Form for forming foundation

Abstract

To provide a form for forming a foundation, which can bear lateral pressure during concrete placement and which can prevent positional deviation of a circular form.SOLUTION: A form for forming a foundation comprises a circular form 10 that is formed of a plate surface of a curved thin plate material 11, and a plurality of form installation members 20 that are mounted on the circular form 10 so as to install the circular form 10 on an installation surface. Each of the plurality of form installation members 20 is thicker than the plate material 11. The plurality of form installation members 20 have a form-side fixing part 21 that is fixed to the circular form 10, and an installation surface-side fixing part 22 that is fixed to the installation surface 140. The form-side fixing part 21 and the installation surface-side fixing part 22 extend in an approximately vertical direction. A part between the form-side fixing part 21 and the circular form 10 and a part between the installation surface-side fixing part 22 and the installation surface 140 are fixed by different means.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a formwork for foundation formation.

Background Art

[0002] Generally, when constructing a foundation concrete, a flat formwork is built and the concrete is placed therein for construction. At that time, the formwork is reinforced with a reinforcing material so as not to be deformed (bulge out) by the lateral pressure of the concrete. Therefore, there has been a problem that it takes a lot of labor and time for construction.

[0003] Therefore, as in Patent Document 1, there is known a method of forming a circular formwork by bending a strip-shaped plate material into a circular shape, placing concrete in the formwork, and constructing a foundation concrete. In this method, by using a circular formwork, the concrete lateral pressure can be converted into the circumferential tensile force of the circular formwork, so that while the formwork is composed of a thin plate material, the advantage that special reinforcement for the formwork is not required can be obtained.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, when pouring (placing) the concrete, the circular formwork may be displaced or deformed.

[0006] The present disclosure has been made in view of such problems, and an object thereof is to provide a formwork for foundation formation that can withstand the lateral pressure during concrete placement and prevent displacement of the circular formwork.

Means for Solving the Problems

[0007] To solve the above problems, the present invention proposes the following means. One aspect of the present disclosure provides a formwork for foundation formation, comprising a circular formwork formed on the plate surface of a thin plate material to be curved, and a plurality of formwork installation members attached to the circular formwork for installing the circular formwork on an installation surface. The thickness of each of the plurality of formwork installation members is greater than the thickness of the plate material. The plurality of formwork installation members include a formwork-side fixing portion fixed to the circular formwork and an installation-surface-side fixing portion fixed to the installation surface. The formwork-side fixing portion and the installation-surface-side fixing portion extend in a direction substantially perpendicular to each other. The formwork-side fixing portion is fixed to the circular formwork by a means different from that between the installation-surface-side fixing portion and the installation surface.

Advantages of the Invention

[0008] The present disclosure can provide a formwork for foundation formation that can withstand the lateral pressure during concrete placement and prevent the displacement of the circular formwork.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0010] Hereinafter, an embodiment of the formwork 1 for foundation formation according to the present disclosure will be described with reference to the drawings. Fig. 1 shows a perspective view of the formwork 1 for foundation formation in the present embodiment.

[0011] The formwork 1 for foundation formation is the formwork 1 for foundation formation used for forming foundation concrete. As shown in FIG. 1, reinforcing bars 110 and anchor bolts 120 are arranged inside the formwork 1 for foundation formation. Note that upper-end bars (not shown) may be provided above the reinforcing bars 110.

[0012] In the present embodiment, four anchor bolts 120 are provided symmetrically about the central axis O1 of the circular formwork 10. The arrangement and number of the anchor bolts 120 are not particularly limited.

[0013] The arrangement and configuration of the reinforcing bars 110 are not particularly limited. The arrangement and configuration of the reinforcing bars 110 can be appropriately set according to, for example, the size of the foundation concrete.

[0014] FIG. 2 shows the formwork 1 for foundation formation installed on the installation surface 140. As shown in FIG. 2, the circular formwork 10 is installed on the installation surface 140 of the excavation part 130 of the ground G1. The circular formwork 10 is fixed by the formwork installation member 20. A discarded concrete layer may be formed on the installation surface 140. By placing the concrete C into the formwork 1 for foundation formation installed in this way, the foundation concrete is constructed.

[0015] FIG. 3 shows the formwork 1 for foundation formation in a plan view. As shown in FIG. 3, the formwork 1 for foundation formation has a circular formwork 10 and a formwork installation member 20.

