DEVICE AND METHOD FOR RELEASING A STRESSING STRAND

Abstract

An apparatus and a method for relieving a tension strand, in particular a tension strand of a prestressed tower, preferably a prestressed concrete tower of a wind power plant. Furthermore, the disclosure relates to a method for dismantling a prestressed tower and to the use of an apparatus. The apparatus comprises a first anchoring unit with a first tension strand receptacle for a first section of the tension strand, a second anchoring unit with a second tension strand receptacle for a second section of the tension strand, and a lifting unit which is configured to change a spacing between the first and second anchoring unit.

Claims

1. An apparatus for relieving a tension strand of a prestressed tower of a wind power plant the apparatus comprising: a first anchoring unit with a first tension strand receptacle for receiving a first section of the tension strand, a second anchoring unit with a second tension strand receptacle for receiving a second section of the tension strand, a lifting unit configured to change a spacing between the first and second anchoring units.

2. The apparatus as claimed in claim 1, wherein the lifting unit is configured to increase and/or decrease the spacing between the first and second anchoring units.

3. The apparatus as claimed in claim 1, wherein the lifting unit connects the first and second anchoring units and is arranged between the first and second anchoring units.

4. The apparatus as claimed in claim 1 wherein the lifting unit is a hydraulic cylinder or a spindle lifting mechanism.

5. The apparatus as claimed in claim 1 wherein at least one of the first anchoring unit or the second anchoring unit is configured in two pieces.

6. The apparatus as claimed in claim 1 wherein at least one of the first anchoring unit or the second anchoring unit has a first anchor base and a first anchor plate.

7. The apparatus as claimed in claim 1 wherein at least one of the first anchoring unit and the second anchoring unit has a length, a width, and a depth, the depth being multiple times smaller than the width and/or the length.

8. The apparatus as claimed in claim 1 wherein at least one of the first anchoring unit or the second anchoring unit has a first clamping unit, the first clamping unit and the second anchoring unit being arranged at least in sections in the first and second tension strand receptacles, respectively.

9. A method for relieving a tension strand of a prestressed tower of a wind power plant, the method comprising: arranging a first section of the tension strand in a first tension strand receptacle, and anchoring the first section of the tension strand in a first anchoring unit, arranging a second section of the tension strand in a second tension strand receptacle, and anchoring the second section of the tension strand in a second anchoring unit, and changing a spacing between the first and second anchoring units using a lifting unit.

10. The method as claimed in claim 9, wherein changing the spacing between the first and second anchoring units using the lifting unit comprises increasing a spacing of the tension strand with respect to an adjacent tension strand and/or with respect to a tower wall.

11. The method as claimed in claim 9, wherein changing the spacing between the first and second anchoring units using the lifting unit comprises decreasing the spacing between the first and second anchoring unit.

12. The method as claimed in claim 9, further comprises severing of the tension strand between the first and second anchoring units.

13. The method as claimed in claim 9, further increasing the spacing between the first and second anchoring units.

14. A method for dismantling a prestressed tower of a wind power plant, the method comprising: relieving of at least one tension strand using the apparatus as claimed in claim 1; and removing the at least one tension strand and/or tower segments.

15. (canceled)

16. The method as claimed in claim 14, wherein the at least one tension strand is a plurality of tension strands.

17. The apparatus as claimed in claim 1 wherein the prestressed tower is a prestressed concrete tower of the wind power plant.

18. The method as claimed in claim 10, wherein increasing the spacing of the tension strand comprises using an air cushion.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0045] Preferred exemplary embodiments will be described by way of example on the basis of the appended figures, in which:

[0046] FIG. 1 shows a diagrammatic illustration of a wind power plant,

[0047] FIG. 2 shows a view of a first exemplary apparatus for relieving a tension strand,

[0048] FIG. 3 shows a view of the apparatus according to FIG. 2 with a severed tension strand,

[0049] FIG. 4 shows a plan view of the apparatus according to FIGS. 2 and 3,

[0050] FIG. 5 shows a view of a further exemplary apparatus for relieving a tension strand, and

[0051] FIG. 6 shows a diagrammatic flow chart of an exemplary method for relieving a tension strand.

