Construction method of invert structure in mountain tunnel

Abstract

To provide a method for constructing an invert part structure capable of constituting an invert part lining body by easily forming the invert part structure using PCa concrete blocks without requiring much labor.SOLUTION: A height adjustment bolt 26 is fitted in a bolt insertion screwing hole 25 formed at three locations so as to vertically penetrate a PCa concrete block 20 having hexahedron shape in a state where a lower end 26a can protrude downward from a lower face part 20b of the PCa concrete block 20. A method for constructing an invert part structure includes a step to adjust height and inclination of the PCa concrete blocks 20 by changing a protruding length of the height adjustment bolt 26 from the lower face part 20b of the PCa concrete block 20 before a step to fill a filling solidification material 22 in gaps 21a, 21b, 21c of the plurality of PCa concrete blocks 20 connected and disposed vertically and horizontally.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a construction method of an invert part structure, and more particularly, to a construction method of an invert part structure in a mountain tunnel using PCa concrete blocks, which is provided in the invert part of a mountain tunnel and constitutes an invert part covering structure.

Background Art

[0002] A mountain tunnel is a tunnel formed by excavating a relatively stable ground such as bedrock, and the excavated inner wall surface is covered with a primary lining or a secondary lining made of concrete or mortar. That is, after excavating the tunnel while performing blasting or the like, for example, a protective layer is formed by preferably spraying mortar or concrete for the primary lining, and then, inside the protective layer formed by the primary lining, for example, a known tunnel lining formwork is installed, and a lining body with a predetermined thickness made of concrete is formed as a secondary lining from the side wall part of the tunnel to the upper arch-shaped part. Further, in the lining body from the side wall parts on both sides of the previously formed tunnel to the upper arch-shaped part, in the part between the receiving parts at the lower ends of the pair of side wall parts, the lining body of the bottom invert part is integrally formed with a predetermined thickness using concrete in the transverse direction of the tunnel, so that the entire circumference of the inner wall surface of the mountain tunnel is continuously covered by the secondary lining.

[0003] In addition, since a mountain tunnel is formed by excavating a relatively stable ground, for example, a tunnel constructed several decades or more ago omits the lining body of the invert part and forms a lining body only in the area from the side wall part of the tunnel to the upper arch-shaped part for secondary lining. For such a mountain tunnel that omits the lining body of the invert part, for example, in the future, it is considered to newly form a lining body of the invert part so as not to be affected by, for example, swelling of the bottom part of the ground.

[0004] As a method of forming the invert lining by connecting it continuously to the lining provided in advance from the side wall portion of the tunnel to the upper arch-shaped portion at the bottom of the tunnel, conventionally, the one using in-situ concrete has been generally used (for example, see Patent Document 1). However, for the invert lining, a high level of skill is required to finish the upper surface so as to have a curved shape. Furthermore, when in-situ concrete is used, since the placed concrete takes a considerable amount of time until a predetermined curing period elapses after hardening, especially when newly forming the invert lining from the side wall portion where the invert lining is omitted to the upper arch-shaped portion lining, the passage in the tunnel will be blocked for a long time. Therefore, it is desirable to be able to complete the construction in a shorter period of time.

[0005] For this reason, shortening the construction period by forming the invert lining using a precast concrete member manufactured in advance at a factory or the like has also been considered (for example, see Patent Document 2 and Patent Document 3).

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0007] However, according to the conventional construction method of the invert part in a mountain tunnel using concrete members made of precast concrete, these concrete members pre-formed in a factory or the like are formed with a length spanning the entire width in the transverse direction of the invert part, or are formed with a length obtained by dividing the invert part into two to three parts in the transverse direction. Therefore, the weight and shape become large, and it takes a lot of labor to assemble a formwork in a factory or the like and accurately form joints and the like. Furthermore, a lot of labor is required for loading and assembling at the construction site. In particular, for example, in a multi-lane road tunnel, when construction is carried out for each lane while maintaining traffic in the other lane, it is necessary to use concrete members of a large size, which involves difficult work.

[0008] The present invention aims to provide a construction method for an invert part structure in a mountain tunnel that can be installed more quickly by using precast concrete blocks (PCa concrete blocks) of appropriate weight and size that are easy to manufacture in a factory or the like, which can be easily formed without requiring much labor and is provided as a component of an invert part covering structure that is continuous with the covering structure of the upper arch-shaped part from the side wall part of the tunnel.

Means for Solving the Problems

[0009] The present invention provides a construction method for an invert structure using a plurality of PCa concrete blocks, which are provided in at least one side region in the transverse direction of a tunnel in an invert portion of a mountain tunnel and constitute an invert covering structure. The PCa concrete blocks are formed as hexahedral blocks having a curved upper surface portion and a curved lower surface portion so as to have a curved shape along the cross-sectional shape of the invert covering structure. The plurality of PCa concrete blocks are arranged in series in the transverse direction of the tunnel while maintaining a gap between adjacent receiving bases and between adjacent PCa concrete blocks, and are also arranged in series in the axial direction of the tunnel while maintaining a gap between adjacent PCa concrete blocks, and are installed in the invert portion by arranging them side by side vertically and horizontally. The plurality of PCa concrete blocks arranged in series vertically and horizontally are integrated through the hardened filling and solidifying material by filling the gap between adjacent receiving bases, the gap between adjacent PCa concrete blocks, and the gap below the lower surface portion of the hexahedral shape communicating with these gaps with a filling and solidifying material and hardening it, so as to constitute at least a part of the invert covering structure. In each of the PCa concrete blocks, bolt insertion and screwing holes are formed at least at three locations penetrating in the vertical direction, and height adjustment bolts are attached to each of the bolt insertion and screwing holes in a state where the lower end portion can protrude downward from the lower surface portion of the PCa concrete block. Prior to the step of filling the gap between adjacent receiving bases, the gap between adjacent PCa concrete blocks, and the gap below the lower surface portion of the hexahedral shape communicating with these gaps with a filling and solidifying material, the protruding lengths of the three height adjustment bolts from the lower surface portion of the PCa concrete block in each of the PCa concrete blocks are changed by a rotational operation from above the PCa concrete blocks, and the height and inclination of each of the PCa concrete blocks are adjusted, thereby achieving the above object by providing a construction method for an invert structure in a mountain tunnel including this step.

[0010] And, in the construction method of the invert part structure in the mountain tunnel of the present invention, a female screw member is fixed to a lower part than the middle in the vertical direction of each of the bolt insertion and screwing holes, and the height adjustment bolt is screwed to the female screw member, so that the height adjustment bolt is preferably attached in a state where the lower end portion can protrude downward from the lower surface portion of the PCa concrete block.

[0011] Further, in the construction method of the invert part structure in the mountain tunnel of the present invention, it is preferable that the bolt insertion and screwing holes are arranged at each corner of a triangular shape surrounding the center of gravity of the PCa concrete block and are formed at three locations.

[0012] Furthermore, in the construction method of the invert part structure in the mountain tunnel of the present invention, it is preferable that the three bolt insertion and screwing holes are arranged at each corner of the isosceles triangle shape in which the bottom side portion is arranged parallel to one of the axial direction opposing surfaces and the top portion is arranged on the other axial direction opposing surface side on the upper surface portion of the PCa concrete block.

[0013] Furthermore, in the construction method of the invert part structure in the mountain tunnel of the present invention, it is preferable that the center of gravity of the PCa concrete block is arranged inside the isosceles triangle shape as viewed from the upper surface portion side of the PCa concrete block.

[0014] Further, in the construction method of the invert part structure in the mountain tunnel of the present invention, it is preferable that the center of gravity of the PCa concrete block is arranged at the centroid position of the isosceles triangle shape as viewed from the upper surface portion side of the PCa concrete block.

[0015] Furthermore, in the construction method of the invert part structure in the mountain tunnel of the present invention, it is preferable that a tiltable grounding adjuster is attached to the lower end portion of the height adjustment bolt.

[0016] Furthermore, in the construction method of the invert part structure in the mountain tunnel of the present invention, on the lower surface part of the PCa concrete block, a small trumpet-shaped recess that tapers the peripheral edge of the opening of the bolt insertion and screwing hole and expands in diameter downward is provided. It is preferable that the grounding adjuster is accommodated in the small trumpet-shaped recess when the height adjustment bolt is retracted upward.

[0017] In addition, in the invert part structure in the mountain tunnel of the present invention, in the bolt insertion and screwing hole, a large trumpet-shaped recess is formed that expands in diameter upward from the part where the female screw member is fixed and opens to the upper surface part of the PCa concrete block. In the large trumpet-shaped recess, it is preferable that a rotation operation jig is locked to the upper end part of the height adjustment bolt, and by rotating the height adjustment bolt, the protruding length from the lower surface part of the PCa concrete block can be changed.

Effect of the Invention

[0018] According to the construction method of the invert part structure in the mountain tunnel of the present invention, by using precast concrete blocks (PCa concrete blocks) of appropriate weight and size that are easy to manufacture in factories and the like, the invert part structure can be easily formed without requiring much labor, and as a component of the invert part covering work that is continuously provided from the side wall part of the tunnel to the upper arch-shaped part covering work, it can be installed more quickly.

Brief Explanation of the Drawings

[0019]

Figure 1

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Figure 15

Mode for Carrying Out the Invention

[0020] The invert part structure 10 formed by the construction method of the invert part structure in a mountain tunnel according to a preferred embodiment of the present invention is, in the mountain tunnel 30 shown in FIG. 1, continuously with the lining 31 in the region from the side wall parts 31a on both sides to the upper arch-shaped part 31b, which is formed in advance so as to cover the inner wall surface of the tunnel, when newly forming an invert part lining 32 in the invert part 33 of the bottom part 30a of the mountain tunnel 30, as shown in FIGS. 2 and 3, it is constructed one side at a time with the center line C in the transverse direction of the tunnel interposed therebetween, and is integrated, and thus is provided as a structure that becomes a component of the invert part lining 32.

[0021] In this embodiment, the mountain tunnel 30 is, for example, a tunnel constructed several decades ago, and since the ground to be excavated was stable, during construction, the lining 31 covering the inner wall surface of the tunnel was formed only on the side wall parts 31a on both sides and the upper arch-shaped part 31b. However, due to the passage of years, concerns about the influence of ground swelling and the like in the bottom part 30a have arisen, so a new invert part lining 32 is formed by the invert part structures 10 on both the left and right sides.

