Linear body laying method

Abstract

To lay a linear body along an excavation surface.SOLUTION: An optical fiber cable 30 is laid along upper and lower excavation surfaces 1 when constructing a tunnel through an installation step in which a steel support 10 provided with a rod-shaped members 22 is installed on the upper and lower excavation surfaces 1, a spraying step in which concrete is sprayed onto the upper and lower excavation surfaces 1 to a thickness that exposes at least a portion of the rod-shaped member 22, and a laying step in which the optical fiber cable 30 is engaged with the rod-shaped member 22 exposed from a concrete sprayed surface and the optical fiber cable 30 is laid along the concrete sprayed surface.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a method for installing a linear object in a tunnel. [Background technology]

[0002] Patent Document 1 discloses a method of laying an optical fiber cable along an excavation surface as a linear object for measuring stress in shotcrete sprayed onto the excavation surface when constructing a tunnel. In the method disclosed in Patent Document 1, the optical fiber cable is tied to a wire mesh installed along the excavation surface via a hook. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-041856 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the installation method described in Patent Document 1, when concrete is sprayed toward the wire mesh as a support member, the optical fiber cable may come off the hook due to the spraying pressure, causing the position of the optical fiber cable embedded in the sprayed concrete to shift partially, or the optical fiber cable may be pressed against the wire mesh by the spraying pressure, causing the optical fiber cable to be locally bent. In order to accurately measure the stress of the concrete sprayed on the excavation surface using the optical fiber cable, it is desirable to lay the optical fiber cable along the excavation surface so that it does not shift or bend.

[0005] An object of the present invention is to lay a linear body along an excavation surface without causing displacement or the like. [Means for solving the problem]

[0006] The present invention is a linear body laying method for laying a linear body along an excavation surface when constructing a tunnel, and includes an installation process for installing a member provided with an engagement portion on the excavation surface, a spraying process for spraying concrete on the excavation surface to a thickness that exposes at least a portion of the engagement portion, and a laying process for engaging the linear body with the engagement portion exposed from the concrete sprayed surface and laying the linear body along the concrete sprayed surface. Effect of the Invention

[0007] According to the present invention, a linear body can be laid along an excavation surface without causing positional deviation or the like. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a front view of a linear object laid in a tunnel by the linear object laying method according to a first embodiment of the present invention, viewed in the direction of excavation. [Diagram 2] 2 is a cross-sectional view showing a cross section taken along line AA in FIG. 1. [Diagram 3] 2 is an enlarged cross-sectional view showing a cross section taken along line BB in FIG. 1. [Figure 4] FIG. 2 is a diagram showing an example of a laying pattern of linear objects laid on the upper and lower half excavation surface sides of a tunnel by the linear object laying method according to the first embodiment of the present invention. [Diagram 5] FIG. 2 is a diagram showing an example of a laying pattern of linear objects laid on the invert excavation face side in a tunnel by the linear object laying method according to the first embodiment of the present invention. [Figure 6] 1 is a diagram showing an example of a laying pattern of a linear object laid in a tunnel by the linear object laying method according to the first embodiment of the present invention. FIG. [Figure 7] FIG. 11 is a front view of a linear object laid in a tunnel by the linear object laying method according to the second embodiment of the present invention, viewed in the direction of excavation. [Figure 8] 8 is a cross-sectional view showing a cross section taken along line CC in FIG. 7. [Figure 9] 8 is an enlarged cross-sectional view showing a cross section taken along line EE in FIG. 7. [Figure 10]FIG. 2 is a front view corresponding to FIG. 1, showing a modified example of the linear object laying method according to the first embodiment of the present invention. [Figure 11] 11 is a cross-sectional view showing a cross section taken along line FF in FIG. 10. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, a linear object installation method according to an embodiment of the present invention will be described with reference to the drawings.

[0010] First Embodiment A linear body laying method according to a first embodiment and a structure used when laying a linear body along an excavation surface by this method will be described with reference to Figures 1 to 3. Figure 1 is a front view of a linear body laid in a tunnel, as viewed toward a face 5 along the excavation direction shown in Figure 2, Figure 2 is a cross-sectional view showing a cross section along line AA in Figure 1, and Figure 3 is an enlarged cross-sectional view showing an enlarged cross section along line BB in Figure 1. Note that each figure is an image diagram showing the structure inside the tunnel in an exaggerated manner for easy understanding, and some parts differ from the actual size and ratio.

[0011] When constructing mountain tunnels by NATM or other methods, the sprayed concrete sprayed on the inner wall of the excavation hole is easily affected by changes in the ground during excavation. For this reason, it is possible to lay a linear object such as an optical fiber cable in the sprayed concrete and measure the distortion of this linear object to continuously grasp changes in the ground condition. For example, if the linear object is an optical fiber cable, the property of the optical fiber cable that the incident pulse light is slightly scattered backwards can be utilized to measure the frequency of the scattered light, and the distortion, stress, and temperature can be calculated from the measured values. Continuously grasping the ground condition is also important for optimizing the structure of the support members from the viewpoints of safety and economy.

[0012] The linear object laying method of this embodiment is a method of laying a linear object such as an optical fiber cable in a tunnel at an appropriate position along the excavation surface in order to continuously monitor changes in the condition of the ground.

[0013] A structure 100 (hereinafter referred to as the "laying structure") used when laying an optical fiber cable 30 (linear body) along an excavation surface by the linear body laying method comprises, as shown in Figures 1 and 2, a steel support 10 erected along an upper and lower half excavation surface 1 (excavation surface) excavated in an arch shape, an invert strut 14 (steel support) erected along an invert excavation surface 6 (excavation surface) excavated downward in an arch shape, and multiple laying jigs 20 provided on each of the steel support 10 and the invert strut 14.

[0014] Fig. 1 shows an example in which an optical fiber cable 30 is composed of a first optical fiber cable 31 that is fastened to an installation jig 20 provided on a steel support 10, and a second optical fiber cable 32 that is fastened to an installation jig 20 provided on an invert strut 14. Note that Fig. 2 does not show the optical fiber cable 30. Also, Fig. 2 does not show steel supports and the like that are erected on the tunnel entrance side prior to the steel support 10.

[0015] As shown in Fig. 3, the steel support 10 is a member formed of an H-shaped steel material having a first flange portion 11a arranged on the upper and lower half excavation surface 1 side, a second flange portion 11b arranged on the tunnel center side, and a web portion 11c sandwiched between the first flange portion 11a and the second flange portion 11b, and is formed in an arch shape curved along the circumferential direction of the upper and lower half excavation surface 1 as shown in Fig. 1. Note that the "circumferential direction" means the direction along the upper and lower half excavation surface 1 excavated in a substantially arc shape, but since the upper and lower half excavation surface 1 is not formed in an exact arc shape, the steel support 10 actually has a shape that generally follows the upper and lower half excavation surface 1.

