tunnel. [Means for solving the problem]

[0009] The present invention is a construction method for mountain tunnel invert structures, in which an invert structure using PCa concrete blocks is installed across the entire transverse area of ​​the invert section of a mountain tunnel to constitute an invert lining, and is constructed in two separate half-areas on either side of the center in the transverse direction, so that one side can be formed in each half-area while ensuring passage in the other half-area. In the center of the transverse direction of the tunnel in the invert section, a plurality of H-shaped steel beams are installed upright at a predetermined interval 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, and by supporting the retaining plate members on the flanges on one half-area of ​​the H-shaped steel beams or on the flanges on the other half-area, the other can be formed. The above-mentioned object has been achieved by providing a construction method for invert structures in mountain tunnels, which includes the steps of: forming one side of an invert structure in one of the side areas using PCa concrete blocks up to a portion that exceeds the flange portion of one of the side areas, while ensuring passage in the other side area by retaining the ground of the passage in that side area; and restoring the passage in that one side area by supporting an earth retaining plate member on the H-shaped steel and retaining the ground that has been created by backfilling the upper portion of the invert structure formed in one of the side areas, and while ensuring passage on the restored passage, forming the remaining invert structure in the other side area using PCa concrete blocks.

[0010] In the construction method of the invert structure in a mountain tunnel of the present invention, in the step of forming one side of the invert structure in one side region using PCa concrete blocks up to the part that exceeds the flange portion on one side region side, it is preferable that a sparser member be interposed between the inner surface of the flange portion on one side region side of the H-shaped steel, so that the retaining plate member is supported on the flange portion on one side region side while being biased toward the other side region side.

[0011] Furthermore, the construction method for invert structures in mountain tunnels of the present invention is preferably such that the invert structures formed in one side region and the other side region are each formed by arranging a plurality of PC 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 them and adjacent PC concrete blocks, and installing them in the invert section, and also by arranging them in a row in the axial direction of the tunnel, while maintaining gaps between them and adjacent PC concrete blocks, and then the block groups formed by installing them in the invert section are integrated via the hardened filling solidification material by filling the gaps between adjacent support bases and between adjacent PC concrete blocks with filling solidification material and allowing it to harden. [Effects of the Invention]

[0012] According to the construction method of the present invention for invert structures in mountain tunnels, when invert structures using PCa concrete blocks that form the lining of the invert section in an existing mountain tunnel are constructed in each side region in the transverse direction of the tunnel, the passageway and the ground below it in the other side region can be formed in one side region while maintaining the passageway and the ground below it in a stable state using a simple configuration. [Brief explanation of the drawings]

[0013] [Figure 1] 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. [Figure 2] This is a schematic top view of Figure 1 viewed from the AA 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. [Figure 3] 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. [Figure 4] 4(a) to 4(f) are schematic top views of the main part of part B in FIG. 3, illustrating a method for constructing an invert structure according to a preferred embodiment of the present invention. [Figure 5] 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. [Figure 6] 4 is a schematic cross-sectional view taken along CC in FIG. 3 before the filling solidification material is filled. FIG. [Figure 7] This is an oblique view of the PCa concrete blocks that make up the invert structure. [Figure 8] (a) is a top view of the PCa concrete blocks that make up the invert structure, (b) is a transverse side view of (a) seen from the right side, and (c) is an axial side view of (a) seen from the front side. [Figure 9] 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. [Figure 10] FIG. 10 is a perspective view illustrating a ground adjuster attached to the lower end of a height adjustment bolt. [Figure 11] 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. [Figure 12] 1 is a schematic cross-sectional view of a PCa concrete block taken along the portion where a filler injection hole is formed, illustrating the filler injection hole and the opening / closing valve. FIG. [Figure 13] This is a schematic top view of the invert structure explaining the injection status of the filling solidification material. [Figure 14] This is an explanatory diagram of the unevenness formed on the surface of the center side of the PCa concrete block. DETAILED DESCRIPTION OF THE INVENTION

[0014] A preferred embodiment of the present invention relates to a construction method for an invert structure in a mountain tunnel. When a new invert lining 32 is formed on the base 30a of an existing mountain tunnel 30 shown in Figure 1, the invert structures 10 that form the components of the invert lining 32 are formed on both the left and right sides of the transverse center line C of the tunnel, one on each side of the tunnel. The invert lining 32 is continuous with the lining 31 that has been previously formed to cover the inner wall surface of the tunnel, from the side wall portions 31a on both sides to the upper arch-shaped portion 31b.

[0015] In this embodiment, the mountain tunnel 30 is a tunnel that was constructed, for example, several decades ago, and the ground to be excavated was stable, so at the time of construction, the lining 31 covering the inner wall surface of the tunnel was formed only from the side wall portions 31a on both sides to the upper arch-shaped portion 31b.However, as time passed, concerns arose about the effects of swelling of the base portion 30a, etc., so a new invert lining 32 was formed using invert structures 10 on both the left and right sides, as shown in Figure 2.

[0016] 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, each step of forming the invert structure 10 is carried out in one side area while ensuring access to the passageway 60 in the other side area in the transverse direction of the tunnel. The construction method for the invert structure in a mountain tunnel of this embodiment allows the invert structure 10 to be efficiently formed in one side area while maintaining the passageway 60 in the other side area and the ground 61 below it in a stable state with a simple configuration when constructing the invert structure 10 in each side area in the transverse direction of the tunnel.

