Floating formwork fixing structure and floating formwork installation method

Abstract

We propose a floating formwork fixing structure and a floating formwork installation method that enable the easy installation of floating formwork. [Solution] A floating formwork fixing structure 1 for holding a floating formwork for forming the haunch portion of an invert, comprising a column member 2 erected along the side wall of a tunnel, a horizontal member 3 extending inward from the lower part of the column member 2, a diagonal member 4 connecting the upper part of the column member 2 and the horizontal member 3, and a formwork holding member 5 attached to the horizontal member 3. The column member 2 is placed on a lower support member 62 provided on the side wall and attached to an upper support member 61 provided on the side wall.

Description

Technical Field

[0001] The present invention relates to a floating formwork fixing structure and a floating formwork installation method when installing a floating formwork during tunnel invert construction.

Background Art

[0002] In mountain tunnels such as NATM, an invert may be formed according to the ground classification. At the end of the invert in the tunnel circumferential direction, a haunch portion with a curved surface is formed as a joint portion with the arch portion (lining concrete). The haunch portion at the end of the invert is formed using a floating formwork (invert formwork).

[0003] As a method for installing a floating formwork, for example, Patent Document 1 discloses a floating formwork fixing structure in which a floating formwork is suspended by an arm member that horizontally protrudes from the side wall of a tunnel. The arm member is attached to the steel support of a part of the side wall of the tunnel at two locations, above and below. When attaching the arm member to the steel support, welding is generally used.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] When reinforcing bars are arranged in the invert, the reinforcing bars for joining are projected from the end of the invert. Also, depending on the situation of groundwater, etc. around the construction site, sheet waterproofing may be installed around the entire circumference of the tunnel, and in that case, the sheet waterproofing may be installed before the invert construction.

[0006] When attaching arm members to shoring while the waterproof sheet is installed, the work must be carried out carefully to avoid damaging the existing sheet waterproofing. Furthermore, when the thickness of the invert or lining concrete members is large, it becomes difficult to reach deep into the gaps between the reinforcing bars with hands or tools, making the installation and removal of floating formwork and arm members time-consuming.

[0007] From this perspective, the object of the present invention is to propose a floating formwork fixing structure and a floating formwork installation method that enable the easy installation of floating formwork. [Means for solving the problem]

[0008] To solve the aforementioned problems, the floating formwork fixing structure of the present invention holds a floating formwork for forming the haunch portion of an invert, and comprises a column member erected along the side wall of a tunnel, a horizontal member extending inward from the lower part of the column member, a diagonal member connecting the upper part of the column member and the horizontal member, and a formwork holding member attached to the horizontal member. The column member is placed on a lower support member provided on the side wall and is attached to an upper support member provided on the side wall.

[0009] Furthermore, the floating formwork installation method of the present invention comprises a support member installation step of fixing an upper support member and a lower support member to the side wall of a tunnel; a column member installation step of placing a column member on the lower support member and attaching the top of the column member to the upper support member; a formwork holding member fixing step of fixing a formwork holding member to a horizontal member extending from the lower part of the column member; and a formwork fixing step of suspending and fixing the floating formwork to the formwork holding member. Note that the column member may be installed in a predetermined position with the horizontal member or the horizontal member and diagonal member fixed in advance, or the horizontal member and diagonal member may be attached after the column member has been installed in a predetermined position.

[0010] This floating formwork fixing structure and floating formwork installation method involves erecting column members along the tunnel's side wall and suspending the floating formwork via horizontal members extending from these column members. As a result, the installation of the floating formwork is easier than in conventional methods. In other words, even when the member thickness of the invert's haunch section is large and the reinforcing bars are densely arranged, the work of reaching deep inside with hands or tools can be reduced or eliminated, resulting in superior workability. Furthermore, since the formwork fixing structure can be formed without welding, there is no risk of damaging the sheet waterproofing.