[0022] In addition, when newly forming the invert part covering structure 32 in the existing mountain tunnel 30, since it is necessary to block the passage of the tunnel, it is desirable to complete the construction in as short a construction period as possible. The construction method of the invert part structure 10 of the present embodiment uses a plurality of precast concrete blocks (PCa concrete blocks) that are manufactured in advance at a factory or the like and have an appropriate weight and size that are easy to handle. By enabling the work of arranging these PCa concrete blocks 20 vertically and horizontally and installing them in the invert part 33 accurately and easily, the invert part covering structure 32 that is continuous with the covering structure 31 from the side wall part 31a to the upper arch-shaped part 31b of the tunnel can be easily formed one side at a time without much labor, and can be installed in a shorter construction period.

[0023] And, as shown in FIGS. 1 to 4, the construction method of the invert part structure in the mountain tunnel of the present embodiment is a construction method of the structure of the invert part 33 using a plurality of PCa concrete blocks 20 provided in at least one side region in the transverse direction of the tunnel in the invert part 33 of the mountain tunnel 30 and constituting the invert part covering structure 32. As shown in FIGS. 5 and 6(a) to (c), each of the PCa concrete blocks 20 is formed as a hexahedron-shaped block having a curved upper surface part 20a and a curved lower surface part 20b so as to have a curved shape along the cross-sectional shape of the invert part covering structure 32.

[0024] These multiple PCa concrete blocks 20 are arranged in a continuous row in the transverse direction of the tunnel while maintaining gaps 21a and 21b between adjacent receiving base portions 31c and between adjacent PCa concrete blocks 20. Also, in the axial direction of the tunnel, they are arranged in a continuous row while maintaining a gap 21b between adjacent PCa concrete blocks, and are arranged side by side vertically and horizontally and installed on the invert portion 33 (see FIGS. 1 to 4). These multiple PCa concrete blocks 20 arranged in a continuous row vertically and horizontally, as shown in FIG. 10, include a gap 21a between adjacent receiving base portions 31c, a gap 21b between adjacent PCa concrete blocks 20, and a gap 21c below the hexahedral lower surface portion communicating with these gaps 21a and 21b. By filling and curing the filling and solidifying material 22, they are integrated through the cured filling and solidifying material 22 and constitute at least a part of the invert portion covering work body 32, forming one side portion of the invert portion covering work body 32. Further, in each PCa concrete block 20, bolt insertion and screwing holes 25 are formed penetrating vertically at least at three locations, and height adjustment bolts 26 are attached to each bolt insertion and screwing hole 25 in a state where the lower end portion 26a can protrude downward from the lower surface portion 20b of the PCa concrete block 20.

[0025] And the construction method of the invert portion structure of this embodiment includes, prior to the step of filling the filling and solidifying material 22 into the gap 21a between adjacent receiving base portions 31c of the multiple PCa concrete blocks 20 arranged in a continuous row vertically and horizontally, the gap 21b between adjacent PCa concrete blocks 20, and the gap 21c below the hexahedral lower surface portion 20b communicating with these gaps, a step of adjusting the height and inclination of each PCa concrete block 20 by changing the protruding length of the three height adjustment bolts 26 from the lower surface portion 20b of the PCa concrete block 20 by a rotational operation from above the PCa concrete block 20.

[0026] Further, in the present embodiment, a female screw member 25a is fixed to a lower portion of each bolt insertion and screwing hole 25 below the middle in the vertical direction, and by screwing a height adjustment bolt 26 to the female screw member 25a, the height adjustment bolt 26 is attached in a state where the lower end portion 26a can protrude downward from the lower surface portion 20b of the PCa concrete block 20 (see FIG. 7). Further, the bolt insertion and screwing holes 25 are arranged at each corner portion of a triangular shape surrounding the center of gravity of the PCa concrete block 20 and are formed at three locations. Further, a tiltable ground adjuster 26b is attached to the lower end portion 26a of the height adjustment bolt 26 (see FIG. 8). Further, on the lower surface portion 20b of the PCa concrete block 20, a small trumpet-shaped concave portion 25c that is formed by notching the opening peripheral edge portion of the bolt insertion and screwing hole 25 in a tapered shape and whose diameter expands downward is provided, and the ground adjuster 26b is accommodated in the small trumpet-shaped concave portion 25c when the height adjustment bolt 26 is retracted upward.

[0027] And in the present embodiment, preferably, a large trumpet-shaped concave portion 25b that expands in diameter upward from the portion where the female screw member 25a is fixed and opens to the upper surface portion 20a of the PCa concrete block is formed in the bolt insertion and screwing hole 25. In the large trumpet-shaped concave portion 25b, a rotation operation jig is locked to the upper end portion 26d of the height adjustment bolt 26, and by rotating the height adjustment bolt 26, the protruding length b from the lower surface portion 20b of the PCa concrete block 20 is changed (see FIG. 7).

[0028] In this embodiment, as described above, the plurality of PCa concrete blocks 20 constituting the invert portion structure 10 are arranged continuously in the transverse direction of the tunnel while maintaining the gaps 21a and 21b filled with the filling and solidifying material 22 between the lower end receiving portion 31c of the adjacent side wall covering member 31a and between the adjacent PCa concrete blocks 20. Also, in the axial direction of the tunnel, they are arranged continuously while maintaining the gap 21b filled with the filling and solidifying material 22 between the adjacent PCa concrete blocks, and are installed in the invert portion 33 side by side vertically and horizontally. Further, as shown in FIGS. 5 and 6(a) to (c), the PCa concrete block 20 is formed as a hexahedral block having a curved upper surface portion 20a and a curved lower surface portion 20b with a curved shape along the cross-sectional shape of the invert covering member 32, and having a pair of flat axial direction opposing surfaces 20c in the front and rear and a pair of flat transverse direction opposing surfaces 20d on the left and right. The upper surface portion 20a and the lower surface portion 20b in a cross-sectional view can be gently curved with a radius of curvature of, for example, about 14000 mm to 14500 mm.

[0029] Furthermore, in each of these PCa concrete blocks 20, a bolt box 23 or a female screw anchor 24 for connecting adjacent PCa concrete blocks 20 using a bolt member (not shown) is embedded and fixed to four side portions in the upper surface portion having a hexahedral shape. The bolt box 23 opens to the upper surface portion 20a of the PCa concrete block 20, and the female screw anchor 24 opens to the upper end portions of the axially opposing surfaces 20c and the laterally opposing surfaces 20d of the side surface portion. Also, as shown in FIG. 7, in the PCa concrete block 20, bolt insertion and screwing holes 25 penetrating the hexahedral shape in the vertical direction are formed at three locations disposed at respective corner portions of an isosceles triangle shape (see FIG. 6(a)). In each bolt insertion and screwing hole 25, a female screw member 25a to which a height adjustment bolt 26 is screwed is fixed to a lower portion than the intermediate portion in the vertical direction. From the portion where the female screw member 25a of each bolt insertion and screwing hole 25 is fixed, a large trumpet-shaped recess 25b that expands in diameter upward and opens to the upper surface portion 20a of the PCa concrete block 20 is formed, and from the portion where the female screw member 25a is fixed, a small trumpet-shaped recess 25c that expands in diameter downward and opens to the lower surface portion 20b of the PCa concrete block 20 is formed. A height adjustment bolt 26 is inserted into each of these bolt insertion and screwing holes 25 and screwed to the female screw member 25a, so that the height adjustment bolt 26 is attached in a state where the lower end portion 26a protrudes from the lower surface portion 20b of the PCa concrete block 20 in a retractable manner. Also, since the large trumpet-shaped recess 25b and the small trumpet-shaped recess 25c have a trumpet shape that expands in diameter in a tapered manner toward the upper and lower openings, the box removal member attached to the box-shaped formwork for concrete placement for forming these trumpet-shaped recesses 25b, 25c can be smoothly removed after the concrete has hardened. From such a viewpoint, it is preferable that the taper gradient of the large trumpet-shaped recess 25b and the small trumpet-shaped recess 25c having a trumpet shape that expands in diameter in a tapered manner is inclined by 10% or more with respect to the central axis of the bolt insertion and screwing hole 25.

[0030] As shown in Fig. 6(a), the three bolt insertion and fastening holes 25 are disposed at the respective corner portions of a virtual isosceles triangle (see the dashed line) formed on the upper surface portion 20a of the PCa concrete block 20, preferably with the bottom side arranged in parallel with one of the axial opposing surfaces 20c and the top side arranged on the other axial opposing surface 20c side (see Fig. 6(a)).

[0031] In the present embodiment, it is preferable that the center of gravity of the PCa concrete block 20 is arranged inside the area surrounded by the virtual isosceles triangle when viewed from the upper surface side of the PCa concrete block 20. Particularly preferably, the center of gravity of the PCa concrete block 20 is arranged at the centroid position of the virtual isosceles triangle. By these arrangements, it becomes possible to accurately adjust the height and inclination of the PCa concrete block 20 by the three height adjustment bolts 26 in a more stable state, and it also becomes possible to support the PCa concrete block 20 with its height and inclination accurately adjusted by the three height adjustment bolts 26 in a more stable state.

[0032] Furthermore, in some of these PCa concrete blocks 20, namely the PCa concrete blocks 20’ (see Fig. 3), as shown in Figs. 10 and 11, there are formed filling material injection holes 27 that penetrate the hexahedral shape in the vertical direction. In each filling material injection hole 27, a female screw member 27a to which the male screw portion of the opening and closing valve 28 is screwed is fixed at an intermediate portion in the vertical direction. From the portion where the female screw member 27a of each filling material injection hole 27 is fixed, an upper-side trumpet-shaped recess 27b that expands in diameter upward and opens to the upper surface portion 20a of the PCa concrete block 20’ is formed, and a lower-side trumpet-shaped recess 27c that expands in diameter downward and opens to the lower surface portion 20b of the PCa concrete block 20’ is formed. In these filling material injection holes 27, the male screw portion of the opening and closing valve 28 is screwed to the female screw member 27a, and by arranging the handle portion 28a above the upper surface portion 20a of the PCa concrete block 20’, the opening and closing valve 28 is detachably attached to the PCa concrete block 20’ in a state where the opening and closing operation of the handle portion 28a can be performed by the operation on the upper surface portion 20a of the PCa concrete block 20’. Also, since the upper-side trumpet-shaped recess 27b and the lower-side trumpet-shaped recess 27c have a trumpet shape that expands in diameter in a tapered manner toward the upper and lower openings, it becomes possible to smoothly remove the core removal member attached to the box-shaped formwork for concrete placement after the concrete has hardened in order to form these trumpet-shaped recesses 27b, 27c. From this perspective, it is also preferable that the taper gradient of these trumpet-shaped recesses 27b, 27c is inclined by 10% or more with respect to the central axis of the filling material injection hole 27.

