Wire net unit, supporting unit, and support assembly method

Abstract

To provide a wire net unit capable of improving the workability and safety during support construction, a supporting unit and a support assembly method.SOLUTION: A supporting unit 3 includes: a wire mesh body 51 provided along the outer face of a steel support 4; multiple supporting members 52 that support the wire mesh body 51; and a wire net unit 5 that includes an attachment member 53 fixed to the base end of the supporting member 52. The support assembly method using the supporting unit 3 includes: a construction step of constructing the supporting unit 3 in an arch shape; and a spray step of spraying a shotcrete 2 over the ground surface Gs.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a wire mesh unit, a shoring unit, and a shoring assembly method.

Background Art

[0002] In tunnel construction by NATM, the ground surface exposed by tunnel excavation is quickly closed by shoring. Generally, tunnel shoring is composed of shotcrete sprayed on the ground surface, steel shoring assembled along the ground surface, rock bolts driven into the ground in the normal direction from the inside of the tunnel, and the like. In addition, depending on the ground conditions, a wire mesh may be used to reinforce the shotcrete for tunnel shoring. Note that a welded wire mesh for structures (150×150×φ5) is generally used for the wire mesh.

[0003] The wire mesh is generally fixed to the ground or the primary shotcrete with anchor bolts. The wire mesh is manufactured in a factory in a shape and weight that can be handled by workers, transported to the site, and installed by workers in the work cage of an erector when building the steel shoring.

[0004] On the other hand, since the installation work of the wire mesh by manual labor requires workers and the like to enter the exposed ground before the shoring is completed or directly under the primary shotcrete to perform the work, it takes time to ensure safety. Furthermore, the installation work of the wire mesh by manual labor is time-consuming.

[0005] Patent Document 1 discloses a construction method in which a wire mesh is attached to a steel shoring and the steel shoring is built. According to the construction method of Patent Document 1, since the wire mesh is pre-attached to the steel shoring, there is no need for the installation work of the wire mesh that is performed manually by entering the exposed ground before the shoring is completed or directly under the primary shotcrete.

Prior Art Documents

Patent Documents

[0006] [Patent Document 1] Utility Model Registration No. 3241438 Gazette [Summary of the Invention] [Problems to be Solved by the Invention]

[0007] In Patent Document 1, a wire mesh is welded to the outer surface of the flange of a steel shoring. The wire mesh needs to be welded at multiple points to the flange of the steel shoring, which is time-consuming. Also, since the welding operation of the wire mesh needs to be carried out by multiple workers, one to hold the wire mesh along the outer surface of the steel shoring and one to weld the wire mesh to the steel shoring, labor costs are also incurred.

[0008] An object of the present invention is to propose a wire mesh unit, a shoring unit, and a shoring assembly method that enable improvement in workability and safety during shoring construction. [Means for Solving the Problems]

[0009] The wire mesh unit of the present invention for solving such problems includes a wire mesh body provided along the outer surface of a steel shoring, a plurality of support members for supporting the wire mesh body, and a mounting member fixed to the base end portion of the support member and attachable to the steel shoring.

[0010] The shoring unit of the present invention further includes a steel shoring composed of a pair of flanges and a web spanned between the pair of flanges, and the wire mesh unit attached to at least the upper portion of the steel shoring.

[0011] Furthermore, the shoring assembly method of the present invention includes an erection step of erecting the shoring unit in an arch shape using a heavy machine, and a spraying step of spraying shotcrete onto the ground surface.

[0012] According to such a wire mesh unit, a support unit, and a method for assembling the support unit, since the wire mesh is pre-installed on the steel support unit, there is no need to enter the exposed ground before the support unit is completed or directly below the first sprayed concrete to perform the wire mesh installation work. Since the mounting member, the support member, and the unitized wire mesh body are attached to the steel support unit, the labor for attaching the wire mesh can be significantly reduced compared to the case of welding the wire mesh to the steel support unit. In addition, since the installation of the wire mesh is completed by attaching the mounting member to the steel support unit, it is not necessary to require a plurality of workers.