[0011] Furthermore, if a slit is formed at the lower end of the column member, the column member can be placed on the lower support member with the lower support member inserted through the slit. It is desirable that the formwork holding material is movable (position adjustable) in the axial and vertical directions of the horizontal member. In this case, the floating formwork can be positioned in a predetermined location by adjusting the position of the formwork holding material by surveying during the holding material fixing process. Furthermore, if the diagonal members are adjustable in length, the angle of the floating formwork can be finely adjusted by adjusting the angle of the inner angle between the column members and the horizontal members using the diagonal members. [Effects of the Invention]

[0012] According to the floating formwork fixing structure and floating formwork installation method of the present invention, floating formwork can be easily installed. [Brief explanation of the drawing]

[0013] [Figure 1] This is a cross-sectional view showing a tunnel according to an embodiment of the present invention. [Figure 2] This is a front view showing the floating formwork fixing structure. [Figure 3] This is a side view showing the floating formwork fixing structure. [Figure 4] This diagram shows a column, with (a) being a side view and (b) being a front view. [Figure 5] (a) is a front view showing the cross member, and (b) is a front view showing the mounting plate. [Figure 6] It is a front view showing a formwork retaining member. [Figure 7] It is a flowchart showing the procedure of the floating formwork installation method of this embodiment. [Figure 8] It is a front view showing the working condition of the floating formwork installation method, where (a) is the support member installation process, (b) is the reinforcement placement process, and (c) is the column member installation process. [Figure 9] It is a front view showing the working condition of the floating formwork installation method following FIG. 8, where (a) is the diagonal member installation process, (b) is the retaining member fixing process, and (c) is the formwork fixing process.

Mode for Carrying Out the Invention

[0014] In this embodiment, the case of constructing the tunnel lining concrete will be described. FIG. 1 shows the tunnel T of this embodiment. As shown in FIG. 1, the tunnel T is lined with a tunnel lining C. The tunnel lining C includes a support (primary lining) C1 made of shotcrete, steel supports, etc., a lining concrete C2 constructed on the inner space side of the support C1, and an invert C3 formed at the bottom of the tunnel T.

[0015] At the circumferential end of the invert C3 in the tunnel direction, as a joint with the arch part of the lining concrete C^2, a haunch part C4 with a curved surface is formed. The haunch part C4 is formed using a floating formwork K. FIGS. 2 and 3 show the floating formwork K and the floating formwork fixing structure 1. As shown in FIGS. 2 and 3, the floating formwork K has a contact surface with the placed concrete presenting a curved surface and has a predetermined length (for example, 6 m) along the tunnel axis direction. In this embodiment, a floating formwork K formed in a box shape with a sector cross-section is used by combining wooden members. Note that the configuration of the floating formwork K is not limited, and for example, it may be formed by combining steel materials and steel plates.

[0016] As shown in FIG. 3, the floating formwork K is held by a plurality of floating formwork fixing structures 1, 1,... arranged side by side along the axial direction of the tunnel T. As shown in FIG. 2, the floating formwork fixing structure 1 includes a column member 2, a cross member 3, a diagonal member 4, and a formwork holding member 5.

[0017] The column member 2 is erected along the side wall of the tunnel T. The column member 2 of the present embodiment is made of L-shaped steel and is processed into a curved shape (arc shape) according to the side wall of the tunnel T. The column member 2 is placed on the lower support member 62 provided on the side wall and attached to the upper support member 61 provided on the side wall, so as to be erected along the side wall. The upper support member and the lower support member of the present embodiment are anchors installed on the side wall (sprayed concrete) of the tunnel T.

[0018] FIG. 4 shows the column member 2. As shown in FIG. 4(a), an anchor through hole 23 is formed in the upper part of the first plate portion 21 (one of the two plate pieces combined in an L shape) of the column member 2, and a slit 24 is formed at the lower end of the first plate portion 21 of the column member 2. The column member 2 is placed on the lower support member (anchor) 62 in a state where the lower support member 62 is inserted through the slit 24 (see FIG. 2). Further, the column member 2 is attached to the upper support member 61 by screwing a nut onto the head of the upper support member 61 in a state where the head of the upper support member 61 is inserted through the anchor through hole 23 (see FIG. 2). In addition, a plurality of jig through holes 25 are formed in the second plate portion 22 (the other plate piece orthogonal to one plate piece) of the column member 2. The jig through holes 25 are formed at positions corresponding to the position of the cross member 3 in the lower part of the column member 2. Further, a diagonal member through hole 26 is formed in the upper part of the second plate portion 22 of the column member 2. In the present embodiment, the plate height of the portion (lower part of the column member 2) of the second plate portion 22 where the diagonal member through hole 26 is formed is made larger than other portions of the second plate portion 22. By doing so, it becomes easier to use tools when fixing the mounting plate 31 to the second plate portion 22 with bolts. In addition, a reinforcing backing plate 27 surrounding the periphery of the slit 24 is fixed to the first plate portion 21 in a stacked state. Further, a plurality of reinforcing ribs 28 are fixed to the column member 2.

