Embedded formwork and method for manufacturing embedded formwork

Abstract

To provide a buried form and a manufacturing method of the buried form capable of improving dynamic integration at an interface with concrete.SOLUTION: A buried form 1 in which a plurality of laminates 3 are vertically laminated is formed by a lower layer laminate forming process for forming a lower layer laminate by discharging a hydraulic composition from a nozzle and an upper layer laminate forming process for forming an upper layer laminate by discharging the hydraulic composition from the nozzle above the lower layer laminate. The laminates 3 adjacent to each other in the up-down direction are arranged side by side in a state where the distal ends thereof in the lateral direction are spaced apart from each other in a plan view.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an embedded formwork and a method for manufacturing the embedded formwork. Regarding. [Background technology]

[0002] In mountain tunnels (such as NATM tunnels), standard support patterns vary depending on the ground grade, resulting in sections with and without inverts. Inverts are constructed by installing bottom forms and pouring concrete in designated sections. However, to ensure a passage from the tunnel entrance to the tunnel face, construction is sometimes performed on both the left and right half sections. In such cases, inverts are constructed by assembling formwork, such as bottom forms, longitudinal forms, and invert forms, on the floor surface formed by excavation, followed by pouring concrete. The bottom forms must be machined to fit the curved shape of the invert's top surface and the curved ground surface after excavation, making this a complex process. Furthermore, formwork assembly is typically performed manually, which is time-consuming. In addition, invert construction requires multiple workers to pour and finish concrete while holding down the concrete as it flows down the large cross-section and along the slope.

[0003] The applicant has disclosed an invert construction method in which, with the aim of reducing the effort required for manufacturing formwork, an invert formwork (buried formwork) is formed using a so-called 3D printer (additive manufacturing device), and an invert is formed by pouring concrete inside this invert formwork with the invert formwork wrapped around it (see Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2023-157494 Summary of the Invention [Problem to be solved by the invention]

[0005] Tunnel inverts are subject to external forces such as ground expansion, ground heave, and earthquakes. Therefore, it is desirable that the compressive strength, bending strength, and shear strength at the joint between the invert formwork and the concrete be equal to or greater than that of an invert formed using only poured concrete using conventional construction methods. It is also desirable that buried formwork used for concrete components other than the invert (for example, columns, walls, etc.) have strength equal to or greater than that of inverts formed using only poured concrete.

[0006] From this perspective, an object of the present invention is to propose an embedded formwork and a method for manufacturing the embedded formwork that can improve the mechanical integrity at the interface with the concrete. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems, the buried formwork of the present invention is formed by stacking a plurality of laminates made of a hydraulic composition one above the other, and adjacent laminates are arranged side by side with their respective shorter-side ends spaced apart in a plan view.

[0008] The method for manufacturing an embedded form of the present invention includes a lower layer laminate forming step of forming a lower layer laminate by discharging a hydraulic composition from a nozzle, and an upper layer laminate forming step of forming an upper layer laminate by discharging a hydraulic composition from a nozzle above the lower layer laminate. In the upper layer laminate forming step, the nozzle is moved so as to follow a trajectory parallel to, and spaced laterally from, the trajectory of the nozzle when forming the lower layer laminate in a plan view.

[0009] According to this buried form and its manufacturing method, unevenness (steps between laminated bodies) is formed on the surface of the form that contacts the concrete, improving the unity with the concrete. As a result, the compressive strength, bending strength, and shear strength at the joint (interface) between the buried form and the concrete are improved, and the necessary strength is exhibited even when external forces such as ground expansion, ground swelling, and earthquakes act on the form.

[0010] The laminate is preferably an assembly in which strips made of the hydraulic composition are stacked in multiple stages (preferably 2 to 3 stages). In this case, the laminate (the lower layer laminate and the upper layer laminate) is formed by an operation of forming a lower layer strip (lower layer filament) by discharging the hydraulic composition from a nozzle, and an operation of forming an upper layer strip (upper layer filament) by discharging the hydraulic composition from a nozzle onto the lower layer strip. At this time, the trajectory of the nozzle when forming the lower layer strip and the trajectory of the nozzle when forming the upper layer strip are made to coincide in a plan view. Note that each laminate may be formed by arranging the strips in multiple rows in the width direction.