[0016] The circular formwork 10 is configured by bending the plate material 11 and connecting it at the connection part 12. The connection part 12 is provided at both ends of the plate material 11. Specifically, the connection parts 12 of the plate materials 11 are overlapped with each other and fixed by the fixing parts 13 (bolts in this embodiment), thereby forming the circular formwork 10. The connection method (fixing part 13) of the plate materials 11 is not limited to bolts. For example, the connection parts 12 of the plate materials 11 to be connected may be overlapped with each other and fixed by welding (e.g., spot welding, etc.). In this embodiment, five fixing parts 13 are provided per one connection part 12 (see FIG. 1, etc.). The number of fixing parts 13 per one connection part 12 is not limited.

[0017] In this embodiment, three plate materials 11 are connected. The number of plate materials 11 is not limited to three, and may be one, two, or four or more.

[0018] The plate material 11 is strip-shaped. The length in the longitudinal direction of the plate material 11 is the length in the circumferential direction of the circular formwork 10. Hereinafter, the length in the longitudinal direction of the plate material 11 is regarded as the length in the circumferential direction. In this embodiment, only one of the plurality of plate materials 11 has a different circumferential length, and the circumferential lengths of the other plate materials 11 are the same. Specifically, the circular formwork 10 in this embodiment is composed of plate materials 11 with two types of circumferential lengths, and there are two plate materials 11a (with a long circumferential length) and one plate material 11b (with a short circumferential length). However, the combination of the number of plate materials 11a and plate materials 11b is not limited to this.

[0019] The combination of the circumferential lengths of the plate materials 11 used for the circular formwork 10 is not limited to the above. The circumferential lengths of all the plate materials 11 used for the circular formwork 10 may be the same, or all may be different. For example, a plurality of types of plate materials 11 with different circumferential lengths are prepared in advance, and by changing the number and types of the plate materials 11 to be combined, a circular formwork 10 suitable for the size of the foundation concrete to be constructed may be formed.

[0020] The plate material 11 in this embodiment is a steel plate. The material of the plate material 11 is not limited to a steel plate.

[0021] FIG. 4 shows a view of FIG. 3 as seen in the direction of arrow A. The length in the short side direction of the plate material 11 (the height of the circular formwork 10) is not limited. The thickness T2 of the plate material 11 only needs to be thinner than the thickness T1 of the formwork installation member 20, and the specific thickness is not limited (see FIG. 5).

[0022] The formwork installation member 20 is used for fixing the circular formwork 10. As shown in FIG. 3, it is preferable that the installation surface side fixing portion 22 of the formwork installation member 20 described later extends in the radius r direction of the circle formed by the circular formwork 10 in a plan view. In the present embodiment, the circular formwork 10 is fixed by four formwork installation members 20 arranged at equal intervals. The number of formwork installation members 20 used for fixing the circular formwork 10 is not limited to four, and may be one, two, three, or five or more. When the number of formwork installation members 20 used for fixing the circular formwork 10 is plural, it is preferable that the formwork installation members 20 are arranged at intervals from each other in the circumferential direction. At this time, the formwork installation members 20 may be arranged at unequal intervals or at equal intervals.

[0023] FIG. 5 shows an enlarged view of the formwork installation member 20 connected to the circular formwork 10 and the installation surface 140. As shown in FIG. 5, the formwork installation member 20 in the present embodiment is an L-shaped metal fitting. Note that the shape and material of the formwork installation member 20 are not limited. When connecting the formwork installation member 20 to the circular formwork 10 and the installation surface 140, the side in contact with the circular formwork 10 is the formwork side fixing portion 21, and the side in contact with the installation surface 140 is the installation surface side fixing portion 22. Note that the formwork side fixing portion 21 and the installation surface side fixing portion 22 extend in a substantially perpendicular direction. Here, the substantially perpendicular means not only when the angle α between the formwork side fixing portion 21 and the installation surface side fixing portion 22 in the side view of the formwork installation member 20 is 90 degrees, but also, for example, the angle α may differ by 10 degrees from 90 degrees, or the angle α may be 80 degrees or more and 100 degrees or less. The ratio of the length L1 in the extending direction of the formwork side fixing portion 21 to the length L2 in the extending direction of the installation surface side fixing portion 22 may be in the range of 1:1.5 to 1:2.0. The length L1 may be shorter than the length L2, and 1.5 ≤ (L2 / L1) ≤ 2.0 may also be acceptable. In this embodiment, the formwork-side fixing portion 21 is integrally attached to the outside of the circular formwork 10, and the installation-surface-side fixing portion 22 extends outward from the circular formwork 10. Note that the formwork-side fixing portion 21 may be integrally attached to the inside of the circular formwork 10, and the installation-surface-side fixing portion 22 may extend inward from the circular formwork 10. Here, being integrally attached means that the circular formwork 10 and the formwork-side fixing portion 21 are in surface contact and fixed.