[0019] As shown in Figure 2, the horizontal member 3 extends inward from the lower part of the column member 2. Figure 5 shows the horizontal member 3. As shown in Figure 5(a), the horizontal member 3 is made of a straight steel material (for example, an L-shaped steel). A through hole 32 for a jig is formed at the base end (the end on the column member 2 side) of the horizontal member 3, and a through hole 33 for a diagonal member is formed at the tip of the horizontal member 3. The horizontal member 3 is fixed to the lower part of the column member 2 via a mounting plate 31. As shown in Figure 5(b), the mounting plate 31 in this embodiment is made of a T-shaped steel plate with a plurality of through holes 34 formed therein. The column member 2 and the horizontal member 3 are connected by arranging a pair of mounting plates 31 with the column member 2 and the horizontal member 3 in between, and screwing nuts onto bolts that are inserted through the mounting plates 31 and the jig through holes 25 or 32.

[0020] As shown in Figure 2, the diagonal member 4 is a member that connects the column member 2 and the horizontal member 3. The diagonal member 4 in this embodiment is a so-called turnbuckle and is adjustable in length. The upper end of the diagonal member 4 is attached to the diagonal member through hole 26 at the top of the column member 2, and the lower end of the diagonal member 4 is attached to the diagonal member through hole 33 at the inner end of the horizontal member 3.

[0021] The formwork holding member 5 is attached to the horizontal member 3. Figure 6 shows the formwork holding member. As shown in Figure 6, the formwork holding member 5 is formed by combining or processing steel materials (e.g., L-shaped steel). The formwork holding member 5 in this embodiment has a U-shape with a pair of vertical pieces 51, 51 and a horizontal piece 52 connecting the lower ends of both vertical pieces 51, 51. As shown in Figure 2, the formwork holding member 5 suspends the floating formwork K by attaching the horizontal piece 52 to the floating formwork K with the upper ends of the vertical pieces 51 attached to the horizontal member 3. The formwork holding member 5 is detachably attached to the horizontal member 3 via a jig such as a clamping fitting (e.g., a clamp, vise, etc.) 53, and is movable in the axial and vertical directions of the horizontal member 3. In other words, the floating formwork fixing structure 1 holds the floating formwork K so that its position can be adjusted in the lateral direction and its height can be adjusted in the vertical direction.

[0022] The following describes a floating formwork installation method using the floating formwork fixing structure 1. Figure 7 shows the procedure for the floating formwork installation method. As shown in Figure 7, the floating formwork installation method comprises a support member installation step S1, a reinforcement bar placement step S2, a column member installation step S3, a diagonal member installation step S4, a retaining member fixing step S5, and a formwork fixing step S6. Figures 8 and 9 show the work status of the floating formwork installation method.

[0023] In the support member installation process S1, as shown in Figure 8(a), two sets of support members 6 (upper support member 61 and lower support member 62) are fixed to the side wall of the tunnel T. In this embodiment, reinforcing bars are embedded in the sprayed concrete of the shoring (primary lining) C1 as anchors for the support members 6. Multiple support members 6 (upper support member 61 and lower support member 62) are installed at predetermined intervals along the axial direction of the tunnel T. In this embodiment, the upper support member 61 and lower support member 62 are installed at predetermined height positions relative to the spring line of the tunnel T. It is preferable that the upper support member 61 be installed at a position higher than the upper end of the reinforcing bar R of the invert.

[0024] In reinforcement step S2, as shown in Figure 8(b), reinforcing bars R are placed to be embedded in the invert. In this embodiment, connecting reinforcing bars (main reinforcement) R that protrude from the end of the invert are placed along the side wall. Note that although the drawing only shows the main reinforcement placed along the circumferential direction of the tunnel T, additional reinforcement not shown is also placed where necessary.

[0025] In the column installation process S3, as shown in Figure 8(c), the column 2 is placed on the lower support member 62, and the top of the column 2 is attached to the upper support member 61. The column 2 is placed on the lower support member 62 with the lower support member 62 inserted into the slit 24. The horizontal member 3 is fixed to the column 2 in advance via the mounting plate 31. The horizontal member 3 may be fixed after the column 2 is attached to the upper and lower support members 6 (after the column installation process S3).

