Foundation structure for wind power generation, and construction method of foundation structure for wind power generation

Abstract

To provide a foundation structure for wind power generation and a construction method of a foundation structure for wind power generation that can easily increase a hub height of a wind turbine for wind power generation at low cost.SOLUTION: A lower end of a wind turbine tower 90 is joined to a foundation structure 10. The foundation structure 10 is made of reinforced concrete or prestressed concrete and comprises a bottom 1, a cylinder portion 3 that stands on the bottom 1 on the ground, and a top end 5 joined to a steel tower 90 at the top of the cylinder portion 3. A hollow portion 7 inside the cylinder portion 3 is filled with filling material 11 up to a predetermined height.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a foundation structure for wind power generation and a construction method for the foundation structure for wind power generation. [Background technology]

[0002] Large wind turbines for wind power generation have a rotor made up of a hub and blades, and a nacelle that houses the generator, located near the top of a cylindrical steel tower. A wind turbine can generate greater power output by catching faster winds. Generally, the wind speeds that blow near the ground surface increase the higher the altitude. For this reason, it is desirable to make the height of the hub above the ground (hereafter simply referred to as "hub height") as high as possible.

[0003] In order to obtain even greater power output, it is also desirable to make the rotor larger so that it can catch the wind over a wider area. However, if the rotor diameter is increased while the vertical length of the tower (i.e., roughly equivalent to the hub height) remains the same, the bottom ends of the blades will pass close to the ground, which is dangerous. Therefore, in order to increase the rotor diameter, it is necessary to make the hub height as high as possible.

[0004] In conventional technology, increasing the hub height requires increasing the vertical length of the tower. However, in order for a vertically long tower to stand with sufficient strength, the outer diameter of the tower must be increased, making the tower thicker.

[0005] Typically, a tower is manufactured in a manufacturing factory in the form of a divided body that is divided into multiple vertical sections and horizontal sections, and then transported to the installation site of the wind turbine and assembled into the tower shape at the installation site.

[0006] However, if a tower with a large (thick) outer diameter is to be installed in consideration of the above-mentioned demands, problems arise when transporting the tower segments over land from the manufacturing factory to the installation site. For example, considering road standards in Japan, if the tower segments are to be placed on a loading platform with their axial direction (the vertical direction of the tower) roughly parallel to the road surface, the height of tunnels and pedestrian bridges becomes an obstacle, and the maximum diameter of the tower can only be about 4.5 m.

[0007] In response to this, a technology has been put into practical use overseas in which a steel tower is divided not only into multiple sections vertically and horizontally, but also into multiple sections when viewed in cross section perpendicular to the vertical direction, and the parts are transported in the form of arc panels, and then joined and assembled into a cylindrical shape at the installation site (for example, Patent Document 1). This technology aims to increase the efficiency of marine transportation, but it has the potential to solve the aforementioned issues with land transportation within Japan. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] International Publication No. 2004 / 083633 Summary of the Invention [Problem to be solved by the invention]

[0009] However, Patent Document 1 requires an extra step of joining and integrating arc-shaped parts into a cylindrical shape, which significantly increases the number of man-hours and the required work space at the installation site. Furthermore, it requires a great deal of effort to ensure that the tower is perfectly round with the required precision in the vertical cross section, making it difficult to say that it is efficient. Furthermore, there is no record of this system obtaining design approval in Japan, and it is thought that it would be difficult to obtain approval and introduce it in accordance with Japan's strict seismic design standards.

[0010] For this reason, there is a demand for new structures and construction methods that can easily increase the hub height at low cost.

[0011] The present invention has been made in consideration of the above-mentioned problems, and its object is to provide a foundation structure for wind power generation that can easily increase the hub height of a wind turbine for wind power generation at low cost, and a construction method for the foundation structure for wind power generation. [Means for solving the problem]

[0012] In order to achieve the above-mentioned object, the first invention is a foundation structure for wind power generation made of reinforced concrete or prestressed concrete, which comprises a bottom, a tubular section that stands above the bottom on the ground, and a top end that is joined to a steel tower at the top of the tubular section, and the hollow section inside the tubular section is filled with fill material up to a predetermined height.

[0013] According to the first invention, the tower is joined to a foundation structure, most of which is built on the ground, allowing for easy and low-cost increases in the hub height of the wind turbine. Since the tower itself is not being lengthened in the vertical direction, problems associated with increasing the tower's diameter to strengthen it are not encountered. Furthermore, since the hollow portion inside the tubular portion is filled with fill material to a predetermined height, the necessary weight to support the tower can be easily achieved using the fill material. Furthermore, there is no need to unnecessarily increase the reinforced concrete (RC) or prestressed concrete (PC) portion to achieve weight; this can be kept to a minimum, thereby reducing construction time and costs. Furthermore, since the fill material is filled only to a predetermined height rather than filling the entire hollow portion, the center of gravity of the foundation structure is prevented from becoming too high. This prevents the foundation from tipping over even during large lateral shaking caused by earthquakes and other events, providing stable support for the tower.

[0014] Furthermore, it is desirable that the fill material be liquefied treated soil. By using liquefied treated soil as the fill material, it is possible to easily maintain a constant density and quality when filling, and it is easy to control the amount of filling, so that the foundation structure can be accurately constructed to the designed weight while reducing the number of management steps and costs.

[0015] It is also desirable that a cable pipe be arranged so as to penetrate the filler material and the bottom. Since the cable pipe is arranged so as to penetrate the filler material and the bottom, by inserting a power transmission cable or the like, it can be easily connected to a power transmission target outside the wind turbine.

