CN211038922U - Tower foundation, tower system and wind generating set - Google Patents

Abstract

The utility model provides a tower basis, tower system and wind generating set, the tower basis includes lower part foundation portion and the upper portion foundation portion that is located the top of lower part foundation portion, be provided with a plurality of prestressed anchorage cable and a plurality of prestressed anchorage bolt that are connected to the tower in the upper portion foundation portion, a plurality of prestressed anchorage cable and a plurality of prestressed anchorage bolt are evenly arranged and coaxial each other along the circumferencial direction of upper portion foundation portion respectively, a plurality of prestressed anchorage cable and a plurality of prestressed anchorage bolt extend in upper portion foundation portion, and at least one of a plurality of prestressed anchorage cable and a plurality of prestressed anchorage bolt further extends to in the lower part foundation portion. According to the utility model discloses a pylon basis has reduced connecting piece corrosion phenomenon, adopts prestressed anchorage cable and the mode that prestressed anchorage bolt used in combination simultaneously, has reduced the use of crab-bolt, and then has reduced the trompil of pylon bottom flange and to the weakening of its intensity, guarantees wind generating set's long-time safe operation, reduces fortune dimension cost.

Description

Tower foundation, tower system and wind generating set

Technical Field

The utility model relates to a wind power generation field, in particular to pylon basis reaches pylon system and wind generating set including this pylon basis.

Background

The tower foundation is an important component of the wind generating set, the position where the tower is connected is the key of the operation of the wind generating set, and the durability of the position is related to the safety and the reliability of the wind generating set.

With the continuous development of the wind power generation industry, the installation amount of the wind generating set in humid areas such as river banks, lakes and the like is increased continuously, and the tower foundation is in a humid environment for a long time due to the influence of underground water level and flood in rainy seasons, so that the foundation ring of the tower foundation like a foundation ring type foundation or the anchor bolt of an anchor bolt type foundation is corroded to different degrees, a certain cost is increased for later operation and maintenance of the wind generating set, and a certain risk potential is brought to the operation of the wind generating set. Moreover, if the connecting piece is corroded in the operation process, the connecting piece needs to be replaced again, and certain difficulty also exists in construction.

SUMMERY OF THE UTILITY MODEL

In order to solve the problem, the utility model provides a pylon basis including lower part foundation portion and upper portion foundation portion through setting up upper portion foundation portion to the height of water level on, has reduced crab-bolt corrosion phenomenon, adopts prestressed anchorage cable and the mode that prestressed anchorage bolt used in combination simultaneously, has reduced the use of crab-bolt, and then has reduced the trompil of pylon bottom flange and to the weakening of the intensity of pylon bottom flange, guarantees wind generating set's long-time safe operation, reduces fortune dimension cost.

According to an aspect of the present invention, there is provided a tower foundation, which may include a lower foundation portion and an upper foundation portion located above the lower foundation portion, wherein a plurality of pre-stressed anchor cables and a plurality of pre-stressed anchor bolts connected to a tower are provided in the upper foundation portion, wherein the plurality of pre-stressed anchor cables and the plurality of pre-stressed anchor bolts are uniformly arranged in a circumferential direction of the upper foundation portion and are coaxial with each other, respectively, wherein the plurality of pre-stressed anchor cables and the plurality of pre-stressed anchor bolts extend in the upper foundation portion, and at least one of the plurality of pre-stressed anchor cables and the plurality of pre-stressed anchor bolts further extends into the lower foundation portion.

The plurality of prestressed anchor lines may extend in the upper base part and the lower base part, and the plurality of prestressed anchor bolts may extend in the upper base part, wherein lower ends of the plurality of prestressed anchor lines may be installed on a prestressed anchor line lower bearing plate, which may be installed on a steel braced system in the lower base part, and lower ends of the plurality of prestressed anchor bolts may be disposed on a lower anchor plate, which may be installed on a steel braced system in the upper base part.

When the height of the upper base portion is greater than 3m, the length of each of the plurality of pre-stressed anchors may be 1/3-1/2 of the height of the upper base portion; when the height of the upper base portion is equal to or less than 3m, each of the plurality of prestressed anchor cables may extend to a length of the lower base portion of at least 2/3 the height of the lower base portion.