[0026] In the diagonal member installation process S4, as shown in Figure 9(a), a diagonal member 4 is installed to connect the top of the column member 2 and the horizontal member 3. Then, if necessary, the length of the diagonal member 4 connecting the horizontal member 3 and the top of the column member 2 is adjusted to adjust the angle of the interior angle between the column member 2 and the horizontal member 3 (ensuring the horizontality of the horizontal member).

[0027] In the retaining material fixing process S5, as shown in Figure 9(b), the formwork retaining material 5 is detachably fixed to the horizontal member 3 that extends from the lower part of the column member 2 via a jig such as a clamping fitting 53. In the retaining material fixing process S5, the position of the formwork retaining material 5 is adjusted so that the floating formwork K is positioned in the predetermined location by surveying.

[0028] In the formwork fixing process S6, the floating formwork K is suspended and fixed to the formwork holding material 5, as shown in Figure 9(c). The floating formwork K is positioned at a distance from the bottom surface of the tunnel T by the floating formwork fixing structure 1. In the formwork fixing process S6, the position of the floating formwork K is confirmed by surveying as needed, and the position of the floating formwork K is adjusted via the formwork holding material 5.

[0029] According to the floating formwork fixing structure 1 and floating formwork installation method of this embodiment, the floating formwork K can be easily installed. Specifically, since the floating formwork K is suspended via horizontal members 3 extending from the column members 2, the installation work of the floating formwork K is easier than in the conventional method. More specifically, the column members 2 are installed by placing them on the lower support member 62 from above and attaching them to the upper support member 61, resulting in excellent workability. Therefore, even when the thickness of the haunch section C4 of the invert C3 is large and the reinforcing bars are densely arranged, the work of reaching in with hands or tools can be reduced or omitted, resulting in excellent workability.

[0030] Furthermore, since a slit 24 is formed at the lower end of the column member 2, the column member 2 is engaged with the lower support member 62 simply by inserting the lower support member 62 through the slit 24 and placing the column member 2 on the lower support member 62. As a result, the work of inserting hands or tools into the back of reinforcing bars, etc., to attach the lower part of the column member 2 can be reduced or eliminated, and positioning becomes easier.

[0031] Since the horizontal member 3 is attached to the column member 2 with bolts via the mounting plate 31, the floating formwork fixing structure 1 can be formed without welding, and there is no risk of damaging the sheet waterproofing. Since the diagonal member 4 is adjustable in length, its length can be adjusted. By adjusting the length of the diagonal member 4 as needed and adjusting the angle of the inner angle between the column member 2 and the horizontal member 3 (ensuring the horizontality of the horizontal member 3), it becomes possible to fine-tune the angle of the floating formwork K.

[0032] Since the formwork support member 5 can be moved (position adjusted) in the axial and vertical directions of the horizontal member 3, the position of the floating formwork K can be finely adjusted by adjusting the position of the formwork support member 5 through surveying.

[0033] Although embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above, and each of the above-mentioned components can be modified as appropriate without departing from the spirit of the present invention. For example, in the above embodiment, a case in which a slit 24 is formed at the lower end of the column member 2 was described, but the slit 24 may be formed as needed. For example, instead of a slit 24, irregularities may be formed at the lower end of the column member 2, or a locking portion that can be locked to the lower support member 62 may be formed or fixed. Furthermore, the material constituting the column member 2 is not limited to L-shaped steel.

[0034] In the above embodiment, the case in which the upper support member 61 and the lower support member 62 are anchors embedded in sprayed concrete was described, but the installation locations of the upper support member 61 and the lower support member 62 are not limited, and for example, they may be fixed (welded) to a steel support structure. Furthermore, the configuration of the upper support member 61 and the lower support member 62 is not limited to anchors as long as they can support the column member 2. Moreover, the material constituting the upper support member 61 and the lower support member 62 is not limited to reinforcing bars, but may be bolts, for example.

