JP7769658B2 - Invert structure construction method - Google Patents

Description

The present invention relates to a construction method for invert structures, and in particular to a construction method for invert structures using PCa concrete blocks that are installed in the inverts of mountain tunnels to form invert linings.

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 excavating the tunnel using blasting or other methods, 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 arched upper 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 the side walls of the tunnel to the arched upper section, thereby continuously covering the entire interior wall of the mountain tunnel with a secondary lining.

Mountain tunnels are also 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 secondary lining in the area from the tunnel's side walls to the upper arch-shaped section. 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 this reason, consideration is being given to shortening the construction period by forming the invert section lining using precast concrete members manufactured in advance in a factory or the like (see, for example, Patent Documents 2 and 3).

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

However, with conventional construction methods for invert sections in mountain tunnels using precast concrete members, these concrete members are pre-formed in factories or other facilities to a length that spans the entire transverse width of the invert section, or to a length that divides the invert section into two or three sections in the transverse direction. This results in large weight and shapes, and requires a great deal of effort to assemble formwork in factories and accurately form joints, etc. Furthermore, transporting and assembling the members at the construction site requires a great deal of labor, and in particular, in the case of multi-lane road tunnels, for example, when construction work is to be carried out for each lane while maintaining traffic in the other lane, the use of bulky concrete members makes the work particularly difficult.

The present invention aims to provide a construction method for an invert structure that can be easily formed without much labor by using precast concrete blocks (PCa concrete blocks) of appropriate weight and size that can be easily manufactured in factories, etc., and can be installed more quickly as a component of the invert lining that extends from the side wall of the tunnel to the lining of the upper arch-shaped section.

The present invention is a construction method for an invert section structure using multiple PCa concrete blocks that are installed in at least one side region of the invert section of a mountain tunnel in the transverse direction of the tunnel and form an invert section lining. The PCa concrete blocks are formed as hexahedral blocks with curved upper and lower surfaces so as to have a curved shape that follows the cross-sectional shape of the invert section lining. The multiple PCa concrete blocks include a base section side block that is arranged adjacent to the base section at the lower end of the side wall section lining, a central section side block that is arranged on the central side of the invert section in the transverse direction, and and one or more intermediate blocks arranged between the adjacent PCa concrete blocks, and the plurality of PCa concrete blocks are arranged in series in the transverse direction of the tunnel with a gap maintained between adjacent receiving base portions and between adjacent PCa concrete blocks, and are also arranged in series in the axial direction of the tunnel with a gap maintained between adjacent PCa concrete blocks, and are installed in the invert section lined up lengthwise and widthwise, and the plurality of PCa concrete blocks arranged in series lengthwise and widthwise are arranged in a manner that maintains a gap between adjacent receiving base portions and between adjacent PCa concrete blocks. The gaps between the adjacent base portions of the PCa concrete blocks arranged in a row and column, the gaps between the adjacent base portions of the PCa concrete blocks arranged in a row and column, and the gaps below the bottom surface of the hexahedron that are connected to these gaps are filled with a filling solidification material and hardened, thereby forming at least a part of the invert portion covering body in an integrated state via the hardened filling solidification material. In the process of filling the gaps between the adjacent base portions of the PCa concrete blocks arranged in a row and column, the gaps between the adjacent PCa concrete blocks, and the gaps below the bottom surface of the hexahedron that are connected to these gaps, the filling solidification material is The above objectives have been achieved by providing a construction method for invert structures in mountain tunnels in which, with the openings of the gaps at the central end faces blocked, filling and solidifying material is sequentially injected through central filling material injection holes that extend vertically through one or more of the central blocks connected in the axial direction of the tunnel. The injection of filling and solidifying material begins from the central filling material injection hole, and the filling of the filling and solidifying material is completed when it is confirmed that the filling and solidifying material has flowed out of the openings of the gaps between the adjacent base blocks held on the upper surfaces of the base blocks.

The construction method for the invert structure of the present invention involves blocking the openings of the gaps on the top surfaces, gable end surfaces, and center end surfaces of the multiple PCa concrete blocks arranged in a row vertically and horizontally, and sequentially injecting the filling material through center-side filler injection holes that extend vertically through one or more of the multiple center-side blocks arranged in a row in the axial direction of the tunnel, and through base-side filler injection holes that extend vertically through one or more of the multiple base-side blocks arranged in a row in the axial direction of the tunnel. It is preferable to start injecting the filling material through the center-side filler injection hole, switch to the base-side filler injection hole to inject more filling material, and then finish injecting the filling material by confirming that the filling material has flowed out of the opening in the gap between the adjacent base blocks held on the top surfaces of the base-side blocks.

Furthermore, the construction method for the invert structure of the present invention preferably involves: a plurality of PCa concrete blocks arranged in a row and column are adjacent to each other in the axial direction of the tunnel of the previously formed existing invert structure; and, with the openings of the gaps between the existing invert structure and the PCa concrete blocks, which open at the top surfaces and central end surfaces of the plurality of PCa concrete blocks arranged in a row and column, being blocked, filling and solidifying material is injected by switching from the filling material injection hole on the existing invert structure side to the filling material injection hole on the gable side.

Furthermore, the construction method for the invert structure of the present invention preferably involves attaching an upper surface band plate-shaped formwork to the upper surface of a plurality of PCa concrete blocks arranged in a row vertically and horizontally, overlapping and fixing the formwork so as to cover the opening of the gap in the upper surface, thereby blocking the opening of the upper surface; attaching an end surface band plate-shaped formwork to the gable end surface, overlapping and fixing the formwork to the gable end surface, thereby blocking the opening of the gap in the gable end surface; and attaching a central side band plate-shaped formwork to the central end surface, overlapping and fixing the formwork to the central end surface, thereby blocking the opening of the gap in the central end surface.

Furthermore, in the construction method for an invert structure of the present invention, the upper surface band plate-shaped formwork, the gable portion band plate-shaped formwork, and the central side band plate-shaped formwork are preferably formed using transparent plate-shaped members, and the filling status of the filling solidification material into the gaps can be visually confirmed through these transparent band plate-shaped formworks.

