Foundation structure of truss hybrid wind power tower

Abstract

The invention discloses a foundation structure of a truss hybrid wind power tower, which comprises four tower leg foundations and foundation connecting beams, a cylindrical short column is arranged in the middle of each tower leg foundation, the axis of the short column is inclined, and the inclination direction of the axis of the short column is that the upper end is closer to the center of a square structure than the lower end; a pre-stressed anchor bolt assembly is arranged in the short column and comprises a supporting piece, a lower anchor plate, a fixing ring, an upper anchor plate, an outer ring anchor bolt and a conversion anchor bolt. The upper anchor plate is located on the upper surface of the short column, and a grouting layer is arranged between the upper anchor plate and the short column; the supporting pieces are located at the bottoms of the short columns. The upper anchor plate and the lower anchor plate are connected through a plurality of outer ring anchor bolts distributed in the circumferential direction, and fixing rings are arranged in the middles of the outer ring anchor bolts in the length direction. A plurality of conversion anchor bolts which are distributed in the circumferential direction are arranged on the inner side of the outer ring anchor bolt; a column foot bottom flange is arranged at the lower end of a column foot of the tower and connected with the upper anchor plate. According to the scheme, the construction difficulty is lowered while the structural stress requirement is met, and the steel bar consumption is reduced.

Description

Technical Field

[0001] This invention belongs to the technical field of tower foundation structure, specifically relating to a truss hybrid wind power tower foundation structure. Background Technology

[0002] In pursuit of higher power generation, wind turbine hubs are becoming increasingly taller. Truss-hybrid wind turbine towers, with a truss lower section and a transition section connecting to a traditional cylindrical tower at the top, are gaining popularity in the wind power industry due to their advantages of requiring less steel and being easier to transport. A key issue that structural design needs to address is how to rationally design the foundation (or pier) scheme in accordance with the technological requirements of truss-hybrid wind turbine towers. Currently, the foundations of truss-type hybrid wind turbine towers are all connected to the upper tower via prestressed steel strands and prestressed anchor bolt assemblies. Based on the different anchoring positions of the steel strands, they can be divided into two types: One type has the anchoring ends of the steel strands located inside the wind turbine foundation. Each of the four tower leg foundations requires a large internal cavity to allow construction and maintenance personnel to enter the foundation for prestressing and maintenance of the steel strands. A reinforced concrete corbel is installed at the top of the cavity, with prestressed anchor bolt assemblies, steel strands, and steel strand ducts embedded within it. The other type has the anchoring ends of the steel strands located at the transition plate on the truss-type hybrid wind turbine tower foundation. Only prestressed anchor bolt assemblies are embedded within the foundation, and no cavity is required.

[0003] For wind turbine foundations where the anchoring ends of the steel strands are set on truss-type hybrid wind turbine tower foundations, the traditional foundation short columns have a rectangular cross-section, the stirrups of the foundation short columns are grid-shaped stirrups, and the upper and lower anchor plate areas of the prestressed anchor bolt assembly are equipped with orthogonally arranged steel mesh. This traditional reinforcement method has the following problems due to the lack of matching with the characteristics of the circumferential arrangement of prestressed anchors: 1) Because the grid-like hoops and orthogonal steel mesh of the short columns of the wind turbine foundation are not matched with the circumferentially arranged prestressed anchors, it will lead to difficulties in tying the steel bars and a large variety of steel bar types during construction; 2) The load of the superstructure is transferred to the wind turbine foundation through anchors, upper anchor plates, and lower anchor plates. The circumferentially arranged steel mesh is more compatible with the stress characteristics of the foundation and the arrangement of the anchors. For the orthogonally arranged steel mesh, when the steel bars pass through the circumferentially arranged anchors, it will inevitably lead to some areas with larger steel bar spacing and some areas with smaller steel bar spacing. For steel bars with larger spacing, it is necessary to increase the diameter of the steel bars. If the steel bars in the steel mesh are all of the same diameter, it will inevitably lead to steel bar waste; 3) The central area of ​​the short columns of the foundation does not directly bear the load from the superstructure, but the orthogonally arranged steel mesh will inevitably pass through the central area of ​​the short columns of the foundation, which will lead to steel bar waste. Summary of the Invention

[0004] The technical problem to be solved by this invention is to provide a foundation structure for a truss-hybrid wind turbine tower. Through structural measures, this invention addresses the shortcomings of traditional truss-hybrid wind turbine tower foundations, such as the large variety of steel reinforcement types, complicated construction, mismatch between the characteristics of foundation reinforcement and the circumferential arrangement of anchor bolts, and large steel reinforcement usage. This invention better matches the circumferential arrangement characteristics of prestressed anchor bolts, ensuring that structural stress requirements are met while reducing the variety of steel reinforcement types, lowering construction difficulty, and reducing steel reinforcement usage.