[0013] In addition, the mounting member of the wire mesh unit includes an insertion portion to be inserted into a sheath pipe fixed to the steel support unit, a connecting portion connecting the insertion portion and the support member, a female screw portion formed at the base end portion of the connecting portion, and an adjustment bolt screwed into the female screw portion so as to be able to advance and retreat. It is desirable that the tip of the adjustment bolt can contact the flange of the steel support unit.

[0014] When using such a wire mesh unit, with the tip of the adjustment bolt in contact with the flange, by further rotating the adjustment bolt, the support member can be rotated about the insertion portion to tilt the wire mesh body. By doing so, contact between the wire meshes can be suppressed at the overlapping portion between the wire mesh of the wire mesh unit and the wire mesh installed on the existing steel support unit.

[0015] In addition, when a net-shaped fixing member to be embedded in the sprayed concrete is fixed to the support member, in the spraying process, a preliminary spraying operation of spraying the sprayed concrete so as to entangle the fixing member while holding the steel support unit by the heavy machine, and after the preliminary spraying operation, a main spraying operation of spraying the sprayed concrete with the holding of the steel support unit by the heavy machine released are performed. By doing so, the fixing portion is embedded in the sprayed concrete, functioning as an anchor and preventing the steel support unit from tipping over. That is, the wire mesh unit functions as an anti-tipping member.

[0016] Furthermore, the wire mesh body has a lattice shape by combining vertical members arranged along the tunnel axis direction and horizontal members arranged along the tunnel transverse direction, with four sides presenting a comb shape, and it is preferably supported by the support member in a state rotated by only a small angle. Also, it is desirable that the wire mesh body is supported by the support member such that the face side end portion protrudes to the face side more than the steel support. In this case, in the building-in process, the steel support is built in such that the shaft mouth side end portion of the wire mesh body overlaps with the face side end portion of the wire mesh body attached to the existing steel support. At this time, since the end portions of the wire mesh body present a comb shape, it is difficult for the wire meshes provided before and after to come into contact with each other. Therefore, the building-in work of the steel support can be efficiently performed.

Advantages of the Invention

[0017] According to the fall prevention member of the present invention and the support erection method using the same, it is possible to improve the workability and safety during the support erection construction.

Brief Description of the Drawings

[0018]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Mode for Carrying Out the Invention

[0019] Hereinafter, the case of tunnel construction by NATM will be described. As shown in FIGS. 1(a) and (b), the tunnel T is stabilized by closing the ground surface Gs exposed by excavating the natural ground G with a support 1 composed of a shotcrete 2 and a steel support 4. Further, at the time of tunnel construction, auxiliary construction methods such as forepoling (short temporary support), mirror bolt work, and leg reinforcement work may be used in combination as necessary.

[0020] In tunnel construction, first, the natural ground G is excavated to form an excavation hole (tunnel T). The excavation method of the tunnel T is not limited, and for example, it may be blasting excavation or mechanical excavation. The advance length of the tunnel T for each cycle is determined according to the ground conditions (ground grade, soil cover, etc.), but in this embodiment, it is set to 1.0 to 1.2 m.

[0021] After the tunnel T is excavated to a predetermined extension (1.0 to 1.2 m in this embodiment), the support 1 is formed along the ground surface Gs exposed by excavating the natural ground G. The support 1 of this embodiment includes a shotcrete 2 composed of a primary shotcrete 21 and a secondary shotcrete 22, and a support unit 3 as shown in FIG. 1(b).

[0022] The shotcrete 2 is the concrete sprayed on the ground surface Gs. In this embodiment, it is sprayed in two steps, the primary shotcrete 21 and the secondary shotcrete 22, before and after the installation of the support unit 3. Note that the shotcrete 2 does not necessarily have to be sprayed in multiple steps, and it may be sprayed to a predetermined thickness in one step.

[0023] The support unit 3 includes a steel support 4 and a wire mesh unit 5 as shown in FIGS. 1(b) and 2.