The plurality of pre-stressed anchor cables and the plurality of pre-stressed anchor bolts may extend in both the upper base part and the lower base part, respectively, wherein lower ends of the plurality of pre-stressed anchor cables may be mounted on a pre-stressed anchor cable lower bearing plate, lower ends of the plurality of pre-stressed anchor bolts may be mounted on a lower anchor plate, and the pre-stressed anchor cable lower bearing plate and the lower anchor plate may be integrally formed and mounted on a steel support system located in the lower base part.

The lower base portion and the upper base portion may both be hollow bases.

The prestressed anchor cables and the prestressed anchor bolts may be respectively arranged in one circle, and the prestressed anchor bolts are arranged outside the prestressed anchor cables.

The lower bearing plate of the prestressed anchor cable can be a steel plate which is integrally annular, or can comprise a plurality of square steel plates or a plurality of round steel plates which are circularly arranged.

The number of the prestressed anchor cables can be 18-25 bundles, and the number of the prestressed anchor bolts can be 55-80.

According to another aspect of the present invention, there is provided a tower system, which may include the tower foundation and the tower located thereon, wherein the lower end of the tower is provided with a tower bottom flange, and the tower bottom flange is fixedly connected to the plurality of prestressed anchor cables and the plurality of prestressed anchor bolts.

According to another aspect of the present invention, a wind turbine generator set is provided, which may comprise a tower system as described above.

According to the utility model discloses a pylon basis can effectively avoid the connecting piece corrosion problem of pylon and basic junction to through the compound mode that adopts prestressed anchorage cable and prestressed anchorage bolt, reduced crab-bolt quantity, reduce whole construction cost, the strong operability. In addition, due to the fact that the use of anchor bolts is reduced, the weakening of the strength of the opening of the flange at the bottom of the tower frame is reduced, long-time safe operation of the wind generating set is guaranteed, and operation and maintenance cost is reduced. In addition, the prestressed structure is safe and reliable, the concrete is in a pressed state for a long time, cracking is avoided, and the structural durability is improved.

Drawings

Fig. 1 is a schematic cross-sectional view showing a tower foundation according to a first embodiment of the invention.

Fig. 2 is a partial sectional view showing a tower foundation according to the first embodiment, which does not show the connection relationship with the tower.

Fig. 3 is a partial schematic view showing grouting leveling of a tower foundation according to a first embodiment of the present invention.

Fig. 4A to 4C are plan views schematically illustrating examples of a prestressed anchor rope lower bearing plate according to an embodiment, respectively.

Fig. 5 is a plan view schematically showing an example of the lower anchor plate according to the embodiment.

Fig. 6 is a schematic cross-sectional view showing a tower foundation according to a second embodiment of the present invention.

Description of reference numerals:

1-a lower base portion; 5-an upper base portion; 4-prestressed anchorage cable; 2-a prestressed anchor cable lower bearing plate; 3-prestressed anchorage device; 7-prestressed anchor bolts; 6-lower anchor plate; 8-lower anchor plate supporting bolts; 9-adjusting the nut; 10-a transition pad; 11-bolt connection holes; 12-grouting material; 13-leveling bolts; 100-a tower; 14-tower bottom flange; 15-anchor bolt connecting hole.

Detailed Description

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

Referring to fig. 1, a tower foundation according to an embodiment of the invention is arranged below a tower 100 and is connected to the tower foundation by a tower bottom flange 14.

According to an embodiment of the invention, the tower foundation comprises a lower foundation part 1 and an upper foundation part 5 located above the lower foundation part 1. Further, a plurality of prestressed anchor lines 4 and a plurality of prestressed anchor bolts 7 connected to the tower 100 are provided in the upper base portion 5, and the plurality of prestressed anchor lines 4 and the plurality of prestressed anchor bolts 7 are respectively uniformly arranged in a circumferential direction of the upper base portion 5 and are coaxial with each other.

Further, a plurality of prestressed anchorage cables 4 and a plurality of prestressed anchorage bolts 7 extend in the upper base portion 5, and at least one of them extends into the lower base portion 1. For example: according to the embodiment shown in fig. 1, a plurality of prestressed anchor lines 4 extend in the upper and lower base portions 5 and 1, and a plurality of prestressed anchor bolts 7 extend only in the upper base portion 5; unlike the embodiment of fig. 1, in the embodiment shown in fig. 6, a plurality of prestressed anchorage cables 4 and a plurality of prestressed anchorage bolts 7 extend both in the upper base portion 5 and in the lower base portion 1. But not limited to, the examples in the drawings, may also be provided in the form of: the plurality of prestressed anchorage cables 4 extend only in the upper base portion 5, and the plurality of prestressed anchorage bolts 7 extend in both the upper base portion 5 and the lower base portion 1.