DETAILED DESCRIPTION

[0052] FIG. 1 shows a diagrammatic illustration of a wind power plant. The wind power plant 100 has a tower 102 and a nacelle 104 on the tower 102. An aerodynamic rotor 106 with three rotor blades 108 and a spinner 110 is provided on the nacelle 104. During operation of the wind power plant, the aerodynamic rotor 106 is set in a rotational movement by way of the wind, and therefore also drives an electrodynamic rotor of a generator which is coupled directly or indirectly to the aerodynamic rotor 106. The electric generator is arranged in the nacelle 104 and generates electric energy. The pitch angles of the rotor blades 108 can be changed by way of pitch motors at the rotor blade roots of the respective rotor blades 108.

[0053] The tower 102 is a prestressed concrete tower with tendons which are guided externally in the interior of the tower 102 and in each case have a plurality of tension strands. In order to relieve tension strands of this type, an apparatus for relieving a tension strand can be used, as described, for example, in FIGS. 2 to 4 and in FIG. 5, a method according to FIG. 6 preferably being used.

[0054] In the figures, identical or substantially functionally identical elements are provided with the same designations. General descriptions relate as a rule to all embodiments in so far as differences are not explicitly specified.

[0055] The exemplary embodiments described herein of the apparatus 200, 300 serve to relieve tension strands 400 which are under tension, for example with tensioning forces S of from approximately 50 kN (kilonewtons) to approximately 250 kN and/or tension strand elongations of from approximately 10 cm (centimeters) to approximately 250 cm.

[0056] The apparatus 200 which is shown in FIGS. 2 to 4 comprises a first anchoring unit 210 with a first tension strand receptacle 213 for a first section of the tension strand 400, and a second anchoring unit 220 with a second tension strand receptacle 223 for a second section of the tension strand 400.

[0057] FIG. 5 shows a further apparatus 300 with a first anchoring unit 310 with a first tension strand receptacle 313 for a first section of the tension strand 400, and a second anchoring unit 320 with a second tension strand receptacle 323 for a second section of the tension strand 400.

[0058] The respective two anchoring units 210, 220, 310, 320 are spaced apart from one another. The spacing A1 between the first and second anchoring unit 210, 220, 310, 320 extends parallel to the longitudinal axis of the tension strand 400. In FIGS. 2 and 4, the tension strand has not yet been severed, and the anchoring units 210, 220, 310, 320 are spaced apart from one another at the small spacing A1, the spacing A1 preferably already having been decreased, with the result that the tension strand between the anchoring units 210, 220, 310, 320 is already completely or largely relieved. In FIG. 3, the tension strand 400 is severed, the anchoring units 210, 220 have been removed from one another by means of the lifting unit 240 and they are now spaced apart at the greater spacing A2, with the result that the tension strand is also relieved outside the apparatus 200, in particular above the first anchoring unit 210 and below the second anchoring unit 220.

[0059] The tension strand receptacles 213, 223, 313, 323 also in each case have a longitudinal axis which runs parallel to or is identical to the longitudinal axis of the tension strand 400 to be relieved. The two anchoring units 210, 220, 310, 320 in each case have a clamping unit in the form of clamping wedges 214, 224, 314, 324. The longitudinal axes of the clamping wedges 214, 224, 314, 324 are also oriented parallel to the tension strand axis. The clamping wedges 214, 224, 314, 324 serve to improve the anchoring of the tension strand 400, which is arranged in the tension strand receptacles 213, 223, 313, 323, in the anchoring units 210, 220, 310, 320.

[0060] The anchoring units 210, 220, 310, 320 with their tension strand receptacles 213, 223, 313, 323 are configured in two pieces, and in each case have an anchor base and an anchor plate, the tension strand receptacle 213, 223, 313, 323 being formed by the anchor base and the anchor plate. The tension strand sections can thus be received simply in the tension strand receptacles 213, 223, 313, 323 of the anchoring units 210, 220, 310, 320. The tension strand receptacle 213, 223, 313, 323 is arranged in each case centrally in the anchor base 212, 222, 312, 322 and the anchor plate 212, 222, 312, 322. The anchor plate 212, 222, 312, 322 is fastened releasably to the anchor base 212, 222, 312, 322 by means of a screw connection via a plurality of Allen screws 230 which are provided on the two sides of the tension strand receptacle 213, 223, 313, 323. As a result, the anchoring units 210, 220, 310, 320 and tension strand receptacles 213, 223, 313, 323 can be opened simply, and controlled and reliable anchoring can take place, for example via the torques which are to be applied to the screw connection.