[0024] As shown in Fig. 3, the steel support 4 is formed by processing a so-called H-shaped steel consisting of a pair of flanges 41, 41 and a web 42 horizontally mounted on the pair of flanges 41, 41, and is assembled in an arch shape. A sheath pipe 43 is fixed to the flange 41 on the outer side (the side of the natural ground G) of the steel support 4. The sheath pipe 43 is made of a steel pipe and is fixed to the flange 41 in a direction along the circumferential direction of the tunnel. In the present embodiment, a plurality of sheath pipes 43 are provided at predetermined intervals.

[0025] As shown in Figs. 1(a) and (b), in the present embodiment, a wire mesh unit 5 is attached to the upper part of the steel support 4. The wire mesh unit 5 is attached to the steel support 4 by using the sheath pipe 43 provided on the steel support 4 as shown in Fig. 2. The wire mesh unit 5 includes a wire mesh body 51, a support member 52, and a mounting member 53 as shown in Fig. 3.

[0026] As shown in Figs. 4(a) and (b), the wire mesh body 51 has a lattice shape by combining vertical members 511 arranged along the tunnel axis direction and horizontal members 512 arranged along the tunnel transverse direction. The intervals between the vertical members 511 and between the horizontal members 512 are not limited, but in the present embodiment, they are set to 150 mm. The end portions of the vertical members 511 protrude in the tunnel axis direction more than the horizontal member 512 provided at the outermost end (the most face side or the most portal side). Similarly, the end portions of the horizontal members 512 protrude in the tunnel axis direction more than the vertical member 511 provided at the outermost end (the uppermost or lowermost stage). That is, the four sides of the wire mesh body 51 have a comb shape. The protruding length of the vertical member 511 or the horizontal member 512 at the four sides of the wire mesh body 51 is preferably 150 mm or more. The wire mesh body 51 is supported by the support member 52 so as to be in a state of being rotated by a small angle α (for example, a gradient of 1 / 130 to 1 / 150) to the right around the center point C of the wire mesh body 51 in a state where it is attached to the steel support 4.

[0027] As shown in Fig. 2, the wire mesh body 51 is provided along the outer surface of the steel support 4. Further, the wire mesh body 51 has a length greater than the interval between the steel supports 4, and is supported by the support member 52 such that the end portion on the face side protrudes more toward the face side than the steel support 4. As shown in Fig. 4(a), a pair of support members 52, 52 are provided on the wire mesh body 51. Note that the number and arrangement of the support members 52 provided on one wire mesh body 51 are not limited and may be determined as appropriate.

[0028] The support member 52 is a member that supports the wire mesh body 51, and as shown in Fig. 5(a), is composed of an L-shaped steel in which the first piece 521 and the second piece 522 intersect at a right angle. The support member 52 is provided such that the first piece 521 is substantially parallel to the flange 41 of the steel support 4 and the second piece 522 is orthogonal to the flange 41. The support member 52 has a length of at least twice the interval between the horizontal members 512 of the wire mesh body 51, and as shown in Fig. 4(a), is fixed to the wire mesh body 51 by welding the first piece 521 to three horizontal members 512.

[0029] As shown in Figs. 5(b) and (c), a fixing member 54 is fixed to the first piece 521 of the support member 52. The fixing member 54 is a mesh member (for example, expanded metal) to be embedded in the sprayed concrete 2. The fixing member 54 has a size that does not interfere with the vertical members 511 and the horizontal members 512 of the wire mesh body 51. In the present embodiment, the length of one side of the fixing member 54 is 125 mm. As shown in Fig. 4(a), the fixing member 54 is fixed (welded) to the support member 52 so as to be disposed in the space surrounded by the vertical member 511 and the horizontal member 512. In the present embodiment, the fixing member 54 is fixed to the intermediate portion of the support member 52, but the fixing position of the fixing member 54 may be determined as appropriate.

[0030] As shown in Fig. 2, when the wire mesh unit 5 is installed on the steel support 4, the support member 52 is provided such that the outer surface of the first piece 521 is flush with the outer surface of the ground side flange 41 of the steel support 4. The support member 52 is fixed to the steel support 4 via the attachment member 53.