[0033] In the present embodiment, the filling material injection holes 27 that penetrate the hexahedral PCa concrete block 20’ in the vertical direction can preferably be arranged and formed at the central portion of the upper surface portion 20a of the PCa concrete block 20’ (see Fig. 6(a)). In particular, the filling material injection holes 27 are preferably arranged and formed at the central portion of the central block 20B located at the lowest position.

[0034] In addition, in the present embodiment, these PCa concrete blocks 20 (20') are preferably provided with spacer jigs 29a and 29b on each of a pair of flat axial opposing surfaces 20c and a pair of flat transverse opposing surfaces 20d of a hexahedral shape, so as to hold a gap 21b with a predetermined interval width between the opposing other opposing surfaces 20c and 20d (see FIGS. 5, 6(b), and 6(c)). On the upper surface portion 20a, which is preferably of a hexahedral shape, a plurality of lifting jigs 29c used when lifting each PCa concrete block 20 are embedded and fixed (see FIG. 6(a)).

[0035] In the present embodiment, these PCa concrete blocks 20 are, for example, formed in a box-shaped formwork assembled along the above-described predetermined hexahedral shape in a manufacturing factory. After placing and curing concrete inside the formwork, they are demolded after a predetermined curing period. Thus, they are preferably formed to have a hexahedral shape with a curved upper surface portion 20a and a lower surface portion 20b, with a lateral width x of about 1385 to 1435 mm, a longitudinal width y of about 730 mm, and a height z of about 500 mm, and have a weight of about 1300 kg. For example, by arranging setup bars inside the box-shaped formwork and supporting them, and attaching box-cutting members for the above-described bolt box 23, female screw anchors 24, bolt insertion and screwing holes 25, and filler injection holes 27, etc., these can be embedded and fixed or temporarily fixed to the PCa concrete blocks 20. In the present embodiment, the size, shape, weight, etc. of the PCa concrete blocks 20 used as invert blocks can be appropriately designed according to the capabilities of a crane, etc., so as to be used without affecting vehicle passage, etc. in the other one-sided region 55B in the work yard 71 of the one-sided region 55A. For example, the weight of the PCa concrete blocks 20 can preferably be set to 1000 to 1500 kg.

[0036] In addition, in the present embodiment, since the plurality of PCa concrete blocks 20 are formed to have the same hexahedron shape, it is possible to limit the types of box-shaped formworks to be used and manufacture them efficiently. Moreover, since the blocks have the same weight, the workability during lifting and transportation is improved, and they can be handled in the same way when being lifted or installed. For example, the work of accurately installing each PCa concrete block 20 at a predetermined position so as to be arranged in a potato-like shape can be easily performed. It is also possible to reduce the cost during manufacturing.

[0037] In the present embodiment, the invert portion structure 10 is constructed in each of the pair of one-side regions sandwiching the center in the transverse direction of the tunnel (see FIGS. 1 and 2). At the center in the transverse direction of the tunnel in the invert portion 33, in order to prevent the other one-side region from being affected when constructing the invert portion structure 10 in each one-side region, H-shaped steels 35 for supporting a retaining plate member, a protective fence, etc. can be driven into the ground of the invert portion 33 at predetermined intervals in the axial direction of the tunnel with their flange portions along the axial direction of the tunnel, and a plurality of them can be erected. Therefore, at the central-side end portions of a pair of PCa concrete blocks (central portion-side blocks) 20B adjacent to each other in the axial direction of the tunnel on the central side in the transverse direction of the tunnel at the positions where these H-shaped steels 35 are erected, notch recesses 20e having a rectangular cross-sectional shape can be formed at both corner portions sandwiching the gap 21b therebetween (see FIG. 3). By these notch recesses 20e at both corner portions, flange arrangement recesses 10a for arranging one flange portion of the H-shaped steel 35 can be provided at the portions where the H-shaped steels 35 are erected on the central-side end surface portions (central-side end surface portions) 10B of each invert portion structure 10 on the central side in the transverse direction of the tunnel.

[0038] That is, in the block groups 20X and 20Y (see FIG. 1) composed of a plurality of PCa concrete blocks 20 that constitute the invert part structure 10 of each one-sided region, the PCa concrete block 20 (central part side block 20B) disposed at the portion where the H-shaped steel 35 stands upright is formed as a hexahedral block having a curved upper surface portion 20a and a lower surface portion 20b with a curved shape along the cross-sectional shape of the invert part covering member 32, and having a pair of flat axial direction opposing surfaces 20c in the front and rear and a pair of flat transverse direction opposing surfaces 20d in the left and right (see FIGS. 6(a) to 6(c)). As shown in FIG. 3, at the corner portion of any one of the axial direction opposing surface 20c and the transverse direction opposing surface 20d, a notch recess 20e having a rectangular cross-sectional shape is provided continuously from the upper surface portion 20a to the lower surface portion 20b, and is cut out so as to have a side portion with a width of at least half of the lateral width of the flange portion of the H-shaped steel 35. As a result, at the central side end portions of the pair of central part side blocks 20B adjacent in the axial direction of the tunnel at the portion where the H-shaped steel 35 stands upright, a flange arrangement recess 10a capable of bypassing the flange portion of the H-shaped steel 35 is formed by these notch recesses 20e.

[0039] And in this embodiment, these multiple PCa concrete blocks 20 that constitute the invert part structure 10 are, as shown in FIGS. 3 and 4, a pedestal-side block 20A arranged adjacent to the pedestal part 31c at the lower end of the side wall covering member 31a, a central part-side block 20B arranged on the central part side in the transverse direction of the invert part, and one or a plurality of intermediate blocks 20C (in this embodiment, one intermediate block 20C) arranged therebetween, having a plurality of transverse direction block rows 20D. These PCa concrete blocks 20A, 20B, 20C are arranged continuously in the transverse direction of the tunnel while maintaining gaps 21a, 21b between adjacent pedestal parts 31c and between adjacent PCa concrete blocks 20A, 20B, 20C, and are also arranged continuously in the axial direction of the tunnel while maintaining a gap 21b between adjacent PCa concrete blocks 20A, 20B, 20C (transverse direction block rows 20D), and are installed in the invert part 33 by arranging them side by side vertically and horizontally. These multiple PCa concrete blocks 20A, 20B, 20C used when constructing the invert part structure 10 can be constructed by the following method for installing PCa blocks in the invert part.

[0040] That is, in the method for installing PCa blocks in the invert part according to this embodiment, for the multiple PCa concrete blocks 20A, 20B, 20C of each transverse direction block row 20D arranged continuously in the transverse direction of the tunnel, as shown in FIG. 4, after installing the pedestal-side block 20A adjacent to the pedestal part 31c and temporarily fixing it with the temporary fixing means 36, the intermediate block 20C and the central part-side block 20B are sequentially installed adjacent to the temporarily fixed pedestal-side block 20A, so that the multiple PCa concrete blocks 20A, 20B, 20C of each row (transverse direction block row) 20D arranged continuously in the transverse direction of the tunnel are installed in the invert part 33.

[0041] For example, after installing the pedestal side block 20A adjacent to the pedestal 31c and temporarily fixing it with the temporary fixing means 36, the intermediate block 20C and the central side block 20B are sequentially installed adjacent to the temporarily fixed pedestal side block 20A. At each adjacent location of these installed blocks 20A, 20B, 20C, through the bolt box 23 disposed on the upper surface portion 20a of at least one of the PCa concrete blocks 20A, 20B, 20C close to the transverse facing surface 20d, after temporarily fixing with a bolt member (not shown), the height and position of each PCa concrete block 20A, 20B, 20C are adjusted, and then the bolt member is tightened. By doing so, the plurality of PCa concrete blocks 20A, 20B, 20C of each transverse block row 20D continuously arranged in the transverse direction of the tunnel can be installed on the invert portion 33.

[0042] Also, for example, after installing the pedestal side block 20A adjacent to the pedestal 31c and temporarily fixing it with the temporary fixing means 36, the intermediate block 20C is installed adjacent to the temporarily fixed pedestal side block 20A. At the adjacent location of the installed intermediate block 20C and the pedestal side block 20A, after temporarily fixing with a bolt member (not shown) through the bolt box 23 disposed on the upper surface portion 20a of at least one of the PCa concrete blocks 20A, 20C close to the transverse facing surface 20d, the height and position of each PCa concrete block 20A, 20C are adjusted, and then the bolt member is tightened. Subsequently, the central side block 20B is installed adjacent to the intermediate block 20C. At the adjacent location of the installed central side block 20B and the intermediate block 20C, after temporarily fixing with a bolt member through the bolt box 23 disposed on the upper surface portion 20a of at least one of the PCa concrete blocks 20C, 20B close to the transverse facing surface 20d, after adjusting the height and position of the central side block 20B, by tightening the bolt member, the plurality of PCa concrete blocks 20A, 20B, 20C of each transverse block row 20D continuously arranged in the transverse direction of the tunnel can also be installed on the invert portion 33.

[0043] Here, in the present embodiment, the temporary fixing means 36 for temporarily fixing the pedestal side block 20A adjacent to the pedestal 31c can preferably be constituted by a cord-like body 36b such as a wire or a chain, with both ends locked 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 suspension jig 29c provided on the pedestal side block 20A. The cord-like body 36b such as a wire or a chain can be provided with a stretch adjustment means 36c such as a turnbuckle or the like that can adjust the length between the both ends to be locked. As a result, the interval width of the gap 21a held between the pedestal 31c and the adjacent pedestal side block 20A can be made adjustable.

[0044] In addition, in the present embodiment, the height adjustment of each of the PCa concrete blocks 20A, 20B, and 20C can be carried out using three height adjustment bolts 26 respectively screwed into the bolt insertion and fastening holes 25 formed at the above-mentioned three positions, as shown in FIGS. 6(a) and 7. That is, in each of the PCa concrete blocks 20A, 20B, and 20C, the bolt insertion and fastening holes 25 are formed at three positions penetrating in the vertical direction, and in each of the bolt insertion and fastening holes 25, the height adjustment bolts 26 are attached in a state where the lower end portions 26a can protrude downward from the lower surface portions 20b of the PCa concrete blocks 20A, 20B, and 20C. Prior to the step of filling the gaps 21a between the adjacent receiving portions 31c of the plurality of PCa concrete blocks 20A, 20B, and 20C arranged longitudinally and transversely, the gap 21b between the adjacent PCa concrete blocks 20A, 20B, and 20C, and the gap 21c below the hexahedral lower surface portion 20b communicating with these gaps 21a and 21b with the filling and solidifying material 22 (see FIG. 10), by a rotation operation from above the PCa concrete blocks 20A, 20B, and 20C, the protruding lengths of the three height adjustment bolts 26 from the lower surface portions 20b of the PCa concrete blocks 20A, 20B, and 20C in each of the PCa concrete blocks 20A, 20B, and 20C are changed, and a step of adjusting the height and inclination of each of the PCa concrete blocks 20A, 20B, and 20C is performed. In the present embodiment, although the bolt insertion and fastening holes 25 are formed at three positions, the present invention is not limited thereto, and they may be formed at four or more positions.

