JP2018021322A - Pile foundation and tower reconstruction method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pile foundation reducing the construction cost by increasing breaking strength of a beam while reducing the size thereof, and to provide a tower reconstruction method capable of reducing the construction cost by suppressing expansion of site for newly building a tower in place of an existing tower as well as expansion of the cost for buying a site therefor.SOLUTION: Disclosed pile foundation 100 is a pile foundation which includes: beam parts 120a to 120d for supporting main leg materials (10a to 10d) of a steel-tower; and a pile part 110 which is built in the center thereof. Each of the main leg materials includes: plural pressure bearing plates 130 attached to a part disposed within the beam; and a helical reinforcement bar 150 or a ring reinforcement which is lied enclosing the main leg material within the beam.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a pile foundation including a beam portion supporting each main leg member of a steel tower and a pile part constructed at the center thereof, and an existing steel tower having a separate existing foundation for each of a plurality of main leg members. The present invention relates to a steel tower rebuilding method for replacing a new steel tower having such a pile foundation.

  Electricity generated at the power plant of an electric power company is transmitted over a long distance through a transmission line stretched over a steel tower built on the ground. Since a power transmission tower located in a mountainous area is a huge structure, its legs are directly supported by a foundation or a deep foundation (for example, Patent Document 1). For flat ground, cast-in-place piles are used instead of deep foundations.

  FIG. 13 is a diagram for explaining the foundation of the steel tower 10. FIG. 13A is an example using the direct foundation 12, and FIG. 13B is an example using the deep foundation 14. As shown in FIG. 13A, the direct foundation 12 has an inverted T shape, and the base portion is buried in the ground. On the other hand, as shown in FIG.13 (b), the foundation foundation 14 is pile shape extended in a height direction.

  The deep foundation 14 shown in FIG. 13 (b) has a smaller width than the direct foundation 12 shown in FIG. 13 (a). Therefore, by using the deep foundation as the foundation of the steel tower, it is possible to reduce the construction site of the steel tower, particularly the land required for the foundation, as compared with the case of using the inverted T-shaped direct foundation that has been conventionally used. In addition, the deep foundation has the merit that it is easy to construct temporary structures such as earth retaining, and the difference in the support layer can be handled by changing the depth.

Patent 3745027

  When constructing deep foundations in mountainous areas, most of the work will be done manually or using small borehole excavators. For this reason, the steel tower is generally configured to include four main legs, but the conventional construction method that forms a deep foundation for each main leg has a high construction cost and a long construction period. turn into. In addition, in a mountainous area, it is difficult to install the four main legs in a stable place in a place where the ridge width is extremely small due to the restriction of the location point due to topography, and the restriction on route setting becomes severe.

  Therefore, development of a construction method using a pile foundation having a pile portion composed of a single deep foundation placed at the center position of the steel tower and a beam portion supporting the main leg material to the pile portion is performed. It is being considered. According to this construction method, since only one foundation is required, the construction cost and the construction period can be greatly reduced.

  Here, when the power transmission line is shaken by wind or the like, tensile stress or compressive stress is applied to the main leg material against the foundation of the steel tower. In order to prevent the main leg material from coming off the foundation due to these stresses, the main leg material is provided with an anchoring material.

  As described above, since tensile stress and compressive stress are applied to the main leg material, the anchoring material is disposed at an intermediate position in the thickness (height direction) of the beam. Then, since the thickness of the beam that can withstand the stress is about half that, it is necessary to sufficiently secure the thickness and width of the beam. Then, since a beam will become large, the construction site must be secured widely, and the advantage by using a deep foundation will be lost.

  As another issue, steel towers will need to be rebuilt when they are aged due to aging, etc., or when the height of the steel tower is insufficient to stretch a transmission line that transmits a large amount of electricity. . At this time, the new steel tower (hereinafter referred to as the new steel tower) has been removed due to the existence of existing structures around the existing steel tower (hereinafter referred to as the existing steel tower) and the wiring of the stretched wires. It is often installed at the same position as the existing steel tower.

  In addition to the temporary construction method for constructing a temporary steel tower that stretches the transmission line instead of the existing steel tower, a new steel tower is constructed outside or inside with the existing steel tower remaining. There is a construction method to do. When the new tower is constructed outside the existing tower, the new tower is necessarily larger than the existing tower. For this reason, it is necessary to purchase additional land around the existing steel tower, which increases the construction cost. On the other hand, when constructing a new steel tower inside an existing steel tower, the new steel tower is necessarily smaller than the existing steel tower. For this reason, the size of the new steel tower is limited.