[0024] In this embodiment, the installation-surface-side fixing portion 22 is fixed to the installation surface 140 at two locations, and the formwork-side fixing portion 21 is fixed to the circular formwork 10 at one location. The installation-surface-side fixing portion 22 may be fixed to the installation portion at one location, or may be fixed at a plurality of locations. The formwork-side fixing portion 21 may be fixed to the circular formwork 10 at one location, or may be fixed at a plurality of locations.

[0025] For example, the installation-surface-side fixing portion 22 may be fixed to the installation surface 140 at one location, and the formwork-side fixing portion 21 may be fixed to the circular formwork 10 at two or more locations. The installation-surface-side fixing portion 22 may be fixed to the installation surface 140 at one location, and the formwork-side fixing portion 21 may be fixed to the circular formwork 10 at one location. The installation-surface-side fixing portion 22 may be fixed to the installation surface 140 at two or more locations, and the formwork-side fixing portion 21 may be fixed to the circular formwork 10 at two or more locations.

[0026] The fixing method of the formwork installation member 20 is not limited. In this embodiment, the installation-surface-side fixing portion 22 is fixed to the installation surface 140 with nails (concrete nails), and the formwork-side fixing portion 21 is fixed to the circular formwork 10 with bolts. The formwork-side fixing portion 21 may be fixed to the circular formwork 10 by spot welding. When using nails or bolts for fixing, the number of nails or bolts used can be the same as the number of fixing locations. When using spot welding for fixing, the number of spot welds can be the same as the number of fixing locations.

[0027] The width of the formwork installation member 20 is not limited. The thickness T1 of the formwork installation member 20 only needs to be thicker than the thickness T2 of the plate material 11, and the specific thickness is not limited. The thickness T1 of the formwork installation member 20 is preferably, for example, the thickness for making the circular formwork 10 stand independently. The thickness T1 of the formwork installation member 20 is preferably, for example, the thickness for stabilizing the shape of the circular formwork 10. When there are a plurality of formwork installation members 20 used for fixing the circular formwork 10, the thicknesses T1 of the plurality of formwork installation members 20 are preferably the same. However, the thicknesses T1 of the plurality of formwork installation members 20 may be different.

[0028] The thickness of the formwork installation member 20 is preferably 3 times or more the thickness of the plate material 11. If the thickness of the formwork installation member 20 is 3 times or more the thickness of the plate material 11, the circular formwork 10 can be made to stand independently and its shape can be stabilized. From the viewpoints of the weight and cost of the formwork installation member 20, the thickness T1 of the formwork installation member 20 is preferably a thickness of 8 times or less the thickness T2 of the plate material 11.

[0029] By placing the concrete C in the foundation formwork 1 described above, the foundation concrete is constructed. At this time, the circular formwork 10 is formed in a circular shape in plan view by receiving, from the concrete C to be placed, a uniform force around the circular formwork 10 according to the height.

[0030] As described above, the foundation formwork 1 according to the present embodiment includes a circular formwork 10 formed on the plate surface of a thin plate material 11 that is curved, and a plurality of formwork installation members 20 attached to the circular formwork 10 for installing the circular formwork 10 on the installation surface 140. The thickness T1 of each of the plurality of formwork installation members 20 is thicker than the thickness T2 of the plate material 11. By using such a formwork installation member 20, the circular formwork 10 made of the thin plate material 11 can be made to stand independently, withstand the lateral pressure during the placement of the concrete C, and prevent the displacement of the circular formwork 10.

[0031] Also, the thicknesses T1 of the plurality of formwork installation members 20 may be the same. If the thickness T1 of the plurality of formwork installation members 20 is the same, when the concrete C is placed inside the formwork 1 for foundation formation, the lateral pressure of the concrete C can be evenly distributed. Therefore, it can withstand the lateral pressure during the placement of the concrete C and prevent the displacement of the circular formwork 10.