[0016] As shown in Fig. 1, the steel support 10 is erected in an excavation shaft by connecting a pair of support materials 11 at the top end of the excavation shaft. The work of erecting the steel support 10 in the excavation shaft is carried out every time the excavation shaft is excavated a preset distance, for example 1 m. In other words, multiple steel supports 10 are erected at predetermined intervals in the excavation direction.

[0017] The pair of support materials 11 are formed almost symmetrically when viewed toward the face 5 along the excavation direction, and are each integrally formed in an arc shape along the upper and lower half excavation surfaces 1 from the top end of the excavation hole to the bottom. A connecting flange portion 12 is provided at the end on the top end side of each support material 11, and the pair of support materials 11 are connected to each other by connecting the connecting flange portions 12 with bolts (not shown). Note that each support material 11 does not need to be formed integrally, and may be formed, for example, by connecting multiple H-shaped steel members formed in an arc shape in the circumferential direction of the upper and lower half excavation surfaces 1.

[0018] The invert strut 14, like the steel support 10, is a member formed from an H-shaped steel material, and is formed in an arch shape curved along the circumferential direction of the invert excavation surface 6, as shown in FIG.

[0019] The invert struts 14 are erected in the excavation hole by connecting the connecting flange parts 16 of a pair of invert strut materials 15 via bolts (not shown) at the lower end of the invert excavation surface 6, thereby connecting the lower end parts of the steel supports 10 erected along the upper and lower half excavation surfaces 1. In other words, the invert struts 14 are erected at the same intervals as the steel supports 10 in the excavation direction.

[0020] 3, the installation jig 20 is a steel member having a plurality of rod-shaped members 22 (locking portions) extending in parallel, a long support portion 21 to which the base ends of the plurality of rod-shaped members 22 are fixed, and a U-shaped pile rack portion 23 provided on the support portion 21, and a plurality of such members are provided at approximately equal intervals along the circumferential direction of the steel support 10 and the invert strut 14. The installation jig 20 may be made of plastic.

[0021] The installation jig 20 provided on the steel support 10 is attached to each support material 11 so that when the steel support 10 is erected along the upper and lower half excavation surfaces 1, the rod-shaped member 22 extends from the support part 21 toward the inside of the tunnel, i.e., the base end of the rod-shaped member 22 fixed to the support part 21 is positioned on the upper and lower half excavation surface 1 side, and the tip of the rod-shaped member 22 points toward approximately the center of the tunnel.

[0022] Similarly, the installation jig 20 provided on the invert strut 14 is attached to each invert strut material 15 so that when the invert strut 14 is erected along the invert excavation surface 6, the rod-shaped member 22 extends from the support part 21 toward the inside of the tunnel, i.e., the base end of the rod-shaped member 22 fixed to the support part 21 is positioned on the invert excavation surface 6 side, and the tip of the rod-shaped member 22 faces approximately toward the center of the tunnel.

[0023] In addition, since the optical fiber cable 30 is fastened to the rod-shaped member 22 of the installation jig 20 as described below, in order to ensure the safety of the operation of fastening the optical fiber cable 30 to the installation jig 20, the installation jig 20 is attached to the opposite side of the face 5 (the tunnel entrance side) rather than to the face 5 side of the steel support 10 and invert strut 14.

[0024] In order to ensure that the installation jig 20 is attached to the steel support 10 and the invert strut 14 in this state, the installation jig 20 is fixed to the steel support 10 via a pile rack portion 23 on the opposite side (the wellhead side) of the face 5 of the first flange portion 11a, which is located on the upper and lower half excavation surface 1 side, of the flange of the support material 11, and is fixed to the invert strut 14 via a pile rack portion 23 on the opposite side (the wellhead side) of the face 5 of the flange portion of the invert strut material 15, which is located on the invert excavation surface 6 side, so that the longitudinal direction of the support portion 21 is aligned with the excavation direction, as shown in Figure 3.

[0025] In this way, the rod-shaped member 22 to which the optical fiber cable 30 is anchored is attached to the tunnel entrance side of the steel support 10 and the invert strut 14 via the support part 21, and extends toward the inside of the tunnel from the support part 21 fixed to the steel support 10 and the invert strut 14.

[0026] In addition, the method of fixing the installation jig 20 to the support material 11 or the invert strut material 15 is not limited to tightening bolts or the like (not shown) provided on the pillar rack portion 23, but may be, for example, by directly welding or gluing the support portion 21 to the flange portion, or by using the attractive force of a magnet provided on the support material 11 or the installation jig 20.

[0027] The optical fiber cable 30 is a cable consisting of an optical fiber and a protective member formed to cover the optical fiber. The optical fiber cable 30 is fixed to the rod-shaped members 22 (locking parts) of the installation jigs 20 via bundling members 26 such as Insulocks, so that the optical fiber cable 30 is stretched between the installation jigs 20 and laid along the steel supports 10 and the invert struts 14, that is, laid along the circumferential direction of the upper and lower half excavation surfaces 1 and the invert excavation surface 6, as shown in Fig. 1. The bundling members 26 are not limited to Insulocks, and may be any member capable of fastening the optical fiber cable 30 to the rod-shaped members 22, for example, wire or rope.

[0028] Both ends of the laid optical fiber cable 30 are connected to a measuring device (not shown) that uses the optical fiber cable 30 to measure the distribution of stress, strain, and temperature in the sprayed concrete 3, 7 described below. Note that a plurality of optical fiber cables 30 may be provided, such as a cable for measuring strain and a cable for measuring temperature, and the installation jig 20 is provided with a number of rod-shaped members 22 (locking portions) sufficient to accommodate the number of optical fiber cables 30 to be laid. Note that the linear body stretched across the installation jig 20 is not limited to the optical fiber cable 30, and may be, for example, a plurality of sensor portions capable of measuring strain and temperature that are arranged in a line.

[0029] Next, a method for laying the optical fiber cable 30 along the upper and lower half excavation surfaces 1 and the invert excavation surface 6 via the cable laying structure 100 having the above-mentioned configuration will be described with reference to FIGS.

[0030] The excavation pit is excavated by blasting, and the upper and lower half excavation surfaces 1 are subjected to finish excavation by an excavation device or the like, and primary shotcrete 2 is sprayed as a support member by a concrete sprayer (not shown). Then, along the surface of the primary shotcrete 2, which has become relatively smooth by being sprayed with the primary shotcrete 2, the steel support 10 having the above configuration is erected as a member provided with a laying jig 20 (erection (installation) process).