[0011] From the viewpoint of bonding to concrete, the distance between the short-side ends of adjacent laminates is preferably less than 0.4 times, and more preferably less than 0.3 times, the width of the strip. [Effects of the Invention]

[0012] According to the buried form and the method for manufacturing the buried form of the present invention, it is possible to improve the mechanical integrity at the interface with the concrete. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a cross-sectional view of a tunnel with an invert. [Figure 2] FIG. 1 is a perspective view showing an outline of an embedded formwork. [Figure 3] 1 is a plan view showing an invert form manufacturing apparatus according to an embodiment of the present invention. FIG. [Figure 4] FIG. 2 is a cross-sectional view showing an invert form manufacturing device. [Figure 5] FIG. 2 is a longitudinal cross-sectional view showing an invert form manufacturing device. [Figure 6] This is an oblique view showing the construction status of the buried formwork, where (a) is the construction status of the lower band of the lower laminate, (b) is the construction status of the upper band of the lower laminate, (c) is the construction status of the lower band of the upper laminate, and (d) is the construction status of the upper band of the upper laminate. [Figure 7] These are cross-sectional views showing the design dimensions of test specimens formed to check the sagging of the hydraulic composition due to the degree of misalignment between the end faces of the laminate, where (a) is Case 1, (b) is Case 2, and (c) is Case 3. [Figure 8] These are photographs of the experimental results confirming the amount of sagging depending on the distance between the end faces of the upper and lower laminates, where (a) is Case 1, (b) is Case 2, and (c) is Case 3. [Figure 9] 1A and 1B are explanatory diagrams showing the design cross section of the formwork used in the experiment, where (a) is an example and (b) is comparative example 1. FIG. [Figure 10] 1 is an explanatory diagram showing an outline of a compressive strength test, in which (a) is an example and (b) is comparative example 1. FIG. [Figure 11] 1 is a graph showing test results of a compressive strength test. [Figure 12] 1 is an explanatory diagram showing an outline of a bending strength test, where (a) is an example and (b) is comparative example 1. FIG. [Figure 13] 10 is a graph showing test results of a bending strength test. [Figure 14] 1 is an explanatory diagram showing an outline of a shear strength test, where (a) is an example and (b) is comparative example 1. FIG. [Figure 15] 1 is a graph showing test results of a shear strength test. DETAILED DESCRIPTION OF THE INVENTION

[0014] In this embodiment, the case of constructing an invert C2 of a tunnel T will be described (see FIG. 1). FIG. 1 shows the tunnel T. The invert C2 is formed so as to be continuous with the lining concrete C1 by forming a formwork for the invert (buried formwork 1) at the bottom of the tunnel T (tunnel floor surface Ts) and pouring concrete into this buried formwork 1. FIG. 2 shows the buried formwork 1.

[0015] The buried formwork 1 is formed by stacking a plurality of laminates 3 made of a hydraulic composition one above the other using an inverted formwork manufacturing apparatus 2 (see FIG. 3). As shown in FIG. 2, the laminates 3 adjacent to each other on the upper and lower sides of the buried formwork 1 are arranged side by side with a gap between their respective lateral ends in a plan view. Here, the laminate 3 is an assembly of strips 4 made of a hydraulic composition stacked in two rows in the width direction, or three levels above and below. The strips 4 are strip-shaped single-layer bodies formed by ejecting the hydraulic composition from a nozzle 23 (described later). In this embodiment, the distance W2 between the lateral ends (end faces) of the vertically adjacent laminates 3, 3 is set to be less than 0.4 times the width W1 of the strips 4. The hydraulic composition is a composition obtained by kneading hydraulic powder (e.g., containing at least one of Portland cement, ground granulated blast furnace slag, and an activator), admixtures (e.g., fly ash, calcium carbonate, etc.), aggregates (fine aggregate, coarse aggregate), fibers (steel fibers, resin fibers, mineral fibers, etc.), water, various admixtures, etc. Since the unhardened hydraulic composition has fluidity, the surface of the strip 4 has a rounded shape (see Figure 8), but for the sake of convenience, in Figures 2, 6, 7, 9, 10, 12, and 14, the strip 4 is shown as a rectangular parallelepiped.