The structure of a tower foundation according to a first embodiment is described below with reference to fig. 1 to 5.

In the tower foundation according to the first embodiment, the lower foundation portion 1 is disposed on the ground and may occupy a large area, for example, the lower foundation portion 1 may employ an enlarged slab foundation or a beam slab foundation. In addition, the upper surface of the upper foundation portion 5 is above the water level H so that the connection position between the tower 100 and the tower foundation is above the water level H. Wherein, the water level height H is determined according to the water level height value of the flood control area. In this way, water is effectively prevented from penetrating into the junction between the tower 100 and the tower foundation, thereby preventing corrosion of the connection at that location.

According to the first embodiment, the plurality of prestressed anchorage cables 4 extend in both the upper foundation portion 5 and the lower foundation portion 1, and the plurality of prestressed anchorage bolts 7 extend only in the upper foundation portion 5, so that it is possible to effectively combine the features and advantages of the prestressed anchorage cables 4 and the prestressed anchorage bolts 7, thereby forming a stable tower foundation, as will be explained in detail below.

Each of the prestressed anchor cables 4 can be formed by a steel strand, and the steel strand is formed by twisting a plurality of thin steel wires, so that even if a broken steel wire exists in the anchor cable, the whole bundle of broken steel wires cannot be generated, the failure is not easy to occur, and the quick installation can be realized without screwing a nut, however, the steel strand has the defects of large prestress loss and larger prestress loss due to shorter length. In addition, the prestressed anchor 7 has the advantage of low cost, however, the prestressed anchor 7 has the following disadvantages: the prestressed anchor bolts 7 are connected to the tower bottom flange 14, and since the diameter of the tower bottom flange 14 is small and the diameter of the nuts (not shown) for mounting the prestressed anchor bolts 7 to the tower bottom flange 14 is large, a stress concentration phenomenon is easily generated, and in addition, the process of screwing the nuts also prolongs the construction period.

Therefore, according to the present invention, the above-mentioned disadvantages can be compensated by using the plurality of prestressed anchorage cables 4 and the plurality of prestressed anchorage bolts 7 in combination.

If only the prestressed anchor bolt 7 is used, the connection reliability of the connection of the tower 100 to the tower foundation is lowered since the nut connecting the prestressed anchor bolt 7 to the tower bottom flange 14 is rotated by vibration. However, the prestressed anchor cable 4 is added on the basis, because the anchor cable clamping pieces (not shown) connected with the prestressed anchor cable 4 are more and more tensioned due to vibration, the reliability of the connection part of the tower 100 and the tower foundation is improved, and the operation safety of the whole wind generating set is improved.

In addition, due to the use of the prestressed anchor cables 4, the number of the prestressed anchor bolts 7 is reduced, so that the connection stress condition of the tower bottom flange 14 can be improved, the process of screwing nuts due to the installation of the prestressed anchor bolts 7 can be reduced, and the construction period can be shortened.

As described above, the stress loss of the prestressed anchor rope 4 is relatively large, and thus if a low-retraction anchor is used to compensate for the stress loss, the cost is greatly increased, and the prestressed anchor bolt 7 is used to compensate for the stress loss of the prestressed anchor rope 4 in the embodiment, so that the cost can be effectively reduced. Further, since the stress loss is larger as the length of the prestressed anchor rope 4 is shorter, in the present embodiment, it is preferable to make the length thereof longer, that is, the prestressed anchor rope 4 extends in both the lower base portion 1 and the upper base portion 5, thereby effectively reducing the stress loss.

Regarding the lengths of the prestressed anchor lines 4 and the prestressed anchors 7, it is preferable that when the height of the upper base portion 5 is more than 3m, the length of each of the plurality of prestressed anchors 7 is 1/3-1/2 of the height of the upper base portion 5; when the height of the upper base portion 5 is 3m or less, each of the plurality of prestressed anchor cables 4 extends into the lower base portion 1 by at least 2/3 the height of the lower base portion 1. However, the lengths of the prestressed anchorage cable 4 and the prestressed anchorage bolt 7 are not limited thereto, and may be adjusted accordingly according to the actual situation.

