Target installation method and target

Abstract

To provide a target installation method capable of installing a target quickly and safely after excavation.SOLUTION: A method for installing a target 1 used to measure inner space displacement in a tunnel comprises pre-installing the target 1 on a surface of a timber support that faces an inner space side before construction, where the target 1 comprises: a base 2; and a target seal 3 affixed to a recessed part 21 formed in the base 2. A slope is formed on an opposite surface Y of a fixed surface X of the base 2 that is fixed to the timber support 10, with a thickness gradually increasing from an end part to a center part. Each of end parts in a slope direction where the slop is formed, is formed with a ridge line where the fixed surface X and the opposite surface Y intersect. The target 1 is pre-installed so that the slope direction of the base 2 and a longitudinal direction of the timber support are substantially coincide with each other.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a method for installing a target used for measuring displacement inside a tunnel. [Background technology]

[0002] A technology has been proposed in which targets used to measure displacement inside a tunnel (measurement of top subsidence and internal displacement) are installed on the tunnel wall (see, for example, Patent Document 1). The targets are attached as measurement points to the tunnel wall constructed with shotcrete, and the two-dimensional coordinates of the prism are measured with a total station to obtain the displacement inside the tunnel.

[0003] The target in Patent Document 1 is attached to the wall of a tunnel and has a plate-shaped main body with an inclined surface whose thickness decreases toward the tunnel face. The inclined surface of the main body is provided for the purpose of preventing damage due to contact with heavy machinery, flying objects, etc. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2023-5352 A Summary of the Invention [Problem to be solved by the invention]

[0005] As shown in Figure 5, underground displacement consists of the preliminary displacement, initial displacement, and field measured displacement, and the preliminary displacement is predicted from the initial displacement and the field measured displacement. The higher the accuracy of obtaining the initial displacement, the higher the prediction accuracy of the preliminary displacement. Therefore, it is desirable to install targets and start measuring underground displacement as soon as possible after excavation.

[0006] However, in the conventional technology, the target is installed on the tunnel wall using an anchor part embedded in the tunnel wall and a bolt that penetrates the main body and is screwed into the anchor part. Therefore, the target needs to be installed close to the tunnel face after the second concrete spraying, and it is not possible to install the target and start measuring the displacement inside the tunnel at an early stage after excavation. In addition, since the target needs to be installed close to the tunnel face, the installation work is dangerous and other work is put on hold.

[0007] The present invention has been made in view of the above circumstances, and has an object to provide a target installation method that can solve the above-mentioned problems and quickly and safely install a target after excavation. [Means for solving the problem]

[0008] The target installation method of the present invention is a method for installing a target used to measure internal displacement of a tunnel, wherein the target comprises a base and a target sticker affixed to a recess formed in the base, and is characterized in that the target is pre-installed on the surface facing the internal space of the support before it is erected. Furthermore, in the target installation method of the present invention, a slope is formed on the side of the base opposite a fixed surface that is fixed to the support, the thickness of which gradually increases from the end to the center, and the end of the slope in the slope direction forms a ridge where the fixed surface and the opposite surface intersect, and the target may be pre-installed so that the slope direction of the base and the longitudinal direction of the support approximately coincide with each other. Furthermore, in the target installation method of the present invention, the target may be pre-installed on the support with a cover attached to cover the recess in the pedestal, and the cover may be attached so that a step is created between the end in the slope direction and the opposite surface of the pedestal. Moreover, the target of the present invention is a target used for measuring internal displacement of a tunnel, and comprises a base and a target seal affixed to a recess formed in the base, and is characterized in that a slope is formed on the surface of the base opposite a fixed surface that is fixed to an object, the thickness of which gradually increases from the end to the center, and the end of the slope direction where the slope is formed forms a ridge where the fixed surface and the opposite surface intersect. Effect of the Invention

[0009] According to the present invention, the erection of the support structure constitutes the actual installation process of the target, which has the effect of making it possible to measure the tunnel's internal displacement (measurement of the top subsidence and internal displacement) immediately after the erection of the support structure. [Brief description of the drawings]