[0045] As described above, in the present embodiment, preferably, a nut member is fixed as a female screw member 25a at a portion below the middle portion in the vertical direction of each bolt insertion and screwing hole 25. By screwing the height adjustment bolt 26 to the nut member 25a, the height adjustment bolt 26 is attached in a state where the lower end portion 26a can project downward from the lower surface portion 20b of the PCa concrete blocks 20A, 20B, and 20C. Further, a tiltable ground contact adjuster 26b can be attached to the lower end portion 26a of the height adjustment bolt 26 (see Fig. 8(a)). By tilting the ground contact adjuster 26b with respect to the lower end portion 26a of the height adjustment bolt 26, the adjuster 26b can be tilted along, for example, the ground surface serving as the filling bottom surface portion 26c. As a result, the lower end portion 26a of the height adjustment bolt 26 can be grounded to the filling bottom surface portion 26c below the lower surface portion 20b in a stable state.

[0046] When the height adjustment bolt 26 is retracted upward, the ground adjusting member 26b is preferably configured to be accommodated in the above-described small trumpet-shaped concave portion 25c that expands in diameter downward. For example, as shown in FIG. 8(b), by forming the small trumpet-shaped concave portion 25c as a trumpet-shaped concave portion that expands in diameter downward and is slightly larger than the outer peripheral shape of the ground adjusting member 26b, the ground adjusting member 26b having the same shape as the small trumpet-shaped concave portion 25c can be easily accommodated inside the small trumpet-shaped concave portion 25c without protruding downward from the lower surface portion 20b of the PCa concrete block 20. As a result, even when the gap 21c between the lower surface portion 20b of the PCa concrete block 20 and the filling bottom surface portion 26c is less than the height of the ground adjusting member 26b, the adjusting member 26b can be grounded to the filling bottom surface portion 26c, enabling fine adjustment of the height of the PCa concrete block 20. Also, when the height position of the filling bottom surface portion 26c after leveling is the same as the design position of the lower surface portion 20b of the PCa concrete block 20 and there is no margin, the entire ground adjusting member 26b can be accommodated in the small trumpet-shaped concave portion 25c, and with these lower surface portions 20b being in contact with the filling bottom surface portion 26c, each PCa concrete block 20 can be installed at a predetermined position.

[0047] It is preferable that the height from the opening in the lower surface portion 20b of the PCa concrete block 20 to the lower end of the female screw member 25a in the small trumpet-shaped concave portion 25c is about 60 to 80 mm, and the opening diameter in the lower surface portion 20b is about 65 to 70 mm. From the viewpoint of facilitating removal of the knockout member after the concrete has hardened, the taper gradient of the small trumpet-shaped concave portion 25c is preferably inclined by 10% or more with respect to the central axis of the bolt insertion and screwing hole 25.

[0048] In addition, in the present embodiment, the upper end portion 26d of the height adjustment bolt 26 is preferably formed to have a square cross section. An extension bar for insertion, for example, is locked to the upper end portion 26d as a rotation operation jig, and the rotation operation of the height adjustment bolt 26 is performed. By working above the upper surface portion 20a of the PCa concrete blocks 20A, 20B, and 20C, the protruding length of the lower end portion 26a of the height adjustment bolt 26 from the lower surface portion 20b of the PCa concrete blocks 20A, 20B, and 20C can be easily changed. As described above, the bolt insertion and screwing hole 25 is formed with a large trumpet-shaped recess 25b that expands upward from the portion where the nut member 25a, which is a female screw member, is fixed and opens to the upper surface portion 20a of the PCa concrete blocks 20A, 20B, and 20C. When the upper end portion 26d of the height adjustment bolt 26 protrudes from the upper surface portion 20a of the PCa concrete blocks 20A, 20B, and 20C or is close to the upper surface portion 20a and sufficient covering thickness cannot be ensured above the upper end portion 26d when the large trumpet-shaped recess 25b is filled with a finishing filler, the upper end portion 26d of the height adjustment bolt 26 can be appropriately cut to a required length in the large trumpet-shaped recess 25b. Thereby, it becomes possible to ensure a desired covering thickness with a finishing filler such as mortar filled in the bolt insertion and screwing hole 25 and prevent the height adjustment bolt 26 from corroding. The operation of cutting the upper end portion 26d of the height adjustment bolt 26 can be performed smoothly because a sufficient working space can be ensured in the large trumpet-shaped recess 25b that expands upward.

[0049] Preferably, the large trumpet-shaped recess 25b has a height of about 360 to 380 mm from the opening in the upper surface portion 20a of the PCa concrete block 20 to the upper end of the female screw member 25a, and an opening diameter in the upper surface portion 20a of about 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 and screwing hole 25 from the viewpoint of facilitating removal of the knockout member after the concrete has hardened.

[0050] And in the present embodiment, as described above, in each of the PCa concrete blocks 20A, 20B, and 20C, bolt insertion and screwing holes 25 are formed at three locations penetrating in the vertical direction. A height adjustment bolt 26 is attached to each bolt insertion and screwing hole 25 in a state where the protruding length of the lower end portion 26a protruding downward from the lower surface portion 20b of the PCa concrete blocks 20A, 20B, and 20C can be adjusted. As a result, the gap 21a between the adjacent receiving base portions 31c of the plurality of PCa concrete blocks 20A, 20B, and 20C arranged continuously in the vertical and horizontal directions, the gap 21b between the adjacent PCa concrete blocks 20A, 20B, and 20C, and the gap 21c below the hexahedral lower surface portion 20b communicating with these gaps 21a and 21b. Prior to the step of filling the filling and solidifying material 22, from the protruding length of the lower end portion 26a of the height adjustment bolt 26 protruding from the lower surface portion 20b of each of the PCa concrete blocks 20A, 20B, and 20C, the interval width b (see FIGS. 7 and 10) of the gap 21c below the hexahedral lower surface portion 20b is measured, and based on this and the area of the lower surface portion 20b of the PCa concrete blocks 20A, 20B, and 20C, the planned filling amount of the filling and solidifying material 22 to be filled in the gap 21c below the hexahedral lower surface portion 20b can be calculated in advance. In the step of filling the filling and solidifying material 22, with reference to the calculated planned filling amount, a predetermined amount of the filling and solidifying material 22 is injected into the gap 21c below the hexahedral lower surface portion 20b and filled and hardened.

[0051] That is, in the present embodiment, a nut member 25a is fixed as a female screw member to a portion below the middle in the vertical direction of each bolt insertion and screwing hole 25. By screwing a height adjustment bolt 26 onto the nut member 25a, the height adjustment bolt 26 is attached in a state where the protruding length of the lower end portion 26a from the lower surface portion 20b of the PCa concrete blocks 20A, 20B, and 20C can be adjusted. Therefore, for example, when the lower end portion 26a of the height adjustment bolt 26 is grounded to the filling bottom surface portion 26c below the hexahedral lower surface portion 20b, the interval width b of the gap 21c below the hexahedral lower surface portion 20b can be easily measured from the length of the height adjustment bolt 26 above the nut member 25a.

[0052] Further, in the present embodiment, a tiltable grounding adjuster 26b is preferably attached to the lower end portion 26a of the height adjustment bolt 26. Therefore, when the grounding adjuster 26b is grounded to the filling bottom surface portion 26c below the hexahedral lower surface portion 20b, the interval width b of the gap 21c below the hexahedral lower surface portion 20b can be easily measured in a more stable state from the length of the height adjustment bolt 26 above the nut member 25a.

[0053] The planned filling amount of the filling and solidifying material 22 can be calculated in advance by calculating the filling amount to be filled in the gap 21c below the hexahedral lower surface portion 20b of each of the PCa concrete blocks 20A, 20B, and 20C based on the average of the interval widths b of the gaps 21c below the hexahedral lower surface portion 20b measured by the three height adjustment bolts 26 attached to the three bolt insertion and screwing holes 25 of each of the PCa concrete blocks 20A, 20B, and 20C.

[0054] Also, the planned filling amount of the filling and solidifying material 22 can be calculated in advance by calculating the filling amount filled in the gaps below the hexahedral lower surface portions 20b of the PCa concrete blocks 20A, 20B, and 20C that make up the invert portion structure 10, based on the overall average of the interval width b of the gaps 21c below the three bolt insertion and screwing holes 25 of each of the three height adjustment bolts 26 attached to the three bolt insertion and screwing holes 25 of all the PCa concrete blocks 20A, 20B, and 20C that make up the invert portion structure 10.

[0055] Furthermore, in this embodiment, in the invert portion structure 10 using the above-described PCa concrete blocks 20A, 20B, and 20C, as a structure of a connecting portion for connecting and arranging the plurality of PCa concrete blocks 20A, 20B, and 20C vertically and horizontally in a state where a gap 21b with a predetermined interval width is maintained between the adjacent PCa concrete blocks 20A, 20B, and 20C and installing them integrally in the invert portion 33, the following connecting portion structure 37 of the PCa blocks in the invert portion structure can be adopted.