[0035] In the above embodiment, the case where the diagonal member 4 is a turnbuckle was described, but the material constituting the diagonal member 4 is not limited. Also, in the above embodiment, the case where the diagonal member 4 is a length-adjustable member was described, but the diagonal member 4 does not necessarily need to be length-adjustable. Furthermore, in a configuration where the buoyancy force during concrete pouring is less than the weight of the floating formwork K and only tensile force acts on the diagonal member 4, it is desirable to use a turnbuckle as the diagonal member 4. On the other hand, if the buoyancy force acting during concrete pouring is greater than the weight of the floating formwork K, it is desirable to use an L-shaped steel or the like as the diagonal member 4 so that it can also resist compressive force.

[0036] The shape of the formwork retainer 5 is not limited to a concave shape. For example, it may be a U-shaped or square-shaped member, or a plurality of vertical members arranged in parallel along the axial direction of the horizontal member 3. Furthermore, the material constituting the formwork retainer 5 is not limited to steel. In addition, the jig used to fix the formwork retainer 5 to the horizontal member 3 is not limited. Moreover, the method of fixing the formwork retainer 5 is not limited to using a jig; for example, bolts or magnets may be used, or welding may be performed.

[0037] In the above embodiment, the case in which the column members 2 with the horizontal members 3 already fixed are installed and then the diagonal members 4 are attached to the column members 2 and the horizontal members 3 was described. However, the procedure for forming the floating formwork fixing structure 1 is not limited to this. For example, the column members 2 may be installed (placed on the lower support members 62) and then the horizontal members 3 may be fixed (horizontal member fixing step). Also, the diagonal members 4 may be attached to the column members 2 and the horizontal members 3 in advance, or they may be attached after the column members 2 are installed in a predetermined position. Reinforcement bars (R) should be placed as needed. Also, single reinforcement bars (R) are acceptable. [Explanation of Symbols]

[0038] 1. Floating formwork fixing structure 2 Pillar material 21 First plate part 22 Second plate part 23 Through holes for anchors 24 slits 25 Through-hole for jigs 26 Through hole for diagonal material 3 Crosspiece 31 Mounting plate 32 Through holes for jigs 33 Through hole for diagonal material 4 Diagonals 5 Formwork retaining material 51 vertical pieces 52 Horizontal piece 53 Clamping hardware 61 Upper support member 62 Lower support member C Tunnel lining C1 Shoring (primary lining) C2 lining concrete (secondary lining) C3 Invert C4 Hunch Section K Floating formwork R-shaped rebar S1 Support member installation process S2 Reinforcement process S3 Pillar installation process S4 Diagonal installation process S5 Holding material fixing process S6 Formwork fixing process T Tunnel

Claims

1. A floating formwork fixing structure for holding a floating formwork for forming the haunch portion of an invert, Columns erected along the side walls of the tunnel, A horizontal member extending inward from the lower part of the column member, A diagonal member connecting the upper part of the column member and the horizontal member, The formwork holding member is attached to the aforementioned horizontal member, A floating formwork fixing structure characterized in that the column material is placed on a lower support member provided on the side wall and attached to an upper support member provided on the side wall.

2. A slit is formed at the lower end of the column member, The floating formwork fixing structure according to claim 1, characterized in that the column member is placed on the lower support member with the lower support member inserted through the slit.

3. The floating formwork fixing structure according to claim 1, characterized in that the formwork holding member is movable in the axial and vertical directions of the horizontal member.

4. The floating formwork fixing structure according to claim 1, characterized in that the diagonal member is adjustable in length.

5. A support member installation process for fixing upper and lower support members to the side wall of the tunnel, A column installation step involves placing the column on the lower support member and attaching the top of the column to the upper support member, A retaining member fixing step is performed to fix the formwork retaining member to the horizontal member that extends from the lower part of the column member, A method for installing floating formwork, characterized by comprising a formwork fixing step of suspending and fixing the floating formwork to the formwork holding material.

6. The floating formwork installation method according to claim 5, characterized in that, in the retaining material fixing step, the position of the formwork retaining material is adjusted by surveying so that the floating formwork is positioned in a predetermined location.

7. The floating formwork installation method according to claim 5, characterized in that the angle of the inner angle between the column member and the horizontal member is adjusted by adjusting the length of the diagonal member connecting the horizontal member and the upper part of the column member.

8. A horizontal member fixing step in which the horizontal member is fixed to the lower part of the column member, The floating formwork installation method according to claim 5, further comprising a step of installing a diagonal member that connects the upper part of the column member and the horizontal member.

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