[0005] According to the technical solution of this invention, this invention provides a foundation structure for a truss-hybrid wind turbine tower, including four tower leg foundations and four foundation connecting beams. The four tower leg foundations and four foundation connecting beams are laterally connected to form a square structure. The tower leg foundations are located at the four corners of the square structure, and the foundation connecting beams are located at the four sides of the square structure. A cylindrical short column is provided in the middle of the tower leg foundation. The axis of the short column is inclined, and the direction of inclination of the axis of the short column is that the upper end is closer to the center of the square structure than the lower end. The tower leg foundations and foundation connecting beams are located below the ground level, and the upper end of the short column is located above the ground level. The upper end of the short column is connected to the column foot of the tower. A prestressed anchor bolt assembly is provided inside the short column. The prestressed anchor bolt assembly includes a support member, a lower anchor plate, and... The structure consists of a fixed ring, an upper anchor plate, outer ring anchors, and transition anchors. The upper anchor plate is located on the upper surface of the short column, and a grouting layer is provided between the upper anchor plate and the short column. A support member is located at the bottom of the short column, and the lower anchor plate is connected to the support member to make the lower anchor plate inclined and parallel to the upper anchor plate. The upper and lower anchor plates are connected by multiple circumferentially distributed outer ring anchors, and a fixed ring is provided in the middle of the length direction of the outer ring anchors. Multiple circumferentially distributed transition anchors are provided on the inner side of the outer ring anchors. The lower end of the transition anchors is connected to the lower anchor plate, and the upper end of the transition anchors extends above the upper anchor plate. The upper and lower anchor plates are perpendicular to the axis of the short column, and the outer ring anchors and transition anchors are parallel to the axis of the short column. The lower end of the column base of the tower has a column base flange, which is connected to the upper anchor plate.

[0006] In some embodiments, the tower leg foundation is provided with bottom bending reinforcement at the bottom of the tower leg foundation, top bending reinforcement at the top of the tower leg foundation, horizontal crack-resistant reinforcement on the side of the tower leg foundation, and tie bars between the bottom and top bending reinforcements; the bottom and top bending reinforcements are both crisscrossing steel meshes; the top bending reinforcements are bent downwards on the side of the tower leg foundation to form horizontal crack-resistant reinforcements; there are multiple tie bars distributed in a distribution, and the upper and lower ends of the tie bars are connected to the bottom and top bending reinforcements, respectively.

[0007] In some embodiments, the tower leg foundation is also provided with outer ring stirrups and outer ring longitudinal bars arranged around the side of the short column, inner ring stirrups and inner ring longitudinal bars located in the middle of the short column, radial bars located between the outer ring stirrups and inner ring stirrups, and circumferential bars located on the radial bars.

[0008] In some embodiments, the outer ring longitudinal reinforcement consists of multiple circumferentially distributed reinforcement bars, and the outer ring stirrups consist of multiple reinforcement bars distributed along the length of the outer ring longitudinal reinforcement bars; the inner ring longitudinal reinforcement consists of multiple circumferentially distributed reinforcement bars, and the inner ring stirrups consist of multiple reinforcement bars distributed along the length of the inner ring longitudinal reinforcement bars; the outer and inner ring longitudinal reinforcement bars are parallel to the axis of the short column; the plane containing the outer and inner ring stirrups is perpendicular to the axis of the short column; the radial reinforcement bars consist of multiple reinforcement bars distributed along the length of the axis of the short column, and each position along the length of the axis is a radially distributed arrangement; the radial reinforcement bars are perpendicular to the axis of the short column, and the two ends of the radial reinforcement bars are connected to the outer and inner ring stirrups respectively; each group of radially distributed radial reinforcement bars is provided with multiple concentric circumferential reinforcement bars.

[0009] In some implementations, top reinforcing bars are also provided in the tower leg foundation; the mesh structure formed by the outer ring stirrups and the outer ring longitudinal bars bends at the top of the short column toward the axis of the short column to form top reinforcing bars.

[0010] In some implementations, the inner hoop is located inside the transition anchor.

[0011] In some implementations, multiple anchor holes are provided on both the upper and lower anchor plates to allow the outer ring anchor bolts and transition anchor bolts to be inserted accordingly.

[0012] In some implementations, the upper end of the outer ring anchor bolt passes through the bottom flange of the column base to connect the bottom flange of the column base to the upper anchor plate; the upper end of the conversion anchor bolt is connected to the conversion anchor bolt fixing member, which is located inside the column base.

[0013] In some implementations, the lower end of the short column protrudes beyond the bottom surface of the tower leg foundation.