[0016] Furthermore, it is desirable that the upper part of the pipe penetrates the top end. Since the upper part of the pipe penetrates the top end, the power transmission cable can be easily inserted from near the bottom end of the tower to the top end, the fill material, the bottom, and the ground.

[0017] In addition, the flange portion at the lower end of the tower may be fixed to the top end with an anchor bolt, and the lower end of the anchor bolt may protrude from the underside of the top end and be fixed to the top end with a base flange. Because the lower end of the anchor bolt protrudes from the underside of the top end and is fixed to the top end with a base flange, the thickness of the top end can be reduced, reducing the amount of RC (or PC) used and resulting in cost savings.

[0018] The foundation structure may be made of reinforced concrete, and the flange portion at the lower end of the tower may be fixed to the top end with anchor bolts, and the anchor bolts may be joined to the main reinforcement inside the top end or the tubular portion. Because the anchor bolts are joined to the main reinforcement inside the top end or the tubular portion, the open portion of the top end can be made larger, reducing the amount of reinforcement used and lowering costs. In addition, because the opening at the top end can be made larger, it becomes possible to install an elevator connecting the hollow portion to the inside of the tower, greatly improving the maintainability of the wind turbine.

[0019] The second invention is a construction method for a foundation structure for wind power generation of the first invention, characterized in that it comprises the steps of constructing a bottom portion on the ground, constructing a tubular portion on top of the bottom portion, filling the inside of the tubular portion with filler material, installing shoring and formwork above the filler material to construct a top portion on top of the tubular portion, and joining a steel tower to the top portion.

[0020] According to the second invention, a foundation structure can be constructed with most of the foundation built on the ground, and the tower can be joined onto it, allowing the hub height of the wind turbine to be increased easily and at low cost. Furthermore, since the hollow portion inside the cylindrical portion is filled with fill material, the weight required to support the tower can be easily obtained using the fill material. Furthermore, there is no need to unnecessarily increase the amount of reinforced concrete (or precast concrete) in order to gain weight, and this can be kept to a minimum, thereby reducing construction time and costs. Furthermore, shoring can be stably installed above the filled fill material 11, making it easier to construct the top end. Furthermore, since the reinforced concrete (or precast concrete) portion is not unnecessarily increased and the fill material covers part of the inner surface of the cylindrical portion within the hollow portion, the surface area of ​​the concrete exposed to air is reduced, preventing a deterioration in durability.

[0021] Furthermore, it is desirable to use liquefied treated soil as the fill material, and in the process of filling the inside of the cylindrical portion with the fill material, to solidify the fill material after filling. Because the fill material is liquefied treated soil, the density and quality of the fill material can be easily maintained constant when filled, and the amount of fill can be easily controlled, reducing management labor and costs while ensuring the foundation structure has the exact weight as designed. Furthermore, because the fill material is solidified after filling, shoring can be stably installed above it, making it easier to construct the top end.

[0022] It is also desirable to further include a step of installing a pipe that penetrates the bottom portion to a predetermined height inside the cylindrical portion, and filling the fill material to a height lower than the top of the pipe. Because the pipe that penetrates the bottom 1 is installed to a predetermined height inside the cylindrical portion and the fill material is filled to a height lower than the top of the pipe, the top of the pipe is not buried in the fill material, and the power transmission cable can be inserted so as to penetrate the fill material and the bottom. Furthermore, because the fill material is filled to a predetermined height rather than filling the entire hollow portion, it is possible to prevent the center of gravity of the foundation structure from becoming too high, making it less likely to tip over even if there is significant lateral shaking due to an earthquake or the like, and to stably support the tower. [Effects of the Invention]

[0023] According to the present invention, it is possible to provide a foundation structure for wind power generation that can easily increase the hub height of a wind turbine for wind power generation at low cost, and a construction method for the foundation structure for wind power generation. [Brief explanation of the drawings]

[0024] [Figure 1] FIG. 1 is a front view of the wind turbine 100. [Figure 2] 2(a) is a cross-sectional view of the base structure 10, and FIG. 2(b) is an enlarged view of A in FIG. 2(a). [Figure 3] 1A and 1B are diagrams explaining the construction method of the foundation structure 10, where (a) is a diagram showing the bottom 1 constructed on the ground 105, (b) is a diagram showing the tubular section 3 constructed on the bottom 1, and (c) is a diagram explaining the process of filling the inside of the tubular section 3 with the filler material 11. [Figure 4] 1A and 1B are diagrams illustrating the construction method of the foundation structure 10, in which (a) is a diagram illustrating the process of installing the support structure 201 above the filler material 11, and (b) is a diagram illustrating the process of installing the formwork for the underside of the top end 203, the formwork for the outer periphery of the top end 205, the formwork for the inner periphery of the top end 207, and anchor bolts 17 arranged on the base 211 above the filler material 11. [Figure 5] A diagram explaining the construction method of the foundation structure 10, (a) a diagram explaining the process of constructing the top end 5 on top of the tubular portion 3, and (b) a diagram showing the constructed top end 5, tubular portion 3, and bottom portion 1. [Figure 6] 6(a) is a cross-sectional view of the base structure 10a, and FIG. 6(b) is an enlarged view of B in FIG. 6(a). [Figure 7] 7(a) is a cross-sectional view of the base structure 10b, and FIG. 7(b) is an enlarged view of C in FIG. 7(a). [Figure 8] This is an enlarged view of D in Figure 7(a) to explain the construction method of the foundation structure 10b, where (a) is a diagram explaining the process of joining the anchor bolt 17b and the main reinforcement 27 and installing the formwork for the underside of the top end 203, the formwork for the outer peripheral surface of the top end 205, and the formwork for the inner peripheral surface of the top end 207, (b) is a diagram explaining the process of constructing the top end 5b, and (c) is a diagram showing the constructed top end 5b and tubular portion 3b. [Figure 9] Cross-sectional view of the base structure 10c. DETAILED DESCRIPTION OF THE INVENTION

[0025] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

[0026] (Windmill 100) 1 is a front view of a wind turbine 100 of the present invention. The wind turbine 100 is erected on the ground 105 and includes a rotor consisting of a hub and blades, a nacelle, a foundation structure 10, a tower 90, and a power transmission cable 103.