[0010] [Figure 1] 1A to 1C are diagrams illustrating a pre-installation step in a target installation method according to the present invention. [Diagram 2] 4A to 4C are diagrams illustrating a main installation step in the target installation method according to the present invention. [Diagram 3] FIG. 2 is a diagram showing a configuration of a target according to the present invention. [Figure 4] FIG. 13 is a diagram showing the configuration of a target with a cover attached. [Diagram 5] FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Next, a mode for carrying out the present invention (hereinafter simply referred to as an "embodiment") will be specifically described with reference to the drawings. In the target installation method of the present embodiment, as shown in FIG. 1, a target 1 used for measuring the internal displacement of a tunnel is installed on the surface (flange surface on the internal space side) of a support 10 before erection as a pre-installation step. The left and right supports 10 are made of, for example, H-beams. The left and right supports 10 are symmetrical arc-shaped, and as shown in FIG. 2, they are erected near the face to form an arch shape. The erection of the left and right supports 10 constitutes the actual installation step of the target 1. In the example shown in FIGS. 1 and 2, the target 1 is installed in one location near the top end of the arch-shaped support 10 and two locations on the left and right, for a total of three locations. The number and locations of the targets 1 to be installed can be set appropriately.

[0012] In the mountain construction method (NATM method), generally, excavation of the face, removal of debris, primary spraying of concrete, erection of shoring 10, secondary spraying of concrete, and installation of rock bolts are repeated. In the target installation method of this embodiment, the target 1 is installed in advance on the shoring 10, so that it becomes possible to measure the displacement inside the tunnel (measurement of the top subsidence and internal displacement) immediately after erecting the shoring 10.

[0013] 3, the target 1 includes a steel base 2 and a target seal (reflective seal) 3 attached to the base 2. In FIG. 3, (a) is a plan view, (b) is an AA cross-sectional view shown in (a), (c) is a BB cross-sectional view shown in (a), and (d) is a CC cross-sectional view shown in (a).

[0014] The base 2 is a rectangular plate with one X surface (hereinafter referred to as the fixed surface X) being flat, and one direction of the Y surface opposite the fixed surface X (hereinafter referred to as the opposite surface Y) is formed with an arc-shaped slope (which may be a linear slope) whose thickness gradually increases from the end to the center. Hereinafter, the direction in which the slope is formed is referred to as the slope direction. The end of the slope direction forms a ridge where the fixed surface X and the opposite surface Y intersect.

[0015] The target 1 is pre-installed on the shoring 10 so that the slope direction of the pedestal 2 and the longitudinal direction of the shoring 10 are approximately aligned. The fixed surface X of the pedestal 2 is the surface that abuts against the shoring 10 and is the surface that is fixed to the shoring 10 by welding, steel adhesive, magnets, etc. Therefore, the step at the end of the pedestal 2 in the longitudinal direction of the shoring 10 is eliminated.

[0016] After erecting the shoring 10, a second spraying of concrete is performed, and after the second spraying of concrete, scraping work is performed to remove the concrete adhering to the shoring 10. In general, scraping work is performed by moving a scraping attachment (scraper) attached to heavy machinery in the longitudinal direction of the shoring 10 to scrape off the concrete adhering to the shoring 10. Because the end of the base 2 in the slope direction forms a ridge, the scraping attachment does not get caught on the base 2 (ridge at the end) and rides up onto the opposite surface Y of the base 2. Therefore, the target 1 previously installed on the shoring 10 will not come off during the scraping work after the secondary spraying.

[0017] A recess 21 is formed on the opposite surface Y, and the target seal 3 is affixed to the recess 21. The scraping attachment moves along the opposite surface Y, so it does not interfere with the target seal 3 in the recess 21. Therefore, the target seal 3 will not peel off during the scraping work after the secondary spraying.

[0018] Lubricating oil, organic solvent, etc. may be applied as a release agent to prevent and suppress adhesion of concrete to the surface of the target seal 3. In this case, adhesion of secondary shotcrete to the target seal 3 can be suppressed, and secondary shotcrete that has adhered to the target seal 3 can be easily peeled off by scraping work.

[0019] As shown in Fig. 4, the target 1 may be pre-installed on the support 10 as a base 2a with a cover 4 attached to cover the recess 21. In Fig. 4, (a) is a plan view, (b) is an AA cross-sectional view shown in (a), (c) is a BB cross-sectional view shown in (a), and (d) is a CC cross-sectional view shown in (a).

[0020] The cover 4 is attached to the recess 21 of the base 2a so that a step for the scraping attachment is created between the end in the slope direction and the opposite surface Y of the base 2a. In this way, the cover 4 can be removed by scraping work, and measurement of the displacement inside the hole can be started immediately after the secondary shotcrete is applied.

[0021] The cover 4 may be made of rubber, silicon, or the like, but is more preferably made of mortar (for example, lightweight mortar mixed on site). If the cover 4 is made of mortar, it can be disposed of together with the secondary shotcrete peeled off by scraping work.