[0014] In some implementations, a concrete cushion layer is provided beneath the tower leg foundation and the foundation connecting beam.

[0015] Compared with the prior art, the beneficial technical effects of the present invention are as follows: 1. The foundation structure of the truss-hybrid wind turbine tower of this invention adopts short columns with an inclined cylindrical structure, which can better match the circumferential arrangement characteristics of the prestressed anchor bolt assembly, as well as the longitudinal reinforcement evenly distributed around the anchor bolt assembly and the stirrups without the need for a grid pattern, making it more construction-friendly and reducing the types and number of steel reinforcements in the wind turbine foundation. Furthermore, a grouting layer is set between the reinforced concrete of the foundation and the upper anchor plate. The local compressive bearing capacity of the grouting material on the upper anchor plate and the local compressive bearing capacity of the foundation reinforced concrete on the grouting layer meet the specifications. When the wind turbine tower is subjected to wind loads, snow loads, gravity loads, and seismic loads, these loads are directly transferred to the upper and lower anchor plates through the prestressed anchor bolt assembly, then to the foundation body, and finally to the ground. Therefore, this solution can better withstand the combined effects of wind loads, snow loads, gravity loads, seismic loads transmitted from the wind turbine tower, the pre-tensioning force of the prestressed anchor bolt assembly, and the aforementioned loads.

[0016] 2. The foundation structure of the truss-hybrid wind turbine tower of this invention solves the shortcomings of traditional truss-hybrid wind turbine tower foundations (i.e., pile caps) through structural measures, such as the large number of types of reinforcing steel, complicated construction, mismatch between the characteristics of foundation reinforcement and the circumferential arrangement of anchor bolts, and large amount of reinforcing steel. This solution uses multiple reinforcing steel structures distributed in specific locations. For wind turbine foundation types where the anchor ends of steel strands are set on the truss-hybrid wind turbine tower foundation, it can ensure that the reinforcement arrangement matches the characteristics of foundation stress and the circumferential arrangement of prestressed anchor bolts, while facilitating construction and reducing the amount of reinforcing steel. The foundation structure of this solution does not have cavities. The short columns are cylindrical, and the longitudinal reinforcing steel of the short columns is evenly distributed along the outside of the prestressed anchor bolt assembly. Stirrups for the foundation short columns are set on the outside of the longitudinal reinforcing steel, without the use of grid stirrups to avoid the stirrups passing through the anchor bolts, and it can also reduce the number of types of reinforcing steel. It is particularly preferable to have radial and circumferential reinforcing bars between the upper and lower anchor plates to form a reinforcing mesh structure. Its arrangement is fully matched with the overall stress characteristics of the foundation and the arrangement of the prestressed anchor bolt components, which can further ensure that the local pressure reinforcing bars play a full role. In addition, the radial and circumferential reinforcing mesh structure means that the central area of ​​the tower leg foundation with less stress does not need to be reinforced, and the radial and circumferential reinforcing mesh does not need to pass through the central area of ​​the short column, which can further reduce the types and amount of reinforcing bars used. Attached Figure Description

[0017] Figure 1 This is a top view schematic diagram of the foundation structure of a truss hybrid wind turbine tower provided by the present invention.

[0018] Figure 2 yes Figure 1 The structural diagram is shown in section AA, where the reinforcing steel bars inside the tower leg foundation are hidden.

[0019] Figure 3Is Figure 2 A structural schematic diagram of a portion of the reinforcing steel is shown on the basis.

[0020] Figure 4 yes Figure 3 The diagram shows a top view of the bottom bending reinforcement.

[0021] Figure 5 Is Figure 2 The structural diagram of another part of the reinforcing steel is shown on the basis.

[0022] Figure 6 yes Figure 5 Cross-sectional view of the middle BB plane.

[0023] Explanation of reference numerals in the attached figures: 1. Tower leg foundation; 2. Foundation connecting beam; 3. Short column; 401. Support component; 402. Lower anchor plate; 403. Fixing ring; 404. Upper anchor plate; 405. Outer ring anchor bolt; 406. Transition anchor bolt; 407. Grouting layer; 501. Column base flange; 502. Transition anchor bolt fixing component; 601. Bottom surface bending reinforcement; 601a. ​​Bottom surface transverse bending reinforcement; 601b. Bottom surface longitudinal bending reinforcement; 602. Top surface bending reinforcement; 603. Horizontal crack-resistant reinforcement; 604. Tie bar; 605. Outer ring stirrup; 606. Inner ring stirrup; 607. Outer ring longitudinal reinforcement; 608. Inner ring longitudinal reinforcement; 609. Radial reinforcement; 610. Circumferential reinforcement; 611. Top surface reinforcing reinforcement; 7. Concrete cushion layer. Detailed Implementation

[0024] This invention provides a foundation structure for a truss-hybrid wind turbine tower. The main objective is to design a structural scheme suitable for truss-hybrid wind turbine tower foundations. This scheme addresses the shortcomings of traditional truss-hybrid wind turbine tower foundations, such as the large variety of steel reinforcement types, complex construction, mismatch between foundation reinforcement and anchor bolt circumferential arrangement characteristics, and large steel reinforcement usage. The improved truss-hybrid wind turbine tower foundation structure better suits the circumferential arrangement characteristics of prestressed anchor bolts, ensuring structural stress requirements are met while reducing the variety of steel reinforcement types, lowering construction difficulty, and reducing steel reinforcement usage.