[0016] The buried formwork 1 is formed using an invert formwork manufacturing apparatus 2. The invert formwork manufacturing apparatus 2 is a so-called 3D printer that produces an invert formwork (buried formwork 1) on the tunnel flooring surface Ts by discharging a hardening material (a hydraulic composition in this embodiment) onto the flooring surface Ts from a nozzle that is movable back and forth and left and right. An overview of the invert formwork manufacturing apparatus 2 is shown in FIGS. 3 to 5. As shown in FIG. 3, the invert formwork manufacturing apparatus 2 includes a pair of fixed beams 21, 21, a movable beam 22, a nozzle 23, a hardening material supply means 24, and a 3D scanner 25.

[0017] As shown in FIGS. 3 and 4, a pair of fixed beams 21 are provided laterally spaced apart above the tunnel floor surface Ts. The pair of fixed beams 21 form part of a frame for supporting the nozzle 23 and the 3D scanner 25. In this embodiment, the fixed beams 21 are provided at the side and center of the tunnel along the tunnel axis (Y direction). The fixed beams 21 are made of steel (H-shaped steel in this embodiment). The fixed beam 21 provided at the center of the tunnel is supported by supports 21a made of steel (e.g., H-shaped steel or channel steel) erected on the tunnel floor surface Ts, as shown in FIGS. 4 and 5. In this embodiment, supports 21a are provided at both ends of the fixed beam 21. The fixed beam 21 provided at the side of the tunnel (on the right side in FIG. 4) is supported by a support member (bracket) 21b (e.g., channel steel) fixed to the shoring. As shown in Fig. 4, the fixed beams 21, 21 provided on the left and right sides are provided to be at the same height. The fixed beams 21, 21 provided on the left and right sides are connected by connecting members 21c, 21c made of steel materials (e.g., angle bars) that are laid horizontally at both ends. In other words, the mounting base is formed by combining the fixed beams 21, the supports 21a, the support members 21b, and the connecting members 21c, 21c.

[0018] As shown in Fig. 5, the movable beam 22 is suspended across a pair of fixed beams 21, 21. The movable beam 22 is movable along the pair of fixed beams 21, 21. In other words, the movable beam 22 is movable along the tunnel axis direction (Y direction). The movable beam 22 is made of steel such as an H-shaped steel, and is suspended across the fixed beams 21, 21 via movement means (not shown) such as traveling wheels or rollers that travel on the fixed beams 21, 21. The movement of the movable beam 22 in the tunnel axis direction is controlled by control means (not shown).

[0019] The nozzle 23 is provided on the movable beam 22. The nozzle 23 is movable along the movable beam 22. That is, the nozzle 23 moves in the tunnel crossing direction (X direction) along the movable beam 22 and also moves along the tunnel axis direction (Y direction) together with the movable beam 22, thereby being movable over the entire construction range in a plan view. The nozzle 23 is also provided so as to be movable in the vertical direction (Z direction) relative to the movable beam 22. The movement of the nozzle 23 in the tunnel crossing direction (movement along the movable beam 22) and in the vertical direction is controlled by control means (not shown). A hardening material hose 26 extending from the hardening material supply means 24 is connected to the nozzle 23. The nozzle 23 discharges the hydraulic composition transported via the hardening material hose 26 toward the bedding surface.

[0020] The solidification material supply means 24 supplies the hydraulic composition to the nozzle 23 via a solidification material hose 26. The solidification material supply means 24 includes a hopper 24a and a concrete pump 24b. The hydraulic composition transported via an agitator vehicle and poured into the hopper 24a is pressure-fed to the nozzle 23 via the solidification material hose 26 by the concrete pump 24b. In this embodiment, the solidification material hose 26 is extended in the tunnel axial direction (Y direction) at the top of the tunnel via a pulley 26a provided at the top of the tunnel, and then connected to the nozzle 23.

[0021] The 3D scanner 25 is provided on the movable beam 22 so as to be movable along the movable beam 22. The 3D scanner 25 in this embodiment is integral with the nozzle 23 or attached to the nozzle 23, and is movable together with the nozzle 23 along the movable beam 22 in the tunnel transverse direction (X direction), and is also movable together with the movable beam 22 in the tunnel axial direction (Y direction). Measurement results by the 3D scanner 25 are transmitted to a terminal (not shown), such as a computer, tablet, or smartphone.

