Base formwork and foundation construction method

Abstract

To provide an inexpensive base formwork used for forming a foundation and a construction method using the base formwork. [Solution] The base formwork 4 is located below each of a pair of riser formworks 2 that form the rising portion of the continuous footing 100, and has a cylindrical shape made from folded cardboard. The base formwork 4 has a first plate 40, a second plate 41, and a third plate 43. The first plate 40 extends diagonally downward from the lower end of the riser formwork 2. The second plate 41 extends in the vertical direction outside the first plate 40. The third plate 43 closes off the upper part of the space 10 defined by the first plate 40 and the second plate 41.

Description

[Technical Field]

[0001] The present invention relates to a base formwork for molding the base portion of a building foundation and a foundation construction method using the base formwork. [Background technology]

[0002] In the temporary formwork described in Patent Document 1, multiple formwork fixing brackets are placed on the surface of the temporary concrete poured on the ground. Formwork connecting members are located above the formwork fixing brackets. Stand-up formworks are located opposite each other and supported by the formwork fixing brackets. Formworks for straight sections are located on both sides below the stand-up formworks. The formworks for straight sections are made of waterproof laminated paper. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-336268 Summary of the Invention [Problem to be solved by the invention]

[0004] Fresh concrete is poured into the internal space defined by the straight section formwork. Since the straight section formwork is subjected to pressure from the inside, it is conceivable to fill the outside of the straight section formwork with soil beforehand. However, if the straight section formwork is subjected to a large load from the outside, it may bend inward. As a result, the cross-sectional area of ​​the foundation formed by the straight section formwork may be smaller than designed. On the other hand, increasing the thickness of the straight section formwork to increase its strength increases the cost required for the straight section formwork.

[0005] The present invention has been made in view of the above problems, and has as its object to provide an inexpensive base formwork for use in forming foundations and a construction method using the base formwork. [Means for solving the problem]

[0006] (1) The base formwork according to the present invention is located below a pair of riser formworks that form the rising portions of a foundation, and is a cylindrical member formed by bending a plate-like member. The base formwork has a first plate, a second plate, and a third plate. The first plate extends diagonally downward from the riser formwork. The second plate extends in the vertical direction outside the first plate. The third plate closes off the upper side of the space partitioned by the first and second plates.

[0007] When the molding material is poured, the first and second plates bend under the load of the molding material and soil. However, because the first and second plates are separated by a space, they do not come into contact, and the cross-sectional structure of the foundation is not affected. In addition, the space allows the allowable range of bending of the first and second plates to be estimated more generously. This allows the use of relatively low-strength, inexpensive materials for the base formwork.

[0008] (2) The base formwork according to (1) above may further include a fourth plate. The fourth folded portion is continuous with the second plate and overlaps with the third plate.

[0009] When the first plate is subjected to a load, the fourth plate abuts against the first plate, thereby suppressing deformation of the first plate.

[0010] (3) The base formwork according to (1) or (2) may further include a first folding portion and a second folding portion. The first folding portion protrudes outward between the first and second boards. The second folding portion protrudes outward between the first and third boards.

[0011] When installing the base formwork, it can be fixed at the first and second folds.

[0012] (4) The base formwork according to any one of (1) to (3) above may further include a fifth plate that is continuous with the third plate and overlaps the second plate.

[0013] When the first plate receives load from the molding material, the fifth plate overlaps with the second plate, providing strong support against loads from the surrounding soil.

[0014] (5) The base formwork according to any one of (1) to (4) above may further include a storage member. The storage member has a cylindrical shape and is stored in a space defined by the first plate, the second plate, and the third plate. The storage member abuts against at least the first plate and the second plate.

[0015] Because the storage member is located within the space of the base formwork, deformation of the first plate relative to the second plate can be suppressed. Also, by opening the top of the base formwork and removing the storage member, space can be easily secured within the base formwork.

[0016] (6) In the base formwork described in any one of (1) to (5) above, one end of the second plate may protrude in the extension direction of the foundation beyond one end of the first plate. The other end of the second plate may be recessed in the extension direction beyond the other end of the first plate.

[0017] When connecting multiple base forms in the extension direction, the protruding portion of the second plate of another base form to be connected can be inserted into the recessed position of the second plate. In this case, it is easy to line up the multiple base forms in the extension direction so that the second plate on the connecting side is aligned with the fifth plate of the base form to be connected.

[0018] (7) In the base formwork described in any one of (1) to (6) above, the first plate may have an insertion piece extending in the extension direction.

[0019] When connecting multiple base formworks in the extension direction, insert pieces can be inserted into the spaces defined by the first, second, and third boards. At this time, the insert pieces, along with the protruding portion of the second board on the connecting side, are supported by the base formwork on the connected side. This allows multiple base formworks to be positioned along the extension direction.

[0020] (8) The protruding corner member according to the present invention may be a protruding corner member continuous with the two base formworks described in any one of (1) to (7) above. The protruding corner member is a plate-shaped member that is bent and placed at a protruding corner of the foundation. The protruding corner member has a sixth plate, a seventh plate, an eighth plate, and a ninth plate. The sixth plate is mountain-folded and connected to the first plate. The seventh plate extends in the vertical direction from the sixth plate on one side of the protruding corner. The eighth plate extends in the vertical direction from the sixth plate on the other side of the protruding corner. The ninth plate closes off the upper part of the space partitioned by the sixth plate, the seventh plate, and the eighth plate.

[0021] The corner member can be connected to two base formworks arranged perpendicular to each other to form a corner of the foundation.

[0022] (9) The external corner member according to (8) may further include a tenth plate and an eleventh plate. The tenth plate is continuous with the eighth plate and overlaps with the seventh plate. The eleventh plate is continuous with the ninth plate and overlaps with the eighth plate. The ninth plate is continuous with the seventh plate.

[0023] The 10th plate overlaps with the 7th plate, and the 11th plate overlaps with the 9th plate. This allows the structure to firmly support the load from the surrounding soil.

[0024] (10) The inside corner member according to the present invention may be an inside corner member continuous with the two base formworks described in any one of (1) to (7) above. The inside corner member is a plate-shaped member that is bent and placed at an inside corner of the foundation. The inside corner member has a 30th plate, a 31st plate, and a 32nd plate. The 30th plate is connected to the first plate by a valley fold. The 31st plate extends above the 30th plate from one side of the inside corner. The 32nd plate extends from the 30th plate from the other side of the inside corner and overlaps the 31st plate.

[0025] The inside corner member can be connected to two base formworks arranged perpendicular to each other to form an inside corner of the foundation.

[0026] (11) In the base formwork described in (1) above, the first plate may have two sub-first plates. The base formwork further has a twelfth plate and a thirteenth plate. The twelfth plate is continuous with a lower end of one of the sub-first plates and extends toward the second plate in the space. The thirteenth plate is continuous with an upper end of the other of the sub-first plates and extends toward the second plate in the space.

[0027] The twelfth and thirteenth plates support the pressure from the molding material, so the load from the molding material can be supported even more firmly.

[0028] (12) The base formwork described in (11) above may further include a fourteenth plate and a fifteenth plate. The fourteenth plate is continuous with the extending end of the twelfth plate and overlaps with the third plate. The fifteenth plate is continuous with the extending end of the thirteenth plate and overlaps with the second plate.

[0029] The pressure exerted by the molding material on the first plate is firmly supported by the overlapping twelfth and thirteenth plates.

[0030] (13) The base formwork described in (12) above may further include a 16th plate and a 17th plate. The 16th plate is continuous with the extending end of the 14th plate and extends toward the 12th plate. The 17th plate is continuous with the extending end of the 15th plate and extends toward the 13th plate.

[0031] Plate 12, which supports one of the first sub-plates, is further supported by plate 16, which is continuous with plate 14. Plate 13, which supports the other of the first sub-plates, is further supported by plate 17, which is continuous with plate 15. This allows the pressure from the molding material to be more firmly supported by plates 12 and 13.

[0032] (14) A foundation construction method according to the present invention includes a molding step, a formwork installation step, a soil filling step, and a pouring step. The molding step involves bending a plate-like member to form a polygonal cylindrical base formwork. The formwork installation step involves installing the base formwork on a rising formwork. The soil filling step involves piling soil around the base formwork installed on the rising formwork. The pouring step involves pouring molding material into the rising formwork and the base formwork.

[0033] The base form is a polygonal cylindrical shape formed by bending a plate-like member. It is possible to construct the foundation using inexpensive materials with relatively low strength for the base form.

[0034] (15) The foundation construction method described in (14) above may further include an opening step and a piping installation step. The opening step opens up the space in the base formwork located outside the foundation after the pouring step. The piping installation step installs piping in the space in the opened base formwork.