  In view of such a problem, the present invention can reduce the size of the beam by increasing the breaking strength, and can reduce the construction cost, as well as the expansion of the site when rebuilding the existing steel tower, and to it An object of the present invention is to provide a steel tower rebuilding method capable of reducing the construction cost by suppressing the additional purchase of land.

  In order to solve the above-mentioned problem, a typical structure of a pile foundation according to the present invention is a pile foundation including a beam portion supporting each main leg member of a steel tower and a pile portion constructed at the center thereof. It is characterized by comprising a plurality of bearing plates attached to a portion of the leg member disposed in the beam part, and a spiral reinforcing bar or a ring reinforcing bar wound so as to surround the main leg member in the beam part.

  According to the above configuration, the concrete around the main leg is constrained by the spiral reinforcing bar or the ring reinforcing bar by the spiral reinforcing bar or the ring reinforcing bar arranged around the main leg in the beam portion. Therefore, the tensile stress and compressive stress applied to the main leg material can be applied to the entire thickness of the beam, so that the fracture strength due to the stress can be increased, and the beam and therefore the pile foundation can be downsized and the construction cost can be reduced. It becomes possible to plan.

  In order to solve the above problems, another structure of a pile foundation according to the present invention is a pile foundation including a beam portion supporting each main leg member of a steel tower and a pile portion constructed in the center thereof. An anchor plate attached to the lower end of the material, a plurality of anchor bolts embedded in the beam portion and fastening the anchor plate to the beam portion, and a helical rebar or ring rebar wound around the outside of the plurality of anchor bolts It is characterized by that. According to this configuration, even when the main leg member is connected to the beam portion by the anchor plate and the anchor bolt, the same effect as described above can be obtained.

The height of the beam portion relative to the pile portion may be different according to the inclination of the ground surface of the steel tower installation location.
Thereby, even if the installation heights of a plurality of main leg members differ depending on the inclination of the ground surface, each main leg member (a plurality of main leg members) can be connected to the pile part via the beam part. it can.

  In order to solve the above-mentioned problems, a typical structure of the steel tower rebuilding method according to the present invention is a new steel tower having a pile foundation described above as an existing steel tower having a separate existing foundation on each of a plurality of main legs. It is a steel tower rebuilding method that replaces the pile foundation, and the pile foundation is installed so that the beam part overlaps the existing foundation.

  According to the pile foundation mentioned above, the beam in a pile foundation can be reduced in size. And according to the said structure, it arrange | positions so that the beam in a pile foundation may overlap with an existing foundation. Thereby, the area which the pile foundation which is the foundation of a new steel tower overhangs the construction site of an existing steel tower can be reduced. Therefore, it is possible to suppress the expansion of the site when rebuilding the existing steel tower and the increase in purchase of the resulting site, thereby reducing the construction cost.

  In the above steel tower rebuilding method, it is preferable to dispose the existing steel tower after constructing the new steel tower outside or inside the existing steel tower by arranging the beams so as to overlap the existing foundation while leaving the existing steel tower. According to such a configuration, when constructing a new steel tower while leaving the existing steel tower, even if the new steel tower is constructed outside or inside the existing steel tower, the site required for the new steel tower is compared with the conventional one. Can be reduced.

  In the above steel tower reconstruction method, the existing steel tower is removed, the existing foundation is extended deep under the beam, the main legs of the existing steel tower are exposed, and the bearing plate is attached to the exposed main legs. It is better to hit the concrete of the beam so as to embed the legs.

  In the above steel tower rebuilding method, the existing steel tower is removed, the existing foundation is extended deep under the beam, the main legs of the existing steel tower are exposed, the exposed main legs are cut, and the existing foundation is mounted. It is better to hit the concrete of the beam.

  According to this structure, the foundation of a new steel tower can be reinforced with the existing foundation. Therefore, it is possible to increase the strength against stress in the new steel tower. Moreover, since it is not necessary to remove the existing foundation effectively, the work and cost required for the removal can be reduced.