[0022] The cover 4 needs to have adhesion that does not come off when the support 10 is transported, and releasability that allows it to be peeled off during scraping work. Slits 22 are formed in the wall surface of the recess 21 of the base 2a to increase the contact area between the cover 4 and the base 2a (recess 21). The adhesion is improved by the slits 22. The releasability is improved by applying a release agent to the surface of the target seal 3 and the recess 21.

[0023] As described above, the target installation method of this embodiment is a target installation method for a target 1 used to measure the internal displacement of a tunnel, in which the target 1 comprises a base 2 and a target seal 3 affixed to a recess 21 formed in the base 2, and the target 1 is pre-installed on the surface facing the internal space of the support structure 10 before erection. With this configuration, in the target installation method of this embodiment, erecting the shoring 10 is the main target installation process, so it becomes possible to measure the tunnel interior displacement (measurement of top subsidence and internal displacement) immediately after erecting the shoring 10. Furthermore, the target installation method of this embodiment is safe as there is no need to approach the tunnel face when installing the target 1. Furthermore, the target installation method of this embodiment does not require a separate work process just for installing the target 1, so other work does not need to be stopped.

[0024] Furthermore, in this embodiment, a slope is formed on the opposite side Y of the fixed side X of the base 2, which is fixed to the support 10, such that the thickness gradually increases from the end to the center, and the end of the slope direction forms a ridge where the fixed side X and the opposite side Y intersect, and the target 1 is pre-installed so that the slope direction of the base 2 and the longitudinal direction of the support 10 approximately coincide with each other. With this configuration, the scraping attachment does not get caught on the base 2 (the ridge line of the end portion) but rides up onto the opposite surface Y of the base 2, thereby preventing the base 2 from peeling off when scraping the secondary shotcrete.

[0025] Furthermore, in this embodiment, the target 1 is pre-installed on the support 10 with a cover 4 attached to cover the recess in the base 2, and the cover 4 is attached so that a step is created between the end in the slope direction and the opposite surface Y of the base 2. This configuration prevents the secondary shotcrete from adhering to the target seal 3, and the cover 4 can be removed when scraping the secondary shotcrete. Therefore, it becomes possible to measure the tunnel interior displacement (measurement of the top settlement and the internal displacement) immediately after the secondary concrete spraying.

[0026] Furthermore, the target 1 of this embodiment is a target used for measuring the internal displacement of a tunnel, and comprises a base 2 and a target seal 3 affixed to a recess 21 formed in the base 2. A slope is formed on the opposite side Y of the fixed surface X, which is fixed to the object (the support 10) of the base 2, such that the thickness gradually increases from the end to the center, and the end of the slope direction where the slope is formed forms a ridge where the fixed surface X and the opposite side Y intersect. With this configuration, the target 1 can be pre-installed so that the slope direction of the pedestal 2 and the longitudinal direction of the support 10 are approximately aligned, thereby preventing the target 1 from being peeled off during scraping.

[0027] The present invention has been described above based on the embodiment. This embodiment is merely an example, and it will be understood by those skilled in the art that various modifications are possible in terms of the combination of the respective components, and that such modifications are also within the scope of the present invention. [Explanation of symbols]

[0028] 1 Target 2, 2a Pedestal 3 Target sticker 4 Cover 10 Shoring 21 Recess 22 Slit

Claims

1. A method for installing a target used to measure internal displacement of a tunnel, comprising the steps of: The target includes a base and a target seal attached to a recess formed in the base, A target installation method, comprising the steps of: pre-installing the target on a surface of a support structure facing the interior space before it is erected.

2. A slope is formed on the opposite side of the fixed surface of the base that is fixed to the support, the thickness of which gradually increases from the end to the center, and the end of the slope direction where the slope is formed forms a ridge where the fixed surface and the opposite surface intersect, 2. The target installation method according to claim 1, wherein the target is installed in advance such that the slope direction of the pedestal and the longitudinal direction of the support structure are substantially aligned.

3. The target is pre-installed on the support with a cover attached to cover the recess of the base, 3. The target installation method according to claim 2, wherein the cover is attached so that a step is formed between the end in the slope direction and the opposite surface of the pedestal.

4. A target used to measure internal displacement of a tunnel, The target sticker is provided with a base and a target seal attached to a recess formed in the base, A target characterized in that a slope is formed on the surface of the base opposite to a fixed surface that is fixed to an object, the thickness of which gradually increases from the end to the center, and the end of the slope in the slope direction forms a ridge where the fixed surface and the opposite surface intersect.

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