[0017] The construction method for the invert structure of this embodiment is a construction method for a mountain tunnel in which the invert structure 10 made of PCa concrete blocks 20, which is installed throughout the entire transverse area of ​​the invert section 33 of the mountain tunnel 30 to form the invert lining 32, is constructed in two separate areas on either side of the center in the transverse direction, so that one side can be formed in each side area while ensuring passage in the other side area (see Figure 3).In the center of the transverse direction of the tunnel in the invert section 33, a plurality of H-shaped steel beams 35 for supporting 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 Figs. 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 Fig. 3), and in one side region 55A, a step of forming the invert structure 10 on one side using PCa concrete blocks 20 up to a portion exceeding the flange portion 35a on the one side region 55A (see Figs. 4(a) and 4(b)); By supporting the retaining plate member 57 on the retaining plate member 35, the upper part of the invert structure 10 on one side formed in one side area 55A is backfilled to create 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 area 55A, and with passage on the restored passage 60' secured, the remaining invert structure 10 on the other side area 55B is formed using PCa concrete blocks 20 (see Figures 4(d) to (f)).

[0018] 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 exceeding 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 one side region 55A in a state where it is biased toward the other side region 55B (see Figures 4(a) and (b)).

[0019] In addition, in this embodiment, the invert section structures 10 formed in one side region 55A and the other side region 55B are preferably formed by arranging a plurality of PCa concrete blocks 20 in a row in the transverse direction of the tunnel and installing them in the invert section 33, with gaps 21a and 21b maintained between the blocks and the receiving base 31c at the lower end of the adjacent side wall lining body 31a and between the adjacent PCa concrete blocks 20, as shown in Figures 1 and 2, and also by arranging a plurality of PCa concrete blocks in a row in the axial direction of the tunnel and installing them in the invert section 33, with gaps 21b maintained between the blocks and the receiving base 31c and between the adjacent PCa concrete blocks 20, and by filling and hardening a filling solidification material 22 into the gaps 21a between the blocks and the receiving base 31c and the gaps 21b between the blocks and the adjacent PCa concrete blocks 20 (see Figure 11), and then integrating the blocks 20X, 10Y via the hardened filling solidification material 22.

[0020] That is, in this embodiment, as shown in Figures 5 and 6, the invert section structure 10 is provided in at least one side region of the invert section 33 of a mountain tunnel 30 in the tunnel transverse direction, and is a structure of the invert section 33 using PCa concrete blocks 20 that constitutes the invert section lining 32. As shown in Figures 7 and 8(a) to (c), the PCa concrete blocks 20 are each formed as a hexahedral block having a curved upper surface portion 20a and a lower surface portion 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 and 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, and are also arranged in series in the tunnel axial direction and installed in the invert section 33, with gaps 21b maintained between adjacent PCa concrete blocks. As shown in Figures 1, 2, and 11, the multiple PCa concrete blocks 20 arranged in a row and column are integrated together through filling solidification 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 lower surface that communicates with these gaps 21a and 21b, and forms at least a part of one side of the invert section covering body 32.

[0021] In this embodiment, the multiple PCa concrete blocks 20 are preferably formed to have similar hexahedral shapes with the same width x in the tunnel transverse direction, the same vertical width y in the tunnel axial direction, and the same height z (see FIGS. 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 (see FIGS. 2 and 5). The gaps 21a between adjacent PCa concrete blocks 20 in the transverse direction of the tunnel, filled with filling solidification material 22, and extending in the axial direction, and the gaps 21b 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 FIGS. 2 and 5). The gaps 21a between adjacent receiving sections 31c and the gaps 21b between adjacent PC concrete blocks, filled with filling solidification material 22, are preferably spaced apart by approximately 15 to 30 mm.

[0022] In this embodiment, the 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 the 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. The PCa concrete blocks 20 are also arranged in a row in the axial direction of the tunnel, with gaps 21b filled with the filling solidification material 22 between adjacent PC concrete blocks, and are installed in the invert section 33 in a row in both directions. As shown in FIGS. 7 and 8(a)-(c), the PCa concrete blocks 20 are formed as hexahedral blocks having curved upper and lower surfaces 20a, 20b that are curved along the cross-sectional shape of the invert section lining 32, and having 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.

[0023] Furthermore, bolt boxes 23 or female screw anchors 24 are embedded and fixed to the four sides of the hexahedral top surface of each PCa concrete block 20 to connect 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 screw anchors 24 open to the upper end of the axially opposing surface 20c or the transversely opposing surface 20d of the side surface. As shown in FIG. 7, the PCa concrete block 20 has three bolt insertion holes 25 that penetrate the hexahedral shape in the vertical direction, located at each corner of an isosceles triangle (see FIG. 8(a)). A female screw member 25a, into which a height adjustment bolt 26 is screwed, 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, since the large trumpet-shaped recess 25b and the small trumpet-shaped recess 25c have a trumpet shape that tapers in diameter 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.

[0024] As shown in Figure 8(a), the three bolt insertion screw holes 25 are formed on the upper surface 20a of the PCa concrete block 20, preferably arranged at each corner of an isosceles triangle (see dotted line) with the base positioned parallel to one axially opposing surface 20c and the apex positioned on the other axially opposing surface 20c.