[0031] Specifically, the steel support 10 is erected in the excavation shaft by connecting the connecting flanges 12 of a pair of support materials 11 with bolts (not shown) at the top end of the excavation shaft. The erected steel support 10 is then connected in the excavation direction to a previously erected steel support (not shown), i.e., a steel support that was previously erected at a position farther away from the working face 5 than the steel support 10 in the excavation direction, by a connecting member (not shown).

[0032] Next, the first layer 3a of the secondary shotcrete 3 is sprayed to a thickness such that the tips of the rod-shaped members 22 (fastening parts) of each installation jig 20 of the erected steel support 10 are exposed (spraying process).

[0033] Specifically, a predetermined thickness of concrete is sprayed onto the surface of the primary sprayed concrete 2 by a concrete sprayer (not shown) so as to fill the space formed between the erected steel support 10 and a steel support (not shown) that was previously erected at a predetermined interval in the direction of tunnel excavation.

[0034] As described above, the installation jig 20 is attached to the tunnel entrance side of the steel support 10 with the support part 21 to which the base end of the rod-shaped member 22 is fixed positioned on the upper and lower half excavation surface 1 side. Therefore, by spraying concrete to a predetermined thickness between the steel support 10 and the previously erected steel support, the installation jig 20 is buried in the sprayed concrete in sequence starting from the support part 21 side.

[0035] The thickness of the concrete sprayed in this process, i.e., the sprayed thickness of the first layer 3a of the secondary sprayed concrete 3, is set to a thickness such that the first flange portion 11a of the support material 11 and the support portion 21 of the installation jig 20 fixed to the first flange portion 11a via the pile rack portion 23 are embedded in the sprayed concrete, while the tip side of the rod-shaped member 22 is exposed to a length sufficient to fix the optical fiber cable 30 via the binding member 26.

[0036] Preferably, the spraying thickness of the first layer 3a of the secondary shotcrete 3 is set so that the optical fiber cable 30 is located approximately in the center of the final spraying thickness of the secondary shotcrete 3 that is sprayed to cover the entire steel support 10. The final spraying thickness of the secondary shotcrete 3 may be a thickness that partially exposes the support material 11, and the spraying thickness of the first layer 3a of the secondary shotcrete 3 may be half the final spraying thickness.

[0037] When the spraying of the first layer 3a of the secondary shotcrete 3 is completed, the first optical fiber cable 31 is laid along the sprayed concrete surface of the first layer 3a (laying step).

[0038] Specifically, as shown in FIG. 3, the first optical fiber cable 31 is anchored via a bundling member 26 to a rod-shaped member 22 exposed from the sprayed concrete surface of the first layer 3a of the secondary shotcrete 3.

[0039] The distance between adjacent installation tools 20 is set to, for example, 80 cm or less, preferably approximately 50 cm to 60 cm, so that the first optical fiber cable 31 is engaged with the rod-shaped member 22 of each installation tool 20, so that the first optical fiber cable 31 is in partial contact with the sprayed concrete surface of the first layer 3a between adjacent installation tools 20.

[0040] Once the first optical fiber cable 31 is engaged with the rod-shaped member 22 and laid along the concrete sprayed surface of the first layer 3a of the secondary shotcrete 3, the second layer 3b of the secondary shotcrete 3 is then sprayed to a thickness sufficient to bury the first optical fiber cable 31 (embedding spraying process).

[0041] Here, when the second layer 3b of the secondary sprayed concrete 3 is sprayed onto the first optical fiber cable 31 by a concrete sprayer not shown, the spraying pressure of the concrete acts on the first optical fiber cable 31 toward the radial outside of the tunnel. However, if there are scattered spaces or spaces exist over a wide area on the opposite side of the first optical fiber cable 31 from the concrete sprayer, the spraying pressure of the concrete may cause the first optical fiber cable 31 to bend locally along the space, or the position of the first optical fiber cable 31 embedded in the sprayed concrete may be partially shifted along the space.

[0042] In contrast, in this embodiment, when the second layer 3b of the secondary shotcrete 3 is sprayed onto the first optical fiber cable 31, the first optical fiber cable 31 is in a state of being substantially in contact with the concrete sprayed surface of the first layer 3a, that is, in a state of being supported in a substantially planar manner from the radially outer side of the tunnel by the concrete sprayed surface of the first layer 3a. Therefore, even if the concrete spraying pressure acts on the first optical fiber cable 31 toward the radially outer side of the tunnel, the first optical fiber cable 31 is supported along the circumferential direction of the upper and lower half excavation surfaces 1 by the concrete sprayed surface of the first layer 3a, so that it is possible to prevent the position of the first optical fiber cable 31 from being partially shifted or locally bent by the spraying pressure.

[0043] In addition, by spraying the secondary shotcrete 3 in two steps and laying the first optical fiber cable 31 along the surface of the concrete sprayed in the first layer 3a, it is possible to lay the first optical fiber cable 31 at an appropriate position along the circumferential direction of the upper and lower half excavation surfaces 1, i.e., at approximately the center of the sprayed thickness of the secondary shotcrete 3.

[0044] In this way, by laying the first optical fiber cable 31 at a predetermined position within the sprayed thickness of the secondary shotcrete 3, the distance between the upper and lower half excavation faces 1 and the first optical fiber cable 31 becomes almost constant in the circumferential direction, and it is possible to accurately measure the stress distribution in the circumferential direction within the secondary shotcrete 3, which changes in response to changes in the ground during excavation of the tunnel. As a result, it becomes possible to accurately grasp changes in the ground condition during excavation in sequence, and the structure of the support member can be optimized by increasing the sprayed thickness of the secondary shotcrete 3 or the number of rock bolts in response to changes in the ground condition.

[0045] Thereafter, as necessary, rock bolts (not shown) are driven radially into the ground within the area where the secondary shotcrete 3 has been sprayed, thereby completing the process of installing supports on the upper and lower half excavation surfaces 1.

[0046] Once the installation of support structures on the upper and lower half excavation surfaces 1 has been completed in this manner, the construction of the invert is then carried out.

[0047] In constructing an invert, first, the ground below the above-mentioned steel support 10 is excavated to form an invert excavation surface 6 in order to install the invert struts 14.

[0048] Then, the invert strut 14 having the above configuration is erected along the excavated invert excavation surface 6 as a member provided with the installation jig 20 (erecting (installation) process).