[0035] Workers can open up the upper part of the space and pile up soil inside it to install the piping, which eliminates the need to dig trenches outside the base formwork and significantly reduces the burden on workers. [Effects of the Invention]

[0036] According to the present invention, an inexpensive base formwork for use in forming a foundation and a construction method using the base formwork can be realized. [Brief explanation of the drawings]

[0037] [Figure 1] FIG. 1 is a perspective view showing a base formwork 4 according to a first embodiment of the present invention installed together with a rising formwork 2. As shown in FIG. [Figure 2] FIG. 2 is an exploded perspective view showing the rising formwork 2 and the base formwork 4 of the formwork 1 for a continuous footing. [Figure 3] FIG. 3 is a view of the base formwork 4 and the rising formwork 2 connected in the front-rear direction as viewed from the right. [Figure 4] FIG. 4 is a view of the base formwork 4 in a folded state as seen from the front. [Figure 5] FIG. 5 is a development view of the surface of the base formwork 4. As shown in FIG. [Figure 6] Fig. 6(a) is an enlarged cross-sectional view of the first cut-and-raised portion 56 engaged in the through-hole 58. Fig. 6(b) is an enlarged cross-sectional view of the second cut-and-raised portion 59 engaged in the through-hole 55. [Figure 7] FIG. 7 is a plan view showing the state in which the base formwork 4, the outside corner members 6, and the inside corner members 8 have been installed. [Figure 8] FIG. 8 is a development view of the corner member 6. As shown in FIG. [Figure 9] Fig. 9(a) is a view of the project corner member 6 in a folded state as seen from the left, Fig. 9(b) is a view of the project corner member 6 in a folded state as seen from the front, and Fig. 9(c) is a view of the project corner member 6 in a folded state as seen from the rear. [Figure 10] FIG. 10 is a development view of the inside corner member 8. [Figure 11] 11(a) is a view of the inside corner member 8 in a folded state as seen from the left, and FIG. 11(b) is a view of the inside corner member 8 in a folded state as seen from the front. [Figure 12] FIG. 12 is a diagram showing the state in which earth has been piled up on the installed base formwork 4, outside corner member 6, and inside corner member 8. [Figure 13] FIG. 13 is a diagram showing the state after ready-mixed concrete 103 has been poured, together with base formwork 4, external corner member 6, and internal corner member 8. [Figure 14] FIG. 14 is a cross-sectional view showing a state in which the base formwork 4 is subjected to pressure from the ready-mixed concrete 103 and the soil 106. [Figure 15] FIG. 15 is a diagram showing the base formwork 4 and the external corner member 6 with holes drilled therein. [Figure 16] FIG. 16 is a diagram showing the base formwork 4 and the external corner member 6 in a state in which the piping 95 has been installed. [Figure 17] FIG. 17 is a cross-sectional view showing a pipe 95 installed in the space 10 of the base formwork 4. As shown in FIG. [Figure 18] FIG. 18 is a view of the base formwork 4A in a folded state according to the first modification of the first embodiment, as viewed from the front. [Figure 19] FIG. 19 is a front view of a base formwork 4B in a folded state according to the second modification of the first embodiment. [Figure 20] FIG. 20 is a front view of a base formwork 4C in a folded state according to the third modification of the first embodiment. [Figure 21] FIG. 21 is a front view of a base formwork 4D according to the second embodiment in a folded state. [Figure 22] FIG. 22 is a front view of a base formwork 4E in a folded state according to the first modification of the second embodiment. [Figure 23] FIG. 23 is a front view of a base formwork 4F in a folded state according to the second modification of the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0038] Hereinafter, an embodiment of the present invention will be described. It should be noted that the embodiment described below is merely an example of the present invention, and it goes without saying that it can be appropriately modified within the scope of the present invention.

[0039] In the following, the vertical direction is defined as the direction perpendicular to the surface on which the base formwork 4 is installed. When the installed base formwork 4 is viewed from above and below, the direction in which one of a pair of base formworks 4 is lined up is defined as the left-right direction, and the direction in which multiple base formworks 4 are connected is defined as the front-rear direction.

[0040] [Overall configuration] In the first embodiment, the base formwork 4, the external corner members 6, and the internal corner members 8 that form the base portion 101 of a continuous footing 100 that supports the skeleton of a building such as a house will be described below. The continuous footing 100 is an example of a foundation. The continuous footing 100 is formed using a continuous footing formwork 1.

[0041] As shown in Figure 1, the formwork 1 for a continuous footing includes a support member 20, a rising formwork 2, a fixing device 3, a base formwork 4, fixing nails 5, an external corner member 6, and an internal corner member 8. The support member 20 is positioned on a spread mortar 12. The spread mortar 12 is laid on the ground after root excavation. The support member 20 is placed on the spread mortar 12 and extends upward in an inverted U-shape. Although not shown in the figure, multiple support members 20 are positioned at predetermined intervals in the direction in which the continuous footing 100 extends.

[0042] As shown in Fig. 1, a rising formwork 2 is supported on a support material 20. A pair of the rising formworks 2 are positioned opposite each other in the left-right direction. The rising formworks 2 form a rising portion 102 of a continuous footing 100.

[0043] As shown in Figures 1 and 2, the rising formwork 2 has wall panels 26, upper crosspieces 27, vertical crosspieces 28, and lower crosspieces 29. The lower crosspieces 29 are an example of the lower end of the rising formwork. The wall panels 26 form the outer surfaces in the left-right direction of the rising portion 102 of the continuous footing 100. The wall panels 26 are rectangular flat plates with flat opposing surfaces.

[0044] The upper crosspiece 27 protrudes outward from the upper end of the wall panel 26. The upper crosspiece 27 is a long, narrow flat plate. The lower crosspiece 29 protrudes outward from the lower end of the wall panel 26. The lower crosspiece 29 is a long, narrow flat plate in the front-to-rear direction.

[0045] The vertical beams 28 extend in the up-down direction on the outer side of the wall panel 26. The vertical beams 28 connect the upper beams 27 and the lower beams 29. A plurality of the vertical beams 28 are positioned at intervals in the front-rear direction.

[0046] As shown in Figure 3, locking members 18 that connect adjacent vertical bars 28 are arranged at connection positions in the front-to-rear direction of the rising formwork 2. The locking members 18 have shafts that are inserted into through holes in the vertical bars 28, and U-shaped arms that clamp the adjacent vertical bars 28.

[0047] Reinforcing bars 14 are placed in the space between the pair of rising formworks 2 and in the space below the rising formworks 2. The reinforcing bars 14 are placed appropriately based on the strength required of the continuous footing 100. The reinforcing bars 14 are supported by, for example, supports 20 or supports (not shown) that straddle the pair of rising formworks 2.

[0048] Below the pair of rising formworks 2, a base formwork 4, an outside corner member 6, and an inside corner member 8 are positioned. The base formwork 4, the outside corner member 6, and the inside corner member 8 are fixed to the spread mortar 12 with fixing nails 5 (see Figure 7). Below, the base formwork 4, the outside corner member 6, and the inside corner member 8 will each be described.

[0049] [Base formwork 4] As shown in Figure 3, the base formwork 4 extends linearly, for example, in the front-to-rear direction, below the riser formwork 2. Multiple base formworks 4 are connected in the front-to-rear direction. As shown in Figure 5, the base formwork 4 is made by folding a plate-shaped cardboard. Cardboard is an example of a plate-shaped member. Cardboard has a uniform thickness and is waterproof. Cardboard is an example of a plate-shaped member. The surface that appears in Figure 5 is the front side of the cardboard, and the surface that does not appear in Figure 5 is the back side of the cardboard. The front side of the cardboard is the surface that faces outward in the base formwork 4 in a folded state. The back side is the surface that defines a space 10 inside the base formwork 4 in a folded state. The dimension of the base formwork 4 in the front-to-rear direction is larger than that of the riser formwork 2.

[0050] 5, the base formwork 4 has a first plate 40, a second plate 41, a first folding portion 42, a third plate 43, a second folding portion 44, a fourth plate 45, and a fifth plate 46. The first plate 40, the second plate 41, the third plate 43, the fourth plate 45, and the fifth plate 46 are each a portion of a single cardboard sheet.

[0051] As shown in FIG. 5, the first plate 40 has a first piece 48 and an insertion piece 49. The first piece 48 has a rectangular shape that is long in the front-to-rear direction. The insertion piece 49 extends rearward from the rear end of the first piece 48. As the first piece 48 extends rearward, it gradually narrows in the width direction, which is the direction along the left-to-right direction. The rear is an example of an extending direction. The width dimension of the first piece 48 (the dimension in the direction perpendicular to the front-to-rear direction) is larger than the width dimension of the second plate 41, the width dimension of the third plate 43, the width dimension of the fourth plate 45, and the width dimension of the fifth plate 46.

[0052] As shown in FIG. 5, the first folding portion 42 is located between the first plate 40 and the second plate 41. The first folding portion 42 is continuous with the first plate 40. The first folding portion 42 is continuous with the second plate 41. The front end of the first folding portion 42 is at the same position in the front-to-rear direction as the front end of the first piece 48. The rear end of the first folding portion 42 is at the same position in the front-to-rear direction as the rear end of the first piece 48. The first folding portion 42 has a plurality of through holes 54 arranged in the front-to-rear direction, which penetrate in a direction perpendicular to the plane of the paper in FIG. 5. The through holes 54 are arranged in pairs in a direction perpendicular to the front-to-rear direction.

[0053] The boundary between the first piece 48 and the first folding portion 42 in the front-to-rear direction is a mountain fold line 50. In the first folding portion 42, the mountain fold line 50 extends in the front-to-rear direction between a pair of through holes 54. In this embodiment, the valley fold lines are indicated by dashed lines. The mountain fold lines are indicated by dashed lines. The valley fold line 51 and the mountain fold line 50 may be indicated by printing on the cardboard of the base formwork 4, or the cardboard may be compressed and deformed in the thickness direction or perforated to make it easier to fold. As shown in FIG. 4 , when the first folding portion 42 is folded and overlapped at the mountain fold line 50, the pair of through holes 54 overlap to form a single through hole.

[0054] As shown in FIG. 5 , the second plate 41 is located on the opposite side of the first folding portion 42 from the first plate 40. The second plate 41 has a rectangular shape that is long in the front-to-rear direction. The dimension of the second plate 41 in the front-to-rear direction is the same as that of the first piece 48. The front end of the second plate 41 is recessed rearward relative to the front end of the first piece 48. The rear end of the second plate 41 protrudes rearward relative to the rear end of the first piece 48. More specifically, the front end of the second plate 41 is located rearward relative to the front end of the first piece 48. The rear end of the second plate 41 is located rearward relative to the rear end of the first piece 48. The rear end of the second plate 41 is located at the same position in the front-to-rear direction as the rear end of the insertion piece 49. The boundary between the second plate 41 and the first folding portion 42 in the front-to-rear direction is a valley fold line 51.

[0055] As shown in FIG. 5, the second folded portion 44 is located between the first piece 48 and the third plate 43. The second folded portion 44 is continuous with the first plate 40. The second folded portion 44 is continuous with the third plate. The front end of the second folded portion 44 is at the same position in the front-to-rear direction as the front end of the first piece 48. The rear end of the second folded portion 44 is at the same position in the front-to-rear direction as the rear end of the first piece 48. The second folded portion 44 has a plurality of notches 57 that penetrate in a direction perpendicular to the plane of the paper in FIG. 5. The multiple notches 57 are lined up in the front-to-rear direction.

