Steel tower foundation and construction method of steel tower foundation

Abstract

To easily construct a steel tower foundation.SOLUTION: The PC member 200 is laminated on the floor board 10 (laminating process). After that, concrete is filled in the laminated structure and solidified to form a concrete filling layer 21 inside, and a column body 20 is formed (concrete filling layer forming process). At this time, a plurality of anchor bolts (steel tower fixtures) 22 can be fixed to the upper portion. In particular, since the anchor bolts 22 are fixed to the concrete layer in a narrow space inside the PC member 200, the fixing can be easily and accurately performed.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a tower foundation, which is the foundation part of a steel tower installed outdoors, etc., and a method for constructing the same. [Background technology]

[0002] Steel towers that are installed outdoors and used for installing overhead power transmission lines and the like are supported by multiple steel tower foundations fixed to the ground. Such steel tower foundations are mainly made of concrete. The steel tower foundation is constructed using an installation hole formed in the ground, and has an inverted T shape that combines a floor plate installed underground as the bottom of the installation hole with a column-like pillar protruding from the floor plate above ground. The steel tower main pillar material that constitutes the steel tower is fixed to the pillar, and the installation hole is then backfilled. A method for constructing such a steel tower foundation is described, for example, in Patent Document 1.

[0003] The construction method is roughly as follows: (1) excavate the ground to form a hole for installation, (2) pour concrete into the bottom of the hole to make a floorboard, (3) place formwork on the floorboard and pour concrete into it to make a column, and (4) remove the formwork. At this time, reinforcing steel bars may also be placed inside the column.

[0004] Patent Document 2 describes a technique in which the pillars are not formed by pouring concrete into the installation holes as described above, but are manufactured in advance as precast concrete and then installed.

[0005] Generally, the main pillars of steel towers are constructed at an angle to ensure the tower's mechanical strength, and the inverted T-shaped column structure described above is used to correspond to this. However, in this case, the column must be constructed at an angle, which requires special skills. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2017-206854 [Patent Document 2] Japanese Patent Application Publication No. 6-316942 Summary of the Invention [Problem to be solved by the invention]

[0007] In particular, large steel towers may be installed in mountainous areas and other locations where installation work is difficult. In such cases, if the components required for installation work are large, it becomes difficult to transport them or install them using a crane or the like, and the technology described in Patent Document 2, for example, could not be applied.

[0008] In the technology described in Patent Document 1, the formwork used for pouring concrete can be formed by combining small pieces, but the reinforcing bars used to reinforce the columns, for example, are long, which makes them difficult to transport.

[0009] Furthermore, not only was it difficult to transport the components, but the conventional construction method was particularly difficult when the tower foundation was large and in places where work was not easy, such as on slopes in mountainous areas.

[0010] The present invention has been made in view of the above circumstances, and aims to solve the above problems. [Means for solving the problem]

[0011] The present invention is a tower foundation that supports a tower on the ground, comprising a floor plate formed at the bottom of an installation hole formed in the ground, and a column body formed to extend upward from the floor plate and connected to the tower, wherein the column body has a layered structure in which a plurality of hollow cylindrical precast concrete members are stacked along the central axis of the cylinder with the central axis being in the vertical direction, and a concrete fill layer is provided from the floor plate side to the upper side, with concrete filled inside on the central axis side. The present invention is characterized in that reinforcing bars are provided to penetrate between adjacent precast concrete members in the vertical direction. The present invention is characterized in that a tower fixing device is embedded and fixed in the upper part of the concrete fill layer, and the tower main pillar material that constitutes the tower is fixed by the tower fixing device. The present invention is a method for constructing a steel tower foundation, comprising a floor plate forming process for pouring concrete into the bottom of the installation hole to form the floor plate, a stacking process for sequentially stacking the precast concrete members on the floor plate to form the layered structure, and a concrete fill layer forming process for forming the concrete fill layer inside the layered structure to construct the column body. The present invention is characterized in that the stacking process includes a tensioning process in which tendons parallel to the central axis are fixed to the stacked precast concrete members and prestress is applied to the precast concrete members via the tendons. The present invention is characterized in that, in the stacking step, reinforcing bars are installed so as to penetrate between adjacent precast concrete members in the vertical direction. The present invention is characterized in that in the concrete fill layer forming process, a tower fixing device to which the tower main column material constituting the tower is fixed is fixed to the top of the concrete fill layer. [Effects of the Invention]