[0025] Please see Figure 1 , Figure 2This invention discloses a truss-type hybrid wind turbine tower foundation structure, comprising four leg foundations 1 and four foundation connecting beams 2. The four leg foundations 1 and the four foundation connecting beams 2 are laterally connected to form a square structure. The leg foundations 1 are located at the four corners of the square structure, and the foundation connecting beams 2 are located at the four sides of the square structure. Generally, the bottom elevation (and top elevation) of the foundation connecting beams 2 are the same as those of the leg foundations 1. A cylindrical short column 3 is provided in the middle of the leg foundation 1. The axis of the short column 3 is inclined, and the direction of inclination of the axis of the short column 3 is that the upper end is closer to the center of the square structure than the lower end (in other words, it is inclined inward). The short column 3 is part of the leg foundation 1 and is usually a reinforced concrete structure. The cross-section of the short column in the existing scheme is rectangular. This scheme optimizes and improves the short column into an inclined cylinder, which is more conducive to stress distribution. The leg foundations 1 and the foundation connecting beams 2 are located below the ground level, and the upper end of the short column 3 is located above the ground level. The upper end of the short column 3 is connected to the column foot of the tower. In a specific embodiment, the tower leg foundation 1 is a flat rectangular parallelepiped with a square base. Figure 1 From the top view shown, the center of the square of the tower leg foundation 1 falls at the end of the square structure, which is also a square; the short column 3 is oriented towards... Figure 1 The diagonal intersection of the square structure is tilted.

[0026] A prestressed anchor bolt assembly is installed inside the short column 3. The prestressed anchor bolt assembly mainly includes a support member 401, a lower anchor plate 402, a fixing ring 403, an upper anchor plate 404, an outer ring anchor bolt 405, and a transition anchor bolt 406. The upper anchor plate 404 is located on the upper surface of the short column 3, and a grouting layer 407 is provided between the upper anchor plate 404 and the short column 3. The grouting layer 407 is formed by creating a recessed groove on the short column 3 and filling it with grout. Therefore, the upper anchor plate 404 is located above or surrounded by the grouting layer 407. Because the upper anchor plate 404 bears a large load, the reinforced concrete of the foundation cannot directly bear the load transmitted from the upper anchor plate 404. Therefore, a grouting layer 407 is provided between the reinforced concrete of the foundation and the upper anchor plate. The local compressive bearing capacity of the grouting material on the upper anchor plate 404 and the local compressive bearing capacity of the foundation reinforced concrete on the grouting material must meet the specifications. Support member 401 is located at the bottom of short column 3. Lower anchor plate 402 is connected to support member 401 so that lower anchor plate 402 is inclined and parallel to upper anchor plate 404. Upper anchor plate 404 and lower anchor plate 402 are connected by a plurality of circumferentially distributed outer ring anchors 405. A fixing ring 403 is provided at the middle of the length of outer ring anchors 405. A plurality of circumferentially distributed conversion anchors 406 are provided on the inner side of outer ring anchors 405. The lower end of conversion anchor 406 is connected to lower anchor plate 402, and the upper end of conversion anchor 406 extends above upper anchor plate 404; that is, the upper end of conversion anchor 406 is located in the concrete structure of the lower column foot of the tower. Upper anchor plate 404 and lower anchor plate 402 are perpendicular to the axis of short column 3, and outer ring anchors 405 and conversion anchors 406 are parallel to the axis of short column 3. The tower has a base flange 501 at the bottom of its column base, which is connected to the upper anchor plate 404.

[0027] Further, please refer to Figures 3 to 6 The tower leg foundation 1 is provided with bottom bending reinforcement 601 at the bottom of the tower leg foundation 1, top bending reinforcement 602 at the top of the tower leg foundation 1, horizontal crack-resistant reinforcement 603 on the side of the tower leg foundation 1, and tie bars 604 between the bottom bending reinforcement 601 and the top bending reinforcement 602.