[0056] That is, in the present embodiment, as shown in FIGS. 3, 4, and 6(a) to (c), the connecting portion structure 37 of the PCa concrete blocks in the inverter portion structure has a transverse direction spacer jig 29a (see FIG. 6(b)) fixed to one of the pair of transverse direction opposing surfaces 20d that face each other in the transverse direction of the PCa concrete blocks 20A, 20B, and 20C adjacent in the transverse direction of the tunnel, and is preferably arranged and interposed at at least three locations. Further, in the bolt box 23 disposed on the upper surface portion 20a of at least one of the PCa concrete blocks 20A, 20B, and 20C close to these transverse direction opposing surfaces 20d, the PCa concrete blocks 20A, 20B, and 20C adjacent to each other in the transverse direction of the tunnel are connected in a state where a gap 21b with a predetermined interval width is maintained between the transverse direction opposing surfaces 20d by the tightening force of a bolt member (not shown) tightened therein. Also, an axial direction spacer jig 29b (see FIG. 6(c)) fixed to one of the pair of axial direction opposing surfaces 20c that face each other in the axial direction of the PCa concrete blocks 20A, 20B, and 20C adjacent in the axial direction of the tunnel is preferably arranged and interposed at at least three locations. Further, in the bolt box 23 disposed on the upper surface portion 20a of at least one of the PCa concrete blocks 20A, 20B, and 20C close to these axial direction opposing surfaces 20c, the PCa concrete blocks 20A, 20B, and 20C adjacent to each other in the axial direction of the tunnel are connected in a state where a gap 21b with a predetermined interval width is maintained between the axial direction opposing surfaces 20c by the tightening force of a bolt member (not shown) tightened therein. The transverse direction spacer jig 29a and the axial direction spacer jig 29b can also be attached to the transverse direction opposing surfaces 20d and the axial direction opposing surfaces 20c at the positions where the bolt box 23 is provided.

[0057] In this embodiment, the transverse direction spacer jig 29a and / or the axial direction spacer jig 29b can be made of a mortar block preferably attached and fixed to either one of the opposing surfaces 20c and 20d. The spacer jigs 29a and 29b made of a mortar block can be detachably attached to the opposing surfaces 20c and 20d and removed after the PCa concrete blocks 20A, 20B, and 20C are fully tightened and connected. The transverse direction spacer jig 29a and / or the axial direction spacer jig 29b can also be made of a male screw member that is fixedly attached with an adjustable protruding length by being screwed into a female screw insert embedded in either one of the opposing surfaces 10c and 10d.

[0058] The transverse direction spacer jig 29a or the axial direction spacer jig 29b, which is preferably fixed to either one of the transverse direction opposing surface 20d or the axial direction opposing surface 20c and arranged at least at three positions, is preferably fixed at least at two positions in a region below the center of gravity position of the PCa concrete blocks 20A, 20B, and 20C. This makes it possible to accurately and appropriately form the gaps 21a and 21b at a predetermined interval in a stable state in a region below the center of gravity position, where it is difficult to confirm that the gaps 21a and 21b are accurately provided without using a special device when installing the PCa concrete blocks 20A, 20B, and 20C.

[0059] In the bolt box 23 disposed on the upper surface portion 20a of at least one of the PCa concrete blocks 20A, 20B, 20C adjacent to the transverse direction facing surface 20d, the bolt member fastened in the bolt box 23, or the bolt member fastened in the bolt box 23 disposed on the upper surface portion 20a of at least one of the PCa concrete blocks 20A, 20B, 20C adjacent to the axial direction facing surface 20c may preferably be fastened across the bolt box 23 disposed on the upper surface portion 20a adjacent to the axial direction facing surface 20c or the transverse direction facing surface 20d of one of the PCa concrete blocks 20A, 20B, 20C and the female screw anchor 24 embedded in the axial direction facing surface 20c or the transverse direction facing surface 20d of the other PCa concrete block 20A, 20B, 20C. Preferably, it may be fastened across the bolt box 23 disposed on the upper surface portion 20a adjacent to the axial direction facing surface 20c or the transverse direction facing surface 20d of one of the PCa concrete blocks 20A, 20B, 20C and the bolt box 23 disposed on the upper surface portion 20a adjacent to the axial direction facing surface 20c or the transverse direction facing surface 20d of the other PCa concrete block 20A, 20B, 20C.

[0060] And in this embodiment, when the mountain tunnel includes a portion having a tunnel alignment that curves in the horizontal direction, a plurality of PCa concrete blocks 20A, 20B, 20C are arranged longitudinally and horizontally in a state where a gap 21b having a predetermined interval width is maintained between the adjacent PCa concrete blocks 20A, 20B, 20C and along the tunnel alignment that curves in the horizontal direction, and can be integrally installed in the invert portion 33.

[0061] That is, in the present embodiment, between each pair of transverse direction facing surfaces 20d of the PCa concrete blocks 20A, 20B, 20C adjacent in the transverse direction of the tunnel and facing each other in the transverse direction, transverse direction spacer jigs 29a (see Fig. 6(b)) fixed to either one of the transverse direction facing surfaces 20d are arranged and interposed at least at three locations. And by the tightening force of a bolt member (not shown), each pair of PCa concrete blocks 20A, 20B, 20C adjacent in the transverse direction of the tunnel are connected while holding a gap 21b with a predetermined interval width between the transverse direction facing surfaces 20d, forming a transverse direction block row 20D composed of a plurality of PCa concrete blocks 20A, 20B, 20C (see Fig. 3). Between each pair of axial direction facing surfaces 20c of the PCa concrete blocks 20A, 20B, 20C adjacent in the axial direction of the tunnel and facing each other in the axial direction, axial direction spacer jigs 29b (see Fig. 6(c)) fixed to either one of the axial direction facing surfaces 20c are arranged and interposed at least at three locations. And by the tightening force of a bolt member (not shown), each pair of PCa concrete blocks 20A, 20B, 20C adjacent in the axial direction of the tunnel are connected while holding a gap 21b with a predetermined interval width between the axial direction facing surfaces 20c (see Fig. 3). And as shown in Fig. 9(a), at one or two or more connection portions 20f in the axial direction of the tunnel between the transverse direction block rows 20D arranged in a plurality in the axial direction of the tunnel, the axial direction spacer jigs 29b interposed between a pair of axial direction facing surfaces 20c in the axial direction of the tunnel are fixed to the outer PCa concrete block 20E located on the outer side of the tunnel linear shape that curves in the horizontal direction in the transverse direction of the tunnel. The interval width of the outer gap 21b held by the axial direction spacer jig 29b is larger than the interval width of the inner gap 21b held by the axial direction spacer jig 29b fixed to the inner PCa concrete block 20F located on the inner side of the tunnel linear shape that curves in the horizontal direction. The intervening width is adjusted and fixed to the axial direction facing surface 20c. Thereby, it becomes possible to vertically and horizontally connect and arrange a plurality of PCa concrete blocks 20A, 20B, 20C along the tunnel linear shape that curves in the horizontal direction and install them integrally in the invert portion 33.Also, this makes it possible to correspond to a tunnel shape that curves horizontally using rectangular PCa concrete blocks 20A, 20B, and 20C without using tapered blocks.

[0062] Here, when the axial spacer jig 29b is made of a mortar block attached and fixed to one of the axial opposing surfaces 20c, in the connecting portion 20f with different intervening widths, by fixing mortar blocks of different sizes to the outer PCa concrete block 20E and the inner PCa concrete block 20F, the intervening width can be adjusted so that the interval width of the outer gap 21b becomes larger than the interval width of the inner gap 21b.

[0063] Also, when the axial spacer jig 29b is made of a male screw member that is fixed in an adjustable protruding length by being screwed into a female screw insert embedded in one of the axial opposing surfaces 20c, in the connecting portion 20f with different intervening widths, by screwing and fixing the male screw member with different screwing amounts to the outer PCa concrete block 20E and the inner PCa concrete block 20F, the intervening width can be adjusted so that the interval width of the outer gap 21b becomes larger than the interval width of the inner gap 21b.

[0064] On the other hand, in the present embodiment, when the mountain tunnel includes a portion having a tunnel shape that curves in the vertical direction, a plurality of PCa concrete blocks 20A, 20B, and 20C are arranged vertically and horizontally in a state where a gap 21b with a predetermined interval width is maintained between adjacent PCa concrete blocks 20A, 20B, and 20C and along the tunnel shape that curves in the vertical direction, and can be installed integrally with the invert portion 33.

[0065] That is, in the present embodiment, between each pair of transverse direction opposing surfaces 20d of the PCa concrete blocks 20A, 20B, 20C adjacent in the transverse direction of the tunnel, a transverse direction spacer jig 29a (see Fig. 6(b)) fixed to either one of the transverse direction opposing surfaces 20d is disposed and interposed at at least three locations. Further, by the tightening force of a bolt member (not shown), each pair of PCa concrete blocks 20A, 20B, 20C adjacent in the transverse direction of the tunnel are connected while holding a gap 21b with a predetermined gap width between the transverse direction opposing surfaces 20d, forming a transverse direction block row 20D composed of a plurality of PCa concrete blocks 20A, 20B, 20C (see Fig. 3). Between each pair of axial direction opposing surfaces 20c of the PCa concrete blocks 20A, 20B, 20C adjacent in the axial direction of the tunnel, an axial direction spacer jig 29b (see Fig. 6(c)) fixed to either one of the axial direction opposing surfaces 20c is disposed and interposed at at least three locations. Further, by the tightening force of a bolt member (not shown), each pair of PCa concrete blocks 20A, 20B, 20C adjacent in the axial direction of the tunnel are connected while holding a gap 21b with a predetermined gap width between the axial direction opposing surfaces 20c. And as shown in Fig. 9(b), in one or two or more axial direction connection portions 20g of the tunnel between the plurality of continuously arranged transverse direction block rows 20D in the axial direction of the tunnel, at least three axial direction spacer jigs 29b interposed between each pair of axial direction opposing surfaces 20c facing in the axial direction of the tunnel are fixed to the axial direction opposing surfaces 20c in a state where the intervening width is adjusted such that the gap width of the upper gap 21b held by the axial direction spacer jig 29b disposed in the upper stage and the gap width of the lower gap 21b held by the axial direction spacer jig 29b disposed in the lower stage are different widths. Thereby, it becomes possible to vertically and horizontally connect and arrange a plurality of PCa concrete blocks 20A, 20B, 20C along a tunnel linear shape that curves in the vertical direction and install them integrally in the invert portion 33. Further, thereby, even without using tapered blocks, it becomes possible to use rectangular parallelepiped-shaped PCa concrete blocks 20A, 20B, 20C to correspond to a tunnel linear shape that curves in the vertical direction.

[0066] For example, in the connecting portion 20g with different intervening widths, by adjusting these intervening widths such that the interval width of the upper gap 21b held by the axial spacer jig 29b disposed in the upper stage is larger than the interval width of the lower gap 21b held by the axial spacer jig 29b disposed in the lower stage, it becomes possible to arrange the plurality of laterally connected block rows 20D along a tunnel linear shape that curves downward in the vertical direction.

[0067] Also, in the connecting portion 20g with different intervening widths, by adjusting these intervening widths such that the interval width of the upper gap 21b held by the axial spacer jig 29b disposed in the upper stage is smaller than the interval width of the lower gap 21b held by the axial spacer jig 29b disposed in the lower stage, it becomes possible to arrange the plurality of laterally connected block rows 20D along a tunnel linear shape that curves upward in the vertical direction.