[0031] The attachment member 53 is fixed to the base end portion of the support member 52 as shown in FIGS. 5(a) to 5(c). The attachment member 53 can be attached to the steel support 4 via the sheath pipe 43. The attachment member 53 includes an insertion portion 531 to be inserted into the sheath pipe 43 fixed to the steel support 4, a connecting portion 532 that connects the insertion portion 531 and the support member 52, a female screw portion 533 formed at the base end portion of the connecting portion 532, and an adjustment bolt 534 that is screwed into the female screw portion 533 so as to be able to advance and retreat.

[0032] The insertion portion 531 is composed of a columnar member that can be inserted into the sheath pipe 43. The insertion portion 531 of the present embodiment is made of a steel bar having an outer diameter equivalent to the inner diameter of the sheath pipe 43, but the material constituting the insertion portion 531 is not limited, and for example, a steel pipe may be used. The insertion portion 531 is welded to the connecting portion 532.

[0033] The connecting portion 532 is made of a steel plate. The tip of the connecting portion 532 is welded to the second piece 522 of the support member 52. Further, the insertion portion 531 is welded to the middle portion of the connecting portion 532. In addition, a female screw portion 533 is formed at the base end portion of the connecting portion 532. Note that the material constituting the connecting portion 532 is not limited, and for example, a steel pipe, an L-shaped steel, or the like may be used.

[0034] The female screw portion 533 is made of a nut and is welded in a state of being erected at the base end portion of the connecting portion 532. Note that the material constituting the female screw portion 533 is not limited, and for example, a steel plate formed with bolt holes may be used. The adjustment bolt 534 is screwed into the female screw portion 533 from the inner cavity side, and the tip can abut against the inner surface of the flange 41 on the outer side (ground side) of the steel support 4.

[0035] Next, the assembling method of the support 1 will be described. The assembling method of the support 1 includes an attachment process (wire mesh attachment process), a primary spraying process, an erection process, and a secondary spraying process (spraying process).

[0036] In the installation process, a wire mesh unit 5 is attached to the steel support 4 to form a support unit 3 (see Fig. 2). The installation process may be carried out before the building-in process, for example, it may be carried out in parallel with the first spraying process.

[0037] In the installation process, first, with the end portion of the wire mesh body 51 on the face side along the outer surface of the flange 41 of the steel support 4, the insertion portion 531 of the attachment member 53 is inserted into the sheath pipe 43. Next, the adjustment bolt 534 screwed into the female screw 533 portion is rotated to abut against the inner surface of the flange 41. Then, by further rotating the adjustment bolt 534 with its tip abutting against the flange 41, the support member 52 is rotated around the insertion portion 531 to incline the wire mesh body 51 with respect to the flange 41. When the adjustment bolt 534 is screwed in, the base end portion of the connecting portion 532 rotates in a direction away from the flange 41. Along with the rotation of this connecting portion 532, the tip of the support member 52 approaches the ground side. At this time, since the vertical member 511 in contact with the flange as shown in Fig. 2 is pressed against the flange, the wire mesh body is bent and deformed, and the reaction force is applied to the vertical member 511, the flange surface, and the tip of the adjustment bolt, thus preventing the wobbling of the wire mesh unit. The tip of the wire mesh body 51 on the shaft mouth side is in a widened state so as to be on the ground side rather than the face side tip.

[0038] In the first spraying process, the first sprayed concrete 21 is sprayed onto the ground surface Gs exposed by excavating the ground G. The first sprayed concrete 21 is sprayed not only on the wall surface (side surface) of the tunnel T but also on the face K. The spraying thickness of the first sprayed concrete 21 may be determined appropriately, for example, it is set to 5 cm.

[0039] In the building-in process, the support unit 3 is built in near the face K. In the erection process, first, using heavy machinery, as shown in FIGS. 6 and 7, a pair of left and right steel shoring members 4, 4 are connected in an arch shape and erected near the face. At this time, as shown in FIGS. 6(a) and (b), the ends of the wire mesh bodies 51 joined to the left and right steel shoring members 4, 4 are in a state where the cross members 512 overlap each other front and back. Here, since the wire mesh body is attached with a slight rotation, the ends of the cross members 512 of the left and right wire mesh bodies 51 are displaced front and back and are difficult to come into contact. At this time, the end of the wire mesh body 51 on the shaft side is overlapped on the ground side of the end of the wire mesh body 51 on the face side attached to the existing steel shoring member 4a, as shown in FIG. 9.