[0027] The foundation structure 10 is made of reinforced concrete and is formed on the ground 105. As will be described later, the foundation structure 10 has a generally cylindrical shape with a hollow interior, and is generally cylindrical. However, this is not limited to this, and the foundation structure 10 may be a generally elliptical cylindrical shape or a generally polygonal cylindrical shape. The detailed structure of the foundation structure 10 will be described later. The lower end of the foundation structure 10 is buried about 1.0 to 1.5 m underground, allowing for the installation of electrical wiring and the like underground.

[0028] The tower 90 is made of steel and holds the rotor (hub) and nacelle. The tower 90 is also hollow and has a roughly cylindrical shape. Like the foundation structure 10, it may be a roughly elliptical or polygonal cylinder. The lower end of the tower 90 is joined to the upper end of the foundation structure 10.

[0029] Here, the vertical length of the foundation structure 10 (the length from the bottom to the top of the foundation structure 10) is approximately 20 to 30 m. However, this is merely a guideline and is not limited to this length. In the wind turbine 100 of the present invention, the tower 90 is joined to such a foundation structure 10, so the hub height can be increased by the height of the tower 90 plus the height of the foundation structure 10. In other words, the hub height can be increased more easily than when a foundation buried underground is used. Furthermore, unlike when attempting to increase the vertical length of the tower 90 itself, there is no need to consider the strength of the tower 90 or the transportation issues that arise from increasing the diameter to strengthen it. In this way, the wind turbine 100 of the present invention allows the hub height of a wind turbine for wind power generation to be increased easily and at low cost.

[0030] The power transmission cable 103 is used to transmit electricity generated by the generator inside the nacelle to the outside of the wind turbine 100, and is laid through the inside of the tower 90 and the foundation structure 10 into the ground 105. However, this is not limitative and any suitable form may be used depending on the arrangement of surrounding power transmission targets.

[0031] (Foundation structure 10) Next, the foundation structure 10 will be described. Figure 2(a) is a cross-sectional view of the foundation structure 10. As mentioned above, the foundation structure 10 is made of reinforced concrete. (Note that illustrations of main reinforcement bars and the like are omitted from Figure 2(a) through Figure 6(b).) The foundation structure 10 is joined to the lower end of the tower 90, and functions as a spread foundation for the tower 90. Details of the joint between the foundation structure 10 and the tower 90 will be described later. The foundation structure 10 comprises a bottom portion 1, a tubular portion 3, and a top portion 5.

[0032] The bottom 1 is formed on the ground 105 and is a substantially cylindrical portion. The lower end of the bottom 1 is buried approximately 1.0 to 1.5 m underground, allowing for the installation of electrical wiring and the like underground. Depending on the layout of the underground wiring, the bottom 1 may be buried deeper or shallower. In addition, a pipe 13 is disposed in the bottom 1, penetrating it in the vertical direction. The pipe 13 is for the power transmission cable 103 of FIG. 1, and the power transmission cable 103 is inserted inside the pipe 13.

[0033] The tubular portion 3 is a generally cylindrical portion that stands above the bottom portion 1 on the ground. There is a hollow portion 7 inside the tubular portion 3, and this hollow portion 7 is filled with a filler material 11 up to a predetermined height. The filler material 11 will be described in detail later. In addition, near the lower end of the tubular portion 3, haunch-shaped portions 9 are provided on the outer and inner surfaces of the tubular portion 3 to strengthen the joint between the bottom portion 1 and the tubular portion 3. Note that the haunch-shaped portions 9 do not need to be provided if the joint strength between the bottom portion 1 and the tubular portion 3 is sufficient.

[0034] The top end 5 is the part that joins to the tower 90 at the top of the tubular section 3. The top end 5 is roughly cylindrical with an opening in the center. This opening connects the space inside the tower 90 with the hollow section 7 of the tubular section 3. A pipe 15 is also arranged in this opening so as to pass through the top end. Like the pipe 13, the pipe 15 is for the power transmission cable 103 in FIG. 1, and is connected to the pipe 13, with the power transmission cable 103 passing through it. The pipe 13 and the pipe 15 do not have to be separate pipes, but may be a continuous, integrated pipe.

[0035] From here on, for the sake of explanation, the surface of the top end 5 that contacts this open portion will be referred to as the top end inner surface, the surface that contacts the hollow portion 7 of the tubular portion 3 will be referred to as the top end lower surface, and the outer surface of the top end 5 will be referred to as the top end outer surface.

[0036] The size of the open portion of the top end 5 (i.e., the diameter of the inner peripheral surface of the top end) is smaller than the inner diameter of the tubular portion 3, and is determined appropriately so as to support the joined tower 90 without any problems, as will be described later. In other words, the top end 5 protrudes toward the center relative to the tubular portion 3. Next, the joining portion between the top end 5 and the tower 90 will be further described.