[0025] Furthermore, as shown in FIGS. 11 and 12, some of these PCa concrete blocks 20, specifically PCa concrete blocks 20′ (see FIG. 5), have filler injection holes 27 that penetrate the hexahedron in the vertical direction. A female screw member 27a, to which the male screw portion of an on-off valve 28 is threaded, is fixed to the vertical middle of each filler injection hole 27. An upper horn-shaped recess 27b is formed, expanding in diameter upward from the portion where the female screw member 27a of each filler injection hole 27 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 screw member 27a is fixed, and opening onto the lower surface 20b of the PCa concrete block 20′. The male threads of an 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', so that the on-off valve 28 can be detachably attached to the PCa concrete block 20' while the handle 28a can be opened and closed by working on the upper surface 20a of the PCa concrete block 20'. Furthermore, the upper trumpet-shaped recess 27b and the lower trumpet-shaped recess 27c have a trumpet shape that tapers toward the upper and lower openings, so that box punching members attached to the box-shaped formwork for concrete pouring to form these trumpet-shaped recesses 27b, 27c can be smoothly removed after the concrete has hardened.

[0026] In this embodiment, the filler injection hole 27 that penetrates the hexahedral PCa concrete block 20' in the vertical direction can be preferably formed by being arranged in the central part of the upper surface 20a of the PCa concrete block 20' (see Figure 8(a)).

[0027] 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 of the hexahedron-shaped PCa concrete blocks 20 (20') to maintain a predetermined gap 21b between the opposing surfaces 20c, 20d (see Figs. 5, 6(b), and 6(c)). Preferably, a plurality of lifting jigs 29c are embedded and fixed in the hexahedron-shaped upper surface 20a to be used when lifting each PCa concrete block 20 (see Fig. 8(a)).

[0028] In this embodiment, the PCa concrete blocks 20 are formed by pouring concrete into a box-shaped formwork assembled in a factory to conform to the predetermined hexahedral shape, allowing it to harden, and then demolding after a predetermined curing period. The resulting blocks are then formed into a hexahedral shape with a curved upper surface 20a and lower surface 20b, preferably measuring approximately 1385-1435 mm in width x, approximately 730 mm in length y, and approximately 500 mm in height z, and weighing approximately 1300 kg. For example, by placing and supporting reinforcement bars inside the box-shaped formwork, the bolt boxes 23, female thread anchors 24, and box-punching members for the bolt insertion and threaded 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 a lifting machine or the like that can be used in the work yard 71 of one side area 55A without affecting the traffic of vehicles in the other side area 55B. For example, the weight of the PCa concrete blocks 20 can preferably be set to 1000 to 1500 kg.

[0029] In this embodiment, the multiple PCa concrete blocks 20 are formed to have similar hexahedral shapes, which allows for efficient production by limiting the type of box-shaped formwork used, and 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, making it easy to accurately install each PCa concrete block 20 in a predetermined position, for example, in a potato-like arrangement, and also reduces manufacturing costs.

[0030] In this embodiment, as described above, the invert structure 10 is constructed in each of the half regions 55A, 55B, with the regions on either side of the center in the transverse direction of the tunnel being treated as a pair of half regions (see FIGS. 1 and 2). As described above, in the center of the transverse direction of the tunnel in the invert section 33, a plurality of H-shaped steel beams 35 supporting retaining plate members 57 for preventing the other half region from being affected when constructing the invert structure 10 in each of the half regions 55A, 55B can be installed upright by driving them into the ground of the invert section 33 at predetermined intervals in the axial direction of the tunnel with the flange portions 35a aligned in the axial direction of the tunnel. For this reason, at the position where these H-shaped steels 35 are to be erected, notched recesses 20e with a rectangular cross section can be formed in the corners on both sides of the gap 21b between the pair of PCa concrete blocks (central blocks) 20B that are adjacent in the axial direction of the tunnel at the central side in the transverse direction of the tunnel at the end portions on the central side of the pair of PCa concrete blocks (central blocks) 20B (see FIG. 5). By using these notched recesses 20e in the corners on both sides, a flange arrangement recess 10a for arranging one flange of the H-shaped steel 35 can be formed in the part where the H-shaped steel 35 is to be erected, on the end face (central end face) 10B on the central side in the transverse direction of the tunnel of each invert structure 10.

[0031] That is, in the block groups 20X, 20Y (see Figure 1) consisting of a plurality of PCa concrete blocks 20 constituting the invert structure 10 of each side region 55A, 55B, the PCa concrete block 20 (central side block 20B) arranged in the portion where the H-shaped steel 35 is installed has a curved upper surface portion 20a and a lower surface portion 20b with 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 Figures 8(a) to (c)), and at the corner portion between any one of the axial opposing surfaces 20c and the transverse opposing surfaces 20d, as shown in Figure 5, a notched recess 20e having a rectangular cross-sectional shape is cut out so as to have a side portion with a width of at least half the width of the flange portion 35a of the H-shaped steel 35, and 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 side blocks 20B that are adjacent in the axial direction of the tunnel at the section where the H-shaped steel 35 is erected, these notched recesses 20e form flange arrangement recesses 10a that can avoid the flange portion of the H-shaped steel 35.

[0032] 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 the invert section 33 lined up vertically and horizontally. The plurality of PCa concrete blocks 20A, 20B, 20C used when constructing the invert structure 10 can be constructed by the following method of installing PCa blocks in the invert.

[0033] That is, in this embodiment, the multiple PCa concrete blocks 20A, 20B, 20C of each transverse block row 20D arranged in the transverse direction of the tunnel are installed in the invert section 33 by installing the receiving base side block 20A adjacent to the receiving base section 31c and temporarily fixing it using temporary fixing means 36, as shown in Figure 6, and then installing the intermediate block 20C and the central side block 20B adjacent to the temporarily fixed receiving base side block 20A.