[0049] Specifically, the invert strut 14 is erected in the excavation hole by connecting the connecting flange parts 16 of a pair of invert strut materials 15 via bolts (not shown) at the lower end of the invert excavation surface 6 to connect the lower end of the steel support 10. As a result, the upper and lower half excavation surfaces 1 and the invert excavation surface 6 exposed by excavation are closed in a ring shape.

[0050] Next, a first layer of invert shotcrete 7 is sprayed to a thickness such that the tip portions of the rod-shaped members 22 (locking portions) of each installation jig 20 of the erected invert struts 14 are exposed (spraying process).

[0051] Specifically, a predetermined thickness of concrete is sprayed onto the surface of the invert excavation surface 6 by a concrete sprayer (not shown) so as to fill the space formed between the erected invert strut 14 and an invert strut (not shown) that was previously erected at a predetermined interval in the direction of tunnel excavation.

[0052] As described above, the installation jig 20 is attached to the entrance side of the invert strut 14 with the support part 21 to which the base end of the rod-shaped member 22 is fixed positioned on the invert excavation surface 6 side. Therefore, by spraying concrete to a predetermined thickness between the invert strut 14 and the previously erected invert strut, the installation jig 20 is buried in the sprayed concrete in sequence starting from the support part 21 side.

[0053] The thickness of the concrete sprayed in this process, i.e., the sprayed thickness of the first layer of invert shotcrete 7, is set to a thickness such that the flange portion arranged on the invert excavation surface 6 side of the invert strut material 15 and the support portion 21 of the installation jig 20 fixed to the flange portion via the pile rack portion 23 are embedded in the sprayed concrete, while the tip side of the rod-shaped member 22 is exposed to a length sufficient to secure the optical fiber cable 30 via the binding member 26.

[0054] Preferably, the spraying thickness of the first layer of invert shotcrete 7 is set so that the optical fiber cable 30 is located approximately in the center of the final spraying thickness of the invert shotcrete 7 that is sprayed to cover the entire invert strut 14. Note that the final spraying thickness of the invert shotcrete 7 may be a thickness that partially exposes the invert strut material 15, and the spraying thickness of the first layer of invert shotcrete 7 may be half the final spraying thickness.

[0055] When the spraying of the first layer of invert shotcrete 7 is completed, the second optical fiber cable 32 is laid along the sprayed surface of the first layer of concrete (laying step).

[0056] Specifically, the second optical fiber cable 32 is anchored via the bundling member 26 to the rod-shaped member 22 exposed from the sprayed concrete surface of the first layer of the invert shotcrete 7 .

[0057] The distance between adjacent installation tools 20 is set to, for example, 80 cm or less, preferably approximately 50 cm to 60 cm, so that the second optical fiber cable 32 is engaged with the rod-shaped member 22 of each installation tool 20, thereby bringing the second optical fiber cable 32 into partial contact with the sprayed surface of the first layer of concrete between adjacent installation tools 20.

[0058] Once the second optical fiber cable 32 is engaged with the rod-shaped member 22 and laid along the concrete sprayed surface of the first layer of invert shotcrete 7, a second layer of invert shotcrete 7 is then sprayed to a thickness sufficient to bury the second optical fiber cable 32 (embedding spraying process).

[0059] Here, when the second layer of invert shotcrete 7 is sprayed onto the second optical fiber cable 32 by a concrete sprayer not shown, the spray pressure of the concrete acts on the second optical fiber cable 32 toward the bottom of the tunnel. However, if there are scattered spaces or spaces exist over a wide area on the opposite side of the second optical fiber cable 32 from the concrete sprayer, the spray pressure of the concrete may cause the second optical fiber cable 32 to bend locally along the space, or the position of the second optical fiber cable 32 embedded in the sprayed concrete may be partially shifted along the space.

[0060] In contrast, in this embodiment, when the second layer of invert shotcrete 7 is sprayed onto the second optical fiber cable 32, the second optical fiber cable 32 is in a state of being substantially in contact with the sprayed surface of the first layer of concrete, that is, in a state of being supported in a substantially planar manner from the bottom side of the tunnel by the sprayed surface of the first layer of concrete. Therefore, even if the spraying pressure of the concrete acts on the second optical fiber cable 32 toward the radial outside of the tunnel, the second optical fiber cable 32 is supported along the circumferential direction of the invert excavation surface 6 by the sprayed surface of the first layer of concrete, so that it is possible to prevent the position of the second optical fiber cable 32 from being partially shifted or locally bent by the spraying pressure.

[0061] In addition, by spraying the invert shotcrete 7 in two layers and laying the second optical fiber cable 32 along the surface of the concrete sprayed in the first layer, it is possible to lay the second optical fiber cable 32 at an appropriate position along the circumferential direction of the invert excavation surface 6, i.e., at approximately the center of the sprayed thickness of the invert shotcrete 7.

[0062] In this way, by laying the second optical fiber cable 32 at a predetermined position within the sprayed thickness of the invert shotcrete 7, the distance between the invert excavation surface 6 and the second optical fiber cable 32 becomes almost constant in the circumferential direction, and it is possible to accurately measure the stress distribution in the circumferential direction within the invert shotcrete 7 that changes in response to changes in the ground during excavation of the tunnel. Furthermore, it is possible to accurately measure the stress distribution within the invert shotcrete 7 that changes in response to the displacement that occurs when the surface of the invert shotcrete 7 is backfilled with the backfill soil 9 and the displacement that occurs when the backfill soil 9 is removed from the surface of the invert shotcrete 7.

[0063] After this, invert concrete 8 will be finally poured on the surface of the invert shotcrete 7, as shown in Figure 1, but the surface of the invert shotcrete 7, where work vehicles will pass over to proceed with excavation work, will first be backfilled with backfill soil 9, as shown in Figure 2.

[0064] As the excavation pit is dug, backfill soil 9 is excavated and removed, and invert concrete 8 is poured using a formwork (not shown) on the surface of the invert shotcrete 7. When the invert concrete 8 and secondary shotcrete 3 are stabilized, lining concrete 4 is poured using a formwork (not shown) on the surface of the secondary shotcrete 3, as shown in FIG.

[0065] For the upper and lower half excavation surfaces 1, the upper and lower halves may be excavated simultaneously using the so-called full section method, or the upper half may be excavated prior to the lower half using the bench cut method. When the upper and lower half excavation surfaces 1 are formed by dividing them into the upper and lower halves, the steel support 10 may be divided into the upper and lower halves. If the ground is stable, the invert shotcrete 7 and invert concrete 8 may be used as support members without providing the invert struts 14 as support members for the invert.