[0040] In the secondary spraying process, the secondary sprayed concrete 22 is sprayed onto the primary sprayed concrete 21 (or the ground surface). In the secondary spraying process of the present embodiment, first, as shown in FIGS. 8 and 9, in a state where the steel shoring member 4 is held by a heavy machine, a pre-spraying operation is performed in which the pre-sprayed concrete 23 is sprayed so as to entangle the fixing member 54. After the pre-spraying operation, when a predetermined strength is developed in the pre-sprayed concrete 23, a main spraying operation is performed in which the sprayed concrete 2 (secondary sprayed concrete 22) is sprayed with the holding of the steel shoring member 4 by the heavy machine released (see FIG. 1(b)).

[0041] According to the wire mesh unit 5, the shoring member unit 3, and the shoring member assembling method of the present embodiment, since the wire mesh (wire mesh body 51) is installed in the steel shoring member in advance, the wire mesh is arranged by erecting the shoring member unit 3. Therefore, for the purpose of installing the wire mesh, it is not necessary for workers or the like to enter and work on the exposed ground before the shoring member 1 is completed, or directly below the primary sprayed concrete 21.

[0042] Since the wire mesh body 51 unitized with the attachment member 53 and the support member 52 is attached to the steel shoring member 4, the labor of attaching the wire mesh can be significantly reduced compared to the case of welding the wire mesh to the steel shoring member 4. Further, since the installation of the wire mesh is completed by attaching the attachment member 53 to the steel shoring member 4, it is not necessary to require a plurality of workers.

[0043] When installing the wire mesh unit 5 on the steel support 4, by tilting the wire mesh body 51, contact between the wire mesh bodies 51 can be suppressed at the overlapping part between the wire mesh body 51 of the wire mesh unit 5 and the wire mesh body 51 installed on the existing steel support. That is, since the end of the wire mesh body 51 of the wire mesh unit 5 is disposed outside (the rock side) of the face side end of the wire mesh body 51 installed on the existing steel support, contact between the wire mesh bodies 51 is suppressed. Since the wire mesh body 51 is rotated and attached by only a small angle, planar intersection interference is avoided.

[0044] The ends of the wire mesh body 51 are in a comb shape formed by vertical members 511 and horizontal members 512 and are attached by rotating by only a small angle, so it is difficult for the wire mesh bodies 51 provided on the front, rear, left, and right to contact each other. Therefore, the construction work of the steel support 4 can be efficiently carried out.

[0045] Since the four sides of the wire mesh body 51 are in a comb shape and are attached by rotating by only a small angle, when the wire mesh units 5 are arranged side by side and attached to the steel support 4, or when the left and right steel supports 4 are combined, it is difficult for the ends of the horizontal members 512 to contact each other. In addition, since the wire mesh unit 5 can be manufactured in a factory and attached to the steel support 4 in the tunnel, compared with the case of assembling and attaching the wire mesh body 51 in the tunnel, the horizontal member 512 can be accurately fixed to the vertical member 511 at a predetermined inclination.

[0046] Since the net-shaped fixing member 54 embedded in the shotcrete 2 is fixed to the tip of the support member 52, the fixing member 54 is embedded in the shotcrete 2 to function as an anchor, preventing the steel support 4 from toppling. That is, the wire mesh unit 5 functions as a fall prevention member for the steel support 4, improving the stability of the steel support 4.

[0047] In addition, since the support unit 3 is configured by combining members with a simple structure and relatively easily available, the manufacturing cost can be kept low.

[0048] The embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and each of the above components can be appropriately changed without departing from the spirit of the present invention.

[0049] For example, the configuration of the attachment member 53 is not limited. For example, the fixing method of the attachment member 53 does not necessarily have to use the sheath pipe 43. Further, the fixing member 54 may be installed as needed.