[0034] Also, for example, the receiving base side block 20A is installed adjacent to the receiving base 31c and temporarily fixed using the temporary fixing means 36, and then the intermediate block 20C is installed adjacent to the temporarily fixed receiving base side block 20A, and at the adjacent location between the installed intermediate block 20C and the receiving base 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 then the height and position of each PCa concrete block 20A, 20C are adjusted and the bolt members are then fully tightened. Next, a central side block 20B is installed adjacent to the intermediate block 20C, and at the adjacent location between the installed central side block 20B and the intermediate block 20C, they are temporarily fixed with bolt members 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 side block 20B, the bolt members are finally tightened, thereby installing the multiple PCa concrete blocks 20A, 20B, 20C of each transverse block row 20D that are connected in the transverse direction of the tunnel in the invert section 33.

[0035] In this embodiment, the temporary fixing means 36 for temporarily fixing the pedestal-side block 20A adjacent to the pedestal 31c preferably comprises a cable 36b such as a wire or chain, 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 cable 36b such as a wire or chain 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.

[0036] 8(a) and 9, the height of each of the PCa concrete blocks 20A, 20B, and 20C can be adjusted using three height-adjusting bolts 26 threaded into the bolt insertion holes 25 formed in the three locations. 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-adjusting bolt 26 is attached to each of the bolt insertion holes 25 in a state in which its lower end 26a can protrude downward from the lower surface 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 a plurality of 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 undersides 20b that communicate with these gaps 21a, 21b with the filling solidification material 22 (see Figure 11), the PCa concrete blocks 20A, 20B, 20C are rotated from above to change the protruding lengths of the three height adjustment bolts 26 in each of the PCa concrete blocks 20A, 20B, 20C from the undersides 20b of the PCa concrete blocks 20A, 20B, 20C, thereby adjusting the height and inclination of each of the PCa concrete blocks 20A, 20B, 20C.

[0037] 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 bolt 26 is threadedly attached to the nut member 25a, allowing the lower end 26a of the height adjustment bolt 26 to protrude downward from the lower surface 20b of the PCa concrete block 20A, 20B, or 20C. A tiltable ground adjuster 26b can be attached to the lower end 26a of the height adjustment bolt 26. This allows the lower end 26a of the height adjustment bolt 26 to be stably grounded on, for example, the ground surface, which serves as the filling bottom surface 26c below the lower surface 20b. The grounding 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 so that it can be accommodated in the above-mentioned small trumpet-shaped recess 25c, which widens downward and is formed in the underside 20b of the PCa concrete blocks 20A, 20B, and 20C.

[0038] In this embodiment, the upper end 26d of the height adjustment bolt 26 is preferably formed to have a rectangular cross section, and by engaging an insert extension bar, for example, as a rotation jig, 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, 20C can be easily changed by working above the upper surface 20a of the PCa concrete block 20A, 20B, 20C. As described above, the bolt insertion hole 25 is formed with a large trumpet-shaped recess 25b that expands upward from the portion where the nut member 25a, which is a female thread member, is fixed and opens to the upper surface 20a of the PCa concrete block 20A, 20B, 20C. If the upper end 26d of the height-adjusting bolt 26, after being adjusted so that its lower end 26a contacts the filling bottom 26c, protrudes from or is close to the upper surface 20a of the PCa concrete block 20A, 20B, or 20C, preventing a sufficient covering thickness above the upper end 26d when the large trumpet-shaped recess 25b is filled with a finishing filler, the upper end 26d of the height-adjusting bolt 26 can be appropriately cut to the required length in the large trumpet-shaped recess 25b. This ensures a desired covering thickness of the finishing filler, such as mortar, filled in the bolt insertion hole 25, preventing corrosion of the height-adjusting bolt 26. The work of cutting the upper end 26d of the height-adjusting bolt 26 can be performed smoothly because sufficient working space is secured in the large trumpet-shaped recess 25b, which expands in diameter upward.

[0039] Furthermore, in this embodiment, in the invert section structure 10 using the above-mentioned PCa concrete blocks 20A, 20B, 20C, a PCa block connection structure 37 in the invert section structure described below can be adopted as the connection section structure for connecting and arranging multiple PCa concrete blocks 20A, 20B, 20C vertically and horizontally while maintaining gaps 21b of a predetermined spacing width between adjacent PCa concrete blocks 20A, 20B, 20C and installing them as a single unit in the invert section 33.

[0040] That is, 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 transverse opposing surfaces 20d of adjacent PCa concrete blocks 20A, 20B, 20C facing each other in the transverse direction of the tunnel, preferably arranged in at least three locations, and 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 adjacent to the transverse opposing surfaces 20d connects each pair of PCa concrete blocks 20A, 20B, 20C adjacent in the transverse direction of the tunnel while maintaining a gap 21b of a predetermined spacing width between the transverse opposing surfaces 20d. Between each pair of axially opposing surfaces 20c of adjacent PCa concrete blocks 20A, 20B, and 20C in the tunnel axial direction, axial spacer jigs 29b (see FIG. 8(c)) are fixed to one of the axially opposing surfaces 20c, preferably at at least three locations. The bolt boxes 23 are provided on the upper surfaces 20a of at least one of the PCa concrete blocks 20A, 20B, and 20C adjacent to the axially opposing surfaces 20c. The bolts (not shown) fasten the upper surfaces 20a of the PCa concrete blocks 20A, 20B, and 20C adjacent to the axially opposing surfaces 20c, thereby connecting the adjacent pairs of PCa concrete blocks 20A, 20B, and 20C in the tunnel axial direction while 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 the axially opposing surfaces 20c at the positions where the bolt boxes 23 are provided.

[0041] 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 either 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 screwed into female threaded inserts embedded in either one of the opposing surfaces 10c, 10d, so that the protruding length can be adjusted.