[0066] Moreover, the first optical fiber cable 31 laid on each steel support 10 may be laid continuously in the axial direction of the tunnel as shown in Fig. 4. Fig. 4 is a development view showing the laying pattern of the first optical fiber cable 31 laid along the upper and lower half excavation surfaces 1, developed on a plane centered on the top end.

[0067] In this way, by laying the first optical fiber cables 31 at predetermined intervals along the circumferential direction of the upper and lower half excavation surfaces 1 and in the axial direction of the tunnel, it becomes possible to grasp the change in stress of the secondary shotcrete 3 in the axial direction of the tunnel. This makes it possible to set the timing for starting pouring of the lining concrete 4 according to the convergence state of the stress change of the secondary shotcrete 3, and to set the strength of the concrete used in the lining concrete 4 based on the stress state of the secondary shotcrete 3, i.e., the state of the ground.

[0068] The second optical fiber cable 32 laid on each invert strut 14 may be laid continuously in the axial direction of the tunnel as shown in Fig. 5. Fig. 5 is a development view showing the laying pattern of the second optical fiber cable 32 laid along the invert excavation surface 6, developed on a plane centered on the lower end of the invert part.

[0069] In this way, by laying the second optical fiber cables 32 at predetermined intervals along the circumferential direction of the invert excavation surface 6 and in the axial direction of the tunnel, it becomes possible to grasp the change in stress of the invert shotcrete 7 in the axial direction of the tunnel. This makes it possible to set the timing for starting pouring of the invert concrete 8 according to the convergence state of the stress change of the invert shotcrete 7, and to set the strength of the concrete used in the invert concrete 8 and the size of the excavation radius of the invert excavation surface 6 based on the stress state of the invert shotcrete 7, i.e., the state of the natural ground.

[0070] In addition, instead of measuring the upper and lower half excavation surfaces 1 and the invert excavation surface 6 using separate optical fiber cables, as shown in Figure 6, a first optical fiber cable 31 laid along the circumferential direction of the upper and lower half excavation surfaces 1 and a second optical fiber cable 32 laid along the circumferential direction of the invert excavation surface 6 may be made into a single optical fiber cable 30, allowing the upper and lower half excavation surfaces 1 and the invert excavation surface 6 to be continuously measured at a predetermined interval in the axial direction of the tunnel.

[0071] By laying only one optical fiber cable 30 in the tunnel in this way, installation is easier than when multiple stress detection sensors are installed, and the required measurement system is significantly simplified, so that the introduction and operation costs of the measurement system can be reduced. In addition, since the measurement points are continuous lines rather than points, measurement omissions are less likely to occur, and as a result, the measurement accuracy can be improved.

[0072] Furthermore, as shown in Figure 6, by configuring the upper and lower half excavation surfaces 1 and the invert excavation surface 6 to be capable of continuous measurement along the axial direction of the tunnel, it becomes possible to measure the stress distribution around the entire circumference of a specified cross section of the tunnel at specified intervals along the axial direction of the tunnel.As a result, it becomes possible to detect changes in the ground and inside the tunnel sequentially, making it easier to maintain and manage the tunnel.

[0073] Furthermore, in order to detect changes in the ground or inside a tunnel, it is possible to simply lay an optical fiber cable along the axial direction of the tunnel. However, for example, in curved sections where the direction changes significantly, the length of the optical fiber cable installed on the inner side will be different from the length of the optical fiber cable installed on the outer side, and even if the same displacement occurs, the detection sensitivity will be different for each, making it difficult to accurately detect changes in the ground or inside the tunnel.

[0074] In contrast, as described above, by measuring the stress distribution around the entire circumference of the tunnel at specified intervals in the axial direction of the tunnel, it is possible to accurately grasp the changes in each cross section at each specified distance of the tunnel, and as a result, the magnitude of changes in the ground or inside the tunnel and the location where the changes have occurred can be accurately detected.

[0075] According to the above-described first embodiment, the following effects are achieved.

[0076] In the linear object laying method described above, after the steel support 10 and the invert strut 14, which are members provided with the rod-shaped member 22 (locking portion), are installed on the excavation surface 1, 6, concrete is sprayed onto the excavation surface 1, 6 to a thickness that exposes a part of the rod-shaped member 22. Then, the optical fiber cable 30 is locked to the exposed rod-shaped member 22, so that the optical fiber cable 30 is laid along the concrete sprayed surface. Concrete is further sprayed onto the optical fiber cable 30 laid along the concrete sprayed surface, but since the optical fiber cable 30 is supported by the concrete sprayed surface, the optical fiber cable 30 is prevented from being partially displaced or locally bent due to the spraying pressure. This allows the optical fiber cable 30 to be laid along the excavation surface 1, 6 without causing positional displacement or the like.

[0077] <Second embodiment> Next, a linear object installation method and installation structure 200 according to a second embodiment of the present invention will be described with reference to Figures 7 to 9. Below, differences from the first embodiment will be mainly described, and descriptions of configurations that are the same as or equivalent to those described in the first embodiment will be omitted.

[0078] The installation structure 200 used when laying an optical fiber cable 30 as a linear body by the linear body installation method of the second embodiment differs from the above-mentioned installation structure 100 in that the installation jig 120 to which the optical fiber cable 30 is engaged is provided on a tie rod 115 as a connecting member that connects steel supports 110A, 110B erected at a predetermined interval in the direction of tunnel excavation.

[0079] As shown in Fig. 7 to Fig. 9, the laying structure 200 comprises steel supports 110A, 110B erected at a predetermined interval in the excavation direction, a plurality of tie rods 115 as connecting members connecting the two steel supports 110A, 110B in the excavation direction, and laying jigs 120 provided on each tie rod 115. Fig. 7 is a front view of the linear body laid in the tunnel as seen toward the face 5 along line DD in Fig. 8, Fig. 8 is a cross-sectional view showing a cross section along line CC in Fig. 7, and Fig. 9 is an enlarged cross-sectional view showing a cross section along line EE in Fig. 7. Note that each figure is an image diagram showing the structure inside the tunnel in an exaggerated manner for easy understanding, and some parts differ from the actual size and ratio.

[0080] The configuration of each steel support 110A, 110B is similar to that of the steel support 10 of the first embodiment described above, and therefore a description thereof will be omitted.

[0081] The tie rod 115 is a rod-shaped member that connects, in the excavation direction, two steel supports 110A, 110B that are erected at a predetermined interval in the excavation direction, and a plurality of tie rods are provided at approximately equal intervals along the circumferential direction of the steel supports 110A, 110B. One end of the tie rod 115 is connected to the web portion of one steel support 110A via a fastening member (not shown), and the other end is connected to the web portion of the other steel support 110B via a fastening member (not shown), thereby connecting the two steel supports 110A, 110B that are arranged at a predetermined interval in the excavation direction.