[0028] Both the bottom bending reinforcement 601 and the top bending reinforcement 602 are crisscrossing steel meshes (or steel mesh sheets); for example Figure 4 As shown, the bottom bending reinforcement 601 includes bottom transverse bending reinforcement 601a and bottom longitudinal bending reinforcement 601b; the structure of the top bending reinforcement 602 is the same as or similar to that of the bottom bending reinforcement 601. The top bending reinforcement 602 is bent downwards on the side of the tower leg foundation 1 to form horizontal crack-resistant reinforcement 603; or, in other words, the top bending reinforcement 602 contains... Figure 3The transverse reinforcing bars are bent downwards, and the reinforcing bars perpendicular to the direction shown in the drawing are only at the top of the tower leg foundation 1. The downward-bent reinforcing bars are further connected to the perpendicular reinforcing bars to form a mesh of horizontal crack-resistant reinforcing bars 603. The top surface bending-resistant reinforcing bars 602 are bent downwards along the side of the foundation slab, and the bent portion serves to enhance the crack resistance of the side of the foundation slab. There are multiple tie bars 604 distributed throughout, and the upper and lower ends of the tie bars 604 are connected to the bottom surface bending-resistant reinforcing bars 601 and the top surface bending-resistant reinforcing bars 602, respectively.

[0029] The tower leg foundation 1 is also provided with outer ring stirrups 605 and outer ring longitudinal bars 607 arranged around the side of the short column 3, inner ring stirrups 606 and inner ring longitudinal bars 608 located in the middle of the short column 3, radial bars 609 located between the outer ring stirrups 605 and inner ring stirrups 606, and circumferential bars 610 located on the radial bars 609.

[0030] The outer ring of longitudinal reinforcing bars 607 consists of multiple bars distributed circumferentially, while the outer ring of stirrups 605 consists of multiple bars distributed along the length of the outer ring of longitudinal reinforcing bars 607. The outer ring of stirrups 605 primarily bears the loads of horizontal force and torque. Similarly, the inner ring of longitudinal reinforcing bars 608 consists of multiple bars distributed circumferentially, while the inner ring of stirrups 606 consists of multiple bars distributed along the length of the inner ring of longitudinal reinforcing bars 608. The outer ring of longitudinal reinforcing bars 607 and the inner ring of longitudinal reinforcing bars 608 are parallel to the axis of the short column 3 and primarily bear the loads of vertical compressive force, vertical uplift force, and bending moment. The plane containing the outer ring of stirrups 605 and the inner ring of stirrups 606 is perpendicular to the axis of the short column 3. Multiple radial reinforcing bars 609 are distributed along the length of the axis of the short column 3, and multiple radial reinforcing bars 609 are arranged at each position along the length of the axis. The radial reinforcing bars 609 are perpendicular to the axis of the short column 3, and the two ends of the radial reinforcing bars 609 are connected to the outer ring stirrups 605 and the inner ring stirrups 606, respectively. Multiple concentric circumferential reinforcing bars 610 are provided on each group of radially distributed radial reinforcing bars 609. The radial reinforcing bars 609 and the circumferential reinforcing bars 610 form a multi-layered radial and circumferential reinforcing bar mesh structure in the short column 3, which plays a role in bearing local pressure.

[0031] Please see Figure 5 Preferably, a top surface reinforcing bar 611 is also provided inside the tower leg foundation 1. The mesh structure formed by the outer ring stirrups 605 and the outer ring longitudinal reinforcing bars 607 bends at the top of the short column 3 toward the axis of the short column 3 to form the top surface reinforcing bar 611, which enhances the crack resistance of the top surface of the short column 3. The structure of the top surface reinforcing bar 611 is similar to the radial and circumferential reinforcing bar mesh formed by the radial reinforcing bars 609 and the circumferential reinforcing bars 610, but it is ring-shaped and terminates outside the grouting layer 407.

[0032] Furthermore, the inner ring stirrup 606 is located inside the conversion anchor 406. This allows the conversion anchor 406 to overlap and intersect with the steel reinforcement structure within the short column 3, further ensuring strength and other properties.

[0033] In some specific embodiments, multiple anchor holes are distributed on both the upper anchor plate 404 and the lower anchor plate 402 to correspondingly insert the outer ring anchor bolt 405 and the transition anchor bolt 406, thus reliably limiting the anchor bolts through the anchor plates. The upper end of the outer ring anchor bolt 405 passes through the column base flange 501 to connect the column base flange 501 to the upper anchor plate 404, making full use of the anchor bolt structure. The upper end of the transition anchor bolt 406 is connected to the transition anchor bolt fixing member 502, which is located inside the column base (within the concrete structure of the column base). The transition anchor bolt fixing member 502, for example, is a small anchor plate used to fix the upper end of the transition anchor bolt 406.