[0032] Further, the circular formwork 10 may be formed in a circular shape in plan view by receiving an equal force around the circular formwork 10 according to the height from the concrete C to be placed. Thereby, even if the plate material 11 constituting the circular formwork 10 is thin, the circular formwork 10 can maintain a perfect circular shape by receiving an equal force around the circular formwork 10. Therefore, it can withstand the lateral pressure during the placement of the concrete C and prevent the displacement of the circular formwork 10.

[0033] The plurality of formwork installation members 20 include a formwork-side fixing portion 21 fixed to the circular formwork 10 and a mounting surface-side fixing portion 22 fixed to the mounting surface 140, and the formwork-side fixing portion 21 and the mounting surface-side fixing portion 22 may extend in a direction substantially perpendicular to each other. Thereby, the plate material 11 of the circular formwork 10 can be installed substantially perpendicular to the mounting surface 140. Therefore, the lateral pressure during the placement of the concrete C can be evenly distributed to the plate material 11, and it can withstand the lateral pressure during the placement of the concrete C and prevent the displacement of the circular formwork 10.

[0034] Further, the formwork-side fixing portion 21 may be attached to the outside of the circular formwork 10. Further, the mounting surface-side fixing portion 22 may extend outward from the circular formwork 10. This is preferable because the formwork installation member 20 does not interfere with the foundation concrete when the concrete C is placed.

[0035] Further, the mounting surface-side fixing portion 22 may extend in the radial direction r of the circle formed by the circular formwork 10 in plan view. When placing concrete C in the circular formwork 10, lateral pressure is applied in the direction from the central axis O1 towards the side surface. Therefore, by installing the mounting surface side fixing portion 22 to extend in the radial direction r of the circle formed by the circular formwork 10 in plan view, it is possible to withstand the lateral pressure during the placement of concrete C and prevent the displacement of the circular formwork 10.

[0036] The mounting surface side fixing portion 22 may be fixed to the mounting surface 140 at two or more locations, and the formwork side fixing portion 21 may be fixed to the circular formwork 10 at one location. As a result, since the mounting surface side fixing portion 22 is fixed at two or more points, it is possible to prevent lateral displacement when a load is applied to the mounting surface side fixing portion 22. Therefore, it is possible to withstand the lateral pressure during the placement of concrete C and prevent the displacement of the circular formwork 10.

[0037] The mounting surface side fixing portion 22 may be fixed to the mounting surface 140 at one or more locations, and the formwork side fixing portion 21 may be fixed to the circular formwork 10 at two locations. As a result, since the formwork side fixing portion 21 is fixed at two or more points, it is possible to prevent lateral displacement when a load is applied to the formwork side fixing portion 21. Therefore, it is possible to withstand the lateral pressure during the placement of concrete C and prevent the displacement of the circular formwork 10.

[0038] The mounting surface side fixing portion 22 may be fixed to the mounting surface 140 at one location, and the formwork side fixing portion 21 may be fixed to the circular formwork 10 at one location. As a result, the cost can be reduced, the work of fixing the mounting surface side fixing portion 22 can be simplified, and the construction can be facilitated.

[0039] The mounting surface side fixing portion 22 may be fixed to the mounting surface 140 at two or more locations, and the formwork side fixing portion 21 may be fixed to the circular formwork 10 at two or more locations. As a result, since both the installation surface side fixing portion 22 and the formwork side fixing portion 21 are fixed at two or more points, the circular formwork 10 can be firmly fixed. Therefore, it can withstand the lateral pressure during the placement of the concrete C and can more reliably prevent the displacement of the circular formwork 10.

[0040] The circular formwork 10 is formed of a plurality of plate materials 11, and the plurality of plate materials 11 may include those having different circumferential lengths of the circular formwork 10. Thereby, by combining the plate materials 11 having different circumferential lengths, circular formworks 10 with various circumferential lengths can be formed. Therefore, it is not necessary to create the plate materials 11 according to the size of the foundation concrete to be constructed, the cost can be reduced, and the formwork 1 for foundation formation that is easy to construct can be obtained. Here, when the plurality of plate materials 11 include those having different circumferential lengths of the circular formwork 10, the plurality of plate materials 11 are composed of a first plate material 11 having a first length in the circumferential direction of the circular formwork 10 and a second plate material 11 having a second length in the circumferential direction of the circular formwork 10, and the first plate material 11 and the second plate material 11 may each be composed of the same number (one or more).