[0037] FIG. 2(b) is an enlarged view of A in FIG. 2(a). As shown in FIG. 2(b), an anchor bolt 17 integrated with a base flange 21 is fixed at a predetermined position on the top end 5. A hole for inserting the anchor bolt 17 is pre-formed in the base flange 21 at a predetermined position corresponding to the position of the anchor bolt 17. The lower end of the anchor bolt 17 protrudes from the underside of the base flange 21 by a predetermined length, and a threaded portion of a predetermined length is formed therein (the threaded portion is not shown in the drawing). The base flange 21 and the anchor bolt 17 are integrated by being screwed together with a pair of nuts 24, 24 that sandwich the base flange 21. The upper end of the anchor bolt 17 protrudes from the upper surface of the top end 5 by a predetermined length, and a threaded portion of a predetermined length is formed in the protruding portion (the threaded portion is not shown in the drawing). The tower 90 also has a flange portion 91 at its lower end. A hole for inserting the anchor bolt 17 is pre-formed in the flange portion 91 at a predetermined position corresponding to the position of the anchor bolt 17. The anchor bolt 17 is inserted through the hole and passes through the flange portion 91, with its upper end protruding from the upper surface of the flange portion 91. The tower 90 and the top end portion 5 (foundation structure 10) are joined by screwing and tightening a nut 23 onto the anchor bolt 17 from above. In this way, the foundation structure 10 serves as the foundation structure of the tower 90.

[0038] Generally, when a horizontal force is applied, the anchor bolt 17 transmits a tensile force to the fixing portion, and at the same time, the flange portion 91 resists the force by transmitting a compressive force to the concrete. In order to prevent so-called cone-shaped failure, in which the concrete cracks and falls out when a tensile force is applied to the anchor bolt 17, it is necessary to appropriately determine the horizontal position and depth position of the anchor bolt 17. Therefore, while it is desirable for the radial size of the top end (outer diameter - inner diameter) to be as small as possible in consideration of reducing the amount of reinforced concrete used, in the foundation structure 10, it is necessary to ensure a certain size or more in order to prevent damage to the top end 5, as described above.

[0039] Next, with reference to Fig. 2(a), the filler material 11 filled in the hollow portion 7 of the tubular portion 3 will be described. As described above, the filler material 11 is filled up to a predetermined height in the hollow portion 7 inside the tubular portion 3. The foundation structure 10 is the foundation structure of the tower 90, and must be heavy enough to support the tower 90. Therefore, the filler material 11 is filled up to a predetermined height or more inside the tubular portion 3.

[0040] On the other hand, the fill material 11 is not filled almost entirely into the hollow portion 7 (up to the vicinity of the underside of the top end), but is filled to a predetermined height in the hollow portion 7. In this regard, if the fill material 11 is filled too high in the hollow portion 7 with the sole emphasis on weight, the center of gravity of the foundation structure 10 will be elevated, thereby reducing stability. For example, if an excessive amount of fill material 11 is present in the hollow portion 7 at a position higher than the predetermined level, in the event of a large lateral shaking, such as during an earthquake, horizontal inertia will generate a force that tries to maintain lateral movement, increasing the overturning moment and potentially causing the entire tower 90 to topple. Therefore, the fill material 11 must be filled to a predetermined height set to prevent the above-mentioned problems from occurring. The predetermined height of the fill material 11 depends on the size and shape of the base 1, the tubular portion 3, and the top end 5, and is set to an appropriate value accordingly (e.g., so that the top surface of the fill material 11 is approximately 50% or less of the total height of the foundation structure 10).

[0041] Furthermore, it is desirable that the fill material 11 in the present invention be liquefied treated soil. As the liquefied treated soil, surplus soil generated when excavating the ground 105 during construction of the bottom 1 can be mainly used. Alternatively, but not limited to, surplus soil generated during construction of the installation site of the wind turbine 100 can be used. This can reduce the amount of surplus soil that is generated and disposed of.

[0042] In this case, by using liquefied soil as the fill material 11 rather than using surplus soil as is, the labor hours and costs required for management can be reduced. As mentioned above, because the foundation structure 10 supports the tower 90 with its own weight, careful attention must be paid to the density and filling amount of the fill material 11 when filling it to ensure the designed weight. If generated surplus soil is used as the fill material 11, frequent density tests and appropriate compaction of the surplus soil are required to maintain a constant density. In contrast, by using liquefied soil as in the present invention, the density and quality can be easily maintained constant during filling, the filling amount can be easily controlled, and management labor hours and costs can be significantly reduced. While liquefied soil is particularly preferred as the fill material 11 as described above, this is not a limitation, and earth, sand, ballast, etc. may also be used.

[0043] (Construction method for foundation structure 10) Next, a construction method for the foundation structure 10 will be described. FIGS. 3 to 5 are diagrams illustrating the construction method for the foundation structure 10. First, the base 1 is constructed on the ground. FIG. 3(a) shows the base 1 constructed on the ground 105. Well-known techniques can be used to construct the base 1. First, the ground 105 is excavated approximately 1.0 to 1.5 m to correspond to the shape of the underside of the base 1. The surplus soil generated during this process can be used for the liquefied soil described above. Next, formwork and reinforced concrete (RC) main reinforcement are placed to correspond to the shape of the base 1, and then the piping 13 is placed in a predetermined position. In this case, the piping 13 is installed to a height at least equal to the thickness of the base 1. That is, the upper end of the piping 13 is positioned so as to protrude above the base 1. Note that, as shown in the figure, the piping 13 may be positioned higher than the height of the fill material 11 to be filled later. The lower end of the piping 13 is positioned appropriately depending on the underground wiring to which the power transmission cable 103 will be connected. Next, concrete is poured to construct the bottom part 1. The pipes 13 penetrate the bottom part 1 to the bottom and are buried in the bottom part 1.

[0044] FIG. 3(b) is a diagram showing the tubular portion 3 constructed on the bottom portion 1. A well-known method can be used to construct the tubular portion 3. First, formwork, RC main reinforcement, etc. are placed on the bottom portion 1 so as to correspond to the shape of the tubular portion 3. Next, concrete is poured to construct the tubular portion 3 having a haunch-shaped portion 9. A hollow portion 7 is formed inside the tubular portion 3.