[0022] The buried formwork 1 is manufactured by the following procedure (manufacturing method for buried formwork). First, the invert formwork manufacturing device 2 is installed (see Figures 3 to 5). A support pillar 21a is erected in the center of the tunnel, and support members 21b are installed on the support pillar 21a and on the side of the tunnel, and a fixed beam 21 is fixed to the support member 21b. Next, a movable beam 22 is laid horizontally across the fixed beams 21, and a nozzle 23 and a 3D scanner 25 are installed on the movable beam 22. Furthermore, a pouring movable beam 31 is laid horizontally across the fixed beams 21, and pouring hoses 32, 32, ... are installed on the pouring movable beam 31.

[0023] Next, the tunnel floor contact surface is scanned. The scanning of the tunnel floor contact surface is performed by the 3D scanner 25 of the invert formwork manufacturing device 2. The 3D scanner 25 is moved in the tunnel transverse direction by moving along the movable beam 22, and the 3D scanner 25 is moved in the tunnel longitudinal direction by moving the movable beam 22 along the fixed beams 21, 21. In this way, the entire construction range of the invert is measured (scanned). The measurement results are sent to a computer or the like. At this time, the concrete pouring movable beam 31 is positioned at the tunnel entrance side end of the fixed beam 21.

[0024] Next, the formwork shape is redesigned according to the on-site conditions. The difference (construction error) between the shape of the tunnel floor contact surface Ts measured by the 3D scanner 25 and the design cross section is calculated, and the height of the buried formwork 1 according to the on-site conditions is calculated. After that, the movement route (XYZ coordinates) of the nozzle 23 is set so that the buried formwork 1 can be formed according to the position of the designed top surface of the invert.

[0025] Then, an embedded formwork 1 is formed on the flooring surface Ts. An invert formwork manufacturing device 2 is used to form the embedded formwork 1. In this embodiment, a plurality of transverse formworks (including bottom formworks) 11, 11, ... are formed at intervals in the longitudinal direction of the tunnel, and a plurality of longitudinal formworks 12, 12, ... are formed at intervals in the transverse direction of the tunnel, thereby constructing a lattice-shaped embedded formwork 1. The transverse formwork 11 is constructed by disposing a movable beam 22 at a predetermined position and then discharging a hydraulic composition while moving a nozzle 23 along the movable beam 22. The hydraulic composition is layered to a predetermined height by moving the nozzle 23 back and forth multiple times. The tunnel wall side end of the transverse formwork 11 has a curved surface shape according to the shape of the side of the invert. The longitudinal formwork 12 is constructed by discharging a hydraulic composition while disposing a nozzle 23 at a predetermined position of the movable beam 22 and moving the movable beam 22 along a fixed beam 21. The hydraulic composition is layered to a predetermined height by moving the movable beam 22 (nozzle 23) back and forth multiple times. After the horizontal formwork 11 and the vertical formwork 12 are constructed, they are cured until they develop a predetermined strength.

[0026] Here, the buried formwork 1 is formed by stacking multiple layers of laminates 3. FIG. 6 shows the construction of the buried formwork 1. First, as shown in FIG. 6(a), the lowermost laminate 3 (lower layer laminate) is formed by discharging the hydraulic composition C0 from the nozzle 23 toward the tunnel floor surface Ts (lower layer laminate formation process). The lower layer laminate is formed by discharging the hydraulic composition C0 from the nozzle 23 to form a lower band 4 (lower layer band 41), and as shown in FIG. 6(b), discharging the hydraulic composition C0 from the nozzle 23 onto the existing band 4 (lower layer band 41) to form a band 4 (upper layer band 42). When forming the upper layer band 42, the trajectory of the nozzle 23 when forming the lower layer band 41 and the trajectory of the nozzle 23 when forming the upper layer band 42 are aligned in a plan view. In this embodiment, the strips 4 are arranged in two rows and three layers of the strips 4 are stacked to form a lower layer laminate (see FIG. 6(c)).