  According to the present invention, it is possible to reduce the size of the beam by increasing the breaking strength and to reduce the construction cost, and to expand the site when rebuilding the existing steel tower and to purchase the site resulting therefrom. It becomes possible to provide a steel tower rebuilding method capable of reducing the construction cost by suppressing the increase.

It is a figure explaining the pile foundation concerning a 1st embodiment. It is a detailed sectional view of a pile foundation concerning a 1st embodiment. It is a perspective view explaining the bearing plate of FIG. It is a perspective view explaining the bar arrangement in the beam part of FIG. It is a figure explaining the effect | action of the stress in a pile foundation. It is a figure explaining the other example of a beam part. It is a detailed sectional view of a pile foundation concerning a 2nd embodiment. It is a figure explaining the pile foundation concerning 3rd Embodiment. It is a figure explaining the steel tower rebuilding method of 4th Embodiment. It is a figure explaining the steel tower rebuilding method of 5th Embodiment. It is a figure explaining the steel tower rebuilding method of 6th Embodiment. It is a figure explaining the steel tower rebuilding method of 7th Embodiment. It is a figure explaining the foundation of a steel tower.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in the embodiments are merely examples for facilitating understanding of the invention, and do not limit the present invention unless otherwise specified. In the present specification and drawings, elements having substantially the same function and configuration are denoted by the same reference numerals, and redundant description is omitted, and elements not directly related to the present invention are not illustrated. To do.

(Pile foundation of the first embodiment)
FIG. 1 is a diagram for explaining a pile foundation 100 according to the first embodiment, and FIG. 1 (a) shows a state in which the pile foundation 100 of the first embodiment is observed from the side, and FIG. b) has shown the state which observed the pile foundation 100 of 1st Embodiment from upper direction. Although the pile foundation 100 is mostly buried in the ground, in order to facilitate understanding, the buried pile foundation 100 was observed from the side or from above in FIGS. 1 (a) and (b). Indicates the state.

  As shown to Fig.1 (a) and (b), the pile foundation 100 of 1st Embodiment has the beam part 120a * 120b * 120c * 120d and the pile part 110 constructed | assembled in the center. The pile part 110 is a pile constructed in the ground by a deep foundation method.

  As shown in FIG.1 (b), in the pile foundation 100 of 1st Embodiment, the beam parts 120a-120d protrude in 4 directions centering | focusing on the pile part 110. As shown in FIG. That is, the pile foundation 100 has a cross shape as a whole when observed from above. The beam portions 120a to 120d support the main leg members 10a to 10d, respectively.

  FIG. 2 is a detailed cross-sectional view of the pile foundation 100 according to the first embodiment. FIG. 3 is a perspective view for explaining the bearing plate 130 of FIG. In addition, since the four beam parts 120a-120d have the same structure, in this embodiment, the beam part 120a is illustrated and demonstrated.

  As shown in FIG. 2, the pile foundation 100 according to the present embodiment includes a plurality of bearing plates 130, a plurality of force distribution bars 140, and a helical reinforcing bar 150. A ring reinforcing bar may be used instead of the helical reinforcing bar. As shown to Fig.3 (a), in this embodiment, the bearing plate 130 is comprised with L-shaped steel. As shown in FIG. 2, a plurality of bearing plates 130 are attached to a portion of the main leg 10 a that is disposed within the beam portion 120 a. As a result, the fixing strength of the main leg member 10a to the beam portion 120a made of concrete can be increased as will be described later.

  FIG. 3B shows another example of the bearing plate. When the main leg member 10f is a steel pipe, a bearing plate can be formed by welding a plurality of ring steels 130a to the main leg member.

  FIG. 4 is a perspective view illustrating the bar arrangement in the beam portion 120a of FIG. In FIG. 4, the main leg material 10a and the bearing plate 130 shown in FIG. 2 are not shown. As shown in FIGS. 2 and 4, a skeleton of the beam portion 120a is formed inside the beam portion 120a by a plurality of main reinforcing bars 122 arranged in the upper and lower portions. The main reinforcing bars 122 are connected by a plurality of reinforcing bars 124 arranged in the horizontal direction and the vertical direction. In FIG. 4, end reinforcing reinforcing bars (T-head method reinforcing bars) are drawn as the distribution bars 124, but ordinary bending reinforcing bars may be used.