[0068] Here, when the axial spacer jig 29b is made of a mortar block that is affixed and adhered to either one of the axial opposing surfaces 20c, in the connecting portion 20g with different intervening widths, by affixing mortar blocks of different sizes in the upper and lower stages, the intervening width can be adjusted so that the interval width of the gap 21b held in the upper part and the interval width of the gap 21b held in the lower part are different widths.

[0069] Also, when the axial spacer jig 29b is made of a male screw member that is fixed so that the protruding length can be adjusted by being screwed into a female screw insert embedded in either one of the axial opposing surfaces 20c, in the connecting portion 20g with different intervening widths, by screwing and fixing the male screw member with different screwing amounts in the upper and lower stages, the intervening width can be adjusted so that the interval width of the gap 21b held in the upper part and the interval width of the gap 21b held in the lower part are different widths.

[0070] And in the present embodiment, a plurality of PCa concrete blocks 20A, 20B, 20C arranged in series vertically and horizontally are integrated through a filled and solidified material 22 filled and cured in a gap 21a between adjacent receiving base portions 31c, a gap 21b between adjacent PCa concrete blocks 20A, 20B, 20C, and a gap 21c below the lower surface portion of a hexahedron shape communicating with these gaps, so as to constitute at least a part of the invert portion covering work body 32. In the present embodiment, the filled and solidified material 22 is filled into the gap 21a between adjacent receiving base portions 31c, the gap 21b between adjacent PCa concrete blocks 20A, 20B, 20C, and the gap 21c below the lower surface portion of a hexahedron shape communicating with these gaps 21a, 21b by the following construction method.

[0071] That is, in the present embodiment, in the step of filling the gap 21a between adjacent receiving base portions 31c of a plurality of PCa concrete blocks 20A, 20B, 20C arranged longitudinally and transversely, the gap 21b between adjacent PCa concrete blocks 20A, 20B, 20C, and the gap 21c below the hexahedral lower surface portion communicating with these gaps 21a, 21b with the filling and solidifying material 22, the openings of the gaps 21a, 21b opening in the upper surface portion 20a, the wife-side end surface portion 10A (see FIGS. 3 and 12), and the central-side end surface portion 10B (see FIGS. 3 and 12) of the plurality of PCa concrete blocks 20A, 20B, 20C arranged longitudinally and transversely are closed. Thereafter, as shown in FIGS. 10 to 12, in one or two or more of the plurality of central portion side blocks 20B arranged in the axial direction of the tunnel, a central portion side filling material injection hole 27d provided to penetrate in the vertical direction, and in one or two or more of the plurality of receiving base portion side blocks 20A arranged in the axial direction of the tunnel, the filling and solidifying material 22 is sequentially injected from a receiving base portion side filling material injection hole 27e provided to penetrate in the vertical direction. Preferably, as shown in FIG. 12, after starting the injection of the filling and solidifying material 22 from the central portion side filling material injection hole 27d, switching to the filling material injection hole 27e on the receiving base portion 31c side and further injecting the filling and solidifying material 22, it is confirmed that the filling and solidifying material 22 flows out from the opening of the gap 21a between the receiving base portion 31c held on the upper surface portion 20a of the receiving base portion side block 20A, and the filling of the filling and solidifying material 22 is completed. Without using the filling material injection hole 27e of the receiving base portion side block 20A, the filling and solidifying material 22 can be injected using only the filling material injection hole 27d of the central portion side block 20B, and it can be confirmed that the filling and solidifying material 22 flows out from the opening of the gap 21a between the receiving base portion 31c held on the upper surface portion 20a of the receiving base portion side block 20A, and the filling of the filling and solidifying material 22 can be completed.

[0072] In addition, in the present embodiment, the plurality of PCa concrete blocks 20A, 20B, 20C arranged longitudinally and transversely are preferably provided adjacent to each other in the axial direction of the tunnel of the existing invert structure 40 (see FIGS. 3 and 12) formed in advance. With the opening portion of the gap 21d between the existing invert structure 40, which opens at the upper surface portion 20a and the central side end surface portion 10B of the plurality of PCa concrete blocks 20A, 20B, 20C arranged longitudinally and transversely, closed, preferably as shown in FIG. 12, while switching from the filling material injection hole 27d on the central side located on the existing invert structure 40 side to the filling material injection hole 27d on the central side located on the wife side, the filling and solidifying material 22 is injected. At the same time, while switching from the filling material injection hole 27e on the pedestal side located on the existing invert structure 50 side to the filling material injection hole 27e on the pedestal side located on the wife side, the filling and solidifying material 22 is injected. After switching from the filling material injection hole 27d of the central block 20B on the existing invert structure 50 side to the filling material injection hole 27d of the central block 20B on the wife side and injecting the filling and solidifying material 22 halfway, it is also possible to further switch from the filling material injection hole 27e of the pedestal side block 20A on the existing invert structure 50 side to the filling material injection hole 27e of the pedestal side block 20A on the wife side and inject the filling and solidifying material 22.

[0073] Furthermore, in this embodiment, preferably, the upper surface strip-shaped formwork 41a is overlapped and fixed to the upper surface portion 20a so as to cover the opening portions of the gaps 21b in the upper surface portions 20a of the plurality of PCa concrete blocks 20A, 20B, 20C arranged longitudinally and laterally in series, whereby the opening portions of the upper surface portion 20a are closed (see FIGS. 10 and 13). Also in the wife-side end surface portion 10A, preferably, the wife-side strip-shaped formwork 41b is overlapped and fixed to the wife-side end surface portion 10A so as to cover the opening portions of the gaps 21a, 21b, 21c, whereby the opening portions of the wife-side end surface portion 10A are closed (see FIG. 14). Also in the central-side end surface portion 10B, similar to the wife-side end surface portion 10A, preferably, the central-side strip-shaped formwork 41c is overlapped and fixed to the central-side end surface portion 10B so as to cover the opening portions of the gaps 21b, 21c, 21d, whereby the opening portions of the central-side end surface portion 10B are closed (see FIG. 10).

[0074] Also, the upper surface strip-shaped formwork 41a, the wife-side strip-shaped formwork 41b, and the central-side strip-shaped formwork 41c are preferably formed using a transparent plate-like member. Thereby, it becomes possible to visually recognize the filling state of the filling and solidifying material 22 into the respective gaps 21a, 21b, 21c, 21d through these transparent strip-shaped formworks.

[0075] Furthermore, the upper surface strip-shaped formwork 41a attached so as to cover the opening portions of the gaps 21a, 21b, 21d in the upper surface portion 20a of the plurality of PCa concrete blocks 20A, 20B, 20C arranged longitudinally and laterally in series is preferably provided with an air vent hose 42 (see FIG. 10) extending from an appropriate position and communicating with the gaps 21a, 21b, 21d in the upper surface portion 20a. Thereby, when the filling and solidifying material 22 is filled, it becomes possible to effectively vent air from the gaps 21a, 21b, 21d through the air vent hose 42, and it also becomes possible to confirm that the filling and solidifying material 22 has been filled by the filling and solidifying material 22 flowing out from these air vent hoses 42.

[0076] In this embodiment, in the step of filling the gap 21a between adjacent receiving base portions 31c of a plurality of PCa concrete blocks 20A, 20B, 20C arranged longitudinally and transversely, the gap 21b between adjacent PCa concrete blocks 20A, 20B, 20C, and the gap 21c below the hexahedral lower surface portion communicating with these gaps 21a, 21b with the filling and solidifying material 22, as described above, with the opening portions of the gaps 21a, 21b, 21c that open in the upper surface portion 20a of the plurality of PCa concrete blocks 20A, 20B, 20C arranged longitudinally and transversely, the wife-side end surface portion 10A, and the central-side end surface portion 10B closed, from the central-side filling material injection holes 27d provided to penetrate vertically through one or more of the plurality of central-side blocks 20B arranged longitudinally in the tunnel axis direction, and from the receiving base-side filling material injection holes 27e provided to penetrate vertically through one or more of the plurality of receiving base-side blocks 20A arranged longitudinally in the tunnel axis direction, the filling and solidifying material 22 is sequentially injected. Opening and closing valves 28 that can be opened and closed are attached to the central-side filling material injection holes 27d and the receiving base-side filling material injection holes 27e, respectively. When filling the filling and solidifying material 22 by sequentially connecting an injection hose to the opening and closing valve 28 of the selected central-side filling material injection hole 27d or the receiving base-side filling material injection hole 27e, the opening and closing valve 28 of the central-side filling material injection hole 27d or the receiving base-side filling material injection hole 27e after completion of filling is closed. The opening and closing valves 28 of the unused central-side filling material injection holes 27d or the receiving base-side filling material injection holes 27e can be left open and used as air venting members. As described above, in the step of filling the filling and solidifying material 22, without using the filling material injection hole 27e of the receiving base-side block 20A, the filling and solidifying material 22 is injected using only the filling material injection hole 27d of the central-side block 20B, and it is also possible to confirm that the filling and solidifying material 22 flows out from the opening portion of the gap 21a between the receiving base 31c held on the upper surface portion 20a of the receiving base-side block 20A, and then finish the filling of the filling and solidifying material 22.By filling the filling and solidifying material 22 from the filling material injection hole 27d on the central part side, it becomes possible to smoothly vent air from the gap 21a between the pedestal part 31c held on the upper surface part 20a of the pedestal part side block 20A, and it becomes possible to effectively avoid the occurrence of air pockets in the filled filling and solidifying material 22.

[0077] Also, in the present embodiment, the plurality of PCa concrete blocks 20A, 20B, 20C arranged in series longitudinally and horizontally are preferably provided adjacent to each other in the axial direction of the tunnel of the existing invert part structure 40 formed in advance as described above. While switching from the on-off valve 28 of the filling material injection hole 27d on the central part side located on the existing invert part structure 40 side to the on-off valve 28 of the filling material injection hole 27d on the central part side located on the wife side, the filling and solidifying material 22 is injected, and while switching from the on-off valve 28 of the filling material injection hole 27e on the pedestal part side located on the existing invert part structure 40 side to the on-off valve 28 of the filling material injection hole 27e on the pedestal part side located on the wife side, the filling and solidifying material 22 is injected. As described above, after switching from the filling material injection hole 27d of the central part side block 20B on the existing invert part structure 50 side to the filling material injection hole 27d of the central part side block 20B on the wife side and injecting the filling and solidifying material 22 halfway, it is also possible to further switch from the filling material injection hole 27e of the pedestal part side block 20A on the existing invert part structure 50 side to the filling material injection hole 27e of the pedestal part side block 20A on the wife side and inject the filling and solidifying material 22.