[0027] Next, as shown in FIG. 6(c), a hydraulic composition C0 is ejected from a nozzle 23 above the lower layer laminate (existing laminate 3) to form a laminate 3 (upper layer laminate) (upper layer laminate formation process). The newly created laminate 3 is formed by moving the nozzle 23 (the center of the nozzle 23) along a trajectory that is parallel to the trajectory (the center of the nozzle 23) of the nozzle 23 when forming the lower laminate (the existing laminate 3) at a position spaced laterally in a plan view.

[0028] The upper layer laminate is formed by an operation of forming a lower layer strip 41 by discharging the hydraulic composition C0 from a nozzle 23 above the lower layer laminate, as shown in Fig. 6(c), and an operation of forming an upper layer strip 42 by discharging the hydraulic composition C0 from the nozzle 23 onto the lower layer strip 41, as shown in Fig. 6(d). When forming the upper layer strip 42, the trajectory of the nozzle 23 when forming the lower layer strip 41 and the trajectory of the nozzle 23 when forming the upper layer strip 42 are made to coincide in a plan view. In this embodiment, the strips 4 are arranged in two rows and three layers of the strips 4 are stacked together to form the upper layer laminate (laminate 3).

[0029] Similarly, the upper layer laminates are stacked until they reach a desired height to form the buried formwork 1. This results in the formation of the buried formwork 1 having irregularities on the left and right side surfaces in cross section (see Figure 2). The invert C2 is formed by pouring concrete into the space surrounded by the horizontal formwork 11 and the vertical formwork 12 and curing it. After the concrete has cured, the joints are treated and invert C2 is backfilled.

[0030] According to the buried form and the method for manufacturing the buried form of this embodiment, the surface of the buried form 1 that comes into contact with the concrete is uneven, improving the unity with the concrete. As a result, the compressive strength, bending strength, and shear strength at the joint between the buried form 1 and the concrete are improved, and the necessary strength is exhibited even when external forces such as ground expansion, ground swelling, and earthquakes act on the buried form 1.

[0031] The results of experiments carried out on the buried formwork of this embodiment will be described below. If the laminates 3 are stacked with a misalignment, there is a risk that the overhanging portions of the lower laminates will sag. If the upper laminate sags too much, the balance of the buried formwork 1 will be lost, which may lead to the collapse of the laminates 3 (buried formwork 1), and the recesses may be filled, reducing the unity with the concrete. Therefore, formwork 10 was formed by changing the amount of misalignment between the laminates 3, and the presence or absence of sagging of the overhanging portions of the laminates 3 was confirmed.

[0032] Figure 7 shows the design dimensions of the formwork 10. As shown in Figures 7(a) to (c), in this experiment, the height of the laminate was fixed at 30 mm, and the lateral displacement (depth of the recess) of the upper laminate relative to the lower laminate was changed to 10 mm (Case 1), 5 mm (Case 2), and 7.5 mm (Case 3), and the degree of sagging was observed. Here, each laminate 3 was formed by arranging strips 4, each 25 mm wide and 10 mm high, side by side in two rows and three stages.

[0033] Figure 8(a) shows Case 1, (b) Case 2, and (c) Case 3. Note that Figure 8 is a photograph of the edge of formwork 10, but because the nozzle was turned around at the edge of formwork 10, the boundary between adjacent strips on the left and right is not visible. In Case 1 shown in Figure 8(a), the sagging of the material that could become formwork was approximately 10 mm, creating an unstable feeling. On the other hand, in Cases 2 and 3 shown in Figures 8(b) and 8(c), the sagging was less than 10 mm, creating a stable feeling. Therefore, the lateral deviation (depth of the recess) of the upper layer laminate relative to the lower layer laminate was preferably 10 mm or less (less than 0.4 times the width of the strip), and more preferably 7.5 mm or less (less than 0.3 times the width of the strip).

[0034] In addition, in Case 1 shown in Figure 8(a), sagging of about 10 mm (thickness of the strip) occurred, reducing the height of the recess accordingly. On the other hand, in Cases 2 and 3 shown in Figure 8(b) and (c), sagging was kept to 10 mm or less, so the height of the recess was more than twice the height of the strip.

[0035] Next, the results of checking the strength at the interface between the buried formwork 1 of this embodiment and concrete will be shown. In this experiment, the hydraulic composition forming the buried formwork 1 was controlled so that the vane shear strength was within the range of 0.4 kPa to 1.0 kPa, which is the range in which the vane shear strength is excellent in self-supporting stability. The vane shear strength during the experiment was within the range of 0.8 kPa to 1.0 kPa.

