A pair of precast slabs for tunnels and their installation method.

Abstract

To provide a precast slab for a tunnel which is excellent in installation workability.SOLUTION: In precast tunnel slabs 11, 21 for a tunnel, which are installed so as to cover an inner surface 3 of an arched tunnel 1 and which abut butt surfaces 17, 17A, 18, 18A provided at a top 13, which is an end in the circumferential direction of the tunnel, with the butt surfaces 27, 27A, 28, 28A at the top of the inner surface 3 of the tunnel 1, the butt surfaces are formed at an angle to the vertical line, so that the butt surfaces 17, 17A, 18, 18A can be easily butted against the butt surfaces 27, 27A, 28, 28A.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention is installed on the inner surface of the arched tunnel hole. a pair This document relates to precast slabs for tunnels and their installation methods. [Background technology]

[0002] Conventional precast slabs for tunnels of this type include curved concrete precast slabs divided into two halves, left and right, circumferentially around the arch-shaped tunnel hole, with interlocking steps formed at the upper ends of the left and right precast slabs (for example, Patent Document 1), and slabs in which the upper ends of the left and right precast slabs have steps consisting of convex and concave portions that fit together alternately, and the lower ends of the left and right precast slabs are positioned and fixed to the upper ends of the side walls with embedded height-adjustment bolts (for example, Patent Document 2).

[0003] In addition, the upper ends of the first and second precast slabs have steps consisting of convex and concave portions that fit together alternately, and at the lower ends a height adjustment bolt protrudes toward the upper end surface of the side wall, and the positioning on the side wall is determined by adjusting the amount of protrusion of this bolt (for example, Patent Document 3), and the concave portion is formed at the upper end by joining adjacent precast slabs along the length of the tunnel.

[0004] In the above Patent Document 1, the right precast slab is slid forward in the lengthwise direction of the tunnel hole to align the front and rear positions of the left and right step sections so that the upper ends of the left and right precast slabs abut, and both threaded bolts are inserted into the stepped holes and both ends of the threaded bolts are fastened with nuts to unite the upper ends of the precast slabs in an abutting state, and the lower ends can be fixed with foundation concrete.

[0005] However, all of Patent Documents 1 to 3 have a connecting member at the lower end of one precast slab and a connecting member at the upper end of the side wall, and if the connecting member of the side wall hits the connecting member of the precast slab, the precast slab cannot be slid in the longitudinal direction of the tunnel hole.

[0006] Furthermore, when installing the inner surface of a tunnel hole and the outer surface of a precast slab close to each other in an existing tunnel hole, if there is no clearance between the tops at the top of the tunnel hole, there is a problem in that it is not possible to lift one precast slab and butt its top against the top of the other precast slab positioned on the inner surface of the tunnel hole.Even if there is a certain amount of clearance between the tops at the top of the tunnel hole, it is a time-consuming task to lift one top from directly below to align it with the other top, and then bring it close to the other top to butt it against the other top. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 5-295992 [Patent Document 2] Japanese Patent Application Laid-Open No. 2005-315029 [Patent Document 3] Japanese Patent Application Laid-Open No. 2007-321450 DISCLOSURE OF THE INVENTION [Problem to be solved by the invention]

[0008] Therefore, the present invention is intended to solve the above problems, and aims to provide a precast slab for a tunnel that is easy to install and an installation method for the same. [Means for solving the problem]

[0009] The invention of claim 1 is an arch-shaped of A precast slab for a tunnel that is installed to cover the inner surface of the tunnel and abuts the abutting surfaces provided at the ends of the tunnel circumferential direction at the top of the inner surface of the tunnel. A pair of precast slabs for tunnels consisting of: The abutting surfaces are formed obliquely with respect to a vertical line. A convex portion extending in the circumferential direction of the tunnel is provided at the center of the width direction of the abutment surface, and concave portions are provided on both sides of the convex portion in the width direction. The abutment surfaces on one side of the tip of the convex portion in the width direction and of the adjacent concave portion are formed obliquely downward, and the abutment surfaces on the other side of the tip of the convex portion in the width direction and of the adjacent concave portion are formed obliquely upward. The abutment surface of the convex portion of one of the left and right tunnel precast slabs is abutted against the abutment surface of the concave portion of the other left and right tunnel precast slab in the longitudinal direction of the tunnel, and the left and right tunnel precast slabs are installed offset from each other in the longitudinal direction of the tunnel. It is characterized by:

[0010] Claim2 The invention is 1 A pair of described For tunnels In the installation method of the precast slab, For tunnels After the precast slab is aligned with the inner surface of the tunnel, For tunnels Lift the precast plate and For tunnels Precast plate downward The aforementioned The left and right sides of the butt joint For tunnels Precast plate upward The aforementioned The butting surfaces are butted together, and the other of the left and right For tunnels It is characterized by the precast slabs being fitted to the inner surface of the tunnel. [Effects of the Invention]

[0011] According to the configuration of claim 1, by forming the mating surfaces at an angle to the vertical line, the mating surfaces can be easily butted together, and the time required for installation can be reduced.