[0056] The boundary between the first piece 48 and the second folded portion 44 in the front-to-rear direction is a valley fold line 51. In the second folded portion 44, a mountain fold line 50 extends in the front-to-rear direction so as to pass through the center of the notch 57. As shown in FIG. 4 , when the second folded portion 44 is folded at the mountain fold line 50 and overlapped, one notch 57 is folded in half to form a notch that opens at the mountain fold line 50.

[0057] As shown in FIG. 5, the third plate 43 is located on the opposite side of the second folded portion 44 from the first plate 40. The third plate 43 has a rectangular shape that is long in the front-to-rear direction. The width dimension of the third plate 43 is greater than the width dimension of the second plate 41. The front end of the third plate 43 is at the same position in the front-to-rear direction as the front end of the first piece 48. The rear end of the third plate 43 is at the same position in the front-to-rear direction as the rear end of the first piece 48. The third plate 43 has a through hole 55 and a first cut-and-raised portion 56.

[0058] The through-hole 55 penetrates the third plate 43 in a direction perpendicular to the plane of the paper in Figure 5. The first cut-and-raised portion 56 is formed by two cuts that extend obliquely forward from the rear end of the third plate 43. The two cuts approach each other as they move forward.

[0059] As shown in FIG. 5 , the fourth plate 45 is located on the opposite side of the second plate 41 from the first folded portion 42. The fourth plate 45 has a rectangular shape that is long in the front-to-rear direction. The width of the fourth plate 45 is smaller than the width of the third plate 43. The width of the fourth plate 45 is larger than the width of the fifth plate 46. The front end of the fourth plate 45 is recessed rearward relative to the front end of the first piece 48. The rear end of the fourth plate 45 protrudes rearward relative to the rear end of the first piece 48. More specifically, the front end of the fourth plate 45 is at the same position as the front end of the second plate 41 in the front-to-rear direction. The rear end of the fourth plate 45 is at the same position as the rear end of the second plate 41 in the front-to-rear direction. The boundary between the fourth plate 45 and the second plate 41 in the front-to-rear direction is a mountain fold line 50. The fourth plate 45 has a through hole 58 and a second cut-and-raised portion 59.

[0060] The through-hole 58 penetrates the third plate 43 in a direction perpendicular to the plane of the paper in FIG. 5. The second cut-and-raised portion 59 is formed by two cuts that extend obliquely rearward from the front end of the fourth plate 45. The two cuts approach each other rearward. In the front-to-rear direction, the position of the through-hole 58 is the same as the position of the first cut-and-raised portion 56. In the front-to-rear direction, the position of the second cut-and-raised portion 59 is the same as the position of the through-hole 55.

[0061] As shown in FIG. 5 , the fifth plate 46 is located on the opposite side of the third plate 43 from the second fold portion 44. The fifth plate 46 has a rectangular shape that is long in the front-to-rear direction. The width dimension of the fifth plate 46 is greater than the width dimension of the second plate 41. The width dimension of the fifth plate 46 is smaller than the width dimension of the fourth plate 45. In the front-to-rear direction, the front end of the fifth plate 46 is at the same position as the front end of the third plate 43. In the front-to-rear direction, the rear end of the fifth plate 46 is at the same position as the rear end of the third plate 43. The boundary between the fifth plate 46 and the third plate 43 along the front-to-rear direction is a mountain fold line 50.

[0062] 4, the bent base form 4 has a cylindrical shape with a substantially triangular outer shape. The bent base form 4 is long in the front-rear direction.

[0063] 1 and 4, the second plate 41 is located outside the first plate 40 (to the right in FIG. 4). The second plate 41 faces the first plate 40. When viewed from the front-to-rear direction, the second plate 41 extends upward from the lower end of the first plate 40. The second plate 41 is parallel to the up-down direction and the front-to-rear direction.

[0064] The first plate 40 comes into direct contact with the ready-mixed concrete 103 when the ready-mixed concrete 103 is poured, and is subjected to pressure from the inside in the left-right direction. The ready-mixed concrete 103 is an example of a molding material. The first plate 40 extends diagonally downward from the upper surface of the lower rail 29, heading outward in the left-right direction.

[0065] When soil 106 is piled up around the base formwork 4, the second plate 41 receives pressure from the outside in the left-right direction.

[0066] As shown in Figure 4, the first folded portion 42 protrudes outward (to the right in Figure 4) from the first plate 40 and the second plate 41. The first folded portion 42 is folded back and overlaps. The first folded portion 42 is continuous with the lower end of the first plate 40 and the lower end of the second plate 41. The dimension of the first folded portion 42 in the left-right direction is greater than the width of the head of the fixing nail 5.

[0067] As shown in FIG. 4, the fourth plate 45 is continuous with the second plate 41. The fourth plate 45 extends inward (to the left in FIG. 4) from the upper end of the second plate 41. The fourth plate 45 faces the first plate 40. The fourth plate 45 is perpendicular to the second plate 41. The fourth plate 45 overlaps with the third plate 43. The fourth plate 45 is located below the third plate 43. An extension end 45a of the fourth plate 45 extending from the second plate 41 abuts against the first plate 40. The fourth plate 45 defines the upper part of the space 10. The fourth plate 45 supports the first plate 40 when the first plate 40 is deformed.

[0068] As shown in Figure 4, the second folded portion 44 protrudes outward (to the left in Figure 4) from the first plate 40 and the third plate 43. The second folded portion 44 is folded back and overlaps. The second folded portion 44 is continuous with the upper end of the first plate 40 and the inner end of the third plate 43 in the left-right direction. The notch 57 is positioned opposite the vertical bar 28 in the front-rear direction.

[0069] As shown in Fig. 4, the third plate 43 closes the upper part of the space 10 defined by the first plate 40 and the second plate 41. The third plate 43 is located above the first plate 40 and the second plate 41. The third plate 43 extends outward (to the right in Fig. 4) from the upper end of the first plate 40.

[0070] As shown in Fig. 6(a), when the third plate 43 and the fourth plate 45 are stacked, the first cut-and-raised portion 56 of the third plate 43 is bent downward. Fig. 6(a) shows the first cut-and-raised portion 56 of the third plate 43 as viewed from behind. The first cut-and-raised portion 56 is engaged in the through-hole 58 of the fourth plate 45 in the bent state.

[0071] As shown in Fig. 6(b), when the third plate 43 and the fourth plate 45 are stacked, the second cut-and-raised portion 59 is bent upward. Fig. 6(b) shows the second cut-and-raised portion 59 of the fourth plate 45 as viewed from the front. The second cut-and-raised portion 59 is engaged in the through-hole 55 of the third plate 43 in the bent state.

[0072] As shown in FIG. 4, the fifth plate 46 is continuous with the third plate 43. The fifth plate 46 extends downward from the outer edge (the right edge in FIG. 4) of the third plate 43. The fifth plate 46 is perpendicular to the third plate 43. The fifth plate 46 is located outward of the second plate 41 (to the right in FIG. 4). The fifth plate 46 overlaps with the second plate 41. The lower end of the fifth plate 46 abuts against the first folded portion 42. The fifth plate 46 supports the first plate 40 when the first plate 40 is deformed.

[0073] As shown in Figures 1 and 2, the fixing device 3 is a member that fixes the base formwork 4 below the rising formwork 2. The fixing device 3 is a metal leaf spring that has elasticity. The fixing device 3 has a flat plate shape with a predetermined thickness.

[0074] [Outside corner member 6] The protruding corner member 6 connected to the base formwork 4 will be described below. The protruding corner member 6 is a formwork used when molding the protruding corner 104 of the continuous footing 100. As shown in FIG. 7 , the protruding corner member 6 is positioned in advance outside the protruding corner 104 of the continuous footing 100 to be molded. In its folded state, the protruding corner member 6 is a three-dimensional object that is open on the front and left sides. The protruding corner member 6 is connected to the protruding corner 104 on the front and left sides, respectively, of the protruding corner 104, with the base formwork 4 also in its folded state.

[0075] The protruding corner member 6 has a uniform thickness and is waterproofed. The protruding corner member 6 is made by folding a plate of cardboard. The side that appears in Figure 8 is the back side of the cardboard, and the side that does not appear in Figure 8 is the front side of the cardboard. The front side of the cardboard is the side that faces outward in the protruding corner member 6 in a folded state. The back side is the surface that defines the internal space 70 in the protruding corner member 6 in a folded state. The internal space 70 is an example of a space.

[0076] 8, the protruding corner member 6 has a sixth plate 60, a seventh plate 61, a third folded portion 62, an eighth plate 63, a fourth folded portion 64, a ninth plate 65, a tenth plate 66, an eleventh plate 67, a first flap 68, and a second flap 69. The sixth plate 60, the seventh plate 61, the eighth plate 63, the ninth plate 65, the tenth plate 66, the eleventh plate 67, the first flap 68, and the second flap 69 are each part of a single cardboard sheet.

[0077] As shown in FIG. 8 , the sixth plate 60 is rectangular. The area of ​​the sixth plate 60 is larger than the seventh plate 61, the eighth plate 63, the ninth plate 65, the tenth plate 66, and the eleventh plate 67. The sixth plate 60 has a diagonal line 71 along which the back surface is mountain-folded. The sixth plate 60 has a first portion 72 on one side that is mountain-folded, and a second portion 73 on the other side. The first portion 72 and the second portion 73 are triangular. The shape of the second portion 73 is symmetrical to the first portion 72 with respect to the diagonal line 71.

[0078] One end of the first portion 72, which is continuous with the third folded portion 62, is shorter than the other end, which is continuous with the first flap 68, and the diagonal line 71. The one end and the other end of the first portion 72 are continuous with each other and face the diagonal line 71. The one end of the second portion 73, which is continuous with the fourth folded portion 64, is shorter than the other end and the diagonal line 71. The one end and the other end of the second portion 73 are continuous with each other and face the diagonal line 71. The other end of the second portion 73 faces one end of the first portion 72. The one end of the second portion 73 faces the other end of the first portion 72.