  As shown in FIG. 2, a plurality of distribution bars 140 are arranged around the main leg member 10a in the beam portion 120a. As shown in FIG. 4, a plurality of power distribution bars 140 are arranged so as to surround the main leg member 10a (see FIG. 2). As shown in FIGS. 2 and 4, a spiral reinforcing bar 150 is wound around the plurality of power distribution bars 140.

  FIG. 5 is a diagram for explaining the action of stress in the pile foundation. Fig.5 (a) is typical sectional drawing which illustrated the pile foundation 100 of this embodiment, FIG.5 (b) is a top view of the pile foundation 100 shown to Fig.5 (a). FIG.5 (c) is typical sectional drawing which illustrated the pile foundation 20 of the comparative example, and FIG.5 (d) is a top view of the pile foundation 20 shown in FIG.5 (c).

  As shown in FIGS. 5C and 5D, in the pile foundation 20 of the comparative example, the anchoring material 16 is attached to a region disposed inside the beam portion 20a in the main leg member 10e. The anchor member 16 needs to withstand both the tensile stress and the compressive stress applied to the main leg member 10e. For this reason, the anchoring material 16 is arrange | positioned in the intermediate position of the thickness (height direction) of the beam part 20a. Then, in the beam portion 20a, the region above the anchoring material 16 receives tensile stress, and the region below the anchoring material 16 receives compressive stress. That is, the thickness of the beam portion 20a that can withstand each stress is as follows. About half of that. Therefore, the thickness T2 of the beam portion 20a is increased to ensure sufficient strength against tensile stress and compressive stress.

  On the other hand, as shown in FIGS. 5A and 5B, in the pile foundation of this embodiment, when tensile stress or compressive stress is applied to the beam portion 120a, shear stress is generated in the plurality of bearing plates 130. . At this time, the concrete around the main leg 10a is constrained by the spiral reinforcing bar 150 wound around the power distribution bar 140. Therefore, when the helical reinforcing bar 150 receives the shear stress, it is possible to receive the tensile stress and the compressive stress in the entire thickness of the beam portion 120a. Therefore, since the strength against stress in the beam portion 120a can be increased, the thickness T1 of the beam portion 120a can be made thinner than T2.

  Moreover, in the pile foundation 20 of a comparative example, as shown in FIG.5 (c) and (d), the fracture surface F2 by the shear stress produced when the tensile stress was applied is large. In order to cover this, it is necessary to ensure that the width W2 of the beam portion 20a is larger than the fracture surface F2. On the other hand, in the pile foundation 100 of this embodiment, the fracture surface F <b> 1 due to the shear stress is smaller than the width of the spiral reinforcing bar 150. Therefore, the width of the fracture surface F2 can be made significantly smaller than when the anchoring material 16 is used as in the comparative example, and the width of the beam portion 120a can be narrowed.

  As described above, according to the pile foundation 100 of the present embodiment, the helical rebar 150 is arranged around the main leg member 10a, so that the tensile stress and the compressive stress applied to the main leg member 10a can be reduced. Can be received throughout the thickness. As a result, the fracture strength due to the stress increases and the fracture surface due to the shear stress decreases, so that it is possible to reduce the size of the beam portion 120a and the pile foundation 100 and reduce the construction cost.

  FIG. 6 is a diagram illustrating another example of the beam portion. In the pile foundation 100 of this embodiment, as shown in FIG.1 (b), the structure by which the four beam parts 120a-120d are provided centering on the pile part 110, ie, the pile foundation 100 becomes cross shape in planar view. However, the present invention is not limited to this.

  In Fig.6 (a), the beam part 120e is circular shape, and the four main leg members 10a-10d are supported in one circular beam part 120e. In FIG. 6B, the beam portion 120f has a quadrangular shape, and the four main leg members 10a to 10d are supported by one quadrangular beam portion 120f. Even if a mat floor board is used instead of the beam portions 120e and 120f having such a shape, that is, the beam portions 120e and 120f, the same effect as described above can be obtained.

(Pile foundation of the second embodiment)
FIG. 7 is a detailed cross-sectional view of a pile foundation 200 according to the second embodiment. In addition, in the following embodiment, about the element which has the same function as the component of the pile foundation 100 of 1st Embodiment, description is abbreviate | omitted by attaching | subjecting the same code | symbol. Since the beam part 220a and the beam part 220b shown in FIG. 7 have the same configuration, the beam part 220a will be described as an example.