[0012] According to the present invention, a steel tower foundation can be easily constructed. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a side perspective view of a steel tower foundation according to an embodiment of the present invention. [Figure 2] 1 is a cross-sectional view perpendicular to the central axis of a precast concrete member used in a steel tower foundation according to an embodiment of the present invention. FIG. [Figure 3] 1 is a cross-sectional view (part 1) illustrating a process of constructing a steel tower foundation according to an embodiment of the present invention. [Figure 4] 5 is a cross-sectional view (part 2) of the process illustrating the method for constructing a steel tower foundation according to the embodiment of the present invention. [Figure 5] 5 is a cross-sectional view (part 3) illustrating the process of constructing a steel tower foundation according to an embodiment of the present invention. [Figure 6] FIG. 2 is a perspective view of a column body in a steel tower foundation according to an embodiment of the present invention, viewed from above. [Figure 7] FIG. 1 is a side perspective view of a conventional steel tower foundation. DETAILED DESCRIPTION OF THE INVENTION

[0014] A method for constructing a steel tower and a steel tower foundation according to an embodiment of the present invention will now be described. FIG. 1 is a perspective view showing the structure of this steel tower foundation 1, viewed from the horizontal direction. This steel tower foundation 1 is configured by combining a floor plate 10 and a column body 20 in an inverted T shape, and is installed inside an installation hole G0 formed in the ground G. The column body 20 is made up of a combination of multiple (eight in the figure) PC members (precast concrete members or precast members) 200. In this case, each PC member 200 can be made small, making transportation and installation easy. Furthermore, a steel tower is fixed to the upper side of the column body 20, and this fixing is also easy. In FIG. 1, the installation hole G0 is actually backfilled with soil after the steel tower is fixed to the steel tower foundation 1, but the illustration of this soil is omitted.

[0015] Each PC member 200 has a common hollow cylindrical shape, and the outer wall of the cylindrical shape has multiple through-holes parallel to the central axis C formed along the circumferential direction of the outer wall. FIG. 2 is a cross-sectional view perpendicular to the central axis C, showing the structure of this PC member 200. These through-holes include multiple tendon through-holes 200A through which PC steel rods (tension members) (described later) pass, and multiple rebar through-holes 200B through which rebars (described later) pass. The shapes of anchor plates used during tensioning work (described later) are indicated by dotted lines at the locations of the tendon through-holes 200A. As described later, the hollow region on the central axis C side of the cylindrical shape is filled with concrete. The process of stacking and connecting the PC members 200 is similar to that described on the PC Well Construction Method Research Association website (https: / / www.pc-well.gr.jp / pcwell.php).

[0016] 3 to 5 are cross-sectional views showing the steps in the method for constructing this tower foundation 1. First, as shown in FIG. 3(a), an installation hole G0 is formed in the ground G. Then, as shown in FIG. 3(b), concrete is poured into the bottom of the installation hole G0 to form a floor panel 10. Although not shown in the figures, a formwork is used as appropriate at this time, and the formwork can be removed afterwards.

[0017] After that, the PC members 200 are stacked on the floor panel 10 (stacking process). First, as shown in FIG. 3(c), the bottom PC member 200 is placed on the floor panel 10. As shown in FIG. 4(d), prestress is applied to this PC member 200 by tensioning it (tensioning process). FIG. 4(d) shows an enlarged view of the PC member 200 in FIG. 3(c). In this process, PC steel rods (tension members) 300 are installed in the tendon through-holes 200A, and anchor plates (not shown) are attached above and below the PC steel rods 300 and tightened. While only one PC steel rod 300 each on the left and right sides is shown in the figure, in reality, a PC steel rod 300 is installed corresponding to each tendon through-hole 200A in FIG. 2. This process is similar to the work described, for example, in JP 2022-188488 A.

[0018] Once the tensioning operation is completed, as shown in FIG. 4(e), the next PC member 200 is stacked on top of it, and as shown in FIG. 4(f), tensioning is similarly performed on this PC member 200. FIG. 4(f) also shows an enlarged view of the state of the PC member 200 in FIG. 4(e). In this case, similar to the technology described in JP 2022-188488 A, the tension members 300 in the first PC member 200 and the tension members 300 in the second PC member 200 can be connected with bolts. In addition, the upper surface of the first PC member 200 and the lower surface of the second PC member 200 can be joined with epoxy resin or the like.