[0036] The concrete used was ready-mix concrete 18-12-20-N (nominal strength 18N / mm 2 The target slump was 12cm, the maximum size of coarse aggregate was 20mm, and the cement type was ordinary cement. The actual slump at the time of acceptance was 14cm, and the compressive strength at 28 days was 21.9N / mm 2 It was.

[0037] As shown in Figure 9(a), the formwork 10 of the example was formed by stacking strips 4, each 10 mm high and 25 mm wide, in two rows horizontally and three rows vertically to form a laminate 3, with a 7.5 mm offset between the end faces of the laminate 3, resulting in a height of 100 mm. Also, as comparative example 1, a formwork 10a was created by stacking strips in two rows horizontally and ten rows vertically, as shown in Figure 9(b).

[0038] The test specimens were formed by pouring concrete C into the formwork 10 of the example or the formwork 10a of Comparative Example 1. The test specimen for the compressive strength test was 10 cm high x 10 cm deep x 20 cm long, and the test specimens for the bending strength test and shear strength test were 10 cm high x 10 cm deep x 40 cm long. In addition, a test specimen in which only concrete was poured was also prepared as Comparative Example 2.

[0039] <Compression strength test> The compressive strength test was carried out in accordance with JIS A 1108 "Method for extracting cores from concrete and method for testing compressive strength," with a 10 cm × 10 cm × 20 cm specimen 5 placed vertically in a formwork 10 with concrete C positioned above and below it, as shown in Fig. 10. Fig. 11 shows the strength ratio when the compressive strength of Comparative Example 2 is taken as 1. As shown in FIG. 11, the compressive strength ratio exceeded the target value (1.00) by more than 30% in both the example and the comparative example, and the results showed that the compressive strength was equal to or greater than that of the conventional construction method.

[0040] <Bending strength test> As shown in Figure 12(a), a 10 cm x 10 cm x 40 cm specimen 5 was placed horizontally with concrete C on either side of a formwork 10, and a bending strength test was conducted using four-point loading in accordance with JISA1106, "Testing Method for Bending Strength of Concrete." Both interfaces between the formwork 10 and the concrete C were subjected to bending stress within the uniform bending zone. As Comparative Example 1, a bending strength test was also conducted on specimen 5a formed using formwork 10a, as shown in Figure 12(b). Similar tests were also conducted on a specimen formed only with concrete C (Comparative Example 2) and a specimen with a joint formed in the middle (target value).

[0041] The results of the bending strength test are shown in Figure 13. As shown in Figure 13(a), the bending strength of the Example was close to that of Comparative Example 2, which did not have a formwork. Also, as shown in Figure 13(b), when the bending strength ratio is calculated assuming that the bending strength of Comparative Example 2 is 1, Comparative Example 1 was slightly below the target value, while the Example exceeded the target value by about 55%. Furthermore, by stacking the laminates in a staggered manner, the Example showed a strength improvement effect of 1.6 times that of Comparative Example 1, which did not have a staggered structure.

[0042] <Shear strength test> As shown in Figure 14(a), a 10 cm x 10 cm x 40 cm specimen 5 was placed horizontally and subjected to a direct double shear shear strength test in accordance with JSCE-G 553-2013, "Test Method for Shear Strength of Steel Fiber Reinforced Concrete." One of the two shear planes was aligned with the interface between the formwork and the concrete, and the other was positioned across the concrete itself. Additionally, as shown in Figure 14(b), a bending strength test was also conducted on specimen 5a formed using formwork 10a (Comparative Example 1). Similar tests were also conducted on a specimen formed solely with concrete C (Comparative Example 2) and a specimen with a joint formed in the middle (target value).

[0043] The shear strength test results are shown in Figure 15. As shown in Figure 15(a), the shear strength of the Example exceeded that of Comparative Example 2, which did not have a formwork. Furthermore, as shown in Figure 15(b), the shear strength ratio, when Comparative Example 2 is set to 1, exceeded the target value for both the Example and Comparative Example 1, resulting in a strength equivalent to or greater than that of conventional construction methods. Furthermore, the Example showed a strength improvement effect of 2.1 times that of Comparative Example 1.