  As shown in FIG. 7, in the pile foundation 200 of the second embodiment, the main leg member 10a is not embedded in the beam part 220a, but the upper surface of the beam part 220a by the anchor plate 202 attached to the lower end of the main leg member. Attached to. The anchor plate 202 is fastened to the beam portion 220a by anchor bolts 204. Thereby, the main leg 10a is fixed to the beam part 220a via the anchor plate 202 and the anchor bolt 204. In addition, a lower end of the anchor bolt 204 located near the lower surface of the beam portion and an end reinforcing plate 206 are attached.

  In the pile foundation 200 of the second embodiment, compressive stress is received on the upper surface of the beam portion 220a, and tensile stress is received on the end reinforcing plate 206 in the beam portion 220a. Therefore, these stresses are received in the entire thickness of the beam portion 220a. It becomes. Therefore, similarly to the pile foundation 100 of the first embodiment, the strength against stress in the beam portion 220a can be increased, and the thickness of the beam portion 220a can be reduced. Further, in the pile foundation 200 of the second embodiment, since the helical rebar 150 is arranged around the anchor bolt 204, the fracture surface due to the shear stress can be reduced similarly to the first embodiment, and the beam portion 220a and therefore It is possible to reduce the size of the entire pile foundation 200.

(Pile foundation of the third embodiment)
Drawing 8 is a figure explaining pile foundation 300 concerning a 3rd embodiment, and has shown the state where pile foundation 300 was observed from the side. As shown in FIG. 8, in the pile foundation 300 of 3rd Embodiment, the height with respect to the pile part 110 of the some beam parts 320a * 320b differs according to the inclination of the ground surface 1 of the installation location of the tower 10. As shown in FIG. In this way, the pile foundation 300 is configured to include a plurality of beam portions 320a and 320b for the plurality of main leg members 10a and 10b of the steel tower 10, respectively, so that the installation height of each main leg member is different. They can also be connected to the piles 110 respectively.

(Steel rebuilding method of the fourth embodiment)
Next, a steel tower rebuilding method will be described in which an existing steel tower having a separate existing foundation on each of a plurality of main legs is replaced with a new steel tower having a pile foundation described above. FIG. 9 is a diagram for explaining the steel tower rebuilding method according to the fourth embodiment. FIG. 9A shows a state in which the steel tower and the pile foundation 100 are observed from the side, and FIG. The state which observed the pile foundation 100 of Fig.9 (a) from upper direction is shown. In addition, in FIG. 9 (a) and (b), the existing steel tower 50 is illustrated with the broken line.

  In the steel tower rebuilding method of the fourth embodiment, an excavation hole (not shown) for the pile portion 110 is first formed inside the existing foundations 52a, 52b, 52c, and 52d of the existing steel tower 50 while leaving the existing steel tower 50 left. Form. And the pile part 110 shown to Fig.9 (a) is constructed | assembled by placing concrete in an excavation hole. If the pile part 110 is constructed | assembled, as shown to FIG.9 (b), by installing the beam parts 120a-120d so that it may overlap with the existing foundations 52a-52d, the beam parts 120a-120d may overlap with the existing foundations 52a-52d. The pile foundation 100 of the steel tower 10 (newly constructed steel tower) is installed. Then, the steel tower 10 is constructed outside the existing steel tower 50, and the existing steel tower 50 is removed (so-called tucking method).

  According to the said structure, as shown in FIG.9 (b), the foundation of a new tower, ie, the pile foundation 100 of this embodiment, is located inside the foundation position P of the conventional squeezing method, It arrange | positions in the substantially same position as the existing foundations 52a-52d. Therefore, in the conventional construction method, it is necessary to purchase more land around the existing steel tower 50, but in the steel tower rebuilding method of this embodiment, it is not necessary to purchase additional land. As a result, it is possible to reduce the construction cost required for rebuilding the steel tower.

  Moreover, since the existing foundations 52a to 52d are used for the new foundation, the rigidity of the new foundation can be increased. In particular, the beam portions 120a to 120d are cantilever beams, and if the vicinity of the tip of the beam is supported by the existing foundations 52a to 52d, the length of the beam arm can be shortened. Accordingly, the rigidity can be dramatically increased and the cross-sectional area of the beam can be reduced.