[0012] Also, Claim 1 According to the configuration, the abutting surface of the convex portion of the left or right tunnel precast slab, left and right The abutting surfaces of the recesses of the other precast slab for the tunnel can be easily butted together by shifting the left and right precast slabs for the tunnel relative to each other in the longitudinal direction of the tunnel and bringing the upward abutting surface close to the downward abutting surface from below.

[0013] Claim 2 According to the configuration of For tunnels The mating surfaces can be easily butted together without moving the precast slabs in the tunnel width direction. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a cross-sectional view of an arched tunnel showing a first embodiment of the present invention. [Figure 2] FIG. 10 is a plan view of the top of the precast slab. [Figure 3]This is a cross-sectional view of the mounting structure of the lower part of the precast slab and the mounting part. [Figure 4] Same as above, a cross-sectional view in the tunnel length direction of the mounting structure of the lower part of the precast slab and the mounting part. [Figure 5] FIG. 10 is a partially cross-sectional front view illustrating the top connection process. [Figure 6] FIG. 10 is a front view of the top of the precast slab. [Figure 7] FIG. 10 is a partially cutaway front view of the same with the tops of the precast slabs connected. [Figure 8] FIG. [Figure 9] FIG. 10 is a front view of the same as above, showing the state in which the lower end loop reinforcement is inserted between the mounting portion side loop reinforcement. [Figure 10] FIG. 10 is an enlarged front view of the same as above, showing the state in which the lower end loop is inserted between the attachment portion loops. [Figure 11] FIG. 10 is a plan view of the top of the precast slab in the joined state. [Figure 12] FIG. 10 is a bottom view of the top of the precast slab in the joined state. [Figure 13] FIG. 10 is a perspective view, partly in section, illustrating the operation of connecting the tops of the first embodiment of the present invention. [Figure 14] FIG. 10 is a perspective view illustrating the connecting process of the top portion of the same. [Figure 15] FIG. [Figure 16] FIG. 10 is a plan view of the top of a precast slab showing Example 2 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] Preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Note that the embodiments described below do not limit the content of the present invention as defined in the claims. Furthermore, not all of the configurations described below are necessarily essential requirements of the present invention. [Example]

[0016] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. FIGS. 1 to 12 show a first embodiment of the present invention. FIG. 1 shows an arch-shaped of The figure shows a cross section of a tunnel 1, which has an existing arch structure 2 constructed in an arch shape, and the inner surface of this arch structure 2 is the inner surface 3 of the existing tunnel 1.

[0017] The left and right inner surfaces 3 of the tunnel 1 are erected on the road surface 4, and side walls 5, 5 are constructed using, for example, cast-in-place concrete. of A pair of left and right tunnel precast slabs 11, 21 made of precast concrete are assembled in an arch shape and installed on the inner surface 3 of the tunnel 1 as decorative slabs having a shape that divides the tunnel 1 in two circumferentially, and the lower ends of each precast slab 11, 21 are supported by the side wall portions 5, 5, respectively, and the upper ends of each precast slab 11, 21 abut against each other. The side wall portions 5, 5 are mounting portions for attaching the lower parts of the precast slabs 11, 21.

[0018] The precast slabs 11, 21 are arranged in parallel along the length of the tunnel, with the length of the tunnel aligned with the width of the tunnel, and the end faces 12, 22 at both ends in the width direction are butted together. The precast slabs 11, 21 are formed to have the same width along the length of the tunnel.

[0019] The top 13, which is the end portion located at the top center of the tunnel of the right precast slab 11, one of the left and right sides, has a convex portion 14 that extends circumferentially around the tunnel in the center of the width, and has concave portions 15, 15A on both sides of the width of this convex portion 14, and step surfaces 16, 16A are formed between the convex portion 14 and the concave portions 15, 15A, and the convex portion 14 has an isosceles trapezoidal shape that narrows toward the tip, and the legs of this isosceles trapezoid are the step surfaces 16, 16A on both sides.

[0020] Furthermore, the width of the bottom surfaces of the recesses 15 and 15A on both sides is half the width of the tip surface 14S of the protrusion 14, but the sum of the widths of the bottom surfaces of the recesses 15 and 15A on both sides may be the width of the tip surface 14S of the protrusion 14.

[0021] As shown in Figure 2, the right precast slab 11, one of the left and right, has a pair of divided tip abutment surfaces 17, 17A formed by dividing the tip surface 14S of the convex portion 14 in two in the width direction, and the bottom surfaces of the concave portions 15, 15A are base abutment surfaces 18, 18. The concave portions 15, 15A are symmetrical with respect to the center of the precast slab 11 in the width direction.

[0022] The right precast slab 11, one of the left and right, has a divided tip abutting surface 17 on one side located on one side in the width direction (lower side in Figure 2) from the width direction center and an adjacent base abutting surface 18 on one side formed slightly obliquely with respect to the vertical line so that they face downward from the vertical. Also, the right precast slab 11, one of the left and right, has a divided tip abutting surface 17A on the other side located on the other side in the width direction (upper side in Figure 2) from the width direction center and an adjacent base abutting surface 18A on the other side formed slightly obliquely with respect to the vertical line so that they face upward from the vertical.

