Tunnel construction method and tunnel reinforcement structure

Abstract

To provide a tunnel construction method and a tunnel reinforcement structure capable of effectively reinforcing the ground around a tunnel.SOLUTION: A tunnel construction method for reinforcing an arch-shaped structure that is a part of a tunnel includes an installation step of installing a structure 10 on a support base 1, a first embankment formation step of forming a first embankment up to a position on the structure 10 corresponding to a location where the maximum shear strain occurs, a placement step of placing reinforcing members 20 extending in a direction perpendicular to the extension direction of the structure 10 on an upper surface of the formed first embankment without being joined to both sides of the structure 10, and a second embankment formation step of forming a second embankment to cover the reinforcing members 20.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a tunnel construction method and a tunnel reinforcement structure, and particularly to a tunnel construction method for reinforcing a structure formed in an arch shape, which is a part of the tunnel, and the like.

Background Art

[0002] Conventionally, in order to suppress deformation of a tunnel due to repeated loads acting on the ground around the tunnel, the ground around the tunnel has been reinforced. As an example of reinforcing the ground, arranging a tubular (bar-shaped) member so as to protrude from the tunnel lining can be mentioned.

[0003] For example, Patent Document 1 discloses a lining structure of an underground cavity in which a semi-cylindrical concrete lining wall is formed along the excavation surface of the underground cavity formed by excavating the natural ground, and PS anchors are driven from this concrete lining wall into the natural ground. According to this lining structure, the introduction force of the PC steel material is transmitted to the steel structural material and the concrete lining wall, and they are integrated to restrain the entire wide loosening area of the underground cavity, disperse the ground stress, suppress concentrated loads and partial displacements, and the steel structural material itself improves the support effect, so that a strong support structure can be obtained even in a large cross-section underground cavity.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, in the above Patent Document 1, the PS anchors are evenly arranged over the entire circumferential direction of the concrete cover wall having a semi-circular cross-section. However, with such a configuration, it is impossible to reduce the load acting on the concrete cover wall, and it is difficult to prevent the deformation of the embankment around the concrete cover wall and effectively reinforce the ground.

[0006] Therefore, an object of the present invention is to provide a tunnel construction method and a tunnel reinforcement structure capable of effectively reinforcing the ground around a tunnel.

Means for Solving the Problems

[0007] Regarding the above problems, the tunnel construction method of the present invention is a tunnel construction method for reinforcing a structure formed in an arch shape that is a part of the tunnel, and includes an installation step of installing the structure on a support base, a first embankment formation step of forming a first embankment up to a position corresponding to a location where the maximum shear strain occurs in the structure, an arrangement step of arranging a reinforcing member extending in a direction orthogonal to the extending direction of the structure on the upper surface of the formed first embankment in a state where it is not joined to both sides of the structure, and a second embankment formation step of forming a second embankment so as to cover the reinforcing member.

[0008] Here, it is desirable that a plurality of the reinforcing members are arranged along the extending direction of the structure. Also, it is desirable that the reinforcing members are arranged in a plurality of stages in the vertical direction with respect to the location where the maximum shear strain occurs. Further, it is desirable that the reinforcing member is a steel bar or a steel plate.

[0009] The tunnel reinforcement structure also includes a structure formed in an arch shape that is a part of the tunnel, a support base that supports the structure, a reinforcing member that extends in a direction orthogonal to the extending direction of the structure and is arranged in a state where it is not joined to both sides of the structure at a position corresponding to a location where the maximum shear strain occurs in the structure, and an embankment that covers the support base, the structure, and the reinforcing member.

[0010] Here, it is desirable that the reinforcing member is a steel bar or a steel plate.

Advantages of the Invention

[0011] The method for constructing a tunnel according to the present invention includes a first embankment forming step of forming a first embankment up to a position corresponding to a location where the maximum shear strain occurs among the structures installed on the support base, an arranging step of arranging, on the upper surface of the formed first embankment, a reinforcing member extending in a direction orthogonal to the extending direction of the structure in a state where the reinforcing member is not joined to both sides of the structure, and a second embankment forming step of forming a second embankment so as to cover the reinforcing member.