Furthermore, in the construction method for the invert structure of the present invention, the upper surface band plate formwork is attached so as to cover the opening of the gap on the upper surface of the multiple PCa concrete blocks arranged vertically and horizontally, and an air vent hose extending from an appropriate position and communicating with the gap is attached. This makes it possible to vent air from the gap when filling the filling solidification material via the air vent hose, and it is also preferable that the filling of the filling solidification material can be confirmed by the flow of the filling solidification material from the air vent hose.

The invert structure construction method of the present invention uses precast concrete blocks (PCa concrete blocks) of appropriate weight and size that can be easily manufactured in factories, etc., allowing the invert structure to be easily formed without much effort and installed more quickly as a component of the invert lining, which extends from the tunnel side wall to the lining of the upper arch-shaped section.

This is a schematic cross-sectional view illustrating a mountain tunnel in which an invert section lining is formed using a construction method for an invert section structure 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 invert section lining formed by the invert section structure spanning the entire transverse direction of the tunnel, including the one side block group and the other side block group. This is a schematic top view of an invert section structure provided in one side region of the tunnel in the transverse direction in the invert section, using a construction method for an invert section structure according to a preferred embodiment of the present invention. FIG. 4 is a schematic cross-sectional view taken along the line BB in FIG. 3. 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. 10A is a perspective view illustrating a grounding adjuster attached to the lower end of a height adjusting bolt, and FIG. 10B is a schematic cross-sectional view illustrating another preferred form of a small trumpet-shaped recess. (a) is a conceptual diagram illustrating the situation in which PCa concrete blocks are connected and arranged in a state that aligns with the tunnel line curved in the horizontal direction, and (b) is a conceptual diagram illustrating the situation in which PCa concrete blocks are connected and arranged in a state that aligns with the tunnel line curved in the vertical direction. 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 taken along a portion where a filler injection hole is formed, illustrating the filler injection hole and the opening/closing valve. FIG. This is a schematic top view of the invert structure explaining the injection status of the filling solidification material. This is an explanatory diagram of an upper surface band plate-shaped formwork that closes gaps on the upper surface of a PCa concrete block. An explanatory diagram of a gable band plate-shaped formwork that closes the gap at the gable end surface. 10 is an explanatory diagram of the unevenness formed on the surface of the central portion of a PCa concrete block 20B. FIG.

The invert structure 10 formed by the invert structure construction method according to a preferred embodiment of the present invention is constructed on each side of the tunnel's transverse centerline C, as shown in Figures 2 and 3, and integrated with the lining 31 previously formed to cover the inner wall surface of the mountain tunnel 30, covering the area from both side wall portions 31a to the upper arch-shaped portion 31b, to form a structure that becomes a component of the invert lining 32 when a new invert lining 32 is formed on the invert portion 33 of the base portion 30a of the mountain tunnel 30.

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 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 necessary to block traffic through the tunnel, so it is desirable to complete the construction work in as short a time as possible. The construction method for the invert structure 10 of this embodiment uses multiple precast concrete blocks (PCa concrete blocks) of an appropriate weight and size that are easy to handle and are manufactured in advance at a factory, etc., and allows for the smooth injection of filler solidification material 22 into the gaps 21a, 21b, 21c between these precast concrete blocks. This allows for easy construction one side at a time without requiring much effort, and enables the invert lining 32, which is continuous with the lining 31 extending from the tunnel's side wall 31a to the upper arch-shaped portion 31b, to be installed in a shorter time.

The invert structure construction method of this embodiment, as shown in Figures 1 to 4, is a construction method for a structure using multiple PCa concrete blocks 20 that are provided in at least one transverse side region of the invert section 33 of a mountain tunnel 30 and that constitute the invert section lining 32. As shown in Figures 5 and 6(a) to 6(c), the PCa concrete blocks 20 are each formed as hexahedral blocks with curved upper and lower surfaces 20a and 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 include a base side block 20A arranged adjacent to the base 31c at the lower end of the side wall lining 31a, a central side block 20B arranged on the transverse center side of the invert section 33, and one or more intermediate blocks 20C arranged between them.

In other words, according to the construction method of the invert section structure of this embodiment, in the process of filling 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 portions that communicate with these gaps 21a, 21b, the opening portions of the gaps 21a, 21b that open on the upper surface portions 20a, gable end surface portions 10A (see Figures 3 and 12), and center end surface portions 10B (see Figures 3 and 12) of multiple PCa concrete blocks 20A, 20B, 20C arranged in a row vertically and horizontally are closed. Thereafter, as shown in Figures 10 to 12, the filling solidification material 22 is sequentially injected through the central filling material injection holes 27d that are provided vertically through one or more of the central blocks 20B that are connected in the axial direction of the tunnel. Injection of the filling solidification material 22 begins from the central filling material injection hole 27d, and is completed when it is confirmed that the filling solidification material 22 has flowed out from the opening of the gap 21a between the central filling material injection hole 27d and the receiving base 31c held by the upper surface 20a of the receiving base block 20A.

In addition, in this embodiment, with the opening portions of the gaps 21a, 21b opening in the upper surface portions 20a (see Figures 3 and 12) and central end surface portions 10B (see Figures 3 and 12) of multiple PCa concrete blocks 20A, 20B, 20C preferably arranged in a row vertically and horizontally blocked, filling solidification material is sequentially injected from the center-side filler injection holes 27d provided in one or more of the multiple center-side blocks 20B arranged in the axial direction of the tunnel, which penetrate in the vertical direction, and from the base-side filler injection holes 27e provided in one or more of the multiple base-side blocks 20A arranged in the axial direction of the tunnel, which penetrate in the vertical direction. Preferably, as shown in Figure 12, injection of the filling solidification material 22 begins from the filling material injection hole 27d on the central side, then switches to the filling material injection hole 27e on the receiving base 31c side to inject more filling solidification material 22, and then finishes filling the filling solidification material 22 when it is confirmed that the filling solidification material 22 has flowed out from the opening of the gap 21a between the adjacent receiving base 31c held on the upper surface 20a of the receiving base side block 20A.

In this embodiment, the multiple PCa concrete blocks 20A, 20B, and 20C arranged in a row and column are preferably arranged adjacent to the tunnel axial direction of the previously constructed existing invert structure 40 (see Figures 3 and 12). 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 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 12. 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.