[0023] Furthermore, a tip step surface 19 is formed in the precast slab arch direction, perpendicular to the precast slab width direction, between the division tip abutting surface 17 on one side and the division tip abutting surface 17A on the other side, which are adjacent in the width direction and have different diagonal directions. Furthermore, as shown in Figure 5, the tip step surface 19 has an upper step surface 19G that is inverted triangular in shape when viewed from the front and a lower step surface 19N that is triangular in shape.

[0024] The left precast slab 21, which is the other of the two, has a top 23 at the end located above the center of the tunnel, with a convex portion 24 at its widthwise center and concave portions 25, 25A on both sides of the convex portion 24, which are symmetrical with respect to the widthwise center of the precast slab 21. Step surfaces 26, 26A are formed between the convex portion 24 and the concave portions 25, 25A, and the convex portion 24 has an isosceles trapezoidal shape that narrows toward the tip, with the legs of this isosceles trapezoid forming the step surfaces 26, 26A on both sides. The width of the bottom surfaces of the concave portions 25, 25A on both sides is half the width of the tip surface 24S of the convex portion 24, but the sum of the widths of the bottom surfaces of the concave portions 25, 25A on both sides may be used as the width of the tip surface 24S of the convex portion 24. Note that 11N denotes the inner surface of the precast slab 11, 11G is the exterior surface of precast plate 11.

[0025] As shown in Figure 2, the left precast slab 21, one of the left and right sides, has the tip surface 24S of the convex portion 24 divided in two widthwise to provide a pair of divided tip butt surfaces 27, 27A, and the bottom surfaces of the concave portions 25, 25A are base end butt surfaces 28, 28A.

[0026] On the other hand, the left precast slab 21, which is the other of the left and right sides, has a division tip abutting surface 27A on the other side, located on the other side in the width direction (upper side in Figure 2), and a base abutting surface 28A on the other side, which are located from the width direction center to the other side in the width direction, formed at a slight angle to the vertical line so as to face upward from the vertical. Also, a division tip abutting surface 27 on one side, located on one side in the width direction (lower side in Figure 2), and a base abutting surface 28 on one side, which are located from the width direction center to one side in the width direction, are formed at a slight angle to the vertical line so as to face downward from the vertical. Note that at the top 13 of the precast slabs 11, 21, the abutting surfaces, which are formed at an angle so that the outer peripheral surface is long and the inner peripheral surface is short, face downward, and the outer peripheral surface is short The inner surface is long The butt surfaces are angled upwards so that the joints are aligned.

[0027] Furthermore, a tip step surface 29 perpendicular to the width direction of the precast slab is formed between the division tip abutting surface 27 on one side and the division tip abutting surface 27A on the other side, which are adjacent in the width direction and have different diagonal directions. Also, as shown in Figure 6, the tip step surface 29 has an inverted triangular step surface upper part 29G and a triangular step surface lower part 29N when viewed from the front, and the step surface upper part 19G corresponds to the step surface upper part 29G, and the step surface lower part 19N corresponds to the step surface lower part 29N.

[0028] Furthermore, the angle θ of these butt surfaces 17, 17A, 18, 18A, 27, 27A, 28, 28A relative to the vertical line during installation is approximately 14 degrees, with a preferred range being 9 degrees or more and 45 degrees or less. As an example, if the thickness of the tops 13, 23 of the precast slabs 11, 21 is 200 mm and the angle θ is approximately 14 degrees, the left-right distance H between the upper ends of the outer surfaces 11G, 21G and the upper ends of the inner surfaces 11N, 21N will be 50 mm, and to make this distance H 30 mm or more, which will ensure improved workability, the angle θ will be 31.6 mm at approximately 9 degrees, so an angle θ of 9 degrees or more is preferred. If the distance H is less than 9 degrees, the distance H will be small and the clearance of the tops 13, 23 during construction will be insufficient.

[0029] On the other hand, if the angle exceeds 45 degrees, the angle of the upper end of the outer surfaces 11G, 21G becomes large, so it is set to 45 degrees or less, and from these points of view, it is more preferable to set it to 12 degrees or more and 30 degrees or less. Note that, depending on the radius or curvature and thickness of the precast slabs 11, 21, the interval may be set to 30 mm or more, more preferably 50 mm or more.

[0030] 2, the upper edge 26J and the lower edge 26K of the step surface 26A, which are the corners of the outer surface 21G and the inner surface 21N of the precast slab 21 and the step surface 26A, are denoted by reference numerals, and the step surface 26A on the other side in the width direction is angled very slightly upward relative to the vertical line. The step surface 26A on one side in the width direction is angled very slightly downward relative to the vertical line, and the angle is smaller than the angle θ.

[0031] On the other hand, the right precast slab 11, which is one of the left and right sides, has step surface 16A on the other widthwise side angled very slightly upward relative to the vertical line, and step surface 16 on one widthwise side angled very slightly upward relative to the vertical line, the angle being smaller than the angle θ. Furthermore, step surface 26 abuts against step surface 16A, and step surface 26A abuts against step surface 16.