[0034] like Figure 2 In the embodiment shown, the lower end of the short column 3 protrudes from the bottom surface of the tower leg foundation 1, so that the support member 401 can be located in the protruding part of the lower end. The support member 401 serves to make the prestressed anchor bolt assembly (the part other than the support member 401) coaxially inclined with the short column 3, and to ensure that the outer ring anchor bolt 405 and the conversion anchor bolt 406 have sufficient length and that the space occupied by the short column 3 can be equipped with sufficient steel reinforcement structure.

[0035] In some specific embodiments, a concrete cushion layer 7 is preferably provided below the tower leg foundation 1 and the foundation connecting beam 2, more preferably a C20 plain concrete cushion layer. In some specific embodiments, such as Figure 1 As shown, a settlement observation point is set on each tower leg foundation 1.

[0036] The functions, principles, and technical effects of the preferred embodiments of the present invention are as follows.

[0037] The truss-type hybrid wind turbine tower foundation (i.e., the pile cap) should be able to withstand the wind load, snow load, gravity load, seismic load transmitted from the wind turbine tower, the prestressing force of the prestressed anchor bolt assembly, and the combined effect of the above loads. When the wind turbine tower is subjected to wind load, snow load, gravity load, and seismic load, these loads are directly transferred to the upper and lower anchor plates through the prestressed anchor bolt assembly, and then transferred to the foundation body by the upper and lower anchor plates, and finally to the ground.

[0038] The pressure transmitted from the wind turbine tower to the prestressed anchor bolt assembly is first transferred to the upper anchor plate via the column base flange, then to the grouting material, and finally to the reinforced concrete body of the tower leg foundation. Ultimately, the pressure is transferred to the ground via the tower leg foundation or through the piles from the tower leg cap. Under pressure, the radial reinforcement 609 and circumferential reinforcement 610 below the grouting layer 407 bear the local pressure, while the radial reinforcement 609 and circumferential reinforcement 610 above the lower anchor plate 402 bear the local pressure caused by the pre-tightening force of the prestressed anchor bolts. The outer longitudinal reinforcement 607 and inner longitudinal reinforcement 608, together with the concrete of the foundation short column 3, share the pressure.

[0039] For the pull-out force transmitted from the wind turbine tower to the prestressed anchor bolt assembly, this pull-out force is first transferred to the prestressed anchor bolts (outer ring anchor bolt 405) through the column base flange. Due to the pull-out force, the interaction force between the upper anchor plate and the column base flange begins to decrease. When the pull-out force exceeds the preload of the prestressed anchor bolt, the upper anchor plate and the column base flange separate. Before the upper anchor plate separates from the column base flange, the pull-out force is not transferred to the lower anchor plate due to the preload of the prestressed anchor bolt. When the upper anchor plate separates from the column base flange, the lower anchor plate begins to bear the pull-out force and transfers it to the reinforced concrete body of the tower leg foundation. To ensure that the tower leg foundation does not separate, the sum of the weight of the foundation and backfill soil must be greater than the pull-out force, or the tower leg foundation must transfer the pull-out force to the ground through piles. Under the action of pull-out force, when the upper anchor plate 404 is not separated from the column base flange 502, the outer longitudinal reinforcement 607, inner longitudinal reinforcement 608, radial reinforcement 609, and circumferential reinforcement 610 have the same function as when the foundation is under pressure. When the upper anchor plate 404 is separated from the column base flange 502, the radial reinforcement 609 and circumferential reinforcement 610 under the grouting layer 407 do not bear the load, the radial reinforcement 609 and circumferential reinforcement 610 above the lower anchor plate 402 bear the local pressure, and the outer longitudinal reinforcement 607 and inner longitudinal reinforcement 608 bear the resistance to pull-out force.

[0040] For the horizontal force transmitted from the wind turbine tower to the prestressed anchor bolt assembly, the horizontal force is transmitted to the concrete body of the tower leg foundation through the prestressed anchor bolts, and then to the ground from the foundation, or from the tower leg foundation to the ground through piles. In the process of bearing and transmitting the horizontal force, the outer ring stirrups 605 and the inner ring stirrups 606 undertake the shear resistance of the foundation.

[0041] For the base plate of the tower leg foundation (the flat rectangular part of tower leg foundation 1 excluding short column 3), the bottom bending reinforcement 601 (including the transverse and longitudinal reinforcement) and the top bending reinforcement 602 (including the transverse and longitudinal reinforcement) bear the role of bending, shear and punching shear resistance of the foundation, ensuring that the bearing capacity and crack resistance meet the requirements of the code.

[0042] The structural measure of setting up foundation connecting beams 2 between the four tower leg foundations 1 enhances the overall integrity of the foundation.