Furthermore, in this embodiment, the upper surface band plate-shaped formwork 41a is attached to and secured to the upper surface 20a of the multiple 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 Figures 10 and 13). Similarly, the end side end surface 10A is also blocked by the end side band plate-shaped formwork 41b, which is attached to and secured to the end side end surface 10A, preferably so as to cover the openings of the gaps 21a, 21b, and 21c (see Figure 14). As with the gable end surface portion 10A, the central end surface portion 10B is also preferably closed by overlapping and fastening the central band plate formwork 41c to the central end surface portion 10B so as to cover the openings of the gaps 21b, 21c, and 21d (see Figure 10).

In this embodiment, the multiple PCa concrete blocks 20 constituting the invert section 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 5 and 6(a)-(c), the PCa concrete blocks 20 are formed as hexahedral blocks with curved upper and lower surfaces 20a, 20b that are curved along 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. The upper surface portion 20a and lower surface portion 20b in cross section can be gently curved with a radius of curvature of, for example, approximately 14,000 mm to 14,500 mm.

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 6(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 and small trumpet-shaped recesses 25b and 25c have a trumpet shape that tapers toward the upper and lower openings, the box punching members attached to the box-shaped formwork for concrete pouring to form these trumpet-shaped recesses 25b and 25c can be smoothly removed after the concrete has hardened. From this perspective, it is preferable that the taper gradient of the large and small trumpet-shaped recesses 25b and 25c, which have a tapered trumpet shape that expands in diameter, be inclined by 10% or more with respect to the central axis of the bolt insertion and threaded hole 25.

As shown in Figure 6(a), the three bolt insertion holes 25 are formed on the top surface 20a of the PCa concrete block 20, preferably at each corner of an imaginary 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 (see Figure 6(a)).

In this embodiment, when viewed from the top side of the PCa concrete block 20, it is preferable that the center of gravity of the PCa concrete block 20 be located inside the area surrounded by an imaginary isosceles triangle, and it is particularly preferable that the center of gravity of the PCa concrete block 20 be located at the centroid of the imaginary isosceles triangle. This makes it possible to more stably and precisely adjust the height and tilt of the PCa concrete block 20 using the three height adjustment bolts 26, and also makes it possible to more stably support the PCa concrete block 20, whose height and tilt have been precisely adjusted, using the three height adjustment bolts 26.

Furthermore, as shown in Figures 10 and 11, some of these PCa concrete blocks 20' (see Figure 3) have filler injection holes 27 that penetrate the hexahedron in the vertical direction. Each filler injection hole 27 has a female threaded member 27a fixed to the vertical middle portion, into which the male threaded portion of an opening/closing valve 28 is threaded. 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 valves 28 are threaded into the female threads 27a of these filler injection holes 27, and the handles 28a are positioned above the upper surface 20a of the PCa concrete block 20'. This allows the on-off valves 28 to be detachably attached to the PCa concrete block 20' while the handles 28a can 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 tools attached to the box-shaped formwork for concrete pouring to form these trumpet-shaped recesses 27b and 27c to be easily removed after the concrete has hardened. From this perspective, it is preferable that the taper gradient of these trumpet-shaped recesses 27b and 27c be at least 10% relative to the central axis of the filler injection hole 27.

In this embodiment, the filler injection holes 27 that penetrate the hexahedral PCa concrete block 20' in the vertical direction can be preferably formed by being disposed in the central portion of the top surface 20a of the PCa concrete block 20' (see Figure 6(a)). It is particularly preferable that the filler injection holes 27 be formed by being disposed in the central portion of the central block 20B, which is located at the lowest position.

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 6(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, the invert structure 10 is constructed in each of a pair of half-regions, each of which is located on either side of the tunnel's transverse center (see Figures 1 and 2). In the transverse center of the invert section 33, multiple H-shaped steel beams 35 supporting retaining plates and protective fences, etc., can be installed at a predetermined interval along the tunnel axis. These steel beams support the earth retaining plates and protective fences to prevent the construction of the invert structure 10 in each half-region from affecting the other half-region. These steel beams are driven into the ground of the invert section 33 with their flanges aligned along the tunnel axis. Therefore, at the positions where these H-shaped steel beams 35 are installed, notched recesses 20e with rectangular cross-sections can be formed in the central ends of a pair of PCa concrete blocks (center-side blocks) 20B adjacent in the axial direction of the tunnel at the center of the tunnel transverse direction, on both corners across the gap 21b between them (see Figure 3). The notched recesses 20e at the corners on both sides allow a flange mounting recess 10a for mounting one flange of the H-shaped steel 35 on the end face (central end face) 10B of each invert structure 10 on the central side in the transverse direction of the tunnel, at the portion where the H-shaped steel 35 is erected.

In other words, in the block groups 20X, 20Y (see Figure 1) made up of multiple PCa concrete blocks 20 that make up the invert structure 10 in each side region, the PCa concrete block 20 (central block 20B) placed in the portion where the H-shaped steel 35 is installed has curved upper and lower surface portions 20a, 20b that have a curved shape that follows the cross-sectional shape of the invert lining body 32, and is formed as a hexahedral block having a pair of flat axially opposing surfaces 20c at the front and rear and a pair of flat transversely opposing surfaces 20d at the left and right (see Figures 6(a) to (c)).At the corner between any one of the axially opposing surfaces 20c and the transversely opposing surfaces 20d, as shown in Figure 3, a notched recess 20e having a rectangular cross-sectional shape is cut out so as to have a side width of at least half the width of the flange portion 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 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 3 and 4, 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 series 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 in 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 the method of installing PCa blocks in the invert section according to 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 FIG. 4, and then installing the intermediate block 20C and the central block 20B adjacent to the temporarily fixed base-side block 20A.

For example, the base-side block 20A is installed adjacent to the base 31c and temporarily fixed using the temporary fixing means 36. Then, the intermediate block 20C and the central block 20B are installed adjacent to the temporarily fixed base-side block 20A. At the adjacent locations of each of these installed blocks 20A, 20B, and 20C, bolts (not shown) are temporarily fixed via bolt boxes 23 disposed on the top surface 20a of at least one of the PCa concrete blocks 20A, 20B, and 20C near the transversely facing surface 20d. The height and position of each PCa concrete block 20A, 20B, and 20C can then be adjusted, and the bolts can then be fully tightened to install the multiple PCa concrete blocks 20A, 20B, and 20C of each transverse block row 20D, which are connected in the transverse direction of the tunnel, in the invert section 33.