[0082] In addition, the connecting member is not limited to the tie rod 115, but may be, for example, a rod-shaped member with both ends bent so that one end is inserted into a sheath tube provided on the flange portion of one steel support 110A and the other end is inserted into a sheath tube provided on the flange portion of the other steel support 110B, or it may be an extension member formed by extending along the excavation direction from each steel support 110A, 110B arranged opposite each other in the excavation direction, and formed so as to be connected at the overlapping portions.

[0083] 9, the installation jig 120 is a steel member having a plurality of rod-shaped members 122 (locking portions) extending in parallel, a long support portion 121 to which the base ends of the plurality of rod-shaped members 122 are fixed, and a U-shaped piecing portion 123 provided on the support portion 121, and one installation jig is provided for each tie rod 115 (connecting member). In other words, the installation jig 120 is provided at approximately equal intervals along the circumferential direction of the steel supports 110A, 110B, in the same number as the tie rods 115. The installation jig 120 may be made of plastic.

[0084] The installation jig 120 is attached to the tie rod 115 so that, when the tie rod 115 connects the two steel supports 110A, 110B in the excavation direction, the rod-shaped member 122 extends from the support part 121 toward the inside of the tunnel, i.e., the base end of the rod-shaped member 122 fixed to the support part 121 is positioned on the upper and lower half excavation surface 1 side, and the tip of the rod-shaped member 122 points toward approximately the center of the tunnel.

[0085] In order to ensure that the installation jig 120 is attached to the tie rod 115 in this manner, the installation jig 120 is fixed to the tie rod 115 via the tie rack portion 123 with the longitudinal direction of the support portion 121 aligned with the tie rod 115, as shown in Figure 9.

[0086] In this way, the rod-shaped member 122 to which the optical fiber cable 30 is anchored is attached to the tie rod 115 via the support portion 121, and extends from the support portion 121 fixed to the tie rod 115 toward the inside of the tunnel.

[0087] The method of fixing the installation jig 120 to the tie rod 115 is not limited to tightening a bolt or the like (not shown) provided on the tie rack portion 123, but may be, for example, by directly welding or gluing the support portion 121 to the tie rod 115, or by the attractive force of a magnet provided on the tie rod 115 or the installation jig 120.

[0088] The optical fiber cable 30 is fixed to the rod-shaped members 122 (locking portions) of each installation jig 120 via binding members 26 such as Insulocks, so that it is spanned between the installation jig 120 fixed to the tie rod 115, as shown in Figures 7 and 8, and laid along the steel supports 110A, 110B, i.e., laid along the circumferential direction of the upper and lower half excavation surfaces 1.

[0089] Both ends of the laid optical fiber cable 30 are connected to a measuring device (not shown) that uses the optical fiber cable 30 to measure the distribution of stress, strain, and temperature in the secondary shotcrete 3, as in the first embodiment described above.

[0090] Next, a method for laying the optical fiber cable 30 along the upper and lower half excavation surfaces 1 via the above-configured cable laying structure 200 will be described with reference to FIGS.

[0091] The excavation shaft is dug by blasting, and finish excavation is performed using an excavation device or the like on the upper and lower half excavation surfaces 1. As in the first embodiment described above, primary sprayed concrete 2 is sprayed onto the upper and lower half excavation surfaces 1 as a support material, and steel support structure 110A is erected along the surface of the primary sprayed concrete 2 (erection process).

[0092] The erected steel support 110A is then connected in the excavation direction to the steel support 110B, which was erected earlier at a position farther from the face 5 than the steel support 110A in the excavation direction, by a plurality of tie rods 115 equipped with installation jigs 120 (connecting process). In other words, after the erecting process and the connecting process, the plurality of tie rods 115 are installed along the inner circumferential surface of the upper and lower half excavation surfaces 1 as members equipped with installation jigs 120 (installation process). Note that the installation jigs 120 may be attached to each tie rod 115 after the two steel supports 110A, 110B are connected by the tie rods 115.

[0093] Next, the first layer 3a of the secondary shotcrete 3 is sprayed to a thickness such that the tip portions of the rod-shaped members 122 (locking portions) of the installation jigs 120 attached to the tie rods 115 are exposed (spraying step).

[0094] Specifically, a predetermined thickness of concrete is sprayed onto the surface of the primary sprayed concrete 2 using a concrete sprayer (not shown) so as to fill the space formed between two steel supports 110A, 110B arranged at a predetermined interval in the excavation direction.

[0095] As described above, the installation jig 120 is attached to each tie rod 115 with the support part 121 to which the base end of the rod-shaped member 122 is fixed positioned on the upper and lower half excavation surface 1 side. Therefore, by spraying concrete to a predetermined thickness between the two steel supports 110A, 110B arranged at a predetermined interval in the excavation direction, the installation jig 120 is buried in the sprayed concrete in sequence from the support part 121 side.

[0096] The thickness of the concrete sprayed in this process, i.e., the sprayed thickness of the first layer 3a of the secondary sprayed concrete 3, is set to a thickness such that the tie rod 115 and the support part 121 of the installation jig 120 fixed to the tie rod 115 via the tie rack part 123 are embedded in the sprayed concrete, while the tip side of the rod-shaped member 122 is exposed to a length sufficient to fix the optical fiber cable 30 via the binding member 26.

[0097] Preferably, the spraying thickness of the first layer 3a of the secondary shotcrete 3 is set so that the optical fiber cable 30 is located approximately in the center of the final spraying thickness of the secondary shotcrete 3 that is sprayed to cover the entire steel supports 110A, 110B. The final spraying thickness of the secondary shotcrete 3 may be a thickness that partially exposes the steel supports 110A, 110B, and the spraying thickness of the first layer 3a of the secondary shotcrete 3 may be half the final spraying thickness.

[0098] When the spraying of the first layer 3a of the secondary shotcrete 3 is completed, the optical fiber cable 30 is laid along the sprayed concrete surface of the first layer 3a (laying step).

[0099] Specifically, as shown in FIG. 9, the optical fiber cable 30 is anchored via the bundling member 26 to a rod-shaped member 122 exposed from the sprayed concrete surface of the first layer 3a of the secondary shotcrete 3.

[0100] The spacing between adjacent installation tools 120, i.e., the installation spacing of the tie rods 115, is set to, for example, 80 cm or less, preferably approximately 50 cm to 60 cm, so that the optical fiber cable 30 is engaged with the rod-shaped member 122 of each installation tool 120, so that the optical fiber cable 30 is in partial contact with the sprayed concrete surface of the first layer 3a between adjacent installation tools 120.