[0042] The transverse spacer jigs 29a and the axial spacer jigs 29b, which are preferably arranged at at least three locations and fixed to either one of the transverse opposing surfaces 20d or the axial opposing surface 20c, are preferably fixed to at least two locations in the region below the center of gravity of the PCa concrete blocks 20A, 20B, and 20C. This makes it possible to stably and accurately form the gaps 21a and 21b of the predetermined intervals in the region below the center of gravity, where it is difficult to confirm that the gaps 21a and 21b have been formed accurately, without using any special equipment when installing the PCa concrete blocks 20A, 20B, and 20C.

[0043] 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 lateral 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 boxes 23 arranged on the upper surface 20a adjacent to the axial opposing surface 20c or lateral opposing surface 20d of one of the PCa concrete blocks 20A, 20B, 20C, and the female thread anchors 24 embedded in the axial opposing surface 20c or lateral 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 upper 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 upper surface 20a adjacent to the axially opposing surface 20c or the transversely opposing surface 20d of the other PCa concrete block 20A, 20B, 20C.

[0044] In this embodiment, the multiple PCa concrete blocks 20A, 20B, and 20C arranged in a row and column are integrated via the filling solidification material 22 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 communicating with these gaps, as shown in Fig. 11, to form at least a portion of the invert section lining 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 communicating with these gaps 21a and 21b by the following construction method.

[0045] That is, in this embodiment, in order to fill the filling solidification material 22 into the gaps 21a between adjacent receiving portions 31c of 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 lower surface portion that communicates with these gaps 21a, 21b, the opening portions of the gaps 21a, 21b that open in the upper surface portion 20a, gable side end surface portion 10A (see Figures 5 and 11) and center side end surface portion 10B (see Figures 5 and 11) of multiple PCa concrete blocks 20A, 20B, 20C arranged in a row vertically and horizontally are closed. 11 to 13, the filling solidification 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 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 pedestal-side blocks 20A arranged in the axial direction of the tunnel. Preferably, as shown in FIG. 13, the filling solidification material 22 is injected first through the center-side filler injection holes 27d, then switched to the pedestal-side filler injection holes 27e, and further injected into the gaps 21a. Finally, the filling solidification material 22 is completed upon confirmation that the filling solidification material 22 has flowed out of the opening of the gap 21a between the pedestal 31c and the upper surface 20a of the pedestal-side block 20A. 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 receiving base side block 20A, and to finish filling the filling solidification material 22 by confirming that the filling solidification material 22 flows out from the opening of the gap 21a between the receiving base 31c held on the upper surface 20a of the receiving base side block 20A.

[0046] 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 formed existing invert structure 40 (see FIGS. 5 and 13). With the openings of the gaps 21d between the upper surfaces 20a and the central end surfaces 10B of the multiple PCa concrete blocks 20A, 20B, and 20C arranged in a row and column and the existing invert structure 40 blocked, the filling solidification material 22 is injected 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 FIG. 13. At the same time, the filling solidification material 22 is injected by switching from the filler injection hole 27e located on the base side of the existing invert structure 50 side to the filler injection hole 27e located on the base side of the existing invert structure 50 side. It is also possible to switch from the filler injection hole 27d of the central side block 20B on the existing invert section structure 50 side to the filler injection hole 27d of the central side 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 receiving base side block 20A on the existing invert section structure 50 side to the filler injection hole 27e of the receiving base side block 20A on the gable side and inject the filling solidification material 22.

[0047] Furthermore, in this embodiment, the strip-shaped formwork 41a is attached by overlapping and fixing to the upper surface 20a of the PCa concrete blocks 20A, 20B, and 20C, preferably arranged vertically and horizontally, so as to cover the openings of the gaps 21b in the upper surface 20a, thereby blocking the openings of the upper surface 20a (see FIG. 11). The strip-shaped formwork is also attached by overlapping and fixing to the end surface 10A, preferably so as to cover the openings of the gaps 21a, 21b, and 21c, at the end surface 10A, thereby blocking the openings of the end surface 10A (not shown). The strip-shaped formwork 41b is also attached by overlapping and fixing to the end surface 10B, preferably so as to cover the openings of the gaps 21b, 21c, and 21d, at the center surface 10B, thereby blocking the openings of the center surface 10B (see FIG. 11).

[0048] Furthermore, it is preferable that these strip-shaped formworks be formed using transparent plate-shaped members, which makes it possible to visually observe the filling status of the filling solidification material 22 into each of the gaps 21a, 21b, 21c, and 21d through these transparent strip-shaped formworks.

[0049] Furthermore, it is preferable to attach air-bleeding hoses 42 (see FIG. 11) extending from appropriate positions to the band-shaped formwork 41a attached so as to cover the openings of the gaps 21a, 21b, 21d in the upper surfaces 20a of the multiple PCa concrete blocks 20A, 20B, 20C arranged vertically and horizontally. This makes it possible to effectively bleed air from the gaps 21a, 21b, 21d via the air-bleeding hoses 42 when filling with the filling solidification material 22, and it is also possible to confirm that the filling solidification material 22 has been filled by the flow of the filling solidification material 22 from the air-bleeding hoses 42.