  Furthermore, since the existing foundation is used as the new foundation, it is not necessary to remove the existing foundation. Removal of existing foundations is a heavy work burden, and heavy concrete foundations become waste, so the transportation burden is also large. This is especially true when it comes to existing foundations in the mountains. Therefore, it is very beneficial to remove the existing foundation.

(Pylon rebuilding method of the fifth embodiment)
FIG. 10 is a diagram for explaining the steel tower rebuilding method according to the fifth embodiment. Fig.10 (a) has shown the state which observed the steel tower and the pile foundation 100 from the side, FIG.10 (b) has shown the state which observed the pile foundation 100 of Fig.10 (a) from upper direction. . In FIGS. 10A and 10B, the existing steel tower 50 is illustrated by broken lines.

  As shown in FIG. 10, in the steel tower rebuilding method of 5th Embodiment, the pile part 110 is built with the existing steel tower 50 remaining like the 4th Embodiment. If the pile part 110 is constructed | assembled, as shown to FIG.10 (b), the beam parts 120a-120d will be installed so that it may overlap with the existing foundations 52a-52d. Thereby, the pile foundation 100 of the steel tower 10 (new steel tower) is installed so that the beam parts 120a-120d may overlap with the existing foundations 52a-52d. Then, the steel tower 10 is constructed inside the existing steel tower 50, and the existing steel tower 50 is removed (so-called mastication method).

  According to the said structure, as shown in FIG.10 (b), the pile foundation 100 which is a foundation of a new steel tower is arrange | positioned so that the beam parts 120a-120d may overlap with the existing foundations 52a-52d, and existing foundations 52a-52d. Is inside. Therefore, since the foundation of the new steel tower does not protrude beyond the construction site of the existing steel tower 50, it is not necessary to purchase additional land, and it is possible to reduce the construction cost required for rebuilding the steel tower.

  Moreover, since the existing foundations 52a to 52d are used for the new foundation, the rigidity of the new foundation can be increased. In particular, the beam portions 120a to 120d are cantilever beams, and if the vicinity of the tip of the beam is supported by the existing foundations 52a to 52d, the beam portions 120a to 120d are both cantilever beams. Accordingly, the rigidity can be dramatically increased and the cross-sectional area of the beam can be reduced.

(Steel rebuilding method of the sixth embodiment)
Drawing 11 is a figure explaining the tower reconstruction method of a 6th embodiment, and has shown the state which observed the tower and the foundation from the side. In addition, in order to make an understanding easy, in FIG.11 (b) and (c), the existing steel tower 50 is illustrated with the broken line.

  As shown to Fig.11 (a), the main leg material (henceforth existing main leg material 50a * 50b) which comprises the existing steel tower 50 is each supported by the existing foundations 52a * 52b. In the steel tower rebuilding method according to the sixth embodiment, first, the existing steel tower 50 shown in FIG. And as shown in FIG.11 (b), the excavation hole 110a which builds the pile part 110 of the pile foundation 100 is formed.

  Next, the existing foundations 52a and 52b are suspended to the depth D corresponding to the lower surfaces of the beam portions 120a and 120b of the pile foundation 100 to expose the existing main leg members 50a and 50b. As shown in FIG. 11B, a supporting plate 130 is attached to the exposed existing main leg members 50a and 50b. When the bearing plate 130 is attached, as shown in FIG. 11C, concrete is cast so as to embed the existing main leg members 50a and 50b, and the beam portions 120a and 120b are constructed.

  According to the said structure, the intensity | strength with respect to the tensile stress and compressive stress of beam part 120a * 120b can be raised with the existing main leg members 50a * 50b embedded in beam part 120a * 120b. Further, by effectively utilizing the existing foundations 50a and 50b, it is not necessary to remove the foundations 50a and 50b, so that the work and cost required for removal can be reduced. In the present embodiment, the configuration in which the bearing plate 130 is attached to the exposed existing main leg members 50a and 50b is illustrated, but the present invention is not limited to this, and a configuration in which the bearing plate 130 is not attached is also possible.

(Steel rebuilding method of the seventh embodiment)
Drawing 12 is a figure explaining the tower reconstruction method of a 7th embodiment, and has shown the state where the tower and the foundation were observed from the side. In addition, about the element which has the same function and structure as the steel tower rebuilding method of 6th Embodiment, description is abbreviate | omitted by attaching | subjecting the same code | symbol.