[0101] Once the optical fiber cable 30 is engaged with the rod-shaped member 122 and laid along the concrete sprayed surface of the first layer 3a of the secondary shotcrete 3, the second layer 3b of the secondary shotcrete 3 is then sprayed to a thickness sufficient to bury the optical fiber cable 30 (embedding spraying process).

[0102] Here, when the second layer 3b of the secondary sprayed concrete 3 is sprayed onto the optical fiber cable 30 by a concrete sprayer (not shown), the spraying pressure of the concrete acts on the optical fiber cable 30 in the radially outward direction of the tunnel. However, if there are scattered spaces or spaces exist over a wide area on the opposite side of the optical fiber cable 30 from the concrete sprayer, the spraying pressure of the concrete may cause the optical fiber cable 30 to bend locally along the space, or the position of the optical fiber cable 30 embedded in the sprayed concrete may be partially shifted along the space.

[0103] In contrast, in this embodiment, when the second layer 3b of the secondary shotcrete 3 is sprayed onto the optical fiber cable 30, the optical fiber cable 30 is in a state of being substantially in contact with the concrete sprayed surface of the first layer 3a, i.e., is supported in a substantially planar manner from the radially outer side of the tunnel by the concrete sprayed surface of the first layer 3a. Therefore, even if the concrete spraying pressure acts on the optical fiber cable 30 toward the radially outer side of the tunnel, the optical fiber cable 30 is supported along the circumferential direction of the upper and lower half excavation surfaces 1 by the concrete sprayed surface of the first layer 3a, and therefore it is possible to prevent the optical fiber cable 30 from being partially displaced or locally bent due to the spraying pressure.

[0104] In addition, by spraying the secondary shotcrete 3 in two steps and laying the optical fiber cable 30 along the surface of the concrete sprayed in the first layer 3a, it is possible to lay the optical fiber cable 30 at an appropriate position along the circumferential direction of the upper and lower half excavation surfaces 1, i.e., at approximately the center of the sprayed thickness of the secondary shotcrete 3.

[0105] In this way, by laying the optical fiber cable 30 at a predetermined position within the sprayed thickness of the secondary shotcrete 3, the distance between the upper and lower half excavation faces 1 and the optical fiber cable 30 becomes almost constant in the circumferential direction, and it is possible to accurately measure the stress distribution in the circumferential direction within the secondary shotcrete 3, which changes in response to changes in the ground during excavation of the tunnel. As a result, it becomes possible to accurately grasp changes in the ground condition during excavation in sequence, and the structure of the support members can be optimized by increasing the sprayed thickness of the secondary shotcrete 3 or the number of rock bolts in response to changes in the ground condition.

[0106] Thereafter, as necessary, the process of installing the support is completed by driving rock bolts (not shown) radially into the ground within the area sprayed with the secondary shotcrete 3. Then, as in the first embodiment, the excavation pit is further excavated, and when the invert concrete (not shown) and the secondary shotcrete 3 are stabilized, lining concrete is poured on the surface of the secondary shotcrete 3 using a formwork (not shown).

[0107] According to the above-described second embodiment, the following effects are achieved.

[0108] In the linear body laying method described above, the tie rod 115 (connecting member) provided with the rod-shaped member 122 (locking portion) is installed on the upper and lower half excavation surfaces 1, and then concrete is sprayed onto the upper and lower half excavation surfaces 1 to a thickness that exposes a part of the rod-shaped member 122. Then, the optical fiber cable 30 is locked to the exposed rod-shaped member 122, so that the optical fiber cable 30 is laid along the concrete sprayed surface. Concrete is further sprayed onto the optical fiber cable 30 laid along the concrete sprayed surface, but since the optical fiber cable 30 is supported by the concrete sprayed surface, the optical fiber cable 30 is prevented from being partially displaced or locally bent due to the spraying pressure. This allows the optical fiber cable 30 to be laid along the upper and lower half excavation surfaces 1 without causing positional displacement or the like.

[0109] In addition, the following modified examples are also within the scope of the present invention, and it is possible to combine the configurations shown in the modified examples with the configurations described in the above-mentioned embodiments, or to combine the configurations described in the different modified examples below.

[0110] In the first embodiment, the second optical fiber cable 32 is anchored to the installation jig 20 provided on the invert strut 14. Alternatively, when the invert strut 14 is not provided as a support member, as shown in Figures 10 and 11, a plurality of installation members 224 provided with installation jigs 220 may be erected on the invert excavation surface 6, and the second optical fiber cable 32 may be anchored to the installation jigs 220 provided along the invert excavation surface 6. Note that Figure 10 is a diagram showing a cross section corresponding to Figure 1, and Figure 11 is a diagram showing a cross section along the line FF in Figure 10.

[0111] In this modified example, the member on which the installation jig 220 is provided is a rod-shaped installation member 224 that is installed on the invert excavation surface 6, as shown in Fig. 10. The installation member 224 is a rod-shaped member such as a reinforcing bar, and is provided integrally with the installation jig 220.

[0112] 11, the installation jig 220 of this modified example is a steel member having a plurality of rod-shaped members 222 (locking parts) extending in parallel and a long support part 221 to which the base ends of the plurality of rod-shaped members 222 are fixed, and an installation member 224 is provided on the support part 221 on the opposite side to the rod-shaped members 222. The installation jig 220 and the installation member 224 may be made of plastic.

[0113] As shown in Figure 11, the installation jig 220 is installed on the invert excavation surface 6 via the installation member 224 so that the longitudinal direction of the support part 221 is aligned with the excavation direction and the rod-shaped member 222 extends from the support part 221 toward the inside of the tunnel, i.e., so that the base end of the rod-shaped member 222 fixed to the support part 221 is positioned on the invert excavation surface 6 side and the tip of the rod-shaped member 222 faces approximately toward the center of the tunnel.

[0114] In this way, the rod-shaped member 222 to which the optical fiber cable 30 is anchored extends toward the inside of the tunnel from the support part 221 attached to the invert excavation surface 6 via the installation member 224.

[0115] Next, a method for laying the optical fiber cable 30 along the invert excavation surface 6 via the installation structure 300 including the installation jig 220 having the above-mentioned configuration will be described with reference to Figs.

[0116] In this case, too, the optical fiber cable 30 is laid in the invert construction process that is carried out after the installation of the steel supports 10 on the upper and lower half excavation faces 1 is completed, as in the first embodiment.