According to the utility model discloses an embodiment, the lower extreme mountable of a plurality of prestressed anchorage cable 4 is on bearing plate 2 under the prestressed anchorage cable. Taking a concrete tower foundation as an example, a prestressed anchor rope lower bearing plate 2 is installed on a steel support system located in a lower base part 1 before concrete is cast, and a plurality of prestressed anchor ropes 4 are fixed to the prestressed anchor rope lower bearing plate 2 by using a prestressed anchorage device 3, thereby forming the lower base part 1 by casting.

Fig. 4A to 4C illustrate various shapes of the prestressed anchor rope lower bearing plate 2, and as shown in the drawings, the prestressed anchor rope lower bearing plate 2 may be a steel plate having a circular shape as a whole (fig. 4A), or include a plurality of square steel plates arranged in a circle (fig. 4B) or include a plurality of circular steel plates arranged in a circle (fig. 4C), and the shape of the prestressed anchor rope lower bearing plate 2 is not limited thereto but may be various forms having a circular shape as a whole.

Referring back to fig. 1, a plurality of prestressed anchor bolts 7 are provided at lower ends thereof on the lower anchor plates 6, and the lower anchor plates 6 are fixedly coupled to reinforcing bars in the upper foundation portion 5. In addition, the upper ends of the plurality of prestressed anchor bolts 7 are mounted to the transition pad 10, and the transition pad 10, the lower anchor plate 6 and the plurality of prestressed anchor bolts 7 together form an anchor cage. Thus, the lower anchor plate 6 and the transition pad plate 10 may each be annular in shape.

In addition, a leveling component for leveling the transition base plate 10 and the lower anchor plate 6 is arranged on the anchor bolt cage.

Specifically, the lower anchor plate 6 is provided with the lower anchor plate support bolt 8, a support (not shown) of the lower anchor plate support bolt 8 can be welded to a steel bar near the lower anchor plate support bolt, and the lower anchor plate 6 can be leveled and the lower anchor plate 6 can be supported at the same time when a screw (not shown) of the lower anchor plate support bolt 8 is connected to the lower anchor plate 6. Further, as shown in fig. 5, the lower anchor plate supporting bolt 8 may be connected to the lower anchor plate 6 through a bolt connection hole 11, the lower anchor plate supporting bolt 8 may be provided in plurality, and the plurality of lower anchor plate supporting bolts 8 may be uniformly arranged in a circumferential direction and arranged outside the plurality of pre-stressed anchor bolts 7. Preferably, 6 lower anchor plate supporting bolts 8 may be provided. In addition, an anchor bolt coupling hole 15 is formed in the lower anchor plate 6, and the plurality of prestressed anchor bolts 7 are respectively mounted to the lower anchor plate 6 through the plurality of anchor bolt coupling holes 15.

Below the transition shim plate 10, leveling bolts 13 and leveling nuts 9 are arranged. The supports (not shown) of the leveling bolts 13 may be welded to the steel bars adjacent thereto, and the screws (not shown) of the leveling bolts 13 are coupled to the transition shim plate 10 and level the transition shim plate 10 under the support of the supports. The leveling nut 9 is screwed on the prestressed anchor bolt 7, and the leveling of the transition base plate 10 is assisted by adjusting the position of the leveling nut 9 relative to the prestressed anchor bolt 7.

Grouting is also required after the concrete is cast to form the upper foundation portion 5 in order to tightly bond the transition pad 10 to the concrete. However, after grouting, it is necessary to ensure that the flatness of the transition mat 10 is within the error range, and therefore, before grouting, the transition mat 10 is also leveled by using the leveling member.

Fig. 3 shows a partial schematic view of grout leveling. As shown in fig. 3, before grouting, the flatness of the transition pad 10 is adjusted by the leveling bolt 13, and then the flatness of the transition pad 10 is retested by adjusting the leveling nut 9, so as to ensure that the flatness of the transition pad 10 is within an error range (for example, the maximum deviation of the flatness of the transition pad 10 is less than or equal to 2 mm). The concrete surface is cleaned (without loose crushed stone, floating slurry, floating ash, oil stain and the like) and then grouted. After grouting, a grouting material 12 is formed as shown in fig. 3, and the transition slab 10 is tightly combined with concrete through the grouting material 12. And then, drawing the steel strands of the lower base part 1 and the upper base part 5 after threading, and then anchoring the tower foundation and the tower into an integral tower system.