[0019] 5(g), reinforcing bars 310 are inserted from above through the reinforcing bar through holes 200B of the second-tier PC member 200 and the first-tier PC member 200. This fixes the first-tier PC member 200 and the second-tier PC member 200 in a state where prestress is applied to each of them. At this time, grout can be filled into the tendon through holes 200A and the reinforcing bar through holes 200B, similar to the technique described in JP 2022-188488 A.

[0020] Thereafter, the upper PC members 200 can be tensioned in the same manner as in the steps of Figures 4(e), (f) and 5(g) and then stacked one after the other. Finally, as shown in Figure 5(h), a stacked structure of eight PC members 200 is obtained, completing the stacking process. Then, concrete is filled into this stacked structure and allowed to harden, forming a concrete fill layer 21 inside, forming the column body 20 shown in Figure 1 (concrete fill layer formation process). At this time, as shown in Figure 5(i), multiple anchor bolts (tower fixing devices) 22 can be fixed to the upper part. In particular, the anchor bolts 22 are fixed to the concrete layer in the narrow space inside the PC member 200, so that the fixing can be performed easily and accurately.

[0021] Figure 6 shows (a) a perspective view of the tower foundation 1 as seen from above in the state shown in Figure 5(i), and (b) a perspective view of the state in which a tower main pillar material 400, which is part of the tower, is fixed to the tower foundation. As shown in Figure 6(a), eight anchor bolts 22 are embedded in the upper side of the concrete fill layer 21 and protrude upward.

[0022] As shown in Figure 6(b), with the plate-shaped fixing portion 410 at the bottom of the tower main pillar material 400 engaged with the anchor bolt 22, the nut 23 is screwed onto the anchor bolt 22, thereby fixing the tower main pillar material 400 to the column body 20. This allows the tower to be easily and firmly fixed to the tower foundation 1. As mentioned above, in the state shown in Figure 6(b), the area around the column body 20 is backfilled with soil. Note that in Figure 6, the through holes shown in Figure 2 are omitted.

[0023] In the technology described in Patent Document 1, the column body 20 is also formed by pouring concrete, which requires formwork. In contrast to this, in the above-mentioned tower foundation 1, PC members 200 are used instead of formwork. In this case, unlike formwork, the PC members 200 remain as they are even after the formation of the concrete fill layer 21, and become components that make up the outside of the column body 20. In this case, the mechanical strength of each PC member 200 is maintained high by the above-mentioned tensioning work, and the mechanical strength of this column body 20 can be increased.

[0024] Furthermore, because the PC members 200 do not need to be removed after construction, unlike formwork, the work shown in FIG. 3 is easier to perform than with the technique described in Patent Document 1, making it easier to work in difficult locations, such as mountain slopes. In this case, each PC member 200 corresponds to a structure obtained by vertically dividing the column 20. Because these members can be made smaller and lighter, transportation and installation are easier than with the technique described in Patent Document 2. Increasing the number of divisions allows for a smaller and lighter PC member 200, but increases the number of steps in the construction method shown in FIGS. 3 to 5. Conversely, fewer divisions reduce the number of steps, but make transportation and installation of each individual PC member 100 more difficult. Therefore, the number of divisions is appropriately determined depending on, for example, the size of the column 20 and the installation environment. In either case, it is clear that transportation of the components used is easier than with the technique described in Patent Document 2, in which columns are manufactured and installed externally.

[0025] Furthermore, although the reinforcing bars 310 are relatively long in the above example, in the construction method described above, their length can be kept to, for example, about twice the height of the PC member 200, making them easy to transport.

[0026] Furthermore, as is well known with the PC construction method and PC well construction method, the individual PC members 200 can be manufactured easily and with high precision in a fixed environment that differs from the construction site. Therefore, compared to when the column is cast in place as in the technique described in Patent Document 1, the construction error of the column is also smaller.

[0027] In the above example, the tensioning work (FIGS. 4(d) and (f)) was performed for each individual PC member 200. However, it is also possible to use PC steel rods 300 of a length corresponding to the laminated structure of, for example, two PC members 200, and perform tensioning work for each laminated structure. Even in this case, the length of the PC steel rods 300 used is at most approximately the same as the reinforcing bars 310.

[0028] In the technology described in Patent Document 1, the column body is formed by casting in place, so the method of fixing the tower main column material to the tower foundation is different. Figure 7 is a diagram showing the structure of such a conventional tower foundation 9, similar to Figure 1. In this case, a floor plate 10 is formed in the same way as the tower foundation 1 described above, but anchor members 130 are installed within it, and tower main column materials 400 are fixed to these anchor members 130. In this state, the column body 120 is formed by pouring concrete over the entire body using formwork. In reality, reinforcing steel bars and the like are also provided inside the column body 120, but this is not shown.