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, a central block 20B is installed adjacent to the intermediate block 20C, and the adjacent central block 20B and intermediate block 20C 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 adjacent to the transverse opposing surface 20d. After adjusting the height and position of the central block 20B, the bolts can be fully tightened to install 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 rope-like member 36b, such as a wire or chain, whose both ends are secured to a locking member attached to a hole-in anchor 36a embedded in the pedestal 31c and a locking member attached to a bolt box 23 or a lifting jig 29c provided on the pedestal-side block 20A. The rope-like member 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.

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 6(a) and 7. 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, and 20C arranged vertically and horizontally with filling solidifying material 22, the gaps 21b between adjacent PCa concrete blocks 20A, 20B, and 20C, and the gaps 21c below the hexahedral undersides 20b that communicate with these gaps 21a and 21b (see Figure 10), the PCa concrete blocks 20A, 20B, and 20C are rotated from above to change the length by which the three height adjustment bolts 26 in each PCa concrete block 20A, 20B, and 20C protrude from the underside 20b of the PCa concrete block 20A, 20B, and 20C, thereby adjusting the height and inclination of each PCa concrete block 20A, 20B, and 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 (see FIG. 8(a)). By tilting the ground adjuster 26b relative to the lower ends 26a of the height adjustment bolts 26, the adjuster 26b can be tilted to align with the filling bottom surface 26c, e.g., the ground surface. This allows the lower ends 26a of the height adjustment bolts 26 to stably rest on the filling bottom surface 26c below the undersides 20b.

The grounding adjuster 26b is preferably designed to fit into the small horn-shaped recess 25c, which expands downward when the height adjustment bolt 26 is retracted upward. For example, as shown in FIG. 8(b), the small horn-shaped recess 25c can be designed to expand downward, conforming to the outer periphery of the grounding adjuster 26b but slightly larger than it. This allows the grounding adjuster 26b, which has a similar shape to the small horn-shaped recess 25c, to be easily accommodated inside the small horn-shaped recess 25c without protruding downward from the underside 20b of the PCa concrete block 20. This allows the adjuster 26b to be grounded against the underside 26c, allowing for fine adjustment of the height of the PCa concrete block 20, even if the gap 21c between the underside 20b and the filling bottom 26c of the PCa concrete block 20 is less than the height of the grounding adjuster 26b. Furthermore, the height position of the filled bottom surface 26c after leveling is the same height as the designed position of the underside 20b of the PCa concrete block 20, so even if there is no room for error, the entire ground contact adjuster 26b can be accommodated in the small trumpet-shaped recess 25c, and with the underside 20b abutting the filled bottom surface 26c, each PCa concrete block 20 can be installed in the specified position.

The small horn-shaped recess 25c preferably has a height from the opening in the underside 20b of the PCa concrete block 20 to the lower end of the female thread member 25a of approximately 60 to 80 mm, and an opening diameter in the underside 20b of approximately 65 to 70 mm. The taper gradient of the small horn-shaped recess 25c is preferably inclined by 10% or more with respect to the central axis of the bolt insertion/threading hole 25, from the perspective of facilitating removal of the box punch member after the concrete has hardened.

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.

The large trumpet-shaped recess 25b preferably has a height from the opening in the upper surface 20a of the PCa concrete block 20 to the upper end of the female screw member 25a of approximately 360 to 380 mm, and an opening diameter in the upper surface 20a of approximately 106 to 110 mm. The taper gradient of the large trumpet-shaped recess 25b is preferably inclined by 10% or more with respect to the central axis of the bolt insertion/threading hole 25, from the perspective of facilitating removal of the box punch member after the concrete has hardened.

In this embodiment, as described above, 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 of the bolt insertion holes 25 in a manner that allows adjustment of the protruding length of the lower end 26a protruding downward from the underside 20b of the PCa concrete block 20A, 20B, and 20C. This allows adjustment of the protruding length of the lower end 26a protruding downward from the underside 20b of the PCa concrete block 20A, 20B, and 20C. Prior to the process of filling the filling solidification material 22 into the gaps 21a between adjacent receiving portions 31c of the multiple PCa concrete blocks 20A, 20B, and 20C arranged vertically and horizontally, the gaps 21b between adjacent PCa concrete blocks 20A, 20B, and 20C, and the gaps 21c below the hexahedral underside 20b that communicate with these gaps 21a and 21b, the gaps 21c below the hexahedral underside 20b of the PCa concrete blocks 20A, 20B, and The gap width b (see Figures 7 and 10) of the gap 21c below the hexahedral underside 20b of each PCa concrete block 20A, 20B, or 20C is measured from the protruding length of the lower end 26a of the height adjustment bolt 26 protruding from the underside 20b of each block. Based on this measurement and the area of the underside 20b of each PCa concrete block 20A, 20B, or 20C, the planned amount of filling solidification material 22 to be filled in the gap 21c below the hexahedral underside 20b can be calculated in advance. In the process of filling the filling solidification material 22, a predetermined amount of filling solidification material 22 is injected into the gap 21c below the hexahedral underside 20b, taking into account the calculated planned filling amount, and then allowed to fill and harden.

In other words, in this embodiment, a nut member 25a is fixed as a female thread member below the vertical middle of each bolt insertion hole 25, and a height adjustment bolt 26 is threadedly attached to the nut member 25a, so that the protrusion length of the lower end 26a of the height adjustment bolt 26 from the underside 20b of the PCa concrete block 20A, 20B, 20C can be adjusted. Therefore, for example, when the lower end 26a of the height adjustment bolt 26 is grounded on the filling bottom surface 26c below the hexahedral underside 20b, the gap width b of the gap 21c below the hexahedral underside 20b can be easily measured from the length of the height adjustment bolt 26 above the nut member 25a.

In addition, in this embodiment, a tiltable ground adjuster 26b is preferably attached to the lower end 26a of the height adjustment bolt 26. This makes it possible to more easily and stably measure the gap width b of the gap 21c below the hexahedral lower surface 20b from the length of the height adjustment bolt 26 above the nut member 25a when the ground adjuster 26b is grounded on the filling bottom surface 26c below the hexahedral lower surface 20b.