[0041] Only one of the plurality of plate materials 11 may have a different circumferential length, and the lengths of the other plate materials 11 in the circumferential direction may be the same. Thereby, by combining the plate materials 11 having different circumferential lengths, circular formworks 10 with various circumferential lengths can be formed, and the types of plate materials 11 to be used can be limited to two. Therefore, the cost can be reduced, and the formwork 1 for foundation formation that is easy to construct can be obtained.

[0042] All of the plurality of plate materials 11 may have different circumferential lengths of the circular formwork 10. Thereby, by combining the plate materials 11 having different circumferential lengths, circular formworks 10 with various circumferential lengths can be formed.

[0043] The circular formwork 10 is formed of a plurality of plate materials 11, and all of the plurality of plate materials 11 may have the same circumferential length of the circular formwork 10. As a result, the type of the plate material 11 to be used can be limited to one type. Therefore, the cost can be reduced, and the formwork 1 for foundation formation that is easy to construct can be obtained.

[0044] The plurality of formwork installation members 20 may be arranged at intervals in the circumferential direction. Thereby, in order to disperse the lateral pressure received from the concrete C to the plurality of formwork installation members 20, the formwork installation members 20 can be arranged at appropriate positions. Therefore, it is possible to withstand the lateral pressure during the placement of the concrete C and prevent the formwork 1 for foundation formation from being displaced.

[0045] The plurality of formwork installation members 20 may be arranged at unequal intervals. Thereby, even if the circumferential lengths of the plurality of plate materials 11 are different, the formwork installation members 20 can be arranged at appropriate positions according to the circumferential lengths of the plate materials 11.

[0046] The plurality of formwork installation members 20 may be arranged at equal intervals. Thereby, the lateral pressure received from the concrete C can be evenly dispersed to the plurality of formwork installation members 20. Therefore, it is possible to withstand the lateral pressure during the placement of the concrete C and prevent the formwork 1 for foundation formation from being displaced.

[0047] The thickness T1 of the formwork installation member 20 is a thickness that is 8 times or less the thickness T2 of the plate material 11. Thereby, it is possible to withstand the lateral pressure during the placement of the concrete C and prevent the formwork 1 for foundation formation from being displaced, and the cost and weight of the formwork installation member 20 can be reduced.

[0048] The ratio of the length L1 in the extending direction of the formwork side fixing portion 21 to the length L2 in the extending direction of the installation surface side fixing portion 22 may be in the range of 1:1.5 to 1:2.0. The length L2 of the installation surface side fixing portion 22 in the extending direction is longer than the length L1 of the formwork side fixing portion 21 in the extending direction. Thereby, the side pressure received from the concrete C can be transmitted to the installation surface 140 through the installation surface side fixing portion 22 having a long length L2. Therefore, it is possible to prevent the circular formwork 10 composed of thin plate materials from falling down. Thus, it is possible to withstand the side pressure during the placement of the concrete C and prevent the displacement of the formwork for foundation formation 1. Further, by suppressing the length L2 of the installation surface side fixing portion 22 in the extending direction to a certain extent (the length L1 of the formwork side fixing portion: the length L2 of the installation surface side fixing portion = 1:1.5 to 1:2.0), it is possible to prevent the formwork installation member 20 from becoming large-sized.

[0049] As described above, although one embodiment of the present disclosure has been described in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and modifications, combinations, deletions, etc. of the configuration within the scope not departing from the gist of the present disclosure are also included.

Explanation of Reference Numerals

[0050] 1 Formwork for foundation formation 10 Circular formwork 11, 11a, 11b Plate materials 12 Connection portion 13 Fixing portion 20 Formwork installation member 21 Formwork side fixing portion 22 Installation surface side fixing portion 140 Installation surface G1 Ground surface O1 Central axis C Concrete L1 Length of the formwork side fixing portion in the extending direction L2 Length of the installation surface side fixing portion in the extending direction T1 Thickness of the formwork installation member T2 Thickness of the plate material

Claims

1. A circular formwork formed of a thin plate surface to be curved; A plurality of formwork mounting members are attached to the circular formwork to mount the circular formwork to a mounting surface; The thickness of each of the plurality of formwork mounting members is greater than the thickness of the plate material, The plurality of formwork mounting members each include a formwork-side fixing portion that is fixed to the circular formwork and an installation surface-side fixing portion that is fixed to the installation surface, The formwork side fixing portion and the installation surface side fixing portion extend in a direction substantially perpendicular to each other, The formwork side fixing portion and the circular formwork are fixed by a means different from that between the installation surface side fixing portion and the installation surface. Formwork for foundation formation.