[0050] In this embodiment, in order to fill the gaps 21a between the adjacent receiving base portions 31c of the plurality of PCa concrete blocks 20A, 20B, 20C arranged in a row vertically and horizontally, the gaps 21b between the adjacent PCa concrete blocks 20A, 20B, 20C, and the gaps 21c below the hexahedral lower surface portions that communicate with these gaps 21a and 21b, as described above, the upper surface portions 20a of the plurality of PCa concrete blocks 20A, 20B, 20C arranged in a row vertically and horizontally, With the openings of gaps 21a, 21b, and 21c at end face 10A and center face 10B closed, filler solidification material 22 is sequentially injected through center-side filler injection hole 27d, which is provided vertically through one or more of the center-side blocks 20B connected together in the axial direction of the tunnel, and through pedestal-side filler injection hole 27e, which is provided vertically through 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 hole 27d and pedestal-side filler injection hole 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 filling process with the filling solidification material 22, the filling solidification material 22 can be filled 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 and 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 released from the gap 21a between the receiving portion 31c held on the upper surface 20a of the receiving portion side block 20A, making it possible to effectively prevent air from accumulating in the filled filling solidification material 22.

[0051] In addition, in this embodiment, the multiple PCa concrete blocks 20A, 20B, 20C arranged in a row and column are preferably arranged adjacent to each other in the axial direction of the tunnel of the 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, 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 filler injection hole 27d on the central side located on the existing invert structure 40 side to the opening / closing valve 28 of the filler injection hole 27d on the central side located on the gable side, and 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 side block 20B on the existing invert section structure 50 side to the filler injection hole 27d of the central side block 20B on the gable side to inject the filling solidification material 22 partway, and then switch again from the filler injection hole 27e of the receiving base side block 20A on the existing invert section structure 50 side to the filler injection hole 27e of the receiving base side block 20A on the gable side to inject the filling solidification material 22.

[0052] As described above, in each of the central filler injection holes 27d and the base-side filler injection holes 27e, the on-off valves 28 can be attached by threading the male threads 28b into the female thread members 27a fixed to the middle of the central filler injection holes 27d or the base-side filler injection holes 27e in the penetration direction, so that they protrude upward from the top surfaces of the multiple PCa concrete blocks 20A, 20B arranged vertically and horizontally. This makes it easy to detachably connect injection hoses by working on the top surfaces 20a of the PCa concrete blocks 20A, 20B, 20C.

[0053] Furthermore, the construction method for invert structures in mountain tunnels in this embodiment makes it possible, when constructing the above-mentioned invert lining body 10 in each of the transverse side regions 55A and 55B of the tunnel, to carry out each process of forming the invert structure 10 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).

[0054] That is, in this embodiment, as described above, in the center of the tunnel in the transverse direction in 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 preferably involves interposing 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 supporting the retaining plate member 57 on the flange portion 35a on one side region 55A while shifting it toward the other side region 55B. This retains the ground 61 of the passageway 60 in the other side region 55B, thereby securing passage in the other side region 55B (see Figure 3), and in one side region 55A, the invert structure 10 on one side is supported to a portion exceeding the flange portion 35a on one side region 55A. The method 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 a retaining plate member 57 on the flange portion 35a on one side region 55A of the H-shaped steel 35, for example, to backfill the upper portion of the inverted structure 10 on one side of the one-side region 55A and create ground 61' (see Figures 4(d) and (e)) by retaining the ground, 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 (see Figures 4(d) to (f)).

[0055] In this embodiment, in the process of forming one side of the invert section structure 10 on one side of the side of the half region 55A, first, the ground 61 below the passage 60 in the other side region 55B is retained, and the passage 60 and the ground 61 below it on one side of the half region 55A are excavated down to the base portion 30a of the mountain tunnel 30. Here, as shown in Figure 4(a), the ground 61 below the passage 60 in the other side area 55B is provided with 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, and both ends of the known earth retaining plate member 57 are attached to the inner surface of the flange portion 35a on one side area 55A of the H-shaped steel beam 35 with a spacer member 56 interposed between the inner surface and the plate member 57. This allows the earth retaining plate member 57 to be attached in a biased position to the other side area 55B, and the flange portion 35a on one side area 55A supports the earth pressure from the other side area 55B, thereby enabling earth retaining in a simple and stable manner.

[0056] 4(a), the invert structure 10 on one side region 55A side can be formed in a state in which the flange portion 35a of the H-shaped steel 35 on one side region 55A side is disposed in the flange disposing recess 10a defined by the notched recess 20e of a pair of PCa concrete blocks (center-side blocks) 20B adjacent in the axial direction of the tunnel, which are formed at the center of the tunnel transverse direction of the invert structure 10 on the side of one side region 55A. This also makes it possible to form the invert structure 10 on one side region 55A side in a state in which the end face of the central-side block 20B, excluding the notched recess 20e, protrudes beyond the flange portion 35a on the one side region 55A side, while ensuring passage through the passageway 60 in the other side region 55B (see FIG. 3).

[0057] In this way, since the invert section structure 10 in one side region 55A is formed to extend beyond the flange portion 35a on one side region 55A side of the H-shaped steel 35, in the process of forming the invert section structure 10 on the other side region 55B side described later, it becomes possible to easily fill and harden the filling solidification material 22 in the gap portion 51 (see Figures 1 and 2) between the one side block group 20X and the other side block group 20Y.

[0058] 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 earth 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 upper surface of the formed invert structure 10 (see dotted portion). Thereafter, as shown in Fig. 4(d), the earth 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, and the removed earth retaining plate member 57 is replaced so that both ends of the earth retaining plate member 57 abut 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 earth retaining plate member 57 is reattached in a state where it is biased toward the one side region 55A. In addition, the resulting gap between the retaining plate member 57 and the ground 61 below the passage 60 in the other side area 55A is backfilled, and the retaining plate member 57 is engaged with the inner surface of the flange portion 35a on one side area 55A of the H-shaped steel 35.