[0032] Then, as shown in Figure 11, one precast slab 21 is shifted in the width direction (tunnel length direction) by half relative to the other precast slab 11 in the left-right direction, and the downward abutting surfaces 17, 18 on one side of the width direction of one of the left and right precast slabs 11 are abutted against the upward abutting surfaces 27A, 28A on the other side of the width direction of the other precast slab 21.

[0033] 3 and 4, a plurality of upward side wall loop reinforcement bars 31 are provided on the upper surface 5J of the side wall portion 5 at intervals in the longitudinal direction of the tunnel, and end portions 31T, 31T of these side wall loop reinforcement bars 31 are embedded in the side wall portion 5. In addition, downward lower end loop reinforcement bars 32 are provided on the lower end surfaces 11K, 21K of the precast slabs 11, 21 at intervals in the width direction of the precast slabs 11, 21, and end portions 32T, 32T of these lower end loop reinforcement bars 32 are embedded in the precast slabs 11, 21.

[0034] Furthermore, loop reinforcements 32 are arranged on the side wall portion 5 in correspondence with the positions of the end faces 12, 22 of the precast slabs 11, 21, and a plurality of loop reinforcements 32 are arranged at equal intervals between the loop reinforcements 32, 32 at the positions of the end faces 12, 22. Furthermore, the loop reinforcements 31 are arranged on the lower end faces 11K, 21K so that at least one loop reinforcement 31 is located between the plurality of loop reinforcements 32, 32...

[0035] Furthermore, a plurality of (two) vertical holes 34 into which the upper portions of the height adjustment bolts 33 are loosely inserted are formed in the lower end surfaces 11K, 21K of the precast slabs 11, 21, and embedded nuts 35 having female threads are provided by insert molding on the lower side of the vertical holes 34 in the precast slabs 11, 21. The lower ends 35T of the embedded nuts 35 protrude from the lower end surfaces 11K, 21K.

[0036] Before installation, the height adjustment bolts 33 are screwed in and the upper sides of the height adjustment bolts 33 are inserted into the vertical holes 34, and when adjusting the height, the height adjustment bolts 33 are made to protrude from the lower end faces 11K, 21K by the required length, the lower ends of the height adjustment bolts 33 are screwed into nuts 37 with backing plates 36, and the backing plates 36 are abutted against the upper surfaces 5J of the side walls 5, and the precast slabs 11, 21 are supported by the plurality of height adjustment bolts 33, and the height of the lower end faces 11K, 21K of the precast slabs 11, 21 can be adjusted. In this way, the precast slabs 11, 21 are supported on the side walls 5, 5 by the plurality of height adjustment bolts 33, 33 provided at the lower ends of the precast slabs 11, 21.

[0037] 5 and 6, through holes 41 are formed in the convex portions 14, 24 in the width direction of the precast slabs 11, 21, and these through holes 41 are formed so as to penetrate through the step surfaces 16, 16A, 26, 26A. Through bolts 42 are inserted into the through holes 41, 41 of the precast slabs 11, 21 that are adjacent in the width direction, and nuts (not shown) are fastened to both ends of the through bolts 42 to fasten the tops 13, 23 of the precast slabs 11, 21 together in the width direction.

[0038] Next, we will explain how to install the precast slabs 11. As shown in Figure 8, the right precast slab 11 is positioned along the inner surface 3 of the tunnel 1 and supported by a forklift 51, which serves as a support device. The precast slab 11 is also supported by a portal frame 52, which serves as a support structure, and the portal frame 52 is supported by the forklift 51. In this case, the top 13 of the front precast slab 11 has downward-facing abutment surfaces 17, 18 located thereon.

[0039] The installation device 53 has a self-propelled main body 54 on which a raising and lowering arm 55 can be raised and lowered, and an attachment 56 is attached to the tip of the raising and lowering arm 55 so that it can swing up and down and left and right, and is also rotatable, and the precast slabs 11, 21 are removably fixed to the attachment 56.

[0040] An attachment 56 is fixed to the precast slab 21 to be installed on the left side, the precast slab 21 is lifted using the installation device 53, and the loop reinforcement bars 32, 32... at the lower end of the precast slab 21 are inserted between the adjacent loop reinforcement bars 31, 31... of the side wall portion 5, as shown in Figures 4 and 10. With the precast slab 21 in this positioned and inserted state, the top 23 of the precast slab 21 is lifted and the upward abutment surfaces 27A, 28A of the precast slab 21 are abutted against the downward abutment surfaces 17, 18.

[0041] In this case, with the conventional installation method, the height of the top 23 of the left-side precast slab 21 would be adjusted to match the top 13 of the already-positioned right-side precast slab 11, and the left-side precast slab 21 would be moved in the direction of the tunnel length so as to approach the right-side precast slab 11, thereby making it possible to butt the left-side base end butt surface 28A and the left-side other side of the left-side divided top end butt surface 27A against the right-side divided tip butt surface 17 and the right-side base end butt surface 18, as shown in Figures 9 and 10. Figure 10 is an enlarged front view of the lower part of the left-side precast slab 21 in Figure 9.