[0012] Therefore, by arranging the reinforcing member aiming at the location where the maximum shear strain that has been obtained in advance occurs, it is possible to prevent the deformation of the embankment around the structure and effectively reinforce the ground. Further, by not joining the reinforcing member to the structure, it is possible to prevent a concentrated load from acting on the structure. As a result, the load from the embankment acting on the structure and the load from the reinforcing member are reduced, and the structure can be made thinner.

[0013] In particular, since a plurality of reinforcing members are arranged along the extending direction of the structure, it is possible to prevent the deformation of the embankment along the extending direction of the structure. Further, by arranging the reinforcing members in a plurality of stages in the vertical direction with respect to the location where the maximum shear strain occurs, it becomes possible to surely reduce the embankment load. Furthermore, if the reinforcing member is a steel bar or a steel plate, it is possible to prevent the deformation of the embankment with a simple configuration.

[0014] The invention of the tunnel reinforcement structure also includes a structure formed in an arch shape that is a part of the tunnel, a support base that supports the structure, and a reinforcing member that extends in a direction orthogonal to the extending direction of the structure and is arranged in a state where the reinforcing member is not joined to both sides of the structure at a position corresponding to a location where the maximum shear strain occurs in the structure, and an embankment that covers the support base, the structure, and the reinforcing member.

[0015] Therefore, by using a reinforcing member arranged aiming at a location where a previously determined maximum shear strain occurs, it is possible to prevent the deformation of the embankment around the structure and effectively reinforce the ground, and also possible to suppress the occurrence of a concentrated load on the structure. Accordingly, the load acting on the structure can be reduced, and the structure can be made thinner.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Mode for Carrying Out the Invention

[0017] Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1(a) is a diagram showing an installation step in a tunnel construction method according to an embodiment of the present invention, FIG. 1(b) is a diagram showing a first embankment formation step in the tunnel construction method according to the embodiment, FIG. 1(c) is a diagram showing an arrangement step in the tunnel construction method according to the embodiment, and FIG. 1(d) is a diagram showing a second embankment layer formation step in the tunnel construction method according to the embodiment.

[0018] As shown in Fig. 1(a), in the installation process as the initial state, the structure 10 is installed on the support base 1. Specifically, in the installation process, it is an installation step of installing the lower end of the structure 10 on the support base 1 that is installed on the ground G at intervals in the tunnel width direction. Here, the support base 1 extends along the tunnel extension direction.

[0019] The structure 10 is, for example, a tunnel structure formed in an arch shape that protrudes upward, and examples thereof include a tunnel structure for a water channel that is buried in an embankment where trains and vehicles run. The structure 10 is a structure formed in a thin-walled shape made of steel such as a corrugated material, and is formed in a semi-cylindrical shape.

[0020] The pair of support bases 1 are members that are installed on the ground G in advance to support the structure 10. The support bases 1 are installed in a pair in a separated state in the width direction of the structure 10 in order to support the lower end of the structure 10. Each support base 1 extends in a continuous state along the extending direction of the structure 10, but may be arranged separately.

[0021] As shown in Fig. 1(b), in the first embankment formation process, the first embankment is formed up to the position corresponding to the location where the maximum shear strain occurs in the structure 10. Specifically, the embankment is constructed so as to cover the outer peripheral surface 10a of the structure 10 from the lower surface (ground G) of the support base 1 to the height H corresponding to the location where the maximum shear strain occurs, and the first embankment layer L1 is formed. The upper surface of the first embankment layer L1 is the first flat surface S located at the height H from the ground G. The first embankment layers L1 formed sandwiching the structure 10 each have the first flat surface S at the same height H.

[0022] Here, the height H corresponding to the location where the maximum shear strain occurs is a numerical value obtained in advance for the structure 10 through analysis, experiments, etc. That is, by applying a hybrid analysis of non-linear FEM and the cumulative damage degree method to the deformation amplification simulation of the artificial vert, the shear strain acting on the ground around the structure 10 is determined. Also, by assuming the occurrence of repeated loads associated with train operation, loads from both the vertical and horizontal directions are applied, and as a result of the analysis, it is found that local shear strain of the ground occurs at the intermediate position in the vertical direction.