[0078] In each of the filling material injection holes 27d on the central part side and the filling material injection holes 27e on the pedestal part side, as described above, the on-off valve 28 can be attached in a state of protruding upward from the upper surface parts of a plurality of PCa concrete blocks 20A and 20B arranged longitudinally and laterally connected by screwing the male screw part 28b to the female screw member 27a fixed to the middle part in the penetrating direction of the filling material injection hole 27d on the central part side or the filling material injection hole 27e on the pedestal part side. Thereby, the operation of detachably connecting the injection hose can be easily performed by the work on the upper surface parts 20a of the PCa concrete blocks 20A, 20B, and 20C.

[0079] And in this embodiment, as shown in FIGS. 1 and 2, the invert part structure 10 having the above-described configuration forms an invert part structure 50 over the entire cross-sectional direction that constitutes an invert part covering structure 32 by being integrally formed by being constructed in each of the pair of one-side regions sandwiching the center in the cross-sectional direction of the tunnel as the one-side regions on both sides.

[0080] That is, the invert part structure 50 over the entire transverse direction is provided over the entire transverse direction of the tunnel in the invert part 33 of the mountain tunnel, and is a structure using PCa concrete blocks 20A, 20B, and 20C that constitute the invert part covering work 32. Each of the PCa concrete blocks 20A, 20B, and 20C is formed as a hexahedral block having a curved upper surface portion 20a and a curved lower surface portion 20b so as to have a curved shape along the cross-sectional shape of the invert part covering work 32 as described above. As shown in FIGS. 1 and 2, in each of one side region and the other side region in the transverse direction of the tunnel, a plurality of PCa concrete blocks 20A, 20B, and 20C are arranged in series in the transverse direction of the tunnel while maintaining gaps 21a and 21b between the lower end receiving portions 31c of the adjacent side wall part covering works 31a and between the adjacent PCa concrete blocks, and are installed in the invert part 33. Also in the axial direction of the tunnel, they are arranged in series while maintaining a gap 21b between the adjacent PCa concrete blocks 20A, 20B, and 20C and are installed in the invert part 33, whereby a one-side block group 20X and an other-side block group 20Y are formed. And in the central portion in the transverse direction of the tunnel, a space portion 51 is maintained between the one-side block group 20X and the other-side block group 20Y. The plurality of PCa concrete blocks 20A, 20B, and 20C arranged in series vertically and horizontally in the one-side block group 20X and the other-side block group 20Y are integrated through a filling and solidifying material 22 filled and hardened in the gaps 21a between the adjacent receiving portions 31c, the gaps 21b between the adjacent PCa concrete blocks 20A, 20B, and 20C, the space portion 51 between the one-side block group 20X and the other-side block group 20Y, and the gaps 21c below the hexahedral lower surface portion communicating with these gaps 21a, 21b, and the space portion 51, so as to constitute the invert part covering work 32.

[0081] In addition, in the present embodiment, the gap 21a between the adjacent receiving base portions 31c filled with the filling and solidifying material 22 and the gap 21b between the adjacent PCa concrete blocks 20A, 20B, 20C preferably have a gap width of 15 to 30 mm, and the interval portion 51 between the one-side block group 20X and the other-side block group 20Y preferably has an interval width of 100 to 130 mm.

[0082] Furthermore, in the present embodiment, the plurality of PCa concrete blocks 20A, 20B, 20C arranged longitudinally and transversely in the one-side block group 20X and the other-side block group 20Y respectively are provided with a gap 21b extending in the axial direction between the PCa concrete blocks adjacent in the transverse direction of the tunnel filled with the filling and solidifying material 22, and a gap extending in the transverse direction between the PCa concrete blocks adjacent in the axial direction of the tunnel, and are preferably arranged in a straight-line continuous manner and installed in the invert portion 33.

[0083] Furthermore, in the present embodiment, on the central-side surface of the PCa concrete block (central-side block) 20B located on the most central side of the one-side block group 20X facing the interval portion 51 and on the central-side surface of the PCa concrete block (central-side block) 20B located on the most central side of the other-side block group, unevenness 52 for improving the adhesion to the filling and solidifying material 22 is preferably formed as shown in FIG. 15, for example.

[0084] The unevenness 52 for improving the adhesion to the filling solidifying material 22 is preferably arranged continuously in the transverse direction of the tunnel while maintaining gaps 21a and 21b between the receiving base portions 31c at the lower ends of the adjacent side wall covering members 31a and between the adjacent PCa concrete blocks 20, and is formed on the transverse direction opposing surfaces 20d facing each other with the held gaps 21a and 21b interposed therebetween in each PCa concrete block 20 installed in the invert portion 33. The unevenness 52 for improving the adhesion to the filling solidifying material 22 is preferably arranged continuously in the axial direction of the tunnel while maintaining a gap 21b between the adjacent PCa concrete blocks 20, and is formed on the axial direction opposing surfaces 20c facing each other with the held gap 21b interposed therebetween in each PCa concrete block 20 installed in the invert portion 33.

[0085] Further, in the present embodiment, it is preferable that the PCa concrete block (central portion side block) 20B located at the most central portion side of the one-side block group 20X and the PCa concrete block (central portion side block) 20B located at the most central portion side of the other-side block group 20Y are connected via a long bolt member (not shown). Thereby, it becomes possible to ensure the installation accuracy of the one-side block group 20X and the other-side block group 20Y, and it also becomes possible to ensure the shear strength of the portion between these block groups 20X and 20Y.

[0086] In this embodiment, the invert part structure 50 across the entire width of the above-described tunnel can be formed by the following construction method. That is, in this embodiment, the construction method of the invert part structure 50 is such that in one side region in the transverse direction of the tunnel, a plurality of PCa concrete blocks 20A, 20B, 20C are arranged in series in the transverse direction of the tunnel while maintaining gaps 21a, 21b between the lower end receiving parts 31c of the adjacent side wall covering members 31a and between the adjacent PCa concrete blocks 20A, 20B, 20C, and are installed in the invert part 33. Also, in the axial direction of the tunnel, they are arranged in series while maintaining a gap 21b between the adjacent PCa concrete blocks 20A, 20B, 20C and installed in the invert part 33, thereby forming a one-side block group 20X. Then, a step of filling and hardening the solidifying material 22 into the gaps 21a between the plurality of PCa concrete blocks 20A, 20B, 20C of the one-side block group 20X arranged in series vertically and horizontally and the adjacent receiving parts 31c, the gaps 21b between the adjacent PCa concrete blocks 20A, 20B, 20C, and the gaps 21c below the hexahedral lower surface parts communicating therewith. And in the other side region in the transverse direction of the tunnel, a plurality of PCa concrete blocks 20A, 20B, 20C are arranged in series in the transverse direction of the tunnel while maintaining gaps 21a, 21b between the lower end receiving parts 31c of the adjacent side wall covering members 31a and between the adjacent PCa concrete blocks 20A, 20B, 20C, and are installed in the invert part 33. Also, in the axial direction of the tunnel, they are arranged in series while maintaining a gap 21b between the adjacent PCa concrete blocks 20A, 20B, 20C and installed in the invert part 33, thereby forming an other-side block group 20Y. And the gaps 21a between the plurality of PCa concrete blocks 20A, 20B, 20C of the other-side block group 20Y arranged in series vertically and horizontally and the adjacent receiving parts 31c, the adjacent PCa concrete blocks 20A, 20B,In addition to the gap 21b between the members 20C and the gap 21c below the hexahedral lower surface portion communicating therewith, a step of filling and curing the filling and solidifying material 22 is also included in the spaced portion 51 between the one-side block group 20X and the other-side block group 20Y. As a result, it becomes possible to easily form an invert portion structure 50 that is provided over the entire transverse direction of the tunnel and constitutes the invert portion covering structure 32.

[0087] For the invert portion structure 50 over the entire transverse direction, for example, when it is possible to perform construction by shutting off the passage of the mountain tunnel 30 for a long period, it is also possible to form it by simultaneously constructing the areas on both sides without constructing one area at a time.

[0088] According to the construction method of the invert portion structure of the present embodiment having the above-described configuration, by using the PCa concrete blocks 20 (20A, 20B, 20C) having an appropriate weight and size that can be easily manufactured in a factory or the like, the invert portion structure 10 can be easily formed without requiring much labor, and as a component of the invert portion covering structure 32 provided continuously with the covering structure 31 of the upper arch-shaped portion 31b from the side wall portion 31a of the tunnel, it becomes possible to install it more quickly.

[0089] That is, according to the present embodiment, in the invert portion structure 10, the PCa concrete blocks 20 constituting the invert portion structure are formed so as to have a hexahedral shape in which the upper surface portion 20a and the lower surface portion 20b are curved, for example, with a horizontal width x of about 1385 to 1435 mm, a vertical width y of about 730 mm, and a height z of about 500 mm, and have a weight of about 1300 kg. Compared with conventional precast concrete invert concrete members having a large and complex weight and shape, in addition to being able to be efficiently manufactured by having an appropriate weight, size, and shape, the workability during lifting and transportation is improved, and the ease of handling during lifting and installation is also improved, so that each PCa concrete block 20 can be accurately installed at a predetermined position with a space therebetween.

[0090] In addition, in the construction method of the invert part structure in the mountain tunnel of the present embodiment, the bolt insertion and screwing holes 25 penetrate vertically and are formed at three locations, and height adjustment bolts 26 are attached to the respective bolt insertion and screwing holes 25 in a state where the lower end parts 26a can protrude downward from the lower surface part 20b of the PCa concrete block 20. As a result, the height of each PCa concrete block 20 can be adjusted accurately and easily by the height adjustment bolts 26, so that the invert part 33 can be formed with high precision and easily so that the upper surface of the invert part 33 is convex downward and is a flat curved surface.

[0091] In addition, since the height adjustment bolts 26 are attached to the bolt insertion and screwing holes 25 formed at three locations, the load of the PCa concrete block 20 is dispersed to the three height adjustment bolts 26 that support the PCa concrete block 20. Therefore, since the load of the PCa concrete block 20 supported by one height adjustment bolt 26 can be reduced, the adjustment work of the protruding length of the height adjustment bolt 26 from the lower surface part 20b of the PCa concrete block 20 by the rotation operation can be easily performed with a small force.