  Also in the steel tower rebuilding method of 7th Embodiment, the existing steel tower 50 of Fig.12 (a) is removed first, and the excavation hole 110a is formed. Next, the existing main legs 50a and 50b are exposed through the existing foundations 52a and 52b to the depth D corresponding to the lower surfaces of the beam portions 120a and 120b of the pile foundation 100, and the exposed existing main legs 50a and 50b are exposed. Cut 50b. Then, by placing concrete so as to ride on the existing foundations 52a and 52b, the beam portions 120a and 120b are constructed on the existing foundations 52a and 52b.

  Also with the above configuration, since the existing foundations 52a and 52b can be effectively used, it is possible to reduce the work and cost required for removal as in the steel tower rebuilding method of the sixth embodiment. Further, the existing foundations 52a and 52b remaining below the beam portions 120a and 120b can increase the strength against compressive stress in the beam portions 120a and 120b. In the seventh embodiment, since the exposed existing main leg members 50a and 50b are cut, the strength against tensile stress is not reinforced, but when one main leg member is subjected to tensile stress, the opposite main leg member is applied. Compressive stress is applied. Therefore, when stress is applied, a reinforcing effect is always obtained in any of the main legs.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to the example which concerns. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

  The present invention relates to a pile foundation including a beam part supporting each main leg member of a steel tower and a pile part built in the center thereof, and an existing steel tower having a plurality of main leg parts each having an existing foundation. It can be used for a steel tower rebuilding method that replaces a new steel tower with a pile foundation.

DESCRIPTION OF SYMBOLS 10 ... Steel tower, 10a-f ... Main leg material, 12 ... Direct foundation, 14 ... Deep foundation foundation, 16 ... Anchor material, 20 ... Pile foundation, 20a ... Beam part, 50 ... Existing steel tower, 50a ... Existing main leg material, 50b ... Existing main legs, 52a ... Existing foundation, 52b ... Existing foundation, 52c ... Existing foundation, 52d ... Existing foundation, 100 ... Pile foundation, 110 ... Pile part, 110a ... Drilling hole, 120a-f ... Beam part, 122 ... main reinforcement, 124 ... force distribution, 130, 130a ... bearing plate, 140 ... force distribution, 150 ... spiral reinforcement, 200 ... pile foundation, 202 ... anchor plate, 204 ... anchor bolt, 206 ... end reinforcement plate , 220a ... beam part, 220b ... beam part, 300 ... pile foundation, 320a ... beam part, 320b ... beam part

Claims (7)

In the pile foundation including the beam part supporting each main leg member of the steel tower and the pile part built in the center,
A plurality of bearing plates attached to a portion of the main leg member disposed in the beam portion;
A spiral reinforcing bar or a ring reinforcing bar wound around the main leg in the beam portion;
Pile foundation characterized by comprising. In the pile foundation including the beam part supporting each main leg member of the steel tower and the pile part built in the center,
An anchor plate attached to the lower end of the main leg,
A plurality of anchor bolts embedded in the beam portion and fastening the anchor plate to the beam portion;
A helical rebar or ring rebar wound around the outside of the plurality of anchor bolts;
Pile foundation characterized by comprising.   3. The pile foundation according to claim 1, wherein a height of the beam portion with respect to the pile portion is different according to an inclination of a ground surface at a place where the steel tower is installed. It is a steel tower rebuilding method for replacing an existing steel tower having a separate existing foundation on each of a plurality of main legs with a new steel tower having a pile foundation according to claim 1,
The steel tower rebuilding method, wherein the pile foundation is installed such that the beam portion overlaps the existing foundation. Place the beam so as to overlap the existing foundation while leaving the existing steel tower,
The tower rebuilding method according to claim 4, wherein the existing tower is removed after a new tower is constructed outside or inside the existing tower. Removing the existing tower,
The existing foundation is exposed at the depth of the lower surface of the beam portion to expose the main legs of the existing tower,
Attach a bearing plate to the exposed main legs,
The steel tower rebuilding method according to claim 4, wherein concrete of the beam portion is hit so as to embed the main leg material. Removing the existing tower,
The existing foundation is exposed at the depth of the lower surface of the beam portion to expose the main legs of the existing tower,
Cutting the exposed main leg material,
5. The steel tower rebuilding method according to claim 4, wherein concrete of the beam portion is hit so as to ride on the existing foundation.

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