[0043] In summary, the truss-hybrid wind turbine tower foundation structure of this invention adopts short columns with an inclined cylindrical structure, which can better match the circumferential arrangement characteristics of prestressed anchor bolts, as well as the longitudinal reinforcement evenly distributed around the anchor bolt assembly and the stirrups without the need for a grid pattern, making it more construction-friendly and reducing the types and number of reinforcements in the wind turbine foundation. Furthermore, a grouting layer is set between the reinforced concrete of the foundation and the upper anchor plate, and the local compressive bearing capacity of the grouting material on the upper anchor plate and the local compressive bearing capacity of the foundation reinforced concrete on the grouting layer meet the specifications. When the wind turbine tower is subjected to wind loads, snow loads, gravity loads, and seismic loads, these loads are directly transferred to the upper and lower anchor plates through the prestressed anchor bolt assembly, then to the foundation body, and finally to the ground. Therefore, this solution can better withstand the combined effects of wind loads, snow loads, gravity loads, seismic loads transmitted from the wind turbine tower, the pre-tensioning force of the prestressed anchor bolt assembly, and the aforementioned loads. This invention addresses the shortcomings of traditional truss-type hybrid wind turbine tower foundations (i.e., pile caps) through structural measures, including the use of multiple types of reinforcing steel, cumbersome construction, mismatch between foundation reinforcement and anchor bolt circumferential arrangement characteristics, and large amounts of reinforcing steel. This solution employs multiple reinforcing steel structures distributed at specific locations. For wind turbine foundations where the steel strand anchorage ends are located on truss-type hybrid wind turbine tower foundations, this ensures that the reinforcing steel arrangement matches the characteristics of foundation stress and prestressed anchor bolt circumferential arrangement, while also facilitating construction and reducing the amount of reinforcing steel. The foundation structure of this solution does not have cavities; the short columns are cylindrical, and the longitudinal reinforcing steel bars of the short columns are evenly distributed along the outer side of the prestressed anchor bolt assemblies. Stirrups for the foundation short columns are set on the outer side of the longitudinal reinforcing steel bars, without using a grid pattern to avoid stirrups penetrating the anchor bolts, and also reduces the number of reinforcing steel types. It is particularly preferable to have radial and circumferential reinforcing bars between the upper and lower anchor plates to form a reinforcing mesh structure. Its arrangement is fully matched with the overall stress characteristics of the foundation and the arrangement of the prestressed anchor bolt components, which can further ensure that the local pressure reinforcing bars play a full role. In addition, the radial and circumferential reinforcing mesh structure means that the central area of ​​the tower leg foundation with less stress does not need to be reinforced, and the radial and circumferential reinforcing mesh does not need to pass through the central area of ​​the short column, which can further reduce the types and amount of reinforcing bars used.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; obviously, the described embodiments are some embodiments of the present invention, but not all embodiments; based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention; in the absence of conflict, the embodiments and features in the embodiments of the present invention can be combined with each other; modifications to the technical solutions described in the foregoing embodiments, or equivalent substitutions for some of the technical features, do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A foundation structure of a hybrid wind turbine tower of truss type, characterized in that, The application relates to a foundation structure of a wind turbine, which comprises four tower leg foundations (1) and four foundation connecting beams (2), the four tower leg foundations (1) and the four foundation connecting beams (2) being connected transversely into a square structure, the tower leg foundations (1) being located at the four corner positions of the square structure, and the foundation connecting beams (2) being located at the four side positions of the square structure; a short column (3) in the shape of a cylinder is arranged in the middle of the tower leg foundation (1), the axis of the short column (3) being inclined, and the upper end of the axis being closer to the center of the square structure than the lower end; the tower leg foundation (1) and the foundation connecting beam (2) are located below the ground level, the upper end of the short column (3) is located above the ground level, and the upper end of the short column (3) is connected with the column foot of the tower. A prestressed anchor bolt assembly is arranged in the short column (3), the prestressed anchor bolt assembly comprising a supporting piece (401), a lower anchor plate (402), a fixing ring (403), an upper anchor plate (404), an outer ring anchor bolt (405) and a conversion anchor bolt (406); the upper anchor plate (404) is located on the upper surface of the short column (3), and a grouting layer (407) is arranged between the upper anchor plate (404) and the short column (3); the supporting piece (401) is located at the bottom of the short column (3), the lower anchor plate (402) is connected with the supporting piece (401) so that the lower anchor plate (402) is inclined and parallel to the upper anchor plate (404); the upper anchor plate (404) and the lower anchor plate (402) are connected through the outer ring anchor bolt (405) which is distributed in a circumferential direction, and the fixing ring (403) is arranged in the middle of the length direction of the outer ring anchor bolt (405); the conversion anchor bolt (406) which is distributed in a circumferential direction is arranged on the inner side of the outer ring anchor bolt (405), the lower end of the conversion anchor bolt (406) is connected with the lower anchor plate (402), and the upper end of the conversion anchor bolt (406) penetrates out above the upper anchor plate (404); the upper anchor plate (404) and the lower anchor plate (402) are perpendicular to the axis of the short column (3), and the outer ring anchor bolt (405) and the conversion anchor bolt (406) are parallel to the axis of the short column (3); the lower end of the column foot of the tower is provided with a column foot bottom flange (501), and the column foot bottom flange (501) is connected with the upper anchor plate (404).