[0061] The anchoring units 210, 220, 310, 320 in each case have a length L, a width B and a depth T, the depth T being multiple times smaller than the width B and the length L. It is preferred, in particular, that the depth T is at most 10 cm, preferably at most 5 cm, in particular at most 4 cm.

[0062] A small depth of the anchoring units 210, 220, 310, 320 has the advantage that the anchoring units 210, 220, 310, 320 can be inserted between adjacent tension strands and/or between the tension strand and the tower inner wall, it being possible for the tension strand 400 to be relieved to be raised beforehand from the adjacent tension strands or the tower inner wall, for example by means of an air cushion.

[0063] The tension strand sections are received and anchored in the tension strand receptacles 213, 223, 313, 323 of the anchoring units 210, 220, 310, 320. An anchoring is a fastening which prevents a relative displacement between the tension strand sections and the respective anchoring unit 210, 220, 310, 320, in particular along the direction of the tension strand axis, in particular also in the case of the application of high forces which can correspond to the prevailing tensioning forces S or can exceed the latter.

[0064] Furthermore, the apparatus 200 has a lifting unit 240 in the form of a spindle lifting mechanism 249. The lifting unit 340 of the apparatus 300 is configured as a hydraulic cylinder 349.

[0065] The spindle lifting mechanism 249 according to FIGS. 2 to 4 has two threaded spindles 241, 242 which are connected via axial bearings 244 to the second anchoring unit 220 and run through nuts 243 which are connected fixedly to the first anchoring unit 210. The spacing A1, A2 between the anchoring units 210, 220 can be changed by way of the application of torques to the threaded spindles 241, 242 via the axial bearings 244.

[0066] The hydraulic cylinder 349 according to FIG. 5 has two hydraulic cylinders 341, 342 which are connected to the first and second anchoring unit 310, 320. By way of actuating, in particular retracting and extending of the hydraulic cylinders 341, 342, the spacing A1 between the anchoring units 310, 320 can be changed.

[0067] The lifting units 240, 340 are configured to change a spacing A1, A2 between the first and second anchoring unit 210, 220, 310, 320, in particular to increase it and/or to decrease it. The lifting units 240, 340 are arranged between the first and second anchoring unit 210, 220, 310, 320, and are connected to the first and the second anchoring unit 210, 220, 310, 320. The lifting units 240, 340 are suitable to apply the required high forces, in order to overcome the tensioning forces of the tension strand 400, for example of from approximately 50 to approximately 250 kN per strand, in the case of the change of the spacing A1, A2 between the two anchoring units 210, 220, 310, 320.

[0068] A decrease in the spacing between the first and second anchoring unit 210, 220, 310, 320 to the spacing A1 leads to relieving of the tensioning strand 400 between the two anchoring units 210, 220, 310, 320. An increase in the spacing between the first and second anchoring unit 210, 220, 310, 320 to the spacing A2 leads to relieving of the tensioning strand 400 in regions outside the apparatus 200, 300, that is to say on the other side of the anchoring units 210, 220, 310, 320.

[0069] The apparatus 200, 300 is used initially to first of all decrease the spacing between the first and second anchoring unit 210, 220, 310, 320 to the spacing A1, in order to relieve the tension strand 400 between the two anchoring units 210, 220, 310, 320, as is shown in FIG. 2, in particular. The tension strand 400 can then be severed. After the severing, the spacing between the first and second anchoring unit 210, 220, 310, 320 is increased to the spacing A12, in order to relieve the tension strand 400 which is then severed in the regions outside the apparatus 200, 300, that is to say, for example, above and below the anchoring units 210, 220, 310, 320, as is shown in FIG. 3, in particular. If the apparatus is then dismantled, that is to say the tension strand sections are released from the tension strand receptacles 213, 223, 313, 323 of the anchoring units 210, 220, 310, 320, the tension strand 400 is preferably already completely relieved, with the result that no uncontrolled movements of the severed tension strand 400 take place.

[0070] This takes place, in particular, by way of a method 1000 for relieving a tension strand 400, which method 1000 can proceed as follows. As preparation, an increase 1004 in a spacing of the tension strand from an adjacent tension strand and/or from