The planned amount of filling solidification material 22 can be calculated in advance by calculating the amount to be filled into the gaps 21c below the hexahedral underside 20b of each PCa concrete block 20A, 20B, 20C based on the average gap width b of the gaps 21c below the hexahedral underside 20b measured using three height adjustment bolts 26 attached to the three bolt insertion and threaded holes 25 of each PCa concrete block 20A, 20B, 20C.

The planned amount of filling solidification material 22 can also be calculated in advance by calculating the amount to be filled into the gaps below the hexahedral undersides 20b of the PCa concrete blocks 20A, 20B, and 20C throughout the entire invert structure 10 based on the overall average of the gap widths b of the gaps 21c below the hexahedral undersides 20b, measured using three height adjustment bolts 26 attached to the three bolt insertion and threaded holes 25 of each of the PCa concrete blocks 20A, 20B, and 20C that make up the invert structure 10.

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 3, 4, and 6(a) to (c), the PCa concrete block connection structure 37 in the invert structure has transverse spacer jigs 29a (see Figure 6(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 transverse spacer jigs 29a (see Figure 6(b)) are fixed to one of the opposing surfaces, and are arranged in bolt boxes 23 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. The fastening force of bolt members (not shown) fastened in bolt boxes 23 is 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, connecting 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 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 6(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, when a mountain tunnel includes a section with a tunnel line that curves horizontally, multiple PCa concrete blocks 20A, 20B, and 20C can be connected vertically and horizontally and installed as a single unit in the invert section 33, with gaps 21b of a predetermined spacing width maintained between adjacent PCa concrete blocks 20A, 20B, and 20C, and aligned along the tunnel line that curves horizontally.

In other words, in this embodiment, transverse spacer jigs 29a (see Figure 6(b)) fixed to one of the transverse opposing surfaces 20d of adjacent PCa concrete blocks 20A, 20B, 20C in the transverse direction of the tunnel are arranged at at least three locations between the opposing transverse surfaces 20d, and the fastening force of bolt members (not shown) 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, thereby forming a transverse block row 20D consisting of a plurality of PCa concrete blocks 20A, 20B, 20C (see Figure 3). Between each pair of axially opposing surfaces 20c of adjacent PCa concrete blocks 20A, 20B, 20C in the axial direction of the tunnel, axial spacer jigs 29b (see Figure 6(c)) fixed to one of the axially opposing surfaces 20c are arranged in at least three locations, and each pair of PCa concrete blocks 20A, 20B, 20C adjacent in the axial direction of the tunnel is connected by the fastening force of bolt members (not shown) while maintaining a gap 21b of a predetermined spacing width between the axially opposing surfaces 20c (see Figure 3). 9(a), at one or more axial connection portions 20f between a plurality of transverse block rows 20D arranged in the tunnel axial direction, axial spacer jigs 29b interposed between a pair of axially opposing surfaces 20c in the tunnel axial direction are fixed to the axially opposing surfaces 20c with the interposition width adjusted so that the width of the outer gap 21b maintained by the axial spacer jigs 29b fixed to the outer PCa concrete block 20E located on the outside of the horizontally curved tunnel alignment in the transverse direction of the tunnel is larger than the width of the inner gap 21b maintained by the axial spacer jigs 29b fixed to the inner PCa concrete block 20F located on the inside of the horizontally curved tunnel alignment. This allows the multiple PCa concrete blocks 20A, 20B, 20C to be connected vertically and horizontally and installed as a unit in the invert section 33 along the horizontally curved tunnel alignment. This also makes it possible to accommodate tunnel alignments that curve horizontally by using rectangular PCa concrete blocks 20A, 20B, and 20C, without using tapered blocks.

Here, if the axial spacer jig 29b is made of a mortar block attached and fixed to one of the axially opposing surfaces 20c, the gap width can be adjusted so that the gap width of the outer gap 21b is larger than the gap width of the inner gap 21b by fixing mortar blocks of different sizes to the outer PCa concrete block 20E and the inner PCa concrete block 20F at the connecting portion 20f, which has a different gap width.

Furthermore, if the axial spacer jig 29b is a male threaded member that is fixed so that the protrusion length can be adjusted by screwing it into a female threaded insert embedded in one of the axially opposing surfaces 20c, then at the connecting portion 20f, which has a different gap width, the male threaded member can be screwed in and fixed with different threading amounts for the outer PCa concrete block 20E and the inner PCa concrete block 20F, thereby adjusting the gap width so that the gap width of the outer gap 21b is larger than the gap width of the inner gap 21b.

On the other hand, in this embodiment, when a mountain tunnel includes a section with a tunnel line that curves vertically, multiple PCa concrete blocks 20A, 20B, and 20C can be connected vertically and horizontally and installed as a single unit in the invert section 33, with gaps 21b of a predetermined spacing width maintained between adjacent PCa concrete blocks 20A, 20B, and 20C, and aligned along the tunnel line that curves vertically.

In other words, in this embodiment, transverse spacer jigs 29a (see Figure 6(b)) fixed to one of the transverse opposing surfaces 20d of adjacent PCa concrete blocks 20A, 20B, 20C in the transverse direction of the tunnel are arranged at at least three locations between the opposing transverse surfaces 20d, and the fastening force of bolt members (not shown) 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, thereby forming a transverse block row 20D consisting of a plurality of PCa concrete blocks 20A, 20B, 20C (see Figure 3). Between each pair of axially opposing surfaces 20c of adjacent PCa concrete blocks 20A, 20B, 20C in the axial direction of the tunnel, axial spacer jigs 29b (see Figure 6(c)) fixed to one of the axially opposing surfaces 20c are arranged in at least three locations, and each pair of PCa concrete blocks 20A, 20B, 20C adjacent in the axial direction of the tunnel is connected by the fastening force of bolt members (not shown) while maintaining a gap 21b of a predetermined spacing width between the axially opposing surfaces 20c. As shown in Figure 9(b), at least three axial spacer jigs 29b are fixed to the axially opposing surfaces 20c at one or more axial connection sections 20g between multiple transverse block rows 20D arranged in the tunnel axial direction, with the upper gap 21b maintained by the upper axial spacer jigs 29b and the lower gap 21b maintained by the lower axial spacer jigs 29b being adjusted to different widths. This allows multiple PCa concrete blocks 20A, 20B, and 20C to be connected vertically and horizontally and installed integrally in the invert section 33 along the vertically curved tunnel alignment. This also makes it possible to use rectangular PCa concrete blocks 20A, 20B, and 20C to accommodate vertically curved tunnel alignments without using tapered blocks.