Referring back to fig. 1, the plurality of prestressed anchorage cables 4 and the plurality of prestressed anchors 7 may be arranged one turn each, and in this case, the number of prestressed anchorage cables 4 may be 18 to 25 tendons and the number of prestressed anchorage bolts 7 may be 55 to 80, and preferably, the number of prestressed anchorage cables may be 20 tendons and the number of prestressed anchorage bolts may be 60 to 70. In addition, fig. 1 shows a form in which a plurality of prestressed anchor cables 4 are provided in an inner race and a plurality of prestressed anchor bolts 7 are provided in an outer race, but the positions of the two are not limited thereto.

Fig. 6 shows a tower foundation according to a second embodiment of the invention.

As shown in fig. 6, in the tower foundation according to the second embodiment, a plurality of pre-stressed anchor lines 4 and a plurality of pre-stressed anchor bolts 7 are extended in both the upper foundation portion 5 and the lower foundation portion 1, and the plurality of pre-stressed anchor lines 4 and the plurality of pre-stressed anchor bolts 7 may have the same length.

In this case, the lower pressure bearing plate 2 and the lower anchor plate 6 of the prestressed anchorage cable may be integrally formed, thereby facilitating installation on site and replacement at a later stage. That is, any one of the prestressed anchor line lower pressure-bearing plates 2 of fig. 4A to 4C may be coaxially provided with the lower anchor plate 6 of fig. 5 as one body.

In addition, the lower base portion 1 and the upper base portion 5 may be preferably provided as a hollow base, so that it is possible to more conveniently install and replace the plurality of prestressed anchor lines 4 and the plurality of prestressed anchor bolts 7 and the integrated prestressed anchor line lower pressure-bearing plate 2 and lower anchor plate 6. But not limited thereto, the lower base portion 1 may be a solid base and the upper base portion 5 may be a hollow base as in the first embodiment; or both may be provided as a solid foundation. When a solid foundation is provided, it may be filled with concrete or the like. As long as the setting strength of the tower foundation can be satisfied.

Other structures according to the second embodiment are the same as or similar to those of the first embodiment, and thus detailed descriptions thereof are omitted.

In manufacturing the tower foundation according to the invention, the lower foundation part 1 and the upper foundation part 5 may be formed separately. For example, a steel support system (e.g., a steel reinforcement cage) is first provided, and after the lower foundation portion 1 is cast, the steel support system for forming the upper foundation portion 5 is provided over the lower foundation portion 1, and then the upper foundation portion 5 is cast. This form is preferably applied to the tower foundation of the first embodiment.

However, the lower base portion 1 and the upper base portion 5 may also be integrally formed. For example, after providing a steel support system for forming the lower foundation portion 1 and the upper foundation portion 5 and installing the prestressed anchor lines 4 and the prestressed anchor bolts 7, the tower foundation is formed by casting together, which is preferably applied to the tower foundation of the second embodiment.

The utility model discloses still can provide a tower system, this tower system can include tower 100 and as above the tower basis, the lower extreme of tower 100 can be provided with tower bottom flange 14, tower bottom flange 14 and a plurality of prestressed anchorage cable 4 and a plurality of prestressed anchorage bolt 7 fixed connection. As shown in fig. 1 and 6, the tower bottom flange 14 may be a T-shaped flange, and the plurality of prestressed anchor cables 4 and the plurality of prestressed anchor bolts 7 may be connected to the inner side and the outer side of the T-shaped flange, respectively, to achieve a stable connection between the tower foundation and the tower 100.

The utility model discloses still can provide a wind generating set, this wind generating set includes above-mentioned pylon system.

According to the utility model discloses a pylon basis can effectively avoid the connecting piece corrosion problem of pylon and basic junction to through the compound mode that adopts prestressed anchorage cable and prestressed anchorage bolt, reduced crab-bolt quantity, reduce whole construction cost, the strong operability. In addition, due to the fact that the use of anchor bolts is reduced, the weakening of the strength of the opening of the flange at the bottom of the tower frame is reduced, long-time safe operation of the wind generating set is guaranteed, and operation and maintenance cost is reduced. In addition, the prestressed structure is safe and reliable, the concrete is in a pressed state for a long time, cracking is avoided, and the structural durability is improved.