[0045] FIG. 3(c) illustrates the process of filling the tubular portion 3 with the filler material 11. As shown in FIG. 3(c), the length of the pipe 13 is extended upward as necessary, and the hollow portion 7 is filled with the filler material 11. Known techniques can be used for this process. For example, the filler material 11 may be filled from above the tubular portion 3, or an opening for filling may be provided in the tubular portion 3 and the filler material 11 may be filled through that opening. The filler material 11 is filled to a predetermined height lower than the top of the tubular portion 13. This prevents the top of the tubular portion 13 from being buried in the filler material 11, allowing for later connection to other piping and insertion of a power transmission cable 103 inside. Furthermore, as described above, if the filler material 11 is liquefied soil made from waste soil, the density and fill volume can be easily and precisely controlled. When liquefied soil is used as the filler material 11, the filler material 11 is filled into the tubular portion 3 and then solidified in the hollow portion 7.

[0046] FIG. 4(a) is a diagram illustrating the process of installing a shoring 201 above the filler material 11. As shown in FIG. 4(a), the shoring 201, which will be used in the subsequent work of constructing the top end 5, is installed on top of the filler material 11. The shoring 201 may be a well-known material such as an H-shaped steel beam or a steel pipe. As described above, there is a distance from the top surface of the filler material 11 to the top end of the tubular section 3 (i.e., the position of the underside of the top end of the top end 5, which will be constructed later). However, by providing the filler material 11 to a predetermined height, the length of the shoring 201 can be shortened compared to when the shoring 201 is installed directly on the base 1, making the work of constructing the top end 5 easier.

[0047] Furthermore, as mentioned above, when the inner surface of the cylindrical portion 3 has a haunch-shaped portion 9 for a strong connection with the bottom portion 1, the only horizontal surface where support can be installed is near the center of the cylindrical portion 3 in the area where the haunch-shaped portion 9 is formed. However, in this embodiment, the filler material 11 is filled up to a predetermined height higher than the haunch-shaped portion 9, so a wide horizontal surface is obtained inside the hollow portion 7, and support 201 can be easily placed at any position. This is extremely useful in the subsequent construction work of the top end portion 5.

[0048] 4(b) is a diagram illustrating the process of installing a top end underside formwork 203, a top end outer peripheral formwork 205, a top end inner peripheral formwork 207, and anchor bolts 17 arranged on a frame 211 above the infill material 11. First, the lower end of pipe 15 is connected to the upper end of pipe 13 so that the top of pipe 15 is positioned higher than the upper surface of the top end 5 to be formed later. Note that instead of using pipe 15, a long pipe 13 may be used in the process of FIG. 3(a), and the upper end of pipe 13 may be positioned higher than the upper surface of the top end 5 to be formed later.

[0049] Next, the top end underside formwork 203 is installed in a predetermined position using the shoring 201. FIG. 4(b) shows an example in which the top end underside formwork 203 is installed so that its upper surface is at the same height as the upper end of the tubular portion 3, but this is not particularly limited. Note that holes for passing the piping 15 are formed in advance in the top end underside formwork 203. Note that, as described above, the shoring 201 can also be installed very close to the inner surface of the tubular portion 3, so the top end underside formwork 203 can be installed stably and horizontally with fewer shoring 201.

[0050] Next, the mount 211 with the anchor bolts 17 placed thereon is installed on the top end underside formwork 203. At this time, the position of the mount 211 is adjusted so that the anchor bolts 17 are placed in the predetermined positions. Next, the RC main reinforcement etc. are placed, and the top end outer peripheral surface formwork 205 and the top end inner peripheral surface formwork 207 are installed in the predetermined positions.

[0051] Figure 5(a) is a diagram illustrating the process of constructing the top end 5 on the top of the tubular portion 3. After Figure 4(b), concrete is poured into the space surrounded by the top end underside formwork 203, the top end outer peripheral formwork 205, and the top end inner peripheral formwork 207 to construct the top end 5. The base 211 is embedded in the concrete as is. (From now on, the base 211 will not be shown in the figures.) The upper end of the anchor bolt 17 protrudes a predetermined length from the top surface of the top end 5, and a threaded portion of a predetermined length is formed in the protruding portion.

[0052] FIG. 5(b) shows the constructed top end 5, tubular portion 3, and bottom portion 1. After FIG. 5(a), the top end outer peripheral formwork 205 and the top end inner peripheral formwork 207 are removed. Note that FIG. 5(b) shows an example in which all formwork and shoring has been removed, but this is not limited to this. For example, the shoring 201 and the top end underside formwork 203 may be removed from a not-shown discharge port formed in the tubular portion 3 as needed, or may remain installed in the hollow portion 7. In the manner described above, the top end 5, tubular portion 3, and bottom portion 1 of the foundation structure 10 are constructed.

[0053] After FIG. 5(b), tower 90 is joined to top end 5 to form the structure shown in FIGS. 2(a) and 2(b). As an example, a portion of tower 90 is lifted, for example, by a crane or the like, and lowered from above top end 5 toward top end 5. Holes for inserting anchor bolts 17 are formed in advance in flange portion 91 at the bottom end of tower 90 at predetermined positions corresponding to the positions of anchor bolts 17, and anchor bolts 17 are inserted into the holes. After tower 90 is lowered onto top end 5, nuts 23 are threaded onto the top ends of anchor bolts 17 and tightened across flange portion 91, joining tower 90 and top end 5. Thereafter, tower 90 is assembled using a known method, a rotor and nacelle are installed, and cables are connected, thereby completing the construction of a wind turbine for wind power generation.