[0042] However, to do this, it is necessary to move the left precast slab 21 in the longitudinal direction of the tunnel, and in this example the precast slab 21 has a lower end loop reinforcement 32, and the side wall loop reinforcement 31 gets in the way, preventing it from moving in the longitudinal direction.

[0043] Also, as shown in Figure 3, the arched of There is only a small gap between the inner surface 3 of the tunnel 1 and the precast slabs 11, 21, and the top 23 of the left precast slab 21 cannot be moved to the left of the center position of the top of the tunnel 1. In the case of conventional precast slabs with a vertical butt surface, it is extremely difficult to align the tops of the left and right precast slabs by lifting the top of the left precast slab from directly below.

[0044] In contrast, as shown in Figure 5, the top 23 of the precast slab 21 can be lifted up so that the upward abutment surfaces 27A, 28A can be easily abutted against the downward abutment surfaces 17, 18 of the right-side precast slab 11.

[0045] After this, the precast slab 21 is supported by a forklift 51, and the downward abutment surfaces 27, 28 are positioned on one widthwise side (front side) of this precast slab 21, and in the same manner, the right precast slab 11 is installed on one widthwise side of the left precast slab 21.

[0046] In addition, the through holes 41, 41 of the precast slabs 11, 21 adjacent in the width direction are death Bolts 42 are inserted through the precast slabs 11, 21, and the tops 13, 23 of the precast slabs 11, 21 are fastened together in the width direction (tunnel length direction) by the through bolts 42.

[0047] 3 and the like, at the lower end of the precast slabs 11, 21, a plurality of reinforcing bars 39 in the tunnel length direction are inserted through the overlapping portion 30 (FIG. 3) of the loop reinforcement 31, 32, and reinforcing bars 39A, 39A in the tunnel length direction are attached to the loop reinforcement 31, 32 on the outside of the overlapping portion 30. Then, the gap between the outer surface 11G, 21G of the precast slabs 11, 21 and the inner surface 5N of the side wall portion 5 is closed with a formwork (not shown), and the gap between the lower end surface 11K, 21K of the precast slabs 11, 21 and the upper surface 5J of the side wall portion 5 is closed. of The space is filled with a hardening agent 43 such as concrete or mortar, and as the hardening agent 43 hardens, the lower ends of the precast slabs 11, 21 are rigidly connected to the side walls 5, 5. In Figure 4, reference numeral 40 denotes an arch-shaped reinforcing bar embedded in the precast slabs 11, 21.

[0048] In this embodiment, the arch-shaped of Precast slabs 11, 21 for tunnels are installed so as to cover the inner surface 3 of the tunnel 1, and abut surfaces 17, 17A, 18, 18A and abut surfaces 27, 27A, 28, 28A provided at the tops 13, 23 which are the ends of the tunnel circumferential direction at the tops of the inner surface 3 of the tunnel 1. A pair of tunnel precast slabs 11, 21 consisting of: The butt surfaces are formed at an angle to the vertical line. A convex portion 14 extending in the circumferential direction of the tunnel is provided in the widthwise center of the abutment surfaces 17, 17A, 18, 18A, and concave portions 15, 15A are provided on both widthwise sides of the convex portion 14. The abutment surfaces 17, 18 on one widthwise side of the tip of the convex portion 14 and of the adjacent concave portion 15 are formed obliquely downward, and the abutment surfaces 17A, 18A on the other widthwise side of the tip of the convex portion 14 and of the adjacent concave portion 15A are formed obliquely upward. In the lengthwise direction of the tunnel, the abutment surface of the convex portion 14 of one of the left and right tunnel precast slabs 11, 21 abuts against the abutment surfaces of the concave portions 25, 25A of the other left and right tunnel precast slabs 21, and the left and right tunnel precast slabs 11, 21 are installed offset from each other in the lengthwise direction of the tunnel. Therefore, the abutting surfaces 17, 17A, 18, 18A and the abutting surfaces 27, 27A, 28, 28A can be abutted against each other easily.

[0049] In this way, in this embodiment ,to A pair of tunnel precast slabs 11, 21 are made up of tunnel precast slabs, and the butt faces 17, 18 of one of the left and right precast slabs 11 facing in the longitudinal direction of the tunnel are formed obliquely downward, while the butt faces 28A, 27A of the other precast slab 21 are formed obliquely upward, so that the butt faces 17, 28A and the butt faces 18, 27A can be easily butted together by bringing the obliquely upward butt faces 28A, 27A closer to the obliquely downward butt faces 17, 18 from below.

[0050] Also, In this way, in this embodiment, claims 1 In response to ,to The left and right tunnel precast slabs 11, 21 can be simply installed by shifting the abutting surfaces of the convex parts 14 of one of the left and right tunnel precast slabs 11 in the longitudinal direction of the tunnel and the abutting surfaces of the concave parts 25, 25A of the other tunnel precast slab 21 in the longitudinal direction of the tunnel.