[0050] The wire mesh body 51 does not necessarily have to have a comb-like end. Also, the length of the wire mesh body 51 is not limited, and for example, it may be equal to the distance between the steel shoring works.

Explanation of Signs

[0051] 1 Shoring work 2 Sprayed concrete 21 Primary sprayed concrete 22 Secondary sprayed concrete 3 Shoring work unit 4 Steel shoring work 41 Flange 42 Web 43 Sheath pipe 5 Wire mesh unit 51 Wire mesh body 511 Vertical member 512 Horizontal member 52 Support member 521 First piece 522 Second piece 53 Attachment member 531 Insertion part 532 Connection part 533 Female screw part 534 Adjusting bolt 54 Fixing member T Tunnel

Claims

1. A wire mesh unit comprising a wire mesh body provided along the outer surface of a steel support, a plurality of support members for supporting the wire mesh body, and a mounting member fixed to the base end portion of the support member, wherein the wire mesh unit is characterized in that it can be attached to the steel support by the mounting member.

2. The mounting member includes an insertion portion to be inserted into a sheath pipe fixed to the steel support, a connecting portion connecting the insertion portion and the support member, a female screw portion formed at the base end portion of the connecting portion, and an adjustment bolt screwed into the female screw portion so as to be able to advance and retreat, wherein the adjustment bolt is characterized in that its tip can abut against the flange of the steel support, and the wire mesh unit according to Claim 1.

3. The wire mesh unit according to Claim 1, characterized in that a net-shaped fixing member embedded in shotcrete is fixed to the support member.

4. The wire mesh body has a lattice shape by combining vertical members arranged along the tunnel axis direction and horizontal members arranged along the tunnel transverse direction, the end portions of the vertical members protrude in the tunnel axis direction from the horizontal members provided at the outermost ends, and the wire mesh unit according to Claim 1, characterized in that the wire mesh body is supported by the support member so that the face-side end portion protrudes to the face side from the steel support.

5. The wire mesh unit according to Claim 4, characterized in that, in a state of being attached to the steel support, the wire mesh body is supported by the support member so as to rotate by a slight angle about the center point.

6. A steel support comprising a pair of flanges and a web spanned across the pair of flanges, and the support unit according to any one of Claims 1 to 5 attached to at least the upper portion of the steel support.

7. An erection process of erecting the support unit according to Claim 6 in an arch shape using a heavy machine, and a spraying process of spraying shotcrete onto the ground surface, characterized in that it comprises a support erection method.

8. A wire mesh attachment step of attaching the wire mesh unit according to Claim 2 to a steel support, an erection step of erecting the steel support in an arch shape using a heavy machine, and a spraying step of spraying shotcrete onto the ground surface, which is a support erection method comprising In the wire mesh attachment step, with the tip of the adjustment bolt in contact with the flange, the adjustment bolt is further rotated to rotate the support member about the insertion portion, thereby tilting the wire mesh body with respect to the flange. A method for assembling a support and retaining structure is characterized by this.

9. A wire mesh attachment step of attaching the wire mesh unit according to claim 3 to a steel support and retaining structure; An erection step of erecting the steel support and retaining structure in an arch shape using a heavy machine; A spraying step of spraying sprayed concrete onto the ground surface. A method for assembling a support and retaining structure includes: The spraying step includes a preliminary spraying operation of spraying sprayed concrete so as to entangle the fixing member while holding the steel support and retaining structure with the heavy machine; After the preliminary spraying operation, a main spraying operation of spraying sprayed concrete with the holding of the steel support and retaining structure by the heavy machine released. A method for assembling a support and retaining structure is characterized by this.

10. A wire mesh attachment step of attaching the wire mesh unit according to claim 4 to a steel support and retaining structure; An erection step of erecting the steel support and retaining structure in an arch shape using a heavy machine; A spraying step of spraying sprayed concrete onto the ground surface. A method for assembling a support and retaining structure includes: In the erection step, the steel support and retaining structure is erected such that the end portion on the shaft mouth side of the wire mesh body overlaps the end portion on the face side of the wire mesh body attached to an existing steel support and retaining structure. A method for assembling a support and retaining structure is characterized by this.

Images