[0054] As described above, according to the foundation structure 10 and construction method of the present invention, the tower 90 is joined to the reinforced concrete foundation structure 10 built on the ground 105, so it is possible to easily increase the hub height of the wind turbine 100 at low cost. In this regard, since there is no attempt to increase the vertical length of the tower 90 itself, there are no problems associated with increasing the diameter of the tower 90 to strengthen it.

[0055] Furthermore, according to the foundation structure 10 and its construction method of the present invention, the hollow portion 7 inside the tubular portion 3 is filled with the fill material 11 to a predetermined height, allowing the fill material 11 to easily obtain the weight necessary to support the tower 90. This also eliminates the need to unnecessarily increase the reinforced concrete portion to gain weight, minimizing the amount of reinforced concrete required, thereby reducing construction time and costs. Furthermore, since the fill material 11 is filled to a predetermined height rather than filling the entire hollow portion 7, the center of gravity of the foundation structure 10 is prevented from becoming too high. This makes it less likely to tip over even during large lateral shaking due to an earthquake or other event, allowing the foundation structure 10 to stably support the tower 90. Furthermore, since the fill material 11 covers a portion of the inner surface of the tubular portion 3 inside the hollow portion 7, the surface area of ​​the concrete exposed to air is reduced, thereby preventing deterioration of the durability of the foundation structure 10.

[0056] Furthermore, filler material 11 may be liquefied treated soil, and if surplus soil generated during the construction of the installation site of wind turbine 100 is used as the liquefied treated soil, the amount of surplus soil generated can be reduced. Furthermore, if filler material 11 is liquefied treated soil, the density and quality of filler material 11 can be easily kept constant when filled, the amount of fill can be easily controlled, and foundation structure 10 can be accurately made to the designed weight while reducing management labor and costs.

[0057] Furthermore, a cable pipe 13 is arranged to penetrate the filler material 11 and the bottom 1, so that by inserting a power transmission cable 103 or the like, it can be easily connected to a power transmission target outside the wind turbine 100.

[0058] In addition, since the upper part of the pipe 15 penetrates the top end 5, by connecting the pipe 15 and the pipe 13, the power transmission cable 103 can be easily inserted from near the lower end of the tower 90 to the top end 5, the filling material 11, the bottom 1, and the ground 105.

[0059] Furthermore, in the construction method of the foundation structure 10, a pipe 13 penetrating the bottom 1 is installed to a predetermined height inside the tubular portion 3, and the filler material 11 is filled to a height lower than the upper end of the pipe 13, so that the upper end of the pipe 13 is not buried in the filler material 11, and the power transmission cable 103 can be inserted so as to penetrate the filler material 11 and the bottom 1.

[0060] The basic structure 10 of the present invention may have other embodiments. Another example of the present invention will be described below. In the following description of the other example, differences from the basic structure 10 will be described, and similar configurations will be denoted by the same reference numerals in the drawings, etc., and description thereof will be omitted.

[0061] (Foundation structure 10a) Below, we will explain a foundation structure 10a, which is another example of the present invention. Figure 6(a) is a cross-sectional view of the foundation structure 10a. The foundation structure 10a is substantially similar to the foundation structure 10 (Figure 2(a)), but the method of fixing anchor bolts 17a to the top end 5a is different. As shown in Figure 6(a), a flange portion 91 at the lower end of a tower 90 is fixed to the top end 5a with anchor bolts 17a.

[0062] FIG. 6(b) is an enlarged view of B in FIG. 6(a). According to FIG. 6(b), unlike the foundation structure 10 (FIG. 2(b)), the lower end of the anchor bolt 17a protrudes from the underside of the top end 5a and is fixed to the top end 5a by the base flange 25. That is, the anchor bolt 17a is embedded in a predetermined position in the top end 5a, and its lower end protrudes from the underside of the top end 5a by a predetermined length. A threaded portion (not shown) of a predetermined length is formed in the protruding portion. A hole for inserting the anchor bolt 17a is formed in the base flange 25 in advance at a predetermined position corresponding to the position of the anchor bolt 17a. The anchor bolt 17a is inserted into the hole, penetrates the base flange 25, and its lower end protrudes from the bottom end of the base flange 25. A nut 24 is screwed into the hole from below and tightened to secure the anchor bolt.

[0063] In foundation structure 10a, the thickness (vertical length) of top end 5a can be made thinner than the thickness of top end 5 of foundation structure 10, allowing for a reduction in the amount of reinforced concrete used. For example, as shown in FIG. 2(a), in foundation structure 10, the lower end of anchor bolt 17, which has base flange 21 nearby, is buried in top end 5, so to ensure strength, reinforced concrete must be applied below the lower end of anchor bolt 17, resulting in a thick top end 5. On the other hand, as shown in FIG. 6(a), in foundation structure 10a, there is no need to apply reinforced concrete below anchor bolt 17a, allowing for a reduction in the thickness of top end 5a.

[0064] The foundation structure 10a can be constructed using a construction method similar to that of the foundation structure 10. That is, first, the same method as that for the foundation structure 10 can be used for the steps corresponding to FIGS. 3(a) to 3(c). Then, in the step corresponding to FIG. 4(a), the support 201 is installed in a position where it does not interfere with the lower ends of the anchor bolts 17a to be installed later. Next, in the step corresponding to FIG. 4(b), holes through which the lower ends of the anchor bolts 17a can be inserted are formed in the top end underside formwork 203 at positions corresponding to the lower ends of the anchor bolts 17a, and the anchor bolts 17a are inserted into the holes. Next, in the step corresponding to FIG. 5(a), concrete is poured in a similar manner to construct the top end 5a.