[0079] The dimension of the other end of the first portion 72 in a first direction 77 is slightly larger than the width dimension of the first piece 48 of the base formwork 4. The first direction 77 is the direction in which the third fold portion 62 extends from the first portion 72. The dimension of the other end of the second portion 73 in a third direction 79 is also slightly larger than the width dimension of the first piece 48. The third direction 79 is the direction in which the fourth fold portion 64 extends from the second portion 73.

[0080] As shown in FIG. 8, the third folded portion 62 is located between the first portion 72 and the seventh plate 61. The third folded portion 62 is continuous with the first portion 72. The third folded portion 62 is continuous with the seventh plate 61. A through hole 75 is located in the third folded portion 62, penetrating in a direction perpendicular to the plane of the paper in FIG. 8. The through holes 75 are arranged in pairs in a first direction 77, which is the direction in which the first portion 72 and the third folded portion 62 are continuous. A plurality of the through holes 75 are arranged along a second direction 78 that is perpendicular to the first direction 77. The second direction 78 is a direction perpendicular to the first direction 77.

[0081] In the third folding portion 62, a valley fold line 51 extends along the second direction 78 between the pair of through holes 75. As shown in Fig. 9(a) , the third folding portion 62 is folded at the valley fold line 51 and overlapped, so that the pair of through holes 75 overlap to form a single through hole.

[0082] As shown in FIG. 8 , the seventh plate 61 is located on the opposite side of the third folded portion 62 from the first portion 72. The seventh plate 61 has a rectangular shape that is long in the second direction 78. The dimension of the seventh plate 61 in the second direction 78 is the same as the dimension of the side of the first portion 72 that is along the second direction 78. The boundary between the seventh plate 61 and the third folded portion 62 along the second direction 78 is the valley fold line 51.

[0083] As shown in FIG. 8 , the fourth folded portion 64 is located between the second portion 73 and the eighth plate 63. The fourth folded portion 64 is continuous with the second portion 73 and the eighth plate 63. A through hole 76 is located in the fourth folded portion 64, penetrating in a direction perpendicular to the plane of the paper in FIG. 8 . A pair of the through holes 76 is arranged in a third direction 79, which is the direction in which the second portion 73 and the fourth folded portion 64 are continuous. A plurality of the through holes 76 are arranged in a fourth direction 97 that is perpendicular to the third direction 79. The fourth direction 97 is a direction perpendicular to the third direction 79.

[0084] In the fourth folding portion 64, a valley fold line 51 extends along the fourth direction 97 between the pair of through holes 76. As shown in Figures 9(b) and (c) , the fourth folding portion 64 is folded and overlapped at the valley fold line 51, so that the pair of through holes 76 overlap to form a single through hole.

[0085] As shown in FIG. 8 , the eighth plate 63 is located on the opposite side of the fourth fold 64 from the second portion 73. The eighth plate 63 has a rectangular shape that is long in the fourth direction 97. The dimension of the eighth plate 63 in the fourth direction 97 is the same as the dimension of the side of the second portion 73 along the fourth direction 97. The dimension of the eighth plate 63 in the third direction 79 is the same as or slightly smaller than the width dimension of the second plate 41 of the base formwork 4. The boundary between the eighth plate 63 and the fourth fold 64 along the fourth direction 97 is the mountain fold line 50. The eighth plate 63 has the same dimension as the seventh plate 61. The angle θ1 between the first direction 77 and the third direction 79 is less than 90 degrees.

[0086] As shown in FIG. 8 , the ninth plate 65 is located on the opposite side of the seventh plate 61 from the third folded portion 62. The ninth plate 65 is square. The ninth plate 65 is continuous with the seventh plate 61. The dimension of the ninth plate 65 in the second direction 78 is slightly smaller than the width dimension of the third plate 43 of the base formwork 4. The first portion 72, the third folded portion 62, the seventh plate 61, and the ninth plate 65 are continuous in the first direction 77 and intersect with the third direction 79 in which the second portion 73, the fourth folded portion 64, and the eighth plate 63 are continuous.

[0087] 8, the tenth plate 66 is located in the fourth direction 97 of the eighth plate 63. The tenth plate 66 has a rectangular shape. The tenth plate 66 is continuous with the eighth plate 63.

[0088] As shown in Figure 8, the eleventh plate 67 is located in the second direction 78 of the ninth plate 65. The tenth plate 66 and the eleventh plate 67 are close to each other. The eleventh plate 67 has a rectangular shape. The eleventh plate 67 is continuous with the ninth plate 65. The direction in which the ninth plate 65 and the eleventh plate 67 are continuous is perpendicular to the direction in which the ninth plate 65 is continuous with the seventh plate 61.

[0089] 8, the first flap 68 is continuous with the other end of the first portion 72. The first flap 68 gradually narrows in the first direction 77 as it extends from the other end of the first portion 72 along the second direction 78.

[0090] The second flap 69 is continuous with the ninth plate 65. The second flap 69 is located on the opposite side of the ninth plate 65 from the eleventh plate 67. The second flap 69 extends from the ninth plate 65 in the opposite direction from the side where the eleventh plate 67 is located relative to the ninth plate 65. The second flap 69 gradually narrows in the first direction 77 as it extends from the ninth plate 65.

[0091] When the outside corner member 6 is folded, the first flap 68 and the second flap 69 are inserted into the space 10 of the base formwork 4, which is also folded. The maximum dimension of the first flap 68 in the first direction 77 is slightly smaller than the width dimension of the first piece 48 of the base formwork 4. When the first flap 68 is inserted into the base formwork 4, it overlaps with the first piece 48. The maximum dimension of the second flap 69 in the first direction 77 is slightly smaller than the width dimension of the third panel 43 of the base formwork 4. When the second flap 69 is inserted into the base formwork 4, it overlaps with the third panel 43.

[0092] As shown in FIG. 9(a), the seventh plate 61 is located behind the first portion 72. The seventh plate 61 faces the first portion 72. When viewed from the left-right direction, the seventh plate 61 extends upward from the lower end of the first portion 72. The seventh plate 61 is parallel to the up-down and left-right directions. The seventh plate 61 receives pressure from behind when soil 106 is piled around the corner member 6.

[0093] 9(a), the first portion 72 comes into direct contact with the ready-mixed concrete 103 when the ready-mixed concrete 103 is poured, and is subjected to pressure from the front. The first portion 72 extends rearward from the lower end of the lower rail 29 and obliquely downward from the lower rail 29.

[0094] As shown in FIG. 9(a), the third folded portion 62 protrudes rearward from the first portion 72 and the seventh plate 61. The third folded portion 62 is folded back and overlaps. The third folded portion 62 is continuous with the lower end of the first portion 72 and the lower end of the seventh plate 61. The dimension of the third folded portion 62 in the front-to-rear direction is greater than the width of the head of the fixing nail 5.

[0095] As shown in FIG. 9(a), the ninth plate 65 extends forward from the upper end of the seventh plate 61. The ninth plate 65 is parallel to the front-rear direction and the left-right direction. The ninth plate 65 faces the first portion 72. The ninth plate 65 is perpendicular to the seventh plate 61. The ninth plate 65 defines the upper part of the internal space 70.

[0096] As shown in Figures 9(a) and 9(b), the tenth plate 66 extends leftward from the rear end of the eighth plate 63. The tenth plate 66 is parallel to the up-down and left-right directions. The tenth plate 66 is perpendicular to the eighth plate 63. The tenth plate 66 overlaps with the seventh plate 61. The upper end of the tenth plate 66 abuts against the ninth plate 65. The tenth plate 66 defines the rear of the internal space 70.

[0097] As shown in Figure 9(b), the eighth plate 63 is located to the right of the second portion 73. The eighth plate 63 faces the second portion 73. The eighth plate 63 extends upward from the lower end of the second portion 73. The upper end of the eighth plate 63 abuts the ninth plate 65. The eighth plate 63 is parallel to the up-down direction and the front-to-back direction. The eighth plate 63 receives pressure from the right when soil 106 is piled around the corner member 6.

[0098] 9(b), the second portion 73 comes into direct contact with the ready-mixed concrete 103 when the ready-mixed concrete 103 is poured, and is subjected to pressure from the left. The second portion 73 extends diagonally downward from the lower end of the lower rail 29 toward the right.

[0099] As shown in FIG. 9(b), the fourth folded portion 64 protrudes rightward from the second portion 73 and the eighth plate 63. The fourth folded portion 64 is folded back and overlaps. The fourth folded portion 64 is continuous with the lower end of the second portion 73 and the lower end of the eighth plate 63. The dimension of the fourth folded portion 64 in the left-right direction is greater than the width of the head of the fixing nail 5.

[0100] As shown in Figures 9(b) and 9(c), the 11th plate 67 extends downward from the right end of the 9th plate 65. The 11th plate 67 is parallel to the up-down direction and the front-to-back direction. The 11th plate 67 is perpendicular to the 9th plate 65. The 11th plate 67 overlaps with the 8th plate 63. The lower end of the 11th plate 67 abuts the fourth folded portion 64. The 11th plate 67 receives pressure from the right when soil 106 is piled around the corner member 6.

[0101] [Inside corner part 8] The inside corner member 8 connected to the base formwork 4 will be described below. The inside corner member 8 is a formwork used when forming the inside corner 105 of the continuous footing 100. As shown in FIG. 7 , the inside corner member 8 is placed in advance inside the inside corner 105 of the continuous footing 100 to be formed. The folded inside corner member 8 is a three-dimensional object that is open on the front and left sides. The folded base formwork 4 is connected to the inside corner member 8 on the front and left sides of the inside corner 105, respectively.

[0102] Like the outside corner member 6, the inside corner member 8 has a uniform thickness and is waterproofed. The inside corner member 8 is made by folding a sheet of cardboard. The side that appears in Figure 10 is the back side of the cardboard, and the side that does not appear in Figure 10 is the front side of the cardboard. The front side of the cardboard is the side that faces outward in the inside corner member 8 in a folded state. The back side is the surface that defines the internal space 87 in the inside corner member 8 in a folded state.

[0103] 10, the inside corner member 8 has a 30th plate 80, a 31st plate 81, a fifth folded portion 82, a 32nd plate 83, a sixth folded portion 84, a third flap 85, and a fourth flap 86. The 30th plate 80, the 31st plate 81, the fifth folded portion 82, the 32nd plate 83, the sixth folded portion 84, the third flap 85, and the fourth flap 86 are each part of a single cardboard sheet.