[0051] In this way, in this embodiment, claims 2 Corresponding to the claim 1 A pair of described For tunnels In the installation method of the precast slab, For tunnels After the precast slab 11 is aligned with the inner surface 3 of the tunnel 1, For tunnels Precast slab 21 is raised and one of the left and right For tunnels The left and right sides of the downward facing butt surface of the precast slab 11 For tunnels The upper butt surfaces of the precast slabs 21 are butted together, and the other left and right For tunnels The precast slab 21 is aligned with the inner surface 3 of the tunnel 1, For tunnels The butting surfaces can be easily butted together without moving the precast slabs 21 in the tunnel width direction.

[0052] Also, arched ofIn precast tunnel slabs 11, 21 that are installed on the inner surface 3 of tunnel 1 and have a shape divided into two circumferentially, left and right, and in which butting surfaces 17, 17A, 18, 18A of tops 13, 23 butt against butt surfaces 27, 27A, 28, 28A, butt surfaces 17, 17A, 18, 18A, 27, 27A, 28, 28A, butt surfaces 17, 17A, 18, 18A and 27, 27A, 28, 28A are formed at an angle, so that butt surfaces 17, 17A, 18, 18A and 27, 27A, 28, 28A can be easily butt against each other.

[0053] Furthermore, the division tip butt surface 17 and base end butt surface 18, which are the butt surfaces of one of the left and right precast panels 11, are formed at an angle downward, and the base end butt surface 28A and division tip butt surface 27A, which are the butt surfaces of the other of the left and right precast panels 21 that butt against the division tip butt surface 17 and base end butt surface 18, are formed at an angle upward.Therefore, by bringing the upwardly slanted base end butt surface 28A and division tip butt surface 27A closer from below to the downwardly slanted division tip butt surface 17 and base end butt surface 18, the two butt surfaces 17, 28A and the two butt surfaces 18, 27A can be easily butt together.

[0054] The tops 13, 23 are provided with recesses 15, 15A, 25, 25A on one and the other widthwise sides of the central protrusions 14, 24, and divided tip abutment surfaces 17, 27 are formed on one widthwise side of the tips of the protrusions 14, 24, as the tip abutment surfaces on one side, which are formed obliquely downward, and divided tip abutment surfaces 17A, 27A are formed on the other widthwise side of the tips of the protrusions 14, 24, as the tip abutment surfaces on the other side, which are formed obliquely upward. The base end butt surfaces 18, 28 are formed at an angle on one side, and the base end butt surfaces 18A, 28A on the other side are formed at an upward angle at the bottom of the recesses 15A, 25A on the other widthwise side, so that the downward butt surfaces 17, 18 on one side from the widthwise center of one of the left and right precast slabs 11 can be easily butted together by approaching them from below with the upward butt surfaces 28A, 27A on the other side from the widthwise center of the other of the left and right precast slabs 21.

[0055] As an effect of the embodiment, side walls 5, 5 are provided at the bottom of the inner surface 3 of the tunnel 1 as attachment parts for attaching the precast slabs 11, 21, side wall loop reinforcement 31 is provided on these side walls 5, 5 as attachment part side loop reinforcement, and lower end loop reinforcement 32 is provided at the bottom of the precast slabs 11, 21 corresponding to the side wall loop reinforcement 31, so that by embedding the loop reinforcement 31, 32 in a hardening agent 43 such as mortar, the bottom of the precast slabs 11, 21 can be rigidly connected to the side wall 5. This provides greater strength than conventional pin connections and also provides a structure that is strong against earthquakes and the like.

[0056] Also, claims Article 1 In the above-described precast slab installation method, after one of the left and right precast slabs 11 is aligned with the inner surface 3 of the tunnel 1, the other of the left and right precast slabs 21 is raised, and the downward abutting surface of one of the left and right precast slabs 11 is abutted with the upward abutting surface of the other of the left and right precast slabs 21, and the other of the left and right precast slabs 21 is aligned with the inner surface 3 of the tunnel 1, so that the abutting surfaces can be abutted easily without moving the precast slabs 21 in the tunnel width direction.

[0057] As an effect of the embodiment described below, the step surface 26A on the other side in the width direction faces very slightly upward relative to the vertical line, and the step surface 16 on one side in the width direction faces very slightly upward relative to the vertical line, so that by lifting the upper part of the other precast slab 21 on the left or right, the step surface 26 is smoothly abutted against the step surface 16A, and the step surface 26A is smoothly abutted against the step surface 16.

[0058] Furthermore, the angle θ of the butt surfaces 17, 17A, 18, 18A, 27, 27A, 28, 28A relative to the vertical line during installation is 9 degrees or more, preferably 13 degrees or more, so that the desired clearance can be obtained between the tops 13, 23 during installation, improving workability.

[0059] In addition, a tip step surface 19 perpendicular to the width direction of the precast slab is formed between the division tip butt surface 17 on one side and the division tip butt surface 17A on the other side, which are adjacent in the width direction and have different diagonal directions, and a tip step surface 29 perpendicular to the width direction of the precast slab is formed between the division tip butt surface 27 on one side and the division tip butt surface 27A on the other side, which are adjacent in the width direction and have different diagonal directions, so that one width side of the top 13 of one precast slab 11 and the other width side of the top 23 of the other precast slab 21 can be joined in a so-called staggered manner.