[0059] 4(e), in one side region 55A, the upper portion of the formed invert structure 10 is backfilled up to the height of the passage 60 in the other side region 55B to create a ground 61' for paving, and the upper surface of the created ground 61' is paved to restore the passage 60' in one side region 55A. After the passage 60' has been restored in one side region 55A, with passage on the restored passage 60' secured, in the other side region 55B, the passage 60 and the ground 61 below it are excavated down to the base 30a of the mountain tunnel 30, with the other side region 55B serving as the new side region where the invert structure 10 is to be formed, in the same manner as described above. Furthermore, 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 via a sparser member 56, the earth pressure from one side region 55A can be supported by the retaining plate member 57, and while retaining the earth in a simple and stable state, it becomes possible to form an invert section structure 10 in the other side region 55B as well.

[0060] 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, so that the upper portion of the invert structure 10 formed in one half region 55A is backfilled to form a ground 61', thereby restoring the access path 60' in that one half region 55A, and then the remaining invert structure 10 is formed in the other half region 55B with passage through the restored access path 60' ensured.

[0061] In addition, in the process of forming the remaining one-side invert structure 10 in the other one-side region 55B, as described below, the gap portion 51 between the one-side block group 20X formed in one one-side region 55A and the other-side block group 20Y formed in the other one-side region 55B can also be filled and solidified with the filling solidification material 22.

[0062] 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 formed invert structure 10 in the other side region 55B is moved to the passage 61 in the one side region 55A. ’ By filling in the ground up to the height position, the ground for paving can be reconstructed, and by paving the top surface of the constructed ground, a path (not shown) can be restored in the other side area 55B as well.

[0063] In this embodiment, the invert section structures 10 formed in one side region 55A and the other side region 55B are configured to form an invert section structure 50 across the entire transverse area, which together constitutes the invert section covering body 32, as shown in Figures 1 and 2.

[0064] That is, the invert section structure 50 covering the entire transverse area is a structure using PCa concrete blocks 20A, 20B, 20C that are provided throughout the entire transverse area of ​​the tunnel in the invert section 33 of the mountain tunnel and constitute the invert section lining body 32, and each of the PCa concrete blocks 20A, 20B, 20C is formed as a hexahedral block having curved upper surface portion 20a and lower surface portion 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 support bases 31c at the lower ends of adjacent side wall linings 31a and between adjacent PCa concrete blocks. Also, adjacent PCa concrete blocks 20A, 20B, and 20C are arranged in series in the axial direction of the tunnel and installed in the invert section 33, with gaps 21b maintained between them. This forms a one-side block group 20X and an other-side block group 20Y. Furthermore, a gap 51 is maintained between the one-side block group 20X and the other-side block group 20Y in the central portion of the tunnel's transverse direction. The multiple PCa concrete blocks 20A, 20B, and 20C arranged vertically and horizontally in the one side block group 20X and the other side block group 20Y are integrated together via the filling solidification material 22 that has been filled and hardened in the gaps 21a between each adjacent receiving portion 31c, the gaps 21b between adjacent PCa concrete blocks 20A, 20B, and 20C, the gap portion 51 between the one side block group 20X and the other side block group 20Y, and the gap 21c below the hexahedral lower surface portion that communicates with these gaps 21a, 21b and the gap portion 51, to form the invert portion covering body 32.

[0065] 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, 20C preferably have a spacing width of 15 to 30 mm, and the spacing 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.

[0066] 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 gaps 21b extending axially between adjacent PCa concrete blocks in the transverse direction of the tunnel and filled with filling solidification material 22, and gaps extending transversely between adjacent PCa concrete blocks in the axial direction of the tunnel, both preferably arranged linearly and continuously.

[0067] 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 provided with irregularities 52 to improve adhesion with the filling solidification material 22, as shown in Figure 14, for example.

[0068] The unevenness 52 for improving adhesion with the filling solidification material 22 can also be formed on the lateral opposing surfaces 20d of each PCa concrete block 20, across the maintained gaps 21a, 21b, of the PCa concrete blocks 20 that are arranged in series in the transverse direction of 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 between adjacent PCa concrete blocks 20. The unevenness 52 for improving adhesion with the filling solidification material 22 can also be formed on the axial opposing surfaces 20c of each PCa concrete block 20, across the maintained gaps 21b, of the PCa concrete blocks 20 that are arranged in series in the axial direction of the tunnel and installed in the invert section 33, preferably with gaps 21b maintained between the PCa concrete blocks 20.

[0069] In this embodiment, the PCa concrete block (center-side block) 20B located most centrally of the one-side block group 20X and the PCa concrete block (center-side block) 20B located most centrally of the other-side block group 20Y are preferably connected via long bolt members (not shown). This ensures installation accuracy of the one-side block group 20X and the other-side block group 20Y, and also ensures shear strength of the portion between these block groups 20X and 20Y.