[0104] As shown in FIG. 10 , the 30th plate 80 is rectangular. The area of ​​the 30th plate 80 is larger than the 31st plate 81 and the 32nd plate 83. The 30th plate 80 has a diagonal line 88 along which the back surface is valley-folded. The 30th plate 80 has a third portion 90 on one side that is valley-folded, and a fourth portion 91 on the other side. The third portion 90 and the fourth portion 91 define the lower part of the internal space 87. The third portion 90 and the fourth portion 91 are triangular. The shape of the fourth portion 91 is symmetrical to the third portion 90 with respect to the diagonal line 88.

[0105] One end of the third portion 90, which is continuous with the fifth fold 82, is shorter than the other end and the diagonal line 71. One end and the other end of the third portion 90 are continuous with each other and face the diagonal line 88. One end of the fourth portion 91, which is continuous with the sixth fold 84, is shorter than the other end of the fourth portion 91, which is continuous with the third flap 85, and the diagonal line 88. One end and the other end of the fourth portion 91 are continuous with each other and face the diagonal line 88. The other end of the fourth portion 91 faces one end of the third portion 90. One end of the fourth portion 91 faces the other end of the third portion 90.

[0106] One end of the third portion 90 and one end of the fourth portion 91 have the same length dimension. The other end of the third portion 90 and the other end of the fourth portion 91 have the same length dimension. The dimension of the other end of the third portion 90 in the fifth direction 110 is slightly larger than the width dimension of the first piece 48 of the base formwork 4. The fifth direction 110 is the direction in which the fifth fold portion 82 extends from the third portion 90. The dimension of the other end of the fourth portion 91 in the seventh direction 112 is also slightly larger than the width dimension of the first piece 48.

[0107] As shown in FIG. 10 , the fifth fold portion 82 is located between the third portion 90 and the thirty-first plate 81. The fifth fold portion 82 is continuous with the third portion 90. The fifth fold portion 82 is continuous with the thirty-first plate 81. The dimension of the fifth fold portion 82 in the sixth direction 111 is the same as that of one end of the third portion 90. The sixth direction 111 is a direction perpendicular to the fifth direction 110. The boundary between the fifth fold portion 82 and the third portion 90 along the sixth direction 111 is a mountain fold line 50. A valley fold line 51 extends along the sixth direction 111 at the center in the fifth direction 110 of the boundary between the fifth fold portion 82 and the third portion 90 and the boundary between the fifth fold portion 82 and the thirty-first plate 81.

[0108] 10 , the thirty-first plate 81 is located on the opposite side of the fifth folded portion 82 from the third portion 90. The thirty-first plate 81 is square. In the sixth direction 111, the thirty-first plate 81 and the fifth folded portion 82 have the same dimensions.

[0109] As shown in FIG. 10 , the sixth fold portion 84 is located between the fourth portion 91 and the thirty-second plate 83. The sixth fold portion 84 is continuous with the fourth portion 91. The sixth fold portion 84 is continuous with the thirty-second plate 83. The dimension of the sixth fold portion 84 in the eighth direction 113 is the same as that of one end of the fourth portion 91. The boundary between the sixth fold portion 84 and the fourth portion 91 along the eighth direction 113 is a mountain fold line 50. A valley fold line 51 extends along the eighth direction 113 at the center in the seventh direction 112 of the boundary between the sixth fold portion 84 and the fourth portion 91 and the boundary between the sixth fold portion 84 and the thirty-second plate 83. The seventh direction 112 is the direction in which the sixth fold portion 84 extends from the fourth portion 91. The eighth direction 113 is perpendicular to the seventh direction 112.

[0110] As shown in FIG. 10 , the 32nd plate 83 is located on the opposite side of the sixth fold 84 from the fourth portion 91. The 32nd plate 83 is square. The dimensions of the 32nd plate 83 in the seventh direction 112 and the eighth direction 113 are the same. The dimension of the 32nd plate 83 in the eighth direction 113 is the same as that of the sixth fold 84. The dimension of the 31st plate 81 in the fifth direction 110 is slightly larger than the width dimension of the fourth plate 45 of the base formwork 4. The angle θ2 between the fifth direction 110 and the seventh direction 112 is smaller than 90 degrees.

[0111] As shown in Figure 10, the third flap 85 is continuous with the other end of the fourth portion 91. As the third flap 85 extends from the other end of the fourth portion 91 along the eighth direction 113, it gradually narrows in the seventh direction 112. The fourth flap 86 is continuous with the 32nd plate 83. The fourth flap 86 is located on the same side of the 32nd plate 83 as the third flap 85 with respect to the fourth portion 91. As the fourth flap 86 extends from the 32nd plate 83, it gradually narrows in the seventh direction 112.

[0112] When the inside corner member 8 is folded, the third flap 85 and the fourth flap 86 are inserted into the space 10 of the base formwork 4, which is also folded. The maximum dimension of the third flap 85 in the seventh direction 112 is slightly smaller than the width dimension of the first piece 48 of the base formwork 4. When the third flap 85 is inserted into the base formwork 4, it overlaps with the first piece 48. The maximum dimension of the fourth flap 86 in the seventh direction 112 is slightly smaller than the width dimension of the third panel 43 of the base formwork 4. When the fourth flap 86 is inserted into the base formwork 4, it overlaps with the third panel 43.

[0113] 11(a), the third portion 90 comes into direct contact with the ready-mixed concrete 103 when the ready-mixed concrete 103 is poured, and is subjected to pressure from behind. The third portion 90 extends diagonally downward while heading forward from a height position at the lower end of the lower rail 29.

[0114] 11(a), the third plate 81 extends forward from the upper end of the third portion 90. The third plate 81 is parallel to the front-rear direction and the left-right direction. The third plate 81 faces the third portion 90 and the fourth portion 91. The third plate 81 defines an upper portion of the internal space 87.

[0115] 11(a), the fifth folded portion 82 protrudes rearward from the third portion 90 and the thirty-first plate 81. The fifth folded portion 82 is folded back and overlaps. The fifth folded portion 82 is continuous with the upper end of the third portion 90 and the rear end of the thirty-first plate 81.

[0116] 11(b), the fourth portion 91 comes into direct contact with the ready-mixed concrete 103 when the ready-mixed concrete 103 is poured, and is subjected to pressure from the right. The fourth portion 91 extends diagonally downward from the height position of the lower end of the lower rail 29 toward the left.

[0117] 11(b), the sixth folded portion 84 protrudes rightward from the fourth portion 91 and the thirty-second plate 83. The sixth folded portion 84 is folded back and overlaps. The sixth folded portion 84 is continuous with the upper end of the fourth portion 91 and the right end of the thirty-second plate 83.

[0118] 11(b), the 32nd plate 83 is located above the 31st plate 81. The 32nd plate 83 overlaps the 31st plate 81. The 32nd plate 83 is parallel to the front-rear direction and the left-right direction.

[0119] [Construction method for 100-foot span footing] A method for constructing a continuous footing 100 using the base formwork 4 according to the first embodiment will be described below with reference to the aforementioned figures as well as Figures 12 to 17. In the method for constructing the continuous footing 100, workers perform a molding process, a formwork installation process, a filling process, a pouring process, an opening process, and a piping installation process.

[0120] Prior to the molding process, workers perform the following work up to installing the rising formwork 2. As shown in FIG. 1, workers install spread mortar 12 and then install supporting materials 20 on top of it. Workers fix reinforcing bars 14 to the supporting materials 20. Workers install the rising formwork 2 on the supporting materials 20. As shown in FIG. 3, multiple rising formworks 2 are connected in the front-to-rear direction and fixed in place by locking members 18.

[0121] After fixing the rising formwork 2, workers perform the molding process of bending the cardboard to create the base formwork 4, the outside corner members 6, and the inside corner members 8. The workers bend the cardboard of the base formwork 4 that has been carried to the construction site from its unfolded state as shown in Figure 5 into a triangular cylindrical shape as shown in Figure 4.

[0122] The worker then prepares the exterior corner member 6 from the cardboard of the exterior corner member 6 in the state before folding shown in FIG. 8. The folded exterior corner member 6 becomes a three-dimensional object with openings on the front and left sides, as shown in FIGS. 9(a), (b), and (c). The worker then prepares the interior corner member 8 having an internal space 87 from the cardboard of the interior corner member 8 in the state before folding shown in FIG. 10. The folded interior corner member 8 becomes a three-dimensional object with openings on the back and right sides, as shown in FIGS. 11(a) and (b). The worker then prepares the required number of base formwork 4, exterior corner members 6, and interior corner members 8 required to cast the continuous footing 100.

[0123] A worker performs a formwork installation process in which the base formwork 4 is installed on the rising formwork 2. As shown in Figures 1 and 2, the worker positions the base formwork 4 so that the second folded portion 44 is placed on the upper surface of the lower crosspiece 29. At this time, the position of the base formwork 4 is adjusted in the front-to-rear direction so that the vertical crosspiece 28 is positioned within the notch 57 of the second folded portion 44. In this state, the worker abuts one end of the fixing device 3 against the underside of the upper crosspiece 27 and pushes the other end toward the wall panel 26, sandwiching the second folded portion 44 between the fixing device 3 and the lower crosspiece 29. The worker drives a fixing nail 5 into the first folded portion 42 of the base formwork 4 fixed to the rising formwork 2 to fix it in the spread mortar 12.

[0124] The worker connects the second base formwork 4 to the base formwork 4 fixed to the riser formwork 2. Specifically, the second board 41, fourth board 45, and insert piece 49 of the base formwork 4 to be connected are inserted into the space 10 of the base formwork 4 to be connected. At this time, the second board 41 of the connecting side overlaps the fifth board 46 of the connected side. The fourth board 45 of the connecting side overlaps the third board 43 of the connected side. The insert piece 49 of the connecting side overlaps the first board 40 of the connected side. The worker clamps the second folded portion 44 of the base formwork 4 to the bottom rail 20 with the fastener 3, just like the base formwork 4 of the connected side. The worker then drives the fixing nails 5 into the first folded portion 42 of the base formwork 4 connected to the base formwork 4 and fixed to the riser formwork 2, and fixes it to the spread mortar 12. If there is another base formwork 4, the same procedure is repeated.