[0029] In this case, it is also necessary to provide anchor members 130 when forming the floor plate 10. Furthermore, in the structure of Figure 7, the tower main pillar material 400 that constitutes the tower is longer by the length of the column body 120 compared to the structure of Figure 6. For this reason, when the above tower foundation 1 is used, the tower main pillar material 400 of the tower above it can be made shorter than when a conventional tower foundation is used, which reduces steel costs and makes tower installation work easier.

[0030] Furthermore, in the prior art described in Patent Documents 1 and 2, as shown in Fig. 7, the pillar material 120 is also inclined in accordance with the inclination of the tower main pillar material 400. However, as mentioned above, in this case, the pillar body 120 needs to be constructed at an incline, which requires special skills.

[0031] In contrast to this, in the above-described tower foundation 1, the central axis of the column body 20 is set to the vertical direction, and therefore, the above-described stacking process can be easily carried out, particularly when the column bodies 20 are stacked in the vertical direction without being inclined in this way. In other words, the tower foundation 1 shown in Fig. 1 can be easily constructed, and the tower (tower main column material) can be easily fixed to it.

[0032] In addition, in Figure 1, the outer diameter and vertical height of all the PC members 200 are the same and are common. However, it is not necessary for all the PC members 200 to have the same height, and it is clear that a column can be constructed in the same way even in this case. In this case, for example, PC members of multiple heights can be manufactured as standard products and these can be appropriately combined to construct a column. In this case, the tower foundation can be constructed particularly inexpensively.

[0033] In the above example, the PC member 200 is assumed to have a hollow cylindrical shape, but a similar configuration is possible even if the shape of the PC member is a hollow tubular shape other than a cylindrical shape (for example, a tubular shape with a cross-sectional outer shape such as a square prism or hexagonal prism).

[0034] The present invention has been described above based on an embodiment. This embodiment is merely an example, and it will be understood by those skilled in the art that various modifications are possible in the combination of the respective components, and that such modifications are also within the scope of the present invention. [Explanation of symbols]

[0035] 1, 9 Tower foundation 10 Floorboards 20, 120 columns 21 Concrete filling layer 22 Anchor bolt (tower fixing device) 23 Nut 130 Anchor wood 200 PC members (precast concrete members, precast members) 200A tendon through hole 200B Rebar Through Hole 300 PC steel bar (tension material) 310 Reinforced concrete 400 Steel tower main pillar material 410 Fixed part C center axis G Ground G0 installation hole

Claims

1. A steel tower foundation that supports a steel tower on the ground, comprising: a floor plate formed at the bottom of an installation hole formed in the ground; and a column body formed to extend upward from the floor plate and connected to the steel tower, The column is a laminated structure in which a plurality of hollow cylindrical precast concrete members are stacked along the central axis of the cylinder, with the central axis being in the vertical direction, and a concrete fill layer is provided from the floor plate side to the upper side on the central axis side.

2. The steel tower foundation according to claim 1, characterized in that reinforcing bars are provided to penetrate between adjacent precast concrete members in the vertical direction.

3. 3. The tower foundation according to claim 1, wherein a tower fixing device is embedded and fixed in the upper part of the concrete infill layer, and the tower main pillar material constituting the tower is fixed by the tower fixing device.

4. The method for constructing a steel tower foundation according to claim 1, a floor board forming step of forming the floor board by pouring concrete into the bottom of the installation hole; a lamination step of sequentially stacking the precast concrete members on the floor plate to form the layered structure; a concrete fill layer forming step of forming the concrete fill layer inside the laminated structure to construct the column body; A method for constructing a steel tower foundation, comprising:

5. A method for constructing a steel tower foundation as described in claim 4, characterized in that during the stacking process, a tensioning process is included in which tendons parallel to the central axis are fixed to the stacked precast concrete members and prestress is applied to the precast concrete members via the tendons.

6. A method for constructing a steel tower foundation as described in claim 4 or 5, characterized in that in the stacking process, reinforcing bars are installed that penetrate between adjacent precast concrete members in the vertical direction.

7. 6. A method for constructing a steel tower foundation according to claim 4 or 5, characterized in that in the concrete fill layer forming step, a steel tower fixing device to which a steel tower main column material constituting the steel tower is fixed is fixed to the top of the concrete fill layer.

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