[0070] In this embodiment, the invert structure 50 for the entire area in the transverse direction of the tunnel is formed as follows. That is, in the invert structure 50 for the entire area in the transverse direction 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 of the lower end of the adjacent side wall lining body 31a and between the adjacent PCa concrete blocks 20A, 20B, 20C, and are installed in the invert section 33. The PCa concrete blocks 20A, 20B, 20C are also arranged in a row with gaps 21b maintained between them, and are then installed in the invert section 33 to form a block group 20X on one side. The PCa concrete blocks 20A, 20B, 20C are arranged in a row with gaps 21b maintained between them, and the gaps 21a between the adjacent receiving base sections 31c of the PCa concrete blocks 20A, 20B, 20C of the block group 20X on one side are arranged in a row vertically and horizontally, and the gaps 21b between the adjacent PCa concrete blocks 20A, 20B, 20C, and the gaps 21a between the adjacent PCa concrete blocks 20A, 20B, 20C, and the gaps 21b ... a step of filling and hardening a filling solidification material 22 into gaps 21c below the lower surface of the hexahedron-shaped block 31a and communicating with the blocks 31a, 31b, and a step of arranging a plurality of PCa concrete blocks 20A, 20B, 20C in the other side region 55B in the transverse direction of the tunnel in a state where gaps 21a, 21b are maintained between the receiving base 31c at the lower end of the adjacent side wall lining body 31a and between the adjacent PCa concrete blocks 20A, 20B, 20C and the invert portion 33; and a step of forming the other-side block group 20Y by arranging the PCa concrete blocks 20A, 20B, 20C in a row and installing them in the invert section 33 while maintaining gaps 21b between the adjacent PCa concrete blocks 20A, 20B, 20C in the axial direction of the tunnel, and by maintaining gaps 21a between the adjacent receiving base sections 31c of the plurality of PCa concrete blocks 20A, 20B, 20C of the other-side block group 20Y that are arranged in a row and horizontally.In addition to the gap 21b between the block group 20C and the gap 21c below the bottom surface of the hexahedron that communicates with these, the process also includes filling and hardening the filling solidification material 22 into the gap 51 between the block group 20X on one side and the block group 20Y on the other side, thereby making it possible to easily form the invert structure 50 that is provided across the entire transverse direction of the tunnel and that constitutes the invert lining body 32.

[0071] Furthermore, according to the construction method of the present invention for invert structures in mountain tunnels having the above-mentioned configuration, when constructing the invert structures 10 that make up the invert lining 32 in each of the side regions 55A, 55B in the transverse direction of the tunnel in an existing mountain tunnel 30, it becomes possible to form the passage 60 in the other side region 55B and the ground 61 below it in one side region 55A while maintaining it in a stable state with a simple configuration.

[0072] The present invention is not limited to the above-described embodiment and can be modified in various ways. For example, the invert section structure of the present invention is not limited to construction work for adding a lining to an invert section in a mountain tunnel in which the lining covering the tunnel inner wall surface is formed only in the region from both side walls to the upper arch-shaped portion, and is not formed in the invert section, but can also be used in construction work for repairing an invert section lining already installed in a mountain tunnel and reinstalling a new invert section lining.

[0073] Furthermore, 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 that has been 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 on one side area of ​​the H-shaped steel, the retaining plate member can be supported by the H-shaped steel, and the ground that has been created by backfilling in one side area can be retained.

[0074] Furthermore, in the process of forming one side of the invert structure using PCa concrete blocks up to the portion beyond the flange on one side of the invert structure, the H-beam can be supported by the earth retaining plate, for example, by engaging both ends of the earth retaining plate with the surface of the flange on the other side of the H-beam. The PCa concrete blocks are not limited to those in the above embodiment, and various shapes and weights can be used. [Explanation of symbols]

[0075] 10 Inverter structure 10a Flange placement recess 10A End face on the side 10B Center side end section 20,20' PCa concrete block 20a Top part 20b Bottom part 20c Axial opposing surface 20d Transverse opposing surface 20e Notched recess 20f, 20g Axial connection part 20A Receiving block 20B Central side block 20C Middle block 20D Transverse Block Row 20E Exterior PCa concrete block 20F Inner PCa concrete block 20X One-Sided Block Group 20Y Other side block group 21a Gap between the base and the 21b Gap between adjacent PCa concrete blocks 21c Lower gap of the underside 21d Gap between the existing invert structure 22 Filling and solidification material 23 Bolt Box 24 Female thread anchor 25 Bolt insertion screw hole 25a Female screw member (nut member) 25b Large trumpet-shaped recess 25c Small trumpet-shaped recess 26 Height adjustment bolt 26a Lower end 26b Grounding adjuster 26c Filled bottom part 26d Upper end 27 Filler injection hole 27a Female thread member 27b Upper trumpet-shaped recess 27c Lower trumpet-shaped recess 27d Filler injection hole on the center side 27e Filler injection hole on the base side 28 Opening and closing valve 28a Handle 29a Transverse spacer jig 29b Axial spacer jig 29c Hanging jig 30 Mountain Tunnel 30a Bottom panel part 31 Lining body 31a Side wall (side wall lining) 31b Arch-shaped part 31c pedestal part 32 Invert lining 33 Inverter 35 H type steel 35a flange 36 Temporary fixing means 36a Hole in Anchor 36b striae 36c Telescopic adjustment means 37 PCa block connection structure 40 Existing invert structure 41a Upper surface band plate formwork 41b Gable band plate formwork 41c Central side band plate formwork 42 Air bleed hose 50 Invert structure throughout the entire tunnel crossing 51 Interval between one side block group and the other side block group 55A One side area 55B Other half area 56 Spasar member 57 Earth retaining plate member 60,60' Passageway 61,61' Ground below the road b Gap below the bottom surface

Claims

1. 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.

2. 2. A method for constructing an invert structure in a mountain tunnel as described in claim 1, wherein in the process of forming one side of the invert structure using PCa concrete blocks up to the part that exceeds the flange portion on one side of the region, a sparser member is interposed between the inner surface of the flange portion on one side of the H-shaped steel, and the retaining plate member is supported on the flange portion on one side of the region while being biased toward the other side of the region.

3. 3. The method for constructing an invert section structure in a mountain tunnel according to claim 1 or 2, wherein the invert section 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 by installing the blocks in a row in the axial direction of the tunnel, while maintaining gaps between them and adjacent PCa concrete blocks. The block groups formed by this method 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.

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