[0065] Thereafter, the formwork 203 for the underside of the top end is removed, and if necessary, any shoring 201 that is in a position that would interfere with the work is also removed. Next, a base flange 25 is placed from the underside of the top end 5a, and the anchor bolts 17a are inserted through holes formed in the base flange 25 for the anchor bolts 17a. Nuts 24 are then threaded onto the bottom ends of the anchor bolts 17a and tightened to secure them in place. The method for joining the flange portion 91 with nuts 23 on the upper side of the top end 5a is the same as for the foundation structure 10. In this manner, the foundation structure 10a shown in Figures 6(a) and 6(b) can be constructed.

[0066] As described above, according to the foundation structure 10a, in addition to obtaining the same effects as the foundation structure 10, the thickness of the top end portion 5a can be reduced, reducing the amount of RC used and lowering costs.

[0067] (Foundation structure 10b) Next, a foundation structure 10b, yet another example of the present invention, will be described. FIG. 7(a) is a cross-sectional view of the foundation structure 10b. The foundation structure 10b has substantially the same configuration as the foundation structure 10 (FIG. 2(a)), but differs in the method of fixing anchor bolts 17b to the top end 5b. First, as shown in FIG. 7(a), a flange portion 91 at the lower end of a tower 90 is fixed to the top end 5b with anchor bolts 17b. Furthermore, the anchor bolts 17b are joined to the main reinforcement 27 inside the top end 5b. Alternatively, the anchor bolts 17b may be joined to the main reinforcement 27 inside the tubular portion 3b. This point will be described later.

[0068] FIG. 7(b) is an enlarged view of C in FIG. 7(a). As shown in FIGS. 7(a) and 7(b), in the foundation structure 10b, anchor bolts 17b are joined to main reinforcements 27 extending from the tubular portion 3b inside the top end portion 5b. Note that for the sake of explanation, only the minimum number of main reinforcements 27 are shown in FIGS. 7(a) and 7(b), but in reality, there are multiple main reinforcements 27 in the tubular portion 3b, and other reinforcing bars, such as shear reinforcement and distribution reinforcement, are arranged as needed. Each anchor bolt 17b is joined to any one of the multiple main reinforcements 27. A known joint technique, such as a lap joint or a mechanical joint, can be used to join the anchor bolts 17b to the main reinforcements 27.

[0069] With foundation structure 10b, there is no need to consider cone-shaped fracture of the anchor bolts, so the open portion of top end 5b can be made larger (i.e., the diameter of the inner peripheral surface of top end 5b can be increased), reducing the amount of reinforced concrete used. Also, because the open portion of top end 5b is large, it becomes possible to install an elevator connecting hollow section 7 with the inside of tower 90, greatly improving the maintainability of wind turbine 100.

[0070] In this regard, the foundation structure 10 in Figures 2(a) and 2(b) uses anchor bolts 17 embedded in the top end 5, and as described above, when a lateral force is applied to the tower 90, a force that attempts to break the top end 5 is transmitted diagonally upward from the left or right edge of the upper surface of the base flange 21. For this reason, it is necessary to keep a certain distance between the anchor bolts 17 and the corners of the top end 5 in the lateral direction, and due to this restriction, the size of the opening in the top end 5 (the diameter of the inner peripheral surface of the top end) could only be kept below a certain size.

[0071] On the other hand, in foundation structure 10b, anchor bolts 17b are joined to main reinforcement 27 and can transmit force to main reinforcement 27, so even if the lateral distance between anchor bolt 17b and the corner of top end 5b becomes small, it is less affected and the open portion of top end 5b can be enlarged without restrictions. Depending on the position of the connected main reinforcement 27, it is also possible to make the open portion of top end 5b roughly the same size as hollow portion 7 (making the diameter of the inner circumferential surface of top end 5b roughly the same as hollow portion 7), which provides a high degree of freedom.

[0072] (Construction method of foundation structure 10b) The foundation structure 10b can be constructed using a construction method that is generally similar to that of the foundation structure 10. For example, the same method as that for the foundation structure 10 can be adopted for the steps corresponding to Figures 3(a) to 4(a).

[0073] Next, Figure 8 is an enlarged view of D in Figure 7(a) to explain the construction method of the foundation structure 10b. Figure 8(a) illustrates the process of joining the anchor bolts 17b and the main reinforcement 27 and installing the top-end underside formwork 203, the top-end outer peripheral formwork 205, and the top-end inner peripheral formwork 207. The shoring 201 is not shown in Figure 8(a). As shown in Figure 8(a), when the tubular portion 3b is constructed using the same method as Figure 3(b), the main reinforcement 27 of the tubular portion 3b extends from the upper end of the tubular portion 3b. In Figure 8(a), the extended main reinforcement 27 is joined to the anchor bolts 17b using, for example, a lap joint. The top-end underside formwork 203, the top-end outer peripheral formwork 205, and the top-end inner peripheral formwork 207 are installed in their designated positions.

[0074] 8(b) is a diagram illustrating the process of constructing the top end 5b. Concrete is poured into the space surrounded by the top end underside formwork 203, the top end outer peripheral formwork 205, and the top end inner peripheral formwork 207, to form the top end 5b.

[0075] Figure 8(c) is a diagram showing the constructed top end 5b and tubular portion 3b. After Figure 8(b), the top end underside formwork 203, the top end outer peripheral formwork 205, the top end inner peripheral formwork 207, and the shoring 201 (not shown) are removed. Note that the top end underside formwork 203 and the shoring 201 may remain installed in the hollow portion 7 if it does not cause any problems.