[0060] Furthermore, a plurality of upward side wall side loop reinforcements 31 are provided on the upper surface 5J of the side wall portion 5 at intervals in the tunnel length direction, and downward lower end side loop reinforcements 32 are provided on the lower end surfaces 11K, 21K of the precast slabs 11, 21 at intervals in the width direction of the precast slabs 11, 21, and the loop reinforcements 31 are arranged so that at least one loop reinforcement 31 is preferably located between the plurality of loop reinforcements 32, 32. A plurality of reinforcing bars 39 are inserted in the longitudinal direction of the tunnel through the overlapping portions 30 (Figure 3) of the loop reinforcement 31, 32, and a hardening agent 43 such as concrete or mortar is filled in the space between the lower end faces 11K, 21K of the precast slabs 11, 21 and the upper faces 5J of the side walls 5, so that the precast slabs 11, 21 are restrained in the vertical, front-to-back (tunnel longitudinal direction) and left-to-right (tunnel width direction) directions relative to the side walls 5, 5, resulting in a connecting structure with excellent strength. [reference example 1]

[0061] 13 to 15 show the present invention. reference example 1 The same parts as in the first embodiment are given the same reference numerals, and the explanation thereof will be omitted. In the first embodiment, a staggered set is used for the tops 13 and 23, whereas in this embodiment, the precast slabs 11 and 21 are flat set.

[0062] The top 13 located at the top center of the tunnel of the right precast slab 11, one of the left and right sides, has an approximately square convex portion 61 on the other side in the width direction, and has an approximately square concave portion 62 on one side in the width direction corresponding to this convex portion 61, and a step surface 63 is formed between the convex portion 61 and the concave portion 62 in the direction perpendicular to the width direction of the precast slab 11.

[0063] 13 and 14, the width of the convex portion 61 and the width of the concave portion 62 are approximately the same, the tip surface of the convex portion 61 is the tip abutment surface 64, and the bottom surface of the concave portion 62 is the base abutment surface 65. The abutment surfaces 64, 65 of the right precast slab 11, which is one of the left and right sides, are formed at a slight angle so as to face downward with respect to the vertical line, and the angle θ with respect to the vertical line is the same as in Example 1.

[0064] The top 23 located at the top center of the tunnel of the left precast slab 21, the other of the left and right sides, has a convex portion 61A on one side in the width direction and a concave portion 62A on one side in the width direction corresponding to this convex portion 61A, and a step surface 63 is formed between the convex portion 61A and the concave portion 62A in a direction approximately intersecting the width direction of the precast slab 21.

[0065] As shown in FIGS. 13 and 14, the width of the convex portion 61A and the width of the concave portion 62A are substantially the same, the tip surface of the convex portion 61A is a tip abutting surface 64A, and the bottom surface of the concave portion 62A is a base abutting surface 65A.

[0066] The two butt surfaces 64A, 65A of the left precast slab 21, which is the other of the left and right sides, are formed at a slight angle to the plumb line so that they face upward from the vertical, and the angle θ with respect to the plumb line is the same as in Example 1. The shapes of the convex portion 61A, concave portion 62A and step surface 63 of the left precast slab 21 are the same as the convex portion 61, concave portion 62 and step surface 63 of the right precast slab 11, except that the orientation of the butt surfaces is different.

[0067] Then, the tip abutting surface 64 of one precast slab 11 is abutted against the base abutting surface 65A of the other precast slab 21, and the base abutting surface 65 of one precast slab 11 is abutted against the tip abutting surface 64A of the other precast slab 21. In addition, the step surfaces 63, 63 of the tops 13, 23 are abutted against each other.

[0068] Furthermore, the precast slabs 11, 21 adjacent to each other in the longitudinal direction of the tunnel are installed with their end faces 12, 22 aligned, so similarly, one of the left and right precast slabs 11 is placed along the inner surface 3 of the tunnel 1 with a forklift 51, and then the other left and right precast slab 21 is installed with an installation device 53.

[0069] Next, as in the first embodiment, the top portions 13, 23 are connected to each other with through bolts 42, and the lower ends of the precast slabs 11, 21 are rigidly connected to the side wall portions 5, 5 with poured concrete.

[0070] In addition, in this embodiment, ,left The butt surface of the right precast slab 11 has a recess 62 and a protrusion 61 formed in the circumferential direction of the tunnel on one and the other widthwise sides, respectively, and the butt surfaces of the other left and right precast slabs 21 have a protrusion 61A and a recess 62A formed in the circumferential direction of the tunnel on one and the other widthwise sides, respectively, and the left and right precast slabs 11, 21 are butted together at the butt surfaces 64, 64A of the protrusions 61, 61A and the butt surfaces 65A, 65 of the recesses 62A, 62.Therefore, the butt surfaces 65, 64 formed at an angle downward can be easily butted together by bringing the butt surfaces 64A, 65A formed at an angle upwards close to each other from below, and the structure of the tops 13, 23 is relatively simple.