[0023] Specifically, as shown in the graph on the right side of FIG. 2, the shear strain is maximized at the central part in the height direction of the structure 10. From this, it can be understood that it is sufficient to intensively reinforce the ground near the central part in the height direction of the structure 10, and it is only necessary to improve the strength of this point corresponding to the height H from the ground G. Note that the magnitude of the shear strain, the position where the shear strain occurs, etc. may vary depending on the material, shape, etc. of the structure 10.

[0024] As shown in FIG. 1(c), in the placement process, steel bars (reinforcing members) 20 extending in a direction orthogonal to the extending direction of the structure 10 are placed on the first flat surface S, which is the upper surface of the formed first embankment layer L1, in a state where they are not joined to both sides of the structure 10. Specifically, a plurality of steel bars 20 are arranged horizontally on the first flat surface S located at the top of the first embankment layer L1. The plurality of steel bars 20 are arranged along the position corresponding to the height H from the ground G.

[0025] Here, each steel bar 20 is arranged with a gap from the outer peripheral surface 10a in the direction protruding from the outer peripheral surface 10a. By providing a gap between the steel bar 20 and the outer peripheral surface 10a, it is possible to prevent the force from being transmitted from the steel bar 20 to the outer peripheral surface 10a (the structure 10). Further, a plurality of steel bars 20 are arranged along the extending direction of the structure 10. Note that the plurality of steel bars 20 may be arranged at equal intervals along the horizontal direction. Thereby, along the extending direction of the structure 10, it is possible to uniformly prevent the deformation of the embankment caused by the load acting on the periphery.

[0026] As shown in FIG. 1(d), in the second embankment formation step, a second embankment is formed so as to cover the steel bar 20. Specifically, a second embankment layer L2 is formed on the upper side of the first embankment layer L1 so as to cover the steel bar 20 and the outer peripheral surface 10a.

[0027] FIG. 3 shows the main part of the reinforcement structure of the tunnel formed through the installation step, the first embankment formation step, the arrangement step, and the second embankment layer formation step. For convenience of explanation, the illustration of the embankment is omitted. The structure 10 is arranged on the support bases 1 arranged separately on the left and right, and a plurality of steel bars 20 are arranged along the horizontal direction so as to protrude in the direction orthogonal to the extending direction of the structure 10. Note that a gap is formed between the outer peripheral surface 10a of the structure 10 and the steel bar 20.

[0028] Thus, the tunnel construction method according to the embodiment includes an installation step of installing the structure 10 on the support base 1, a first embankment formation step of forming the first embankment up to the position corresponding to the location where the maximum shear strain occurs in the structure 10, an arrangement step of arranging steel bars 20 extending in the direction orthogonal to the extending direction of the structure 10 on the first flat surface S which is the upper surface of the formed first embankment in a state where they are not joined to both sides of the structure 10, and a second embankment formation step of forming a second embankment so as to cover the steel bars 20.

[0029] Thereby, since the load acting on the structure 10 from the embankment covering the periphery of the structure 10 is reduced, the structure 10 can be made thinner. Further, since the embankment is also reinforced by the steel bars 20, the deformation can be suppressed.

[0030] Here, the reinforcing member is the steel bar 20, and a plurality of them may be arranged along the extending direction of the structure 10. Thereby, the deformation of the embankment can be prevented along the extending direction of the structure 10.

[0031] FIG. 4(a) is a diagram for explaining the reinforcement structure of the tunnel according to the first modification. In the first modification, the same components as those in the above embodiment are denoted by the same reference numerals and the description thereof is omitted. Also, for convenience of explanation, the illustration of the embankment covering the structure 10 is omitted.

[0032] In the reinforcement structure of the tunnel according to the first modification, the steel bars 20 are arranged at different height positions on the left and right sides of the structure 10. Specifically, as shown in FIG. 4(a), the heights of the plurality of steel bars 20 arranged along the horizontal direction on the right side of the structure 10 and the plurality of steel bars 20 arranged along the horizontal direction on the left side of the structure 10 from the support base 1 are different. Here, the steel bar 20 arranged on the right side of the structure 10 may be made to coincide with the height H, or the steel bar 20 arranged on the left side of the structure 10 may be made to coincide with the height H.