For example, by adjusting the spacing widths of the upper gaps 21b held by the axial spacer jigs 29b arranged in the upper tier at connecting sections 20g with different spacing widths so that the spacing width is larger than the spacing width of the lower gaps 21b held by the axial spacer jigs 29b arranged in the lower tier, it becomes possible to arrange multiple consecutive transverse block rows 20D along the tunnel alignment that curves downward in the vertical direction.

Furthermore, by adjusting the spacing widths of the upper gaps 21b held by the axial spacer jigs 29b arranged in the upper tier at connecting portions 20g with different spacing widths so that the spacing width of the upper gaps 21b held by the axial spacer jigs 29b arranged in the lower tier is smaller than the spacing width of the lower gaps 21b held by the axial spacer jigs 29b arranged in the lower tier, it is possible to arrange multiple consecutive transverse block rows 20D along the tunnel line that curves upward in the vertical direction.

Here, if the axial spacer jig 29b is made of mortar blocks attached and fixed to one of the axially opposing surfaces 20c, the gap width can be adjusted so that the gap width of the gap 21b held at the upper part and the gap width of the gap 21b held at the lower part are different by fixing mortar blocks of different sizes to the upper and lower parts of the connecting part 20g, which have different gap widths.

Furthermore, if the axial spacer jig 29b is made of a male threaded member that is fixed so that the protruding length can be adjusted by screwing it into a female threaded insert embedded in one of the axial opposing surfaces 20c, then by screwing and fixing the male threaded member with different screwing depths in the upper and lower stages of the connecting portion 20g, which have different spacing widths, the spacing width can be adjusted so that the spacing width of the gap 21b held in the upper part and the spacing width of the gap 21b held in the lower part are different widths.

In this embodiment, as described above, the multiple PCa concrete blocks 20A, 20B, and 20C arranged in a row and column are integrated 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, and 20C, and the gaps 21c below the hexahedral undersides that communicate with these gaps, as shown in FIG. 10, to form 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, according to the construction method of the invert section structure of this embodiment, as described above, in the process of filling the gaps 21a between adjacent receiving base 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 portions that communicate with these gaps 21a, 21b, the opening portions of the gaps 21a, 21b that open on the upper surface portions 20a, gable end surface portions 10A (see Figures 3 and 12), and center end surface portions 10B (see Figures 3 and 12) of multiple PCa concrete blocks 20A, 20B, 20C arranged in a row vertically and horizontally are closed. 10 to 12, the filling solidification material 22 is sequentially injected 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. 12, the injection of the filling solidification material 22 is started from 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 solidification material 22 is completed upon confirmation that the filling solidification material 22 has flowed out from the opening of the gap 21a between the pedestal 31c held by 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 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.

Furthermore, in the construction method of the invert section structure of this embodiment, as described above, the multiple PCa concrete blocks 20A, 20B, 20C arranged in a row vertically and horizontally are preferably arranged adjacent to the axial direction of the tunnel of the existing invert section structure 40 (see Figures 3 and 12) that was formed previously. With the opening portion of the gap 21d between the existing invert structure 40 and the upper surface 20a and central end surface 10B of multiple PCa concrete blocks 20A, 20B, 20C arranged vertically and horizontally blocked, the filling solidification material 22 is injected by switching from the filler material injection hole 27d on the central side located on the existing invert structure 40 side to the filler material injection hole 27d on the central side located on the gable side, preferably as shown in Figure 12, and the filling solidification material 22 is injected by switching from the filler material injection hole 27e on the receiving base side located on the existing invert structure 50 side to the filler material injection hole 27e on the receiving base side 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 the construction method for the invert structure of this embodiment, as described above, the upper surface band plate-shaped formwork 41a is attached to and secured 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 the gaps 21b in the upper surface 20a, thereby blocking the openings in the upper surface 20a (see Figures 10 and 13). Similarly, the end side end surface 10A is also blocked by the end side band plate-shaped formwork 41b being attached to and secured to the end side end surface 10A, preferably so as to cover the openings of the gaps 21a, 21b, and 21c (see Figure 14). As with the gable end surface portion 10A, the central end surface portion 10B is also preferably closed by overlapping and fastening the central band plate formwork 41c to the central end surface portion 10B so as to cover the openings of the gaps 21b, 21c, and 21d (see Figure 10).

It is also preferable that the top band-shaped formwork 41a, the gable band-shaped formwork 41b, and the center band-shaped formwork 41c be formed using transparent plate-shaped members. This makes it possible to visually check the filling status of the solidification material 22 in each gap 21a, 21b, 21c, and 21d through these transparent band-shaped formworks.

Furthermore, it is preferable to attach air vent hoses 42 (see Figure 10) extending from appropriate positions to the upper surface band plate formwork 41a, which is attached so as 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. Furthermore, 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 the process of filling the gaps 21a between the adjacent receiving base portions 31c of the multiple PCa concrete blocks 20A, 20B, and 20C arranged in a row vertically and horizontally, the gaps 21b between the adjacent PCa concrete blocks 20A, 20B, and 20C, and the gaps 21c below the hexahedral bottom surfaces that communicate with these gaps 21a and 21b, the filling solidification material 22 is filled into the gaps 21a between the adjacent receiving base portions 31c of the multiple PCa concrete blocks 20A, 20B, and 20C arranged in a row vertically and horizontally, as described above. 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 pedestal-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 pedestal-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 on-off 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. The valves can be attached 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.

In this embodiment, the invert structure 10 having the above-mentioned configuration is constructed in each of a pair of half regions, each of which is formed by sandwiching the center of the tunnel in the transverse direction, as shown in Figures 1 and 2. Together, these regions form the invert lining body 32, forming the invert structure 50 across the entire transverse area.