[0071] Furthermore, the top 13 of one of the left and right precast slabs 11 has a recess 62 and a protrusion 61 on one and the other widthwise side, and a base end abutting surface 65 and a tip end abutting surface 64 formed at a downward angle are formed at the bottom of the recess 62 and the tip of the protrusion 61, respectively. The top 23 of the other of the left and right precast slabs 21 has a protrusion 61A and a recess 62A on one and the other widthwise side, and a tip end abutting surface 64A and a base end abutting surface 65A formed at an upward angle are formed at the tip of the protrusion 61A and the bottom of the recess 62, respectively. Therefore, the tip end abutting surface 64A and the base end abutting surface 65A formed at an upward angle can be easily abutted by bringing them close from below to the base end abutting surface 65 and the tip end abutting surface 64 formed at a downward angle, and the structure of the tops 13, 23 is relatively simple. [reference example 2]

[0072] FIG. 16 shows the present invention reference example 2 indicates the previous Memorial Example 1 and Reference Example 1 In this example, the step surface 63 between the protrusion 61 and the recess 62 is narrowed toward the tip end surface, and the recess 62 is narrowed toward the bottom surface. reduction It is formed at an angle so that

[0073] In addition, the outer surface 21G and inner surface 21N of the precast slab 21 and the upper edge 63J and lower edge 63K of the step surface 63, which are the corners of the step surface 63, are given symbols, and the step surface 63 of the precast slab 21 is slightly upward relative to the vertical line, and the step surfaces 63, 63 of the precast slab 11 are slightly downward relative to the vertical line.

[0074] In addition, since the step surface 63 of one of the left and right precast slabs 11 is inclined downward and the step surface 63 of the other of the left and right precast slabs 21 is inclined upward, the step surfaces 63, 63 can be smoothly butted together during construction. Furthermore, since the convex portions 61, 61A become narrower toward the tip, the angle of the step surface 63 can be made relatively large, and the downward angle of one of The step surface 63 and the other upwardly facing surface approaching it from below. ofThe step surfaces 63 can be easily butted together.

[0075] The present invention is not limited to the present embodiment, and various modifications are possible within the scope of the present invention. For example, in the embodiment, an example is shown in which a precast slab is installed on the inner surface of an existing tunnel. However, the inner surface of the existing tunnel may be partially or entirely chipped and then the precast slab installed, or the existing tunnel may be widened and then the precast slab installed. Furthermore, the shapes of the convex and concave portions at the top can be selected as appropriate as long as they fit together. It goes without saying that the diagonal directions of the butting surfaces of the left and right precast slabs may be reversed. [Explanation of symbols]

[0076] 1 to tunnel 3. Inner Surface 5 Side wall (mounting part) 11 For tunnels Precast plate (one side, left and right) 13 Top (end) 14 Convex part 15 recess 15A Recess 17 Split end butt surface on one side (end butt surface) 17A Other side split tip butt surface (tip butt surface) 18 Base end butt surface 18A Base end butt surface twenty one For tunnels Precast plate (left and right) 23 Top (end) 24 Convex part 25 recess 25A recess 27 Split end butt surface on one side (end butt surface) 27A Other side split tip butt surface (tip butt surface) 28 Base end butt surface 28A Base end butt surface 31 Side wall loop reinforcement (loop part on mounting part side) 32 Lower loop bar 61,61A convex part 62,62A Recess 64,64A Tip butt surface 65,65A Base end butt surface

Claims

1. A pair of tunnel precast slabs are installed to cover the inner surface of an arch-shaped tunnel, and the butt surfaces provided at the ends of the tunnel circumferential direction at the inner apex of the tunnel are butted together. The abutting surfaces are formed obliquely with respect to a vertical line, A convex portion extending in the tunnel circumferential direction is provided at the center of the width direction of the abutting surface, and a concave portion is provided on both sides of the convex portion in the width direction, The abutting surface of the adjacent recess and one side of the tip of the protrusion in the width direction are formed obliquely downward, The other widthwise side of the tip of each of the protrusions and the abutting surface of the adjacent recess are formed obliquely upward, A pair of tunnel precast slabs characterized in that the abutting surface of the convex portion of one of the left and right tunnel precast slabs is abutted against the abutting surface of the concave portion of the other of the left and right tunnel precast slabs in the longitudinal direction of the tunnel, and the left and right tunnel precast slabs are installed offset from each other in the longitudinal direction of the tunnel.

2. 2. The method for installing a pair of precast slabs for a tunnel according to claim 1, A method for installing a pair of tunnel precast slabs, characterized by: aligning one of the left and right tunnel precast slabs along the inner surface of the tunnel; then, raising the other of the left and right tunnel precast slabs; abutting the downward abutting surface of one of the left and right tunnel precast slabs with the upward abutting surface of the other of the left and right tunnel precast slabs; and aligning the other of the left and right tunnel precast slabs along the inner surface of the tunnel.

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