[0125] As shown in Figure 7, a worker places the protruding corner member 6 in a position where the protruding corner 104 of the continuous footing 100 will be formed. The worker inserts the insertion piece 49, second board 41, and fourth board 45 into the internal space 70 of the protruding corner member 6 from the front. The worker then inserts the first flap 68 and second flap 69 of the protruding corner member 6 toward the left into the space 10 of the base formwork 4 located to the right, connecting them. The protruding corner member 6 and the base formwork 4 connected to it form an L-shape extending forward and leftward from the protruding corner member 6.

[0126] A worker places the inside corner member 8 in a position where the inside corner 105 of the slab footing 100 will be formed. The worker inserts the insertion piece 49, second board 41, and fourth board 45 into the internal space 87 of the inside corner member 8 from the left. The worker inserts the third flap 85 and fourth flap 86 of the inside corner member 8 facing forward into the space 10 of another base formwork 4 to connect them. The inside corner member 8 and the base formwork 4 connected to it form an L-shape extending forward and to the left, similar to the outside corner member 6. The worker drives fixing nails 5 into the first folded portion 42 of the base formwork 4 and the third folded portion 62 and fourth folded portion 64 of the outside corner member 6 to secure them in place.

[0127] After installing the base formwork 4, external corner members 6, and internal corner members 8, workers pile up soil 106. As shown in FIG. 12 , soil 106 is piled on the outside of the base formwork 4 and external corner members 6, which are installed in an L-shape, and on the inside of the base formwork 4 and internal corner members 8. As a result, the base formwork 4 is subjected to pressure from the soil 106 at the second plate 41 and the fifth plate 46. The load on the second plate 41 is supported by the extended end of the fourth plate 45 abutting against the first plate 40. The load on the fifth plate 46 is supported by the third plate 43 and the second plate 41. The height of the piled soil 106 is adjusted depending on the load that the first plate 40 receives from the ready-mixed concrete 103.

[0128] As shown in FIG. 13 , workers perform a pouring process to pour fresh concrete 103 into the space surrounded by the upright formwork 2 and the base formwork 4. As the fresh concrete 103 is poured, the first plate 40 of the base formwork 4, the sixth plate 60 of the external corner member 6, and the thirtieth plate 80 of the internal corner member 8 are subjected to loads. As shown in FIGS. 4 and 14 , the first plate 40 is not expanded prior to use and slightly bends from its flat state in the direction indicated by arrow P in FIG. 14 . In other words, when the fresh concrete 103 is poured, a restoring force acts on the first plate 40, preventing the cross-sectional structure of the base portion 101 from expanding significantly. This reduces the consumption of fresh concrete 103. Because the first plate 40 displaces only in the direction expanding toward the space 10, the cross-sectional structure of the base portion 101 is less likely to be damaged. Furthermore, when soil 106 is piled on the outside of the base formwork 4, the second plate 41 and the fifth plate 46 will bend slightly in the direction indicated by the arrow Q in Fig. 14. However, because there is a space 10 between the first plate 40 and the second plate 41, even if the second plate 41 is bent by the soil 106, it will not come into contact with the first plate 40, and the base portion 101 will not be damaged.

[0129] After the pouring step, workers perform an opening step to open upward the space 10 of the base formwork 4 located outside the continuous footing 100 and the internal space 70 of the external corner member 6. The opening step is performed for the purpose of installing piping 95 in the space 10 or the internal space 70. As shown in Figure 15, workers drill holes in the third plate 43 and fourth plate 45 of the base formwork 4 and the ninth plate 65 of the external corner member 6.

[0130] A worker performs a piping installation process to install piping 95 in the space 10 of the opened base formwork 4 and the internal space 70 of the external corner member 6. This piping installation process can be used when sufficient space from the boundary of the adjacent land for installing piping 95 cannot be secured during the design stage or during on-site construction. As shown in FIGS. 16 and 17 , a worker piles soil 106 to a predetermined height in the drilled space 10 of the base formwork 4 and the internal space 70 of the external corner member 6. The worker installs piping 95 on top of the piled soil 106 in the space 10. In the piping installation process, the piping 95 may be installed within a portion of the space 10 of the base formwork 4, or may be installed across the spaces 10 of multiple base formworks 4. In the piping installation process, the piping 95 may be connected in the internal space 70 of the external corner member 6 as needed.

[0131] [Effects of the first embodiment] When the ready-mixed concrete 103 is poured, the first plate 40 receives a load from the ready-mixed concrete 103 and bends into the space 10. The second plate 41 receives a load from the soil 106 piled up around it and bends into the space 10. However, since the first plate 40 and the second plate 41 are separated by the space 10, they do not come into contact with each other, and the cross-sectional structure of the continuous footing 100 is not affected. Furthermore, the existence of such a space 10 makes it possible to overestimate the allowable range of bending of the first plate 40 and the second plate 41, and therefore allows the use of inexpensive materials with relatively low strength, such as cardboard or corrugated cardboard, for the base formwork 4.

[0132] When the base formwork 4 is installed, it can be fixed to the lower rail 29 of the rising formwork 2 at the second folding portion 44, and can be fixed to the spread mortar 12 at the first folding portion 42. Therefore, the first board 40, the second board 41, and the third board 43 are not deformed by installation.

[0133] When the first plate 40 receives a load from the ready-mixed concrete 103, the fifth plate 46 abuts against the first folded portion 42, thereby preventing the first plate 40 from deforming. In addition, the fifth plate 46 overlaps with the second plate 41, so that the fifth plate 46 can firmly support the load from the surrounding soil 106.

[0134] When connecting multiple base formworks 4 in the extension direction, the second plate 41 of another base formwork 4 to be connected can be inserted into the recessed position of the second plate 41. At this time, it becomes easy to line up multiple base formworks 4 in the extension direction so that the second plate 41 on the connecting side is aligned with the fifth plate 46 of the base formwork 4 on the connecting side.

[0135] When connecting multiple base formworks 4 in the extension direction, the insert piece 49 can be inserted into the space 10 defined by the first plate 40, the second plate 41, and the third plate 43. At this time, the insert piece 49, together with the second plate 41 on the connecting side, is supported by the base formwork 4 on the connected side. Therefore, the base formwork 4 on the connecting side is positioned relative to the base formwork 4 on the connected side in a direction perpendicular to the extension direction. This allows the multiple base formworks 4 to be positioned along the extension direction.

[0136] When the protruding corner member 6 is connected to two base formworks 4 arranged perpendicular to each other, the two base formworks 4 and the protruding corner member 6 are positioned in an L-shape when viewed from above. This makes it possible to form the protruding corner 104 of the continuous footing 100.

[0137] The tenth plate 66 overlaps with the seventh plate 61, and the eleventh plate 67 overlaps with the eighth plate 63. Therefore, the outside of the corner member 6 is supported doubly, and can firmly support the load received from the surrounding soil 106.

[0138] By connecting the inside corner member 8 to two base formworks 4 arranged perpendicular to each other, the two base formworks 4 and the inside corner member 8 are positioned in an L-shape when viewed from above, similar to the outside corner member 6. This makes it possible to form an inside corner of the foundation.

[0139] The base formwork 4 is a triangular cylindrical shape formed by bending a plate-like member. Specifically, a relatively low-strength material such as cardboard or corrugated cardboard can be used for the base formwork 4. This allows for cost-effective foundation construction.

[0140] A worker can install the piping 95 in the space 10 by opening the top of the space 10 and piling soil 106 in the space 10. Therefore, there is no need to dig a trench outside the base formwork 4 when installing the piping 95, which can significantly reduce the burden on the worker.

[0141] In the first embodiment described above, the base formwork 4 has been described as having a triangular cylindrical shape, but is not limited to this configuration. The base formwork 4 may also have a polygonal cylindrical shape, such as a square or pentagon.

[0142] In the first embodiment described above, the base formwork 4 is made of cardboard, but the present invention is not limited to this configuration. The base formwork 4 may be made of cardboard or a resin plate, for example. The base formwork 4 may be any material that can be bent into a cylindrical shape and is waterproof.

[0143] In the first embodiment described above, the extended end of the fourth plate 45 of the folded base formwork 4 abuts the first plate 40, but this is not the only possible configuration. The extended end of the fourth plate 45 may be sandwiched between the folded-back portion of the second fold 44.

[0144] In the first embodiment described above, the first plate 40 does not need to have the insertion piece 49. When the base formwork 4 is connected to the corner member 6, the rear ends of the second plate 41 and the fourth plate 45 are inserted into the space 10 of the base formwork 4.

[0145] In the first embodiment described above, an example was given in which the second plate 41 has a rectangular shape that is long in the front-to-rear direction, and the fourth plate 45 has a rectangular shape that is also long in the front-to-rear direction. However, this configuration is not limited to this. The second plate 41 may be cut out on the side adjacent to the first fold portion 42 so that it does not abut against the other base formwork 4 when connected to the projected corner member 6. Similarly, the fourth plate 45 may be cut out on the side opposite to the side adjacent to the second plate 41.

[0146] In the first embodiment, the case where the soil 106 is piled up around the fifth plate 46 in the soil piling step has been described as an example, but the present invention is not limited to this configuration. The soil 106 may be piled up on the third plate 43 at a position higher than the fifth plate 46.

[0147] In the first embodiment described above, an example was given in which a plurality of base formworks 4 are connected in the front-to-rear direction, but the present invention is not limited to this configuration. The base formwork 4 may be a single piece that is long in the front-to-rear direction.

[0148] In the first embodiment described above, an example was described in which the tenth plate 66 is continuous with the eighth plate 63 and overlaps with the seventh plate 61, but this configuration is not limiting. The tenth plate 66 may be continuous with the seventh plate 61 and overlap with the eighth plate 63. In this case, the ninth plate 65 is continuous with the eighth plate 63, and the eleventh plate 67 is continuous with the ninth plate 65 and overlaps with the seventh plate 61.