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 transversely opposite regions of the tunnel, a plurality of PCa concrete blocks 20A, 20B, and 20C are arranged in series in the transverse direction of the tunnel and installed in an inverted section 33, with gaps 21a and 21b maintained between the receiving bases 31c at the lower ends of adjacent side wall linings 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 inverted 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 transversely central portion of the tunnel. 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 such a way that the gaps 21b extending in the axial direction between adjacent PCa concrete blocks in the transverse direction of the tunnel, filled with filling solidification material 22, and the gaps extending in the transverse direction between adjacent PCa concrete blocks in the axial direction of the tunnel, are preferably arranged in a potato-like pattern that is continuous in a straight line.

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 FIG. 15, 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 direction of the tunnel described above can be formed by the following construction method. That is, in this embodiment, the construction method for the invert structure 50 is to install a plurality of PCa concrete blocks 20A, 20B, 20C in one side region of the tunnel in the transverse direction, by arranging them in series in the transverse direction of the tunnel and installing them in the invert section 33, 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 also maintaining gaps 21b between adjacent PCa concrete blocks 20A, 20B, 20C in the axial direction of the tunnel. and a process 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 these, and a process 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 these, and a process of filling and hardening a filling solidification material 22 into the gaps 21a between the adjacent 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 these, and a process of filling and hardening a filling solidification material 22 into the gaps 21b between the adjacent PCa concrete blocks 20A, 20B, 20C of the one side block group 20X arranged in a row and row, and the gaps 21c below the lower surface portions of the hexahedrons communicating with these, and a process of hardening a filling solidification material 22 into the gaps 21b between the adjacent PCa concrete blocks 20A, 20B, 20C of the one side block group 20X The PCa concrete blocks 20A, 20B, 20C are arranged in series in the transverse direction of the tunnel and installed 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 in the axial direction of the tunnel while maintaining gaps 21b between the adjacent PCa concrete blocks 20A, 20B, 20C, and installed in the invert section 33. The process includes a step of filling and hardening the filling solidification material 22 into the gaps 21a between adjacent receiving portions 31c of the PCa concrete blocks 20A, 20B, and 20C, the gaps 21b between adjacent PCa concrete blocks 20A, 20B, and 20C, and the gaps 21c below the hexahedral undersides that communicate with these, as well as into the gaps 51 between the 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 invert structure 50 can be formed across the entire transverse area by constructing both areas simultaneously, rather than constructing each side area at a time, for example, if construction can be carried out while blocking traffic through the mountain tunnel 30 for an extended period of time.

The construction method for the invert structure of this embodiment, which has the above-mentioned configuration, uses PCa concrete blocks 20 (20A, 20B, 20C) of appropriate weight and size that can be easily manufactured in a factory, etc., making it possible to easily form the invert structure 10 without much effort and more quickly install it as a component of the invert lining 32, which is provided continuously from the tunnel side wall 31a to the lining 31 of the upper arch-shaped portion 31b.

In other words, according to this embodiment, the invert structure 10 is constructed such that the PCa concrete blocks 20 that make up the invert structure are formed in a hexahedral shape with a curved upper surface 20a and lower surface 20b, measuring, for example, a width x of approximately 1385 to 1435 mm, a length y of approximately 730 mm, and a height z of approximately 500 mm, and weighing approximately 1300 kg. Compared to conventional precast concrete invert concrete components, which are heavy and complex in shape, the PCa concrete blocks have a moderate weight, size, and shape, which not only allows for efficient manufacturing but also improves workability during lifting and transportation, and ease of handling during lifting and installation, making it possible to precisely install each PCa concrete block 20 at predetermined intervals.

In addition, in the construction method for the invert structure of this embodiment, the work of injecting and hardening the filling solidification material into gaps and gaps between adjacent PCa concrete blocks 20 arranged vertically and horizontally is performed by blocking the openings of gaps 21a, 21b, and 21c on the top surfaces 20a, gable end surfaces 10A, and center end surfaces 10B of the PCa concrete blocks arranged vertically and horizontally, and then injecting the filling solidification material 22 through the filling material injection holes 27d, 27e that penetrate vertically through the center-side block 20B and the base-side block 20A. Because the filling material injection holes 27d, 27e are thus provided that penetrate vertically through the center-side block 20B and the base-side block 20A, the work of injecting the filling solidification material 22 into gaps and gaps between the PCa concrete blocks 20 can be easily performed from the top surfaces 20a of the concrete blocks, where work space is secured.

Furthermore, the filler injection holes 27d on the center side are provided in one or more of the multiple center-side blocks 20B that are connected in the axial direction of the tunnel, and the filler injection holes 27e on the receiving section side are provided in one or more of the multiple receiving section-side blocks 20A that are connected in the axial direction of the tunnel. The filling solidification material 22 is then injected sequentially from these filler injection holes 27d, 27e. This allows the filling solidification material 22 to flow in an orderly manner in one direction, avoiding factors that hinder filling, such as air pockets, and enabling smooth injection work.

Furthermore, the injection of the filling solidification material 22 begins through the filler injection hole 27d on the central side, then switches to the filler injection hole 27e on the receiving base 31c side to inject more filling solidification material 22. After confirming that the filling solidification material 22 is flowing out of the opening in the gap 21a between the receiving base 31c and the upper surface 20a of the receiving base-side block 20A, the injection of the filling solidification material 22 is completed. In this way, by sequentially switching the injection location of the filling solidification material 22 from the lower location of the filler injection hole 27d on the central side to the higher location of the filler injection hole 27e on the receiving base 31c side, the filling solidification material 22 is injected in an orderly manner, starting from the lower location, thereby reliably pushing out any air in gaps and other gaps in the PCa concrete block 20. By checking that the filling solidification material 22 flows out of the opening in the gap 21a between the receiving block 31c held on the top surface 20a of the receiving block side block 20A, which is the highest gap or space between the blocks, it is possible to reliably expel all air in the gaps and spaces between the PCa concrete blocks 20. This makes it easier to inject the filling solidification material 22 into the gaps and spaces between the PCa concrete blocks 20.

As described above, after each PCa concrete block 20 is precisely installed at a predetermined interval, the work of injecting the filling solidification material 22 into the gaps and gaps between the PCa concrete blocks 20 can be carried out easily and smoothly. Therefore, since it is easy to form an invert structure 10 in which these PCa concrete blocks 20 are firmly integrated, it can be installed even more quickly and easily as a component of the invert lining 32, which is provided continuously from the tunnel side wall 31a to the lining 31 of the upper arch-shaped portion 31b.