2. A circular formwork formed of a thin plate surface to be curved; A plurality of formwork mounting members are attached to the circular formwork to mount the circular formwork to a mounting surface; The thickness of each of the plurality of formwork mounting members is greater than the thickness of the plate material, The plurality of formwork mounting members each include a formwork-side fixing portion that is fixed to the circular formwork and an installation surface-side fixing portion that is fixed to the installation surface, The formwork side fixing portion and the installation surface side fixing portion extend in a direction substantially perpendicular to each other, The formwork side fixing part is fixed to the circular formwork by a bolt inserted into the formwork side fixing part from the outside of the circular formwork. Formwork for foundation formation.

3. 3. The formwork for forming a foundation according to claim 1 or 2, wherein the thickness of the formwork mounting member is large enough to allow the circular formwork to stand on its own.

4. The formwork for forming a foundation according to claim 1 or 2, wherein the thickness of the formwork mounting member is large enough to stabilize the shape of the circular formwork.

5. The formwork for forming a foundation according to claim 1 or 2, wherein the thicknesses of the plurality of formwork mounting members are the same.

6. The formwork for foundation formation according to claim 1 or 2, wherein the circular formwork is formed into a circular shape when viewed in a plane by receiving equal force from the concrete being poured around the circular formwork depending on its height.

7. The formwork for foundation formation according to claim 1 or 2, wherein the formwork side fixing portion is attached to the outside of the circular formwork.

8. The formwork for foundation formation according to claim 1 or 2, wherein the installation surface side fixing portion extends outward from the circular formwork.

9. The formwork for foundation formation according to claim 1 or 2, wherein the installation surface side fixing portion extends in a radial direction of a circle formed by the circular formwork in a plan view.

10. The mounting surface side fixing portion is fixed to the mounting surface at two or more points, The formwork for forming a foundation according to claim 1 or 2, wherein the formwork side fixing portion is fixed to the circular formwork at one location.

11. The mounting surface side fixing portion is fixed to the mounting surface at one point, The formwork for foundation formation according to claim 1 or 2, wherein the formwork side fixing portion is fixed to the circular formwork at two or more points.

12. The mounting surface side fixing portion is fixed to the mounting surface at one point, The formwork for forming a foundation according to claim 1 or 2, wherein the formwork side fixing portion is fixed to the circular formwork at one location.

13. The mounting surface side fixing portion is fixed to the mounting surface at two or more points, The formwork for forming a foundation according to claim 1 or 2, wherein the formwork side fixing portion is fixed to the circular formwork at two or more points.

14. The circular formwork is formed of a plurality of plate materials, The formwork for forming a foundation according to claim 1 or 2, wherein the plurality of plate materials include plate materials having different lengths in the circumferential direction of the circular formwork.

15. The formwork for forming a foundation according to claim 14, wherein the circumferential length of only one of the plurality of plate members is different, and the circumferential lengths of the other plate members are uniform.

16. The formwork for forming a foundation according to claim 14, wherein all of the plurality of plate materials have different lengths in the circumferential direction of the circular formwork.

17. The circular formwork is formed of a plurality of plate materials, The formwork for forming a foundation according to claim 1 or 2, wherein all of the plurality of plate materials have the same length in the circumferential direction of the circular formwork.

18. The formwork for forming a foundation according to claim 1 or 2, wherein the plurality of formwork mounting members are arranged spaced apart from each other in the circumferential direction.

19. The formwork for forming a foundation according to claim 18, wherein the formwork mounting members are arranged at uneven intervals.

20. The formwork for forming a foundation according to claim 18, wherein the plurality of formwork mounting members are arranged at equal intervals.

21. 3. A formwork for forming a foundation according to claim 1 or 2, wherein the thickness of said formwork mounting member is 8 times or less the thickness of said plate material.

22. A formwork for foundation formation as described in claim 1 or 2, wherein the ratio of the length of the formwork side fixing part in the extension direction to the length of the installation surface side fixing part in the extension direction is in the range of 1:1.5 to 1:2.0.

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