[0092] In addition, prior to the step of filling the gaps 21a between the adjacent receiving base parts 31c of the plurality of PCa concrete blocks 20 arranged continuously vertically and horizontally, the gap 21b between the adjacent PCa concrete blocks 20, and the gap 21c below the lower surface part 20b of the hexahedron shape communicating with these gaps with the filling and solidifying material 22, by a rotation operation from above the PCa concrete block 20, in each PCa concrete block 20, the protruding length of the three height adjustment bolts 26 from the lower surface part 20b of the PCa concrete block 20 is changed, and the step of adjusting the height and inclination of each PCa concrete block 20 is included. As a result, the work of adjusting the height and inclination of each PCa concrete block 20 can be easily and quickly performed from the upper surface part 20a of the PCa concrete block where the work space is secured.

[0093] As described above, after each PCa concrete block 20 is installed at a predetermined position with a gap therebetween with high precision and easily, the operation of injecting the filling and solidifying material 22 into the gaps and intervals of the PCa concrete blocks 20 and the like can be performed easily and smoothly. Therefore, the invert part structure 10 in which these PCa concrete blocks 20 are firmly integrated can be easily formed, so that it can be installed more quickly and easily as a component of the invert part lining 32 provided continuously with the lining 31 of the upper arch-shaped part 31b from the side wall part 31a of the tunnel.

[0094] Also, in the present embodiment, female screw members 25a are fixed to lower portions of each bolt insertion and screwing hole 25 below the middle in the vertical direction, and height adjustment bolts 26 are screwed to the female screw members 25a, so that the height adjustment bolts 26 are attached in a state where the lower end portions 26a can project downward from the lower surface portion 20b of the PCa concrete block 20. For this reason, the height and inclination of the PCa concrete block 20 can be easily adjusted by a simple operation of merely screwing the height adjustment bolts 26. Further, since the female screw members 25a to which the height adjustment bolts 26 are screwed are fixed to lower portions of each bolt insertion and screwing hole 25 below the middle in the vertical direction, the maximum protruding length of the height adjustment bolts 26 from the lower surface portion 20b of the PCa concrete block 20 can be increased. Therefore, the adjustment ranges of the height and inclination of the PCa concrete block 20 can be made wider, so that each PCa concrete block 20 can be installed with higher precision.

[0095] In addition, in the present embodiment, the bolt insertion and screwing holes 25 are formed at three locations, each disposed at the corner portion of the triangular shape surrounding the center of gravity of the PCa concrete block 20. Therefore, according to the construction method of the invert structure in the mountain tunnel of the present embodiment, the three height adjustment bolts 26 attached to the bolt insertion and screwing holes 25 can stably support the PCa concrete block 20 from below. Further, since the bolt insertion and screwing holes 25 are formed at three locations, each disposed at the corner portion of the triangular shape, the inclination of the PCa concrete block 20 in the transverse direction and the axial direction of the tunnel can be adjusted with high precision and easily. Therefore, each PCa concrete block 20 can be installed at a predetermined position with high precision and easily at intervals.

[0096] Further, on the lower surface portion 20b of the PCa concrete block 20, there is provided a small trumpet-shaped recess 25c formed by notching the opening peripheral edge portion of the bolt insertion and screwing hole 25 in a tapered shape and expanding in diameter downward. In the small trumpet-shaped recess 25c, the grounding adjuster 26b is accommodated when the height adjustment bolt 26 is retracted upward. Therefore, when the PCa concrete block 20 is moved downward by retracting the height adjustment bolt 26 upward, it is possible to avoid the lower surface portion 20b of the PCa concrete block 20 from interfering with the grounding adjuster 26b. Therefore, since the adjustment range of the height and inclination of the PCa concrete block 20 can be made wider, each PCa concrete block 20 can be installed with higher precision.

[0097] Note that the present invention is not limited to the above-described embodiments, and various modifications are possible. For example, the invert portion structure of the present invention is not limited to the construction of extending the lining body to the invert portion in a mountain tunnel where the lining body covering the inner wall surface of the tunnel is formed only in the region from the side wall portions on both sides to the upper arch-shaped portion and not formed in the invert portion. When newly forming a mountain tunnel, it can be adopted in the construction of providing a lining body over the entire circumference including the invert portion on the inner wall surface of the tunnel, or in the construction of modifying the lining body of the existing invert portion in a mountain tunnel and newly reinstalling the lining body of the invert portion.

Explanation of Reference Numerals

[0098] 10 Invert portion structure 10a Flange-provided recess 10A Wife-side end face portion 10B Center-side end face portion 20, 20’ PCa concrete block 20a Upper face portion 20b Lower face portion 20c Axial direction facing surface 20d Transverse direction facing surface 20e Notch recess 20f, 20g Axial direction connection portion 20A Support base portion side block 20B Center portion side block 20C Intermediate portion block 20D Transverse direction block row 20E Outer PCa concrete block 20F Inner PCa concrete block 20X One-side block group 20Y The other-side block group 21a Gap between the support base portion 21b Gap between adjacent PCa concrete blocks 21c Gap below the lower face portion 21d Gap between the existing invert portion structure 22 Filling and solidifying material 23 Bolt box 24 Female screw anchor 25 Bolt insertion and fastening hole 25a Female screw member (nut member) 25b Large trumpet-shaped recess 25c Small trumpet-shaped recess 26 Height adjustment bolt 26a Lower end part 26b Grounding adjuster 26c Filling bottom surface part 26d Upper end part 27 Filling material injection hole 27a Female screw member 27b Upper side trumpet-shaped recess 27c Lower side trumpet-shaped recess 27d Central part side filling material injection hole 27e Receiver part side filling material injection hole 28 On-off valve 28a Handle part 29a Transverse direction spacer jig 29b Axial direction spacer jig 29c Hanging jig 30 Mountain tunnel 30a Chassis part 31 Lining work 31a Side wall part (side wall lining work) 31b Arch-shaped part 31c Receiver part 32 Invert part lining work 33 Invert part 35 H-shaped steel 36 Temporary fixing means 36a Hollow-in anchor 36b Cable body 36c Telescopic adjustment means 37 Connecting part structure of PCa block 40 Existing invert part structure 41a Upper surface belt plate-shaped formwork 41b Side part belt plate-shaped formwork 41c Central side belt plate-shaped formwork 42 Air vent hose 50 Invert part structure of the entire cross-sectional direction of the tunnel The space between the one-side block group and the other-side block group b The gap below the lower surface part

Claims

1. A construction method of an invert structure using a plurality of PCa concrete blocks, which is provided in at least one side region in the transverse direction of a tunnel in the invert part of a mountain tunnel and constitutes an invert covering structure, wherein the PCa concrete block is formed as a hexahedral block having a curved upper surface and a curved lower surface so as to have a curved shape along the cross-sectional shape of the invert covering structure, a plurality of the PCa concrete blocks are arranged continuously in the transverse direction of the tunnel while maintaining a gap between adjacent receiving bases and between adjacent PCa concrete blocks, and are also arranged continuously in the axial direction of the tunnel while maintaining a gap between adjacent PCa concrete blocks, and are installed in the invert part by arranging them side by side vertically and horizontally, a plurality of the PCa concrete blocks arranged continuously vertically and horizontally are filled with a filling and solidifying material in the gaps between adjacent receiving bases, the gaps between adjacent PCa concrete blocks, and the gaps below the lower surface of the hexahedral shape communicating with these gaps, and are cured, so as to constitute at least a part of the invert covering structure in an integrated state via the cured filling and solidifying material, in each of the PCa concrete blocks, bolt insertion and screwing holes are formed at least at three locations penetrating in the vertical direction, and height adjustment bolts are attached to each of the bolt insertion and screwing holes in a state where the lower end portions can protrude downward from the lower surface of the PCa concrete block, a construction method of an invert structure in a mountain tunnel, including a step of adjusting the height and inclination of each of the PCa concrete blocks by changing the protruding length of the three height adjustment bolts from the lower surface of the PCa concrete block in each of the PCa concrete blocks by a rotation operation from above the PCa concrete block prior to the step of filling the gaps between adjacent receiving bases, the gaps between adjacent PCa concrete blocks, and the gaps below the lower surface of the hexahedral shape communicating with these gaps with a filling and solidifying material.

2. A female screw member is fixed to a portion below the vertical middle of each of the bolt insertion and screwing holes, and the height adjustment bolt is screwed to the female screw member, so that the height adjustment bolt is attached in a state where the lower end portion can protrude downward from the lower surface portion of the PCa concrete block. The construction method of the invert portion structure in a mountain tunnel according to claim 1.

3. The bolt insertion and screwing holes are disposed at respective corner portions of a triangular shape surrounding the center of gravity of the PCa concrete block and are formed at three locations. The construction method of the invert portion structure in a mountain tunnel according to claim 1.

4. The three bolt insertion and screwing holes are disposed at respective corner portions of an isosceles triangle shape, in which the bottom side portion is arranged in parallel with one axial direction facing surface side on the upper surface portion of the PCa concrete block and the top portion is arranged on the other axial direction facing surface side. The construction method of the invert portion structure in a mountain tunnel according to claim 3.

5. When viewed from the upper surface portion side of the PCa concrete block, the center of gravity of the PCa concrete block is arranged inside the area surrounded by the isosceles triangle shape. The construction method of the invert portion structure in a mountain tunnel according to claim 3 or 4.

6. When viewed from the upper surface portion side of the PCa concrete block, the center of gravity of the PCa concrete block is arranged at the centroid position of the isosceles triangle shape. The construction method of the invert portion structure in a mountain tunnel according to claim 3 or 4.

7. A tiltable grounding adjuster is attached to the lower end portion of the height adjustment bolt. The construction method of the invert portion structure in a mountain tunnel according to claim 1 or 2.

8. On the lower surface portion of the PCa concrete block, a small trumpet-shaped concave portion that is formed by notching the opening peripheral edge portion of the bolt insertion and screwing hole in a tapered shape and has a diameter that expands downward is provided, and when the height adjustment bolt is retracted upward, the grounding adjuster is accommodated in the small trumpet-shaped concave portion. The construction method of the invert portion structure in a mountain tunnel according to claim 7.

9. In the bolt insertion and screwing hole, a large trumpet-shaped recess is formed that expands upward from the portion where the female screw member is fixed and opens to the upper surface portion of the PCa concrete block. In the large trumpet-shaped recess, a rotation operation jig is locked to the upper end portion of the height adjustment bolt, and by rotating the height adjustment bolt, the protruding length from the lower surface portion of the PCa concrete block is changed. The construction method of the invert portion structure in the mountain tunnel according to claim 2, wherein the construction method is as described above.

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