[0149] In the above-described first embodiment, an example has been described in which holes are drilled in the base formwork 4 or the recessed corner members 6 to install the pipes 95 in the space 10 or the internal space 70 in the pipe installation step. However, the pipes 95 do not necessarily have to be installed in the space 10 or the internal space 70. Also, holes do not have to be drilled in the base formwork 4 or the recessed corner members 6. The base formwork 4, the recessed corner members 6, and the recessed corner members 8 may be filled with soil 106 as they are without being subjected to the opening step and the pipe installation step.

[0150] [Modification 1 of the First Embodiment] In the first embodiment described above, the base formwork 4 is connected to the third plate 43 and has a fifth plate 46 extending downward from the outer edge of the third plate 43 in the left-right direction, but the present invention is not limited to this configuration. As shown in Figure 18, the base formwork 4A may not have a fifth plate 46.

[0151] In this case, the second plate 41 is in direct contact with the piled up soil 106 around the base formwork 4A. Because the base formwork 4A receives a load from the piled up soil 106, when the ready-mixed concrete 103 is poured, the first plate 40 comes into contact with the extending end of the fourth plate 45, thereby suppressing deformation.

[0152] [Modification 2 of the First Embodiment] In the first embodiment described above, the base formwork 4 in the folded state defines a space 10 by the first plate 40, the second plate 41, and the fourth plate 45. While the description has been given taking the example of a case where the space 10 is hollow, the present invention is not limited to this configuration. As shown in FIG. 19, the base formwork 4B may have a storage member 120B stored in the space 10.

[0153] Storage member 120B is located within space 10 and abuts against first plate 40 and second plate 41. Storage member 120B is made by folding cardboard and has a roughly triangular cylindrical shape. Storage member 120B has an eighteenth plate 121, a nineteenth plate 122, a twentieth plate 123, and a twenty-first plate 124.

[0154] The 18th plate 121 extends along the first plate 40. The 18th plate 121 overlaps the first plate 40. The 19th plate 122 is continuous with the lower end of the 18th plate 121. The 19th plate 122 extends upward from the lower end of the 18th plate 121. The 19th plate 122 is parallel to the up-down direction and the front-to-rear direction. The 19th plate 122 extends along the second plate 41. The 19th plate 122 overlaps the second plate 41.

[0155] The twentieth plate 123 is continuous with the upper end of the eighteenth plate 121. The twentieth plate 123 extends from the upper end of the eighteenth plate 121 toward the nineteenth plate 122. The twenty-first plate 124 is continuous with the upper end of the nineteenth plate 122. The twenty-first plate 124 extends from the upper end of the nineteenth plate 122 and abuts against the first plate 40. The twenty-first plate 124 is located above and overlaps the twenty-first plate 123.

[0156] Although not shown, the eighteenth plate 121, the nineteenth plate 122, the twentieth plate 123, and the twenty-first plate 124 are each a rectangular shape that is long in the front-to-rear direction. The dimensions of each plate in the front-to-rear direction are the same and are smaller than the dimension of the first piece 48 in the front-to-rear direction.

[0157] Because storage member 120B is located within space 10 of base formwork 4B and abuts against first plate 40 and second plate 41, deformation of first plate 40 relative to second plate 41 can be prevented. Furthermore, because storage member 120B is made of folded cardboard, it can be easily removed from space 10 by opening the top of base formwork 4B. This makes it easy to ensure space 10 when installing piping 95 within base formwork 4B.

[0158] [Modification 3 of the First Embodiment] In the above-described second modification, a case where one storage member 120B is stored in the base formwork 4B has been described as an example, but this is not limiting. As shown in Figure 20, the base formwork 4C may store a second storage member 120C.

[0159] Storage member 120C is located within space 10 and above storage member 120B. Storage member 120C abuts against first plate 40, third plate 43, and twenty-first plate 124. Storage member 120C has a generally triangular cylindrical shape and is larger than storage member 120B. Storage member 120C has a twenty-second plate 130, a twenty-third plate 131, a twenty-fourth plate 132, and a twenty-fifth plate 133.

[0160] The 22nd plate 130 extends along the first plate 40. The 22nd plate 130 overlaps the first plate 40. The 23rd plate 131 is continuous with the upper end of the 22nd plate 130. The 23rd plate 131 extends outward in the left-right direction from the upper end of the 22nd plate 130. The 23rd plate 131 is parallel to the front-rear direction and the left-right direction. The 23rd plate 131 is aligned with the fourth plate 45. The 23rd plate 131 overlaps with the fourth plate 45.

[0161] The 24th plate 132 is continuous with the lower end of the 22nd plate 130. The 24th plate 132 extends from the lower end of the 22nd plate 130 toward the 23rd plate 131. The 25th plate 133 is continuous with the extending end of the 23rd plate 131. The 25th plate 133 extends from the extending end of the 23rd plate 131 and abuts against the first plate 40. The 25th plate 133 is located below and overlaps the 24th plate 132. The 25th plate 133 also overlaps the 21st plate 124.

[0162] Although not shown, the 22nd plate 130, the 23rd plate 131, the 24th plate 132, and the 25th plate 133 are each a rectangular shape that is long in the front-rear direction. The dimensions of each plate in the front-rear direction are the same as those of the storage member 120B.

[0163] The 21st plate 124 and the 25th plate 133 abut against each other, and the 20th plate 123 and the 24th plate 132 further overlap, so that the first plate 40 can be firmly supported relative to the second plate 41.

[0164] In the above-described first embodiment, modified example 1, modified example 2, and modified example 3, the base formwork 4, 4A, 4B, and 4C have the first folding section 42 and the second folding section 44. However, this configuration is not limiting. The base formwork 4, 4A, 4B, and 4C may not have the first folding section 42 and the second folding section 44, and may be fixed directly to the bottom rail 29 and the bed mortar 12, for example.

[0165] In the above-described second and third modifications, the storage members 120B and 120C are described as triangular cylindrical shapes made by folding cardboard, but the present invention is not limited to this configuration. The storage members 120B and 120C may be removable from the space 10 and may be made of paper, wood, resin, or metal, which can support the first board 40 relative to the second board 41.

[0166] [Second embodiment] The second embodiment will be described below. A triangular cylindrical base formwork 4D according to the second embodiment has a first plate 40D, a second plate 41D, a third plate 43D, a twelfth plate 140D, and a thirteenth plate 141D, as shown in Fig. 21. The base formwork 4D is made by bending a single piece of cardboard.

[0167] The first plate 40D has a first sub-plate 142D and a first sub-plate 143D. Although not shown, the first sub-plate 142D and the first sub-plate 143D have a rectangular shape that is long in the front-rear direction. The first sub-plate 142D is located above the first sub-plate 143D.

[0168] The first sub-plate 143D is parallel to the first sub-plate 142D. The upper end of the first sub-plate 143D abuts the lower end of the first sub-plate 142D. The width dimension of the first sub-plate 143D is the same as that of the first sub-plate 142D and is smaller than the first plate 40D, the second plate 41D, and the third plate 43D.

[0169] The second plate 41D is continuous with the lower end of the first sub-plate 143D. The second plate 41D extends upward from the lower end of the first sub-plate 143D. The second plate 41D is parallel in the up-down direction and the front-rear direction. The second plate 41D faces the first sub-plate 143D.

[0170] The third plate 43D is continuous with the upper end of the first sub-plate 142D and the upper end of the second plate 41D. The third plate 43D extends along the front-rear and left-right directions. The third plate 43D faces the first sub-plate 142D.

[0171] The twelfth plate 140D is continuous with the lower end of the first sub-plate 142D. The twelfth plate 140D extends from the lower end of the first sub-plate 142D toward the second plate 41D, which directly receives the pressure of the soil 106. The twelfth plate 140D faces the third plate 43D.

[0172] The thirteenth plate 141D is continuous with the upper end of the first sub-plate 143D. The thirteenth plate 141D extends from the upper end of the first sub-plate 143D toward the second plate 41D. The thirteenth plate 141D overlaps with the twelfth plate 140D. The thirteenth plate 141D faces the second plate 41D.

[0173] When the twelfth plate 140D and the thirteenth plate 141D are stacked on top of each other, they can support the pressure exerted on the sub-first plates 142D and 143D from the ready-mixed concrete 103. This allows for stronger support than when supported by a single plate.

[0174] [Modification 1 of the second embodiment] In the second embodiment described above, the base formwork 4D includes a first panel 40D, a second panel 41D, a third panel 43D, a twelfth panel 140D, and a thirteenth panel 141D. However, the base formwork 4D is not limited to this configuration. As shown in Figure 22, the base formwork 4E may further include a fourteenth panel 146E and a fifteenth panel 147E in addition to the base formwork 4D.

[0175] The fourteenth plate 146E is continuous with the upper end of the twelfth plate 140D. The fourteenth plate 146E extends inward in the left-right direction from the upper end of the twelfth plate 140D. The fourteenth plate 146E is parallel to the front-rear and left-right directions. The fourteenth plate 146E is aligned with the third plate 43D. The fourteenth plate 146E overlaps with the third plate 43D.

[0176] The fifteenth plate 147E is continuous with the upper end of the thirteenth plate 141D. The fifteenth plate 147E extends downward from the upper end of the thirteenth plate 141D. The fifteenth plate 147E is parallel to the up-down direction and the front-rear direction. The fifteenth plate 147E is aligned with the second plate 41D. The fifteenth plate 147E overlaps with the second plate 41D.

[0177] Since the twelfth plate 140D and the thirteenth plate 141D are overlapped with each other, the first plate 40D, which is subjected to the load from the ready-mixed concrete 103, can be firmly supported.

[0178] [Modification 2 of the Second Embodiment] In the first modification, the base formwork 4E further includes a fourteenth plate 146E and a fifteenth plate 147E in addition to the base formwork 4D. However, the base formworks 4D and 4E are not limited to this configuration. As shown in Figure 23, the base formwork 4F may further include a sixteenth plate 150F and a seventeenth plate 151F in addition to the base formwork 4E.