2. The foundation structure of the hybrid truss wind tower according to claim 1, characterized in that, The tower leg foundation (1) is provided with a bottom surface bending-resistant steel bar (601) located at the bottom of the tower leg foundation (1), a top surface bending-resistant steel bar (602) located at the top of the tower leg foundation (1), a horizontal anti-cracking steel bar (603) located at the side of the tower leg foundation (1) and a tie bar (604) located between the bottom surface bending-resistant steel bar (601) and the top surface bending-resistant steel bar (602). The bottom surface bending-resistant steel bar (601) and the top surface bending-resistant steel bar (602) are both longitudinal and horizontal intersecting steel meshes; the top surface bending-resistant steel bar (602) is bent downward at the side of the tower leg foundation (1) to form the horizontal anti-cracking steel bar (603); the tie bar (604) is distributed in multiple, and the upper and lower ends of the tie bar (604) are respectively connected with the bottom surface bending-resistant steel bar (601) and the top surface bending-resistant steel bar (602).

3. The foundation structure of a hybrid truss wind tower according to claim 2, characterized in that, The tower leg foundation (1) further comprises outer hoop reinforcement (605) and outer longitudinal reinforcement (607) arranged around the side surface of the short column (3), inner hoop reinforcement (606) and inner longitudinal reinforcement (608) arranged at the middle part of the short column (3), radial reinforcement (609) arranged between the outer hoop reinforcement (605) and the inner hoop reinforcement (606), and hoop reinforcement (610) arranged on the radial reinforcement (609).

4. The foundation structure of a hybrid truss wind tower according to claim 3, characterized in that, The outer longitudinal reinforcement (607) is circumferentially distributed, and the outer hoop reinforcement (605) is circumferentially distributed along the length direction of the outer longitudinal reinforcement (607). The inner longitudinal reinforcement (608) is circumferentially distributed, and the inner hoop reinforcement (606) is circumferentially distributed along the length direction of the inner longitudinal reinforcement (608). The outer longitudinal reinforcement (607) and the inner longitudinal reinforcement (608) are parallel to the axis of the short column (3). The outer hoop reinforcement (605) and the inner hoop reinforcement (606) are perpendicular to the axis of the short column (3). The radial reinforcement (609) is circumferentially distributed along the length direction of the axis of the short column (3), and is radially distributed at each position along the length direction of the axis. The radial reinforcement (609) is perpendicular to the axis of the short column (3), and the two ends of the radial reinforcement (609) are connected to the outer hoop reinforcement (605) and the inner hoop reinforcement (606), respectively. The hoop reinforcement (610) is circumferentially distributed on each group of radial reinforcement (609).

5. The foundation structure of the hybrid truss wind tower according to claim 3, characterized in that, The tower leg foundation (1) further comprises top surface reinforcement (611). The mesh structure formed by the outer hoop reinforcement (605) and the outer longitudinal reinforcement (607) is bent at the top of the short column (3) to form the top surface reinforcement (611).

6. The foundation structure of the hybrid truss wind tower according to claim 3, characterized in that, The inner hoop reinforcement (606) is arranged inside the conversion anchor bolt (406).

7. The foundation structure of a hybrid truss wind tower according to any one of claims 1 to 6, characterized in that, The upper anchor plate (404) and the lower anchor plate (402) are both circumferentially distributed with a plurality of anchor bolt holes corresponding to the outer anchor bolt (405) and the conversion anchor bolt (406).

8. The foundation structure of a hybrid truss wind tower according to any one of claims 1 to 6, characterized in that, The upper end of the outer anchor bolt (405) penetrates the column foot bottom flange (501) to connect the column foot bottom flange (501) and the upper anchor plate (404). The upper end of the conversion anchor bolt (406) is connected to the conversion anchor bolt fixing member (502), and the conversion anchor bolt fixing member (502) is arranged in the column foot.

9. The foundation structure of a hybrid truss wind tower according to any one of claims 1 to 6, characterized in that, The lower end of the short column (3) protrudes from the bottom surface of the tower leg foundation (1).

10. The foundation structure of a hybrid truss wind tower according to any one of claims 1 to 6, characterized in that, The tower leg foundation (1) and the foundation connecting beam (2) are arranged below the concrete cushion (7).

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