Although exemplary embodiments of the present invention have been described above in detail, it should be understood by those skilled in the art that various modifications and changes may be made to the embodiments of the present invention without departing from the principles and spirit of the invention. It will be understood that modifications and variations will occur to those skilled in the art, which modifications and variations will still fall within the scope of the invention as defined by the appended claims.

Claims (10)

1. A tower foundation, characterized in that it comprises a lower foundation part (1) and an upper foundation part (5) located above the lower foundation part (1), in which upper foundation part (5) there are arranged a number of pre-stressed anchor lines (4) and a number of pre-stressed anchor bolts (7) connected to a tower (100),

wherein the plurality of prestressed anchorage cables (4) and the plurality of prestressed anchorage bolts (7) are respectively arranged uniformly in the circumferential direction of the upper base portion (5) and are coaxial with each other,

wherein the plurality of pre-stressed anchor lines (4) and the plurality of pre-stressed anchor bolts (7) extend in the upper base part (5) and at least one of the plurality of pre-stressed anchor lines (4) and the plurality of pre-stressed anchor bolts (7) further extends into the lower base part (1).

2. The tower foundation of claim 1, wherein the plurality of pre-stressed anchor lines (4) extend in the upper foundation portion (5) and the lower foundation portion (1), the plurality of pre-stressed anchor bolts (7) extend in the upper foundation portion (5),

wherein the lower ends of the plurality of prestressed anchor lines (4) are installed on a prestressed anchor line lower bearing plate (2), the prestressed anchor line lower bearing plate (2) is installed on a steel support system located in the lower base part (1), and

the lower ends of the plurality of prestressed anchor bolts (7) are arranged on a lower anchor plate (6), and the lower anchor plate (6) is installed on the steel bars located in the upper foundation portion (5).

3. A tower foundation according to claim 2,

when the height of the upper base part (5) is greater than 3m, the length of each of the plurality of prestressed anchor bolts (7) is 1/3-1/2 of the height of the upper base part (5);

each of the plurality of prestressed anchor cables (4) extends to 2/3 where the length of the lower base portion (1) is at least the height of the lower base portion (1) when the height of the upper base portion (5) is 3m or less.

4. The tower foundation of claim 1, wherein the plurality of pre-stressed anchor lines (4) and the plurality of pre-stressed anchor bolts (7) extend in both the upper foundation portion (5) and the lower foundation portion (1), respectively,

wherein the lower ends of the prestressed anchor cables (4) are arranged on the prestressed anchor cable lower bearing plate (2), the lower ends of the prestressed anchor bolts (7) are arranged on the lower anchor plate (6),

the prestressed anchor line lower bearing plate (2) and the lower anchor plate (6) are integrally formed and mounted on a steel support system located in the lower foundation portion (1).

5. A tower foundation according to claim 4, characterised in that said lower foundation portion (1) and said upper foundation portion (5) are both hollow foundations.

6. The tower foundation of claim 1, wherein the pre-stressed anchor cables (4) and the pre-stressed anchor bolts (7) are arranged in a circle, and the pre-stressed anchor bolts (7) are arranged outside the pre-stressed anchor cables (4).

7. A tower foundation according to claim 2 or 4, wherein said prestressed anchor line lower bearing plate (2) is a steel plate having a circular ring shape as a whole, or comprises a plurality of square steel plates or a plurality of circular steel plates arranged in a circle.

8. The tower foundation of claim 1, wherein the number of the prestressed anchor cables (4) is 18-25 bundles, and the number of the prestressed anchor bolts (7) is 55-80.

9. A tower system, characterized in that the tower system comprises a tower foundation according to any one of claims 1-8 and a tower (100) thereon, a lower end of the tower (100) is provided with a tower bottom flange (14), and the tower bottom flange (14) is fixedly connected with the plurality of prestressed anchor lines (4) and the plurality of prestressed anchor bolts (7).

10. A wind park arrangement, characterized in that the wind park arrangement comprises a tower system according to claim 9.

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