[0076] In the above example, the joint between the anchor bolt 17b and the main reinforcement 27 is located only within the top end 5b. However, the joint can also be located within the tubular portion 3b. The vertical length of the tubular portion 3b is several meters or more. When constructing such a tubular portion 3b, the construction is carried out in multiple vertical stages, starting from the bottom. As shown in FIG. 8(a), the main reinforcement 27 of the newly constructed portion extends from the top of the constructed portion. New reinforcing bars are joined to the main reinforcement 27 with joints or the like, forming the main reinforcement 27 of the next portion to be constructed. If the anchor bolt 17b is placed and joined at a predetermined position on the main reinforcement 27, the anchor bolt 17b will be joined to the main reinforcement 27 inside the tubular portion 3b after the concrete is poured into the tubular portion 3b.

[0077] As described above, foundation structure 10b not only provides the same effects as foundation structure 10, but also allows the opening at top end 5b to be larger, reducing the amount of reinforced concrete used and lowering costs. It also makes it possible to install an elevator connecting hollow section 7 with the inside of tower 90, greatly improving the maintainability of wind turbine 100.

[0078] (Foundation structure 10c) Next, a further example of the present invention, a foundation structure 10c, will be described. Figure 9 is a cross-sectional view of the foundation structure 10c. The foundation structure 10c is substantially similar to the foundation structure 10 (Figure 2(a)), but differs in the shape of the filling material 11 and the piping 13c that penetrates the bottom portion 1. As shown in Figure 9, the piping 13c is bent within the bottom portion 1, and one end (the end opposite to the end connected to the piping 15) is exposed from the side of the bottom portion 1.

[0079] According to the foundation structure 10c, the power transmission cable 103 and the like can be inserted through the piping 13c and taken out from the side of the bottom 1. In this way, the cable routing form can be changed depending on the piping 13c. It goes without saying that the piping 13c of the foundation structure 10c can also be applied appropriately to the foundation structures 10a and 10b described above.

[0080] While the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to these examples. It is clear that those skilled in the art can conceive of various modifications and alterations within the scope of the technical ideas disclosed in this application, and it is understood that these modifications and alterations also fall within the technical scope of the present invention.

[0081] For example, for maintenance and management work on the wind turbine 100, a work stage or equipment such as a winch for lifting materials and equipment from the ground may be provided on the upper surface or outer periphery of the top end 5 as appropriate. Also, a work entrance / exit may be provided near the bottom end of the tower 90 to allow easy movement from above the top end 5 to the inside of the tower 90. In this case, stairs or the like may be provided on the outer periphery of the foundation structure 10, etc., to ensure a route for workers to move up to above the top end 5.

[0082] It is also possible to provide a work entrance / exit in the cylindrical portion 3 above the filler material 11 so that workers can enter the hollow portion 7 from the outside. In this case, a staircase or the like may be provided on the outer circumferential surface of the cylindrical portion 3 to the entrance / exit provided in the cylindrical portion 3 to ensure a line of movement for workers. Furthermore, although the foundation structure has been described as being made of reinforced concrete, it may also be made of precast concrete instead of reinforced concrete. [Explanation of symbols]

[0083] 1……Bottom 3, 3b……Cylinder part 5, 5a, 5b...Top end 7……Hollow part 9... Haunch 10, 10a, 10b, 10c……Fundamental structure 11...Filling material 13, 13c, 15...Piping 17, 17a, 17b...Anchor bolts 21, 25...Base flange 23, 24... Nut 27……Main story 90...Tower 91...Flange section 100……Windmill 103...Power transmission cable 105……ground 201……Shoring 203.... Formwork for underside of top end 205....Formwork for outer periphery of top end 207....Formwork for inner surface of top end 211... Mounting stand

Claims

1. A reinforced concrete or prestressed concrete foundation structure for wind power generation, comprising: a bottom portion, a cylindrical portion standing on the bottom portion on the ground, and a top end portion joined to a steel tower at the top of the cylindrical portion; Equipped with A foundation structure for wind power generation, characterized in that the hollow portion inside the cylindrical portion is filled with a filler material up to a predetermined height.

2. 2. The foundation structure for wind power generation according to claim 1, wherein the fill material is liquefied treated soil.

3. 2. The foundation structure for wind power generation according to claim 1, wherein a piping for cables is arranged to pass through the filling material and the bottom portion.

4. 4. The wind power generation foundation structure according to claim 3, wherein an upper portion of the piping penetrates the top end portion.

5. The flange portion at the lower end of the tower is fixed to the top end with anchor bolts, 2. The wind power generation foundation structure according to claim 1, wherein the lower ends of the anchor bolts protrude below the bottom surface of the top end portion and are fixed to the top end portion by a base flange.

6. the foundation structure is made of reinforced concrete; The flange portion at the lower end of the tower is fixed to the top end with anchor bolts, 2. The wind power generation foundation structure according to claim 1, wherein the anchor bolts are joined to the main reinforcement bars at the top end or inside the cylindrical portion.

7. A construction method for a wind power generation foundation structure according to any one of claims 1 to 6, constructing a base on the ground; constructing a tube on the base; a step of filling the inside of the cylindrical portion with a filler material; A step of installing a support and a formwork above the filling material to construct a top end portion on the upper part of the cylindrical portion; a step of joining a steel tower to the top end; A construction method for a foundation structure for wind power generation, comprising:

8. The construction method for a foundation structure for wind power generation according to claim 7, characterized in that liquefied treated soil is used as the fill material, and in the process of filling the inside of the cylindrical portion with the fill material, the fill material is solidified after filling.

9. 9. The construction method for a foundation structure for wind power generation according to claim 8, further comprising the step of installing a pipe penetrating the bottom portion to a predetermined height inside the cylindrical portion, and filling the fill material to a height lower than the upper end of the pipe.

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