In addition, in this embodiment, the multiple PCa concrete blocks 20A, 20B, 20C arranged in a row vertically and horizontally are preferably arranged adjacent to each other in the axial direction of the tunnel of the previously constructed existing invert structure 40 (see Figures 3 and 12). As shown in Figure 12, the filling and solidifying 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, and the filling and solidifying material 22 is injected by switching from the filler injection hole 27e on the receiving base side located on the existing invert structure 50 side to the filler injection hole 27e on the receiving base side located on the gable side.

The present invention is not limited to the above-described embodiment and various modifications are possible. For example, the invert section structure formed by the construction method 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 portion, and not in the invert section. It can also be used in construction work to install a lining around the entire inner wall surface of a tunnel, including the invert section, when constructing a new mountain tunnel, or in construction work to repair an invert section lining already installed in a mountain tunnel and then reinstall a new invert section lining.

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 36 Temporary fixing means 36a Hole-in anchor 36b Cord-like body 36c Expansion adjustment means 37 PCa block connection portion 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 Spacing portion b between one side block group and the other side block group Gap below the underside

Claims (6)

A construction method for an invert section structure using a plurality of PCa concrete blocks that are provided in at least one side region of the invert section of a mountain tunnel in the transverse direction of the tunnel to form an invert section lining,
The PCa concrete block is formed as a hexahedral block having curved upper and lower surfaces so as to have a curved shape that follows the cross-sectional shape of the invert section covering body,
The plurality of PCa concrete blocks include a base portion side block arranged adjacent to the base portion at the lower end of the side wall covering body, a central portion side block arranged on the transverse center side of the invert portion, and one or more intermediate portion blocks arranged between them,
The PCa concrete blocks are arranged in a row in the transverse direction of the tunnel, with a gap of 15 to 30 mm maintained between adjacent support sections and between adjacent PCa concrete blocks, and are also arranged in a row in the axial direction of the tunnel, with a gap of 15 to 30 mm maintained between adjacent PCa concrete blocks, and are installed in the invert section lined up vertically and horizontally,
The PCa concrete blocks arranged in a row and column are configured to form at least a part of the invert section covering body by filling and hardening a filling solidification material into the gaps between the adjacent receiving base sections, the gaps between the adjacent PCa concrete blocks, and the gaps below the lower surface of the hexahedron shape that communicate with these gaps, and are integrated via the hardened filling solidification material,
In the process of filling the gaps between the adjacent receiving portions of the plurality of PCa concrete blocks arranged in a row vertically and horizontally, the gaps between the adjacent PCa concrete blocks, and the gaps below the lower surface of the hexahedron shape that communicate with these gaps,
With the openings of the gaps at the top surfaces, end surfaces, and center surface of the PCa concrete blocks arranged in a row vertically and horizontally closed, filling and solidifying material is sequentially injected from filling material injection holes on the center side that are provided vertically through one or more of the center side blocks arranged in a row in the axial direction of the tunnel,
A construction method for an invert section structure in a mountain tunnel, in which air is removed through an air removal hose connected to the gaps whose openings are blocked on the upper surfaces of multiple PCa concrete blocks, while starting to inject filling solidification material from the filling material injection hole on the central side, and finishing filling the filling solidification material when it is confirmed that the filling solidification material is flowing out from the openings of the gaps between adjacent receiving sections held on the upper surfaces of the receiving section side blocks. With the openings of the gaps at the top surfaces, end surfaces and central surface surfaces of the PCa concrete blocks arranged in a row vertically and horizontally closed, filling and solidifying material is sequentially injected from the filling material injection holes on the central side that are provided vertically through one or more of the central side blocks arranged in a row in the axial direction of the tunnel, and from the filling material injection holes on the receiving side that are provided vertically through one or more of the base side blocks arranged in a row in the axial direction of the tunnel,
A construction method for an invert section structure in a mountain tunnel as described in claim 1, in which the injection of filling solidification material is started from the filling material injection hole on the central side, then switched to the filling material injection hole on the receiving section side to inject more filling solidification material, and then the filling of the filling solidification material is completed when it is confirmed that the filling solidification material is flowing out from the opening of the gap between the adjacent receiving section held on the upper surface of the receiving section side block. The plurality of PCa concrete blocks arranged in a row vertically and horizontally are adjacent to each other in the axial direction of the tunnel of the existing invert section structure formed previously,
A construction method for invert structures in mountain tunnels as described in claim 1 or 2, in which the filling solidification material is injected by switching from the filling material injection hole on the existing invert structure side to the filling material injection hole on the gable side, while blocking the opening portion of the gap between the existing invert structure and the upper surface and central end surface of the multiple PCa concrete blocks arranged in a vertical and horizontal row. A construction method for an invert structure in a mountain tunnel as set forth in claim 1 or 2, wherein an upper surface band plate-shaped formwork is attached by overlapping and fixing to the upper surface of a plurality of PCa concrete blocks arranged vertically and horizontally so as to cover the opening of the gap on the upper surface, thereby blocking the opening of the upper surface; an end portion band plate-shaped formwork is attached by overlapping and fixing to the end surface so as to cover the opening of the gap on the end surface, thereby blocking the opening of the end surface; and a central side band plate-shaped formwork is attached by overlapping and fixing to the end surface so as to cover the opening of the gap on the center surface, thereby blocking the opening of the center surface. A construction method for an invert structure in a mountain tunnel as described in claim 4, wherein the upper surface band plate formwork, the end portion band plate formwork, and the central side band plate formwork are formed using transparent plate-like members, and the filling status of the filling solidification material into the gaps can be visually observed through these transparent band plate formworks. A construction method for an invert structure in a mountain tunnel as described in claim 4, wherein the upper surface band plate formwork is attached so as to cover the opening of the gap on the upper surface of a plurality of the PCa concrete blocks arranged vertically and horizontally, and the air vent hose extending from an appropriate position and communicating with the gap is attached, making it possible to vent air from the gap when filling the filling solidification material through the air vent hose, and the filling of the filling solidification material can be confirmed by the flow of the filling solidification material from the air vent hose.