[0044] As described above, it has been confirmed that the buried formwork 1 of this embodiment can improve bending strength and shear strength. Furthermore, because 3D printing, which offers a high degree of freedom in design, is used, unevenness can be formed on the surface of the buried formwork 1 without requiring additional labor or cost compared to when no unevenness is formed.

[0045] The present invention is not limited to the above-described embodiment, and each of the above-described components can be appropriately modified without departing from the spirit of the present invention. For example, in the above embodiment, an embedded formwork used for an invert was described, but the use of the embedded formwork is not limited, and it may also be used, for example, as an embedded formwork for pillars, walls, etc.

[0046] In the above embodiment, from the viewpoint of bonding to concrete, the distance W2 between the short-side ends of adjacent laminates is set to 0.4 times or less the width W1 of the strip 4. However, from the viewpoint of stackability, it is more preferable to set it to 0.3 times or less the width W1 of the strip 4, and even more preferable to set it to a range of 0.2 to 0.3 times. Furthermore, from the viewpoint of bonding to concrete, it is preferable that the distance W2 is 3 mm or more.

[0047] In the above embodiment, the laminate is formed by arranging the strips 4 in two rows in the width direction and stacking them vertically in three rows, but the number of rows in the width direction and the number of rows in the vertical direction are not limited. The number of rows in the width direction may be one row or three or more rows. The number of rows in the vertical direction may be, for example, two rows or four or more rows.

[0048] In addition, in the above embodiment, the invert construction is performed on one side at a time, but if the cross-sectional shape of the tunnel is small, construction may be performed across the entire width at the same time. In the above embodiment, the case where the invert formwork manufacturing device 2 is equipped with the 3D scanner 25 has been described, but the 3D scanner 25 may be omitted. In this case, scanning of the flooring surface is omitted. Also, a laser rangefinder may be used instead of the 3D scanner 25. When using a laser rangefinder, the distance from the laser rangefinder to the flooring surface Ts or the upper surface of the solidification material is measured, and the solidification material is discharged according to the measurement result. Measurement of the flooring surface by the 3D scanner 25 may be performed only at the locations where the horizontal formwork 41 and the vertical formwork 42 are formed. [Explanation of symbols]

[0049] 1 Buried formwork 11 Cross formwork 12 Vertical formwork 2. Invert formwork manufacturing equipment 21 Fixed beam 22 Movable beam 23 nozzles 24 Solidification material supply means 25 3D scanner 3 Laminate 4. Band

Claims

1. An embedded formwork formed by stacking a plurality of laminates made of a hydraulic composition one on top of the other, The buried formwork is characterized in that the stacks adjacent to each other in the vertical direction are arranged side by side with their respective shorter-side tips spaced apart in a plan view.

2. 2. The buried formwork according to claim 1, wherein the laminate is an assembly of strips made of the hydraulic composition stacked in multiple stages.

3. 3. The embedded formwork according to claim 2, wherein the distance between the ends of the stacks in the shorter direction adjacent to each other is less than 0.4 times the width of the strip.

4. 2. The buried formwork according to claim 1, wherein the laminate is an assembly of strips made of the hydraulic composition stacked in a plurality of rows in the width direction and in a plurality of layers up and down.

5. a lower layer laminate forming step of forming a lower layer laminate by discharging a hydraulic composition from a nozzle; an upper layer laminate forming step of forming an upper layer laminate by discharging a hydraulic composition from a nozzle above the lower layer laminate, A method for manufacturing an embedded formwork, characterized in that in the upper layer laminate formation process, the nozzle is moved so as to follow a trajectory parallel to the trajectory of the nozzle when forming the lower layer laminate, at a position laterally spaced apart in a plan view.

6. a step of forming a lower layer band-shaped body by discharging a hydraulic composition from a nozzle from the lower layer laminate and the upper layer laminate; and forming an upper layer belt by discharging a hydraulic composition from a nozzle onto the lower layer belt, 6. The method for manufacturing an embedded formwork according to claim 5, wherein a trajectory of the nozzle when forming the lower layer band and a trajectory of the nozzle when forming the upper layer band are made to coincide in a plan view.

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