[0033] In this way, as long as it is around where the maximum shear strain of the structure 10 occurs, the heights of the left and right steel bars 20 can also be made different.

[0034] FIG. 4(b) is a diagram for explaining the reinforcement structure of the tunnel according to the second modification. In the second modification, the same components as those in the above embodiment and the first modification are denoted by the same reference numerals and the description thereof is omitted. Also, for convenience of explanation, the illustration of the embankment covering the structure 10 is omitted.

[0035] In the reinforcement structure of the tunnel according to the second modification, the steel bars 20 are arranged in a plurality of stages in the vertical direction with respect to the location where the maximum shear strain occurs. Specifically, as shown in FIG. 4(b), two steel bars 20 are arranged vertically on both sides of the structure 10. That is, a plurality of pairs of steel bars 20 spaced apart in the vertical direction are arranged along the horizontal direction.

[0036] In this way, the steel bars 20 are arranged in a plurality of stages in the vertical direction with respect to the location where the maximum shear strain occurs, so that the embankment around where the maximum shear strain occurs can be reinforced over a wide range in the vertical direction.

[0037] FIG. 5 is a diagram for explaining the reinforcement structure of a tunnel according to a third modification. In the third modification, the same components as those in the above-described embodiment and the first and second modifications are denoted by the same reference numerals and the description thereof is omitted. For convenience of explanation, the illustration of the embankment covering the structure 10 is omitted.

[0038] In the reinforcement structure of the tunnel according to the third modification, a flat steel plate 21 is arranged along the extending direction of the structure 10 instead of the steel bar 20 as the reinforcement member. Specifically, as shown in FIG. 5, steel plates 21 extending along the horizontal direction are arranged on both the left and right sides of the structure 10. The steel plates 21 are arranged in a state where there is a gap from the outer peripheral surface 10a without being joined to the structure 10. Note that the heights of the steel plates 21 from the ground G may be different on both sides of the structure 10.

[0039] In this way, by arranging the steel plate 21 as the reinforcement member along the extending direction of the structure 10, the embankment located around the structure 10 can be continuously reinforced over a wide range along the horizontal direction. Thereby, deformation of the embankment around the structure 10 can be prevented and the ground can be effectively reinforced.

[0040] Also, a plurality of steel plates 21 may be arranged along the extending direction of the structure 10, and the plurality of steel plates 21 may be arranged at equal intervals along the horizontal direction. Thereby, deformation of the embankment around the structure 10 can be prevented over a wider range.

[0041] As described above, the embodiments of the present invention have been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and design changes that do not depart from the gist of the present invention are included in the present invention.

Explanation of Reference Numerals

[0042] 1: Support stand 10: Structure 20: Steel bar (reinforcing member) 21: Steel plate (reinforcing member)

Claims

1. A tunnel construction method for reinforcing a structure formed in an arch shape that is part of a tunnel, comprising: an installation step of installing the structure on a support base; a first embankment formation step of forming a first embankment up to a position corresponding to a location where the maximum shear strain occurs in the structure; an arrangement step of arranging, on the upper surface of the formed first embankment, a reinforcing member extending in a direction orthogonal to the extending direction of the structure in a state where it is not joined to both sides of the structure; a second embankment formation step of forming a second embankment so as to cover the reinforcing member. The tunnel construction method is characterized by comprising these steps.

2. The tunnel construction method according to Claim 1, wherein a plurality of the reinforcing members are arranged along the extending direction of the structure.

3. The tunnel construction method according to Claim 1 or 2, wherein the reinforcing members are arranged in a plurality of stages in the vertical direction with respect to the location where the maximum shear strain occurs.

4. The tunnel construction method according to Claim 1 or 2, wherein the reinforcing member is a steel bar or a steel plate.

5. An arch-shaped structure that is part of a tunnel; a support base for supporting the structure; a reinforcing member that extends in a direction orthogonal to the extending direction of the structure and is arranged in a state where it is not joined to both sides of the structure at a position corresponding to a location where the maximum shear strain occurs in the structure; An embankment covering the support base, the structure, and the reinforcing member. The tunnel reinforcement structure is characterized by comprising these components.

6. The tunnel reinforcement structure according to Claim 5, wherein the reinforcing member is a steel bar or a steel plate.

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