[0117] In the invert construction process, first, the ground below the steel support 10 is excavated to form an invert excavation surface 6 so that invert shotcrete 7 can be sprayed as a support material.

[0118] Then, a plurality of installation members 224, which are members provided with the installation jigs 220, are installed at predetermined intervals along the circumferential direction of the invert excavation surface 6 (installation process). Specifically, one end of the installation member 224 is inserted into the ground.

[0119] Next, the first layer 7a of invert shotcrete 7 is sprayed to a thickness that exposes the tip of the rod-shaped member 222 (locking portion) of the installation jig 220 installed on the invert excavation surface 6 via the installation member 224 (spraying process).

[0120] Specifically, concrete is sprayed onto the surface of the invert excavation surface 6 in a predetermined thickness by a concrete sprayer (not shown).

[0121] As described above, the installation jig 220 is installed on the invert excavation surface 6 with the support part 221 to which the base end of the rod-shaped member 222 is fixed positioned on the invert excavation surface 6 side. Therefore, by spraying concrete to a predetermined thickness, each installation jig 220 will be buried in the sprayed concrete in sequence from the support part 221 side.

[0122] The thickness of the concrete sprayed in this process, i.e., the sprayed thickness of the first layer 7a of the invert shotcrete 7, is set to a thickness such that the support part 221 of the installation jig 220 is embedded in the sprayed concrete, while the tip side of the rod-shaped member 222 is exposed to a length sufficient to secure the optical fiber cable 30 via the binding member 26.

[0123] Preferably, the sprayed thickness of the first layer 7a of the invert shotcrete 7 is set so that the optical fiber cable 30 is located approximately in the center of the final sprayed thickness of the invert shotcrete 7. Note that the sprayed thickness of the first layer 7a of the invert shotcrete 7 may be half the thickness of the final sprayed thickness.

[0124] When the spraying of the first layer 7a of the invert shotcrete 7 is completed, the second optical fiber cable 32 is laid along the sprayed concrete surface of the first layer 7a (laying step).

[0125] Specifically, the second optical fiber cable 32 is fastened via the bundling member 26 to the rod-shaped member 222 exposed from the concrete sprayed surface of the first layer 7a of the invert shotcrete 7.

[0126] The distance between adjacent installation tools 220 is set to, for example, 80 cm or less, preferably approximately 50 cm to 60 cm, so that the second optical fiber cable 32 is engaged with the rod-shaped member 222 of each installation tool 220, so that the second optical fiber cable 32 is in partial contact with the sprayed concrete surface of the first layer 7a between adjacent installation tools 220.

[0127] Once the second optical fiber cable 32 is engaged with the rod-shaped member 222 and laid along the concrete sprayed surface of the first layer 7a of the invert shotcrete 7, the second layer 7b of the invert shotcrete 7 is then sprayed to a thickness sufficient to bury the second optical fiber cable 32 (embedding spraying process).

[0128] In this modification, as in the first embodiment, when the second layer 7b of the invert shotcrete 7 is sprayed onto the second optical fiber cable 32, the second optical fiber cable 32 is in a state of being substantially in contact with the concrete sprayed surface of the first layer 7a, that is, is in a state of being substantially supported in a planar manner from the bottom side of the tunnel by the concrete sprayed surface of the first layer 7a. Therefore, even if the concrete spraying pressure acts on the second optical fiber cable 32 toward the radial outside of the tunnel, the second optical fiber cable 32 is supported along the circumferential direction of the invert excavation surface 6 by the concrete sprayed surface of the first layer 7a, so that it is possible to prevent the second optical fiber cable 32 from being partially displaced or locally bent by the spraying pressure.

[0129] After that, invert concrete 8 is finally poured onto the surface of the invert shotcrete 7, as in the first embodiment.

[0130] In addition, in each of the above embodiments, one optical fiber cable 30, 31, 32 is engaged with the installation jig 20, 120, 220, but the number of optical fiber cables 30, 31, 32 engaged with the installation jig 20, 120, 220 may be two or more, and the rod-shaped members 22, 122, 222 may be increased or decreased depending on the number of optical fiber cables 30, 31, 32 to be engaged.

[0131] Although the embodiments of the present invention have been described above, the above-mentioned embodiments merely show some of the application examples of the present invention, and it is not intended that the technical scope of the present invention be limited to the specific configurations of the above-mentioned embodiments. [Explanation of symbols]

[0132] 100,200,300...Laying structure 1...Upper and lower half excavation surface (excavation surface) 3. Secondary sprayed concrete 5. Face 6. Invert excavation surface (excavation surface) 7. Invert Shotcrete 10...Steel shoring 14. Invert strut (steel support) 20,120,220...Installation jig 21,121,221...Support part 22, 122, 222... Rod-shaped member (locking portion) 26... Binding member 30···Optical fiber cable (linear member) 31...First optical fiber cable (linear body) 32...Second optical fiber cable (linear body) 110A...Steel shoring 110B...Steel shoring 115... Tie rod (connecting member) 224...Installation parts

Claims

1. A linear object laying method for laying a linear object along an excavation surface when constructing a tunnel, comprising the steps of: an installation step of installing a member provided with an engaging portion on the excavation surface; A spraying step of spraying concrete onto the excavation surface to a thickness such that at least a portion of the engaging portion is exposed; and a laying step of engaging the linear body with the engaging portion exposed from the concrete sprayed surface and laying the linear body along the concrete sprayed surface. Linear body laying method.

2. In the installation step, the steel support provided with the engaging portion is erected along the excavation surface, In the spraying process, concrete is sprayed between the steel supports erected at predetermined intervals in the tunnel excavation direction.

2. A method for laying a linear object according to claim 1.

3. The engaging portion is attached to the tunnel mouth side of the steel support via a support portion, The engaging portion extends from the support portion fixed to the steel support toward the inside of the tunnel, and its base end side is covered with the concrete sprayed in the spraying process, and its tip side is exposed from the concrete sprayed surface. The method for laying a linear object according to claim 2.

4. The installation step includes: erecting a steel support along the excavation surface; and a step of connecting the steel supports erected at a predetermined interval in the tunnel excavation direction by using connecting members provided with the locking portions, In the spraying process, concrete is sprayed between the steel supports erected at predetermined intervals in the tunnel excavation direction. A method for laying a linear object according to claim 1.

5. The engaging portion is a rod-shaped member extending toward the inside of the tunnel.

5. A method for laying a linear object according to claim 1 .

6. The concrete spraying step further includes spraying concrete to a thickness such that the linear body laid along the concrete spraying surface is buried.

5. A method for laying a linear object according to claim 1 .

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