[0179] The sixteenth plate 150F is continuous with the extending end of the fourteenth plate 146E. The sixteenth plate 150F extends downward from the inward end of the fourteenth plate 146E in the left-right direction. The sixteenth plate 150F is parallel to the up-down direction and the front-rear direction. The extending end of the sixteenth plate 150F abuts against the twelfth plate 140.

[0180] The seventeenth plate 151F is continuous with the extending end of the fifteenth plate 147E. The seventeenth plate 151F extends inward in the left-right direction from the lower end of the fifteenth plate 147E. The seventeenth plate 151F is parallel to the front-rear and left-right directions. The extending end of the seventeenth plate 151F abuts against the thirteenth plate 141D.

[0181] The twelfth plate 140 supporting the first sub-plate 142D is further supported by the sixteenth plate 150F, which is continuous with the fourteenth plate 146E. Furthermore, the thirteenth plate 141D supporting the first sub-plate 143D is further supported by the seventeenth plate 151F, which is continuous with the fifteenth plate 147E. Therefore, the pressure exerted by the ready-mixed concrete 103 on the first sub-plates 142D and 143D is more firmly supported by the twelfth plate 140D and the thirteenth plate 141D.

[0182] 21 to 23, which illustrate the second embodiment, Modification 1, and Modification 2 of the second embodiment, have been described with reference to an example in which the first folded portion 42 and the second folded portion 44 are not provided. However, the first folded portion may protrude outward (to the right in FIGS. 21 to 23) from the first sub-plate 143D and the second plate 41D. The first folded portion may also protrude outward (to the left in FIGS. 21 to 23) from the first sub-plate 142D and the third plate 43D. In this case, the first folded portion is continuous with the lower end of the first sub-plate 143D and the lower end of the second plate 41D. The second folded portion is continuous with the upper end of the first sub-plate 142D and the left end of the third plate 43D.

[0183] [Appendix 1] A cylindrical base formwork is formed by bending a plate-like member and is located below a pair of rising formworks that form the rising portion of the foundation, The device has a first plate, a second plate, and a third plate, The first plate extends obliquely downward from the rising formwork, the second plate extends in the vertical direction outside the first plate, The third board is a base formwork that blocks the upper part of the space defined by the first board and the second board.

[0184] [Appendix 2] The base formwork of claim 1, further comprising a fourth plate continuous with the second plate and overlapping the third plate.

[0185] [Appendix 3] a first folding portion that protrudes outward between the first plate and the second plate; A base formwork as described in Appendix 2, further having a second fold portion protruding outward between the first plate and the third plate.

[0186] [Appendix 4] 3. The base formwork of claim 1 or 2, further comprising a fifth plate that is continuous with the third plate and overlaps the second plate.

[0187] [Appendix 5] the device further includes a cylindrical storage member stored in a space defined by the first plate, the second plate, and the third plate, The base formwork according to claim 1 or 2, wherein the storage member abuts at least the first plate and the second plate.

[0188] [Appendix 6] A base formwork as described in Appendix 4, wherein one end of the second plate protrudes in the extension direction of the foundation more than one end of the first plate, and the other end is recessed in the extension direction more than the other end of the first plate.

[0189] [Appendix 7] The base formwork described in Appendix 6, wherein the first plate has an insert piece extending in the extension direction.

[0190] [Appendix 8] A plate-shaped member is bent and placed at the corner of the foundation, and the corner member is continuous with the two base formworks according to claim 1 or 2, a sixth plate that is mountain-folded and connected to the first plate; a seventh plate extending in the vertical direction from the sixth plate on one side of the protruding corner; an eighth plate extending in the vertical direction from the sixth plate on the other side of the protruding corner; and a ninth plate that closes off the top of the space defined by the sixth plate, the seventh plate, and the eighth plate.

[0191] [Appendix 9] a tenth plate continuous with the eighth plate and overlapping the seventh plate; The device further includes an eleventh plate that is continuous with the ninth plate and overlaps the eighth plate, The ninth plate is a corner member according to Appendix 8, which is continuous with the seventh plate.

[0192] [Appendix 10] An inside corner member in which a plate-like member is bent and placed at an inside corner of the foundation and is continuous with the two base formworks according to claim 1 or 2, a 30th plate that is valley-folded and connected to the first plate; a 31st plate extending upward from the 30th plate from one side of the inside corner; a 32nd plate extending from the 30th plate on the other side of the inside corner and overlapping with the 31st plate;

[0193] [Appendix 11] The first plate has two sub-first plates, a twelfth plate that is continuous with one lower end of the first sub-plate and extends toward the second plate in the space; A base formwork as described in Appendix 1, further comprising a 13th plate that is continuous with the other upper end of the sub-first plate and extends toward the second plate in the space.

[0194] [Appendix 12] a fourteenth plate that is continuous with the extending end of the twelfth plate and overlaps the third plate; A base formwork as described in Appendix 11, further comprising a 15th plate that is continuous with the extended end of the 13th plate and overlaps the 2nd plate.

[0195] [Appendix 13] a sixteenth plate that is continuous with the extending end of the fourteenth plate and extends toward the twelfth plate; 13. The base formwork of claim 12, further comprising a 17th plate that is continuous with the extended end of the 15th plate and extends toward the 13th plate.

[0196] [Appendix 14] a forming step of bending a plate-like member to form a polygonal cylindrical base form; a formwork installation step of installing the base formwork on the rising formwork; a piling step of piling soil around the base formwork installed on the rising formwork; A foundation construction method comprising a casting step of casting a molding material into the rising formwork and the base formwork.

[0197] [Appendix 15] an opening step of opening the space of the base formwork located outside the foundation upward after the pouring step; A foundation construction method as described in Appendix 14, further comprising a piping installation step of installing piping in the space of the opened base formwork. [Explanation of symbols]

[0198] 2. Standing formwork 4. Base formwork 4A···Base formwork 4B···Base formwork 4C···Base Formwork 4D base formwork 4E···Base formwork 4F: Base formwork 6. Outside corner member 8. Inside corner member 10...space 29. Bottom end of bottom rail or rising formwork 40...1st board 41...2nd board 42...1st folding section 43...3rd board 44...2nd folding section 45...4th board 46...5th board 49 Insert piece 60...6th board 61...7th board 63...8th board 65...9th board 66...10th board 67...11th board 70....interior space or space 80...30th board 81...31st board 83...32nd board 95 Piping 100...Strip footing or foundation 102... rising part 103 Ready-mixed concrete or molding material 104....Outside corner 105...Inside corner 106···Sat 120B Storage material 120C···Storage material 140D...12th plate 141D...13th board 142D···Sub-1st plate 143D···Sub 1st plate 146E...14th board 147E...15th board

Claims

1. A cylindrical base formwork is located below a pair of rising formworks that form the rising portion of the foundation, and is made of a bent plate-like member. The device has a first plate, a second plate, and a third plate, The first plate extends obliquely downward from the rising formwork, the second plate extends in the vertical direction outside the first plate, The third board is a base formwork that closes off the top of the space defined by the first board and the second board.

2. 2. The base form according to claim 1, further comprising a fourth plate continuous with said second plate and overlapping said third plate.

3. a first folding portion protruding outward between the first plate and the second plate; The base formwork according to claim 2, further comprising a second folded portion projecting outward between the first plate and the third plate.

4. 3. The base formwork according to claim 1, further comprising a fifth plate that is continuous with the third plate and overlaps the second plate.

5. the device further includes a cylindrical storage member stored in a space defined by the first plate, the second plate, and the third plate, The base formwork according to claim 1 or 2, wherein the storage member abuts against at least the first plate and the second plate.

6. A base formwork as described in claim 4, wherein one end of the second plate protrudes in the extension direction of the foundation more than one end of the first plate, and the other end is recessed in the extension direction more than the other end of the first plate.

7. The base formwork according to claim 6, wherein the first plate has an insert piece extending in the extending direction.

8. A corner member in which a plate-like member is bent and placed at the corner of the foundation, and which is continuous with the two base formworks according to claim 1 or 2, a sixth plate that is mountain-folded and connected to the first plate; a seventh plate extending in the vertical direction from the sixth plate on one side of the protruding corner; an eighth plate extending in the vertical direction from the sixth plate on the other side of the protruding corner; and a ninth plate that closes off the upper side of the space defined by the sixth plate, the seventh plate, and the eighth plate.

9. a tenth plate continuous with the eighth plate and overlapping the seventh plate; The ninth plate is continuous with the eleventh plate and overlaps the eighth plate.

9. The corner member according to claim 8, wherein the ninth plate is continuous with the seventh plate.

10. An inside corner member that is continuous with the two base formworks according to claim 1 or 2, wherein a plate-like member is bent and placed at an inside corner of the foundation, a 30th plate that is valley-folded and connected to the first plate; a 31st plate extending upward from the 30th plate from one side of the inside corner; a 32nd plate extending from the other side of the inside corner from the 30th plate and overlapping the 31st plate;

11. The first plate has two sub-first plates, a twelfth plate that is continuous with one lower end of the first sub-plate and extends toward the second plate in the space; 2. The base formwork according to claim 1, further comprising a thirteenth plate that is continuous with the other upper end of the first sub-plate and extends toward the second plate in the space.

12. a fourteenth plate that is continuous with the extending end of the twelfth plate and overlaps the third plate; The base form according to claim 11, further comprising a fifteenth plate that is continuous with the extended end of the thirteenth plate and overlaps the second plate.

13. a sixteenth plate that is continuous with the extending end of the fourteenth plate and extends toward the twelfth plate; The base form according to claim 12, further comprising a seventeenth plate that is continuous with the extended end of the fifteenth plate and extends toward the thirteenth plate.

14. a forming step of bending a plate-like member to form a polygonal cylindrical base form; a formwork installation step of installing the base formwork on the rising formwork; a piling step of piling soil around the base formwork installed on the rising formwork; A foundation construction method comprising a casting step of casting a molding material into the rising formwork and the base formwork.

15. an opening step of opening the space of the base formwork located outside the foundation upward after the pouring step; The foundation construction method according to claim 14, further comprising a piping installation step of installing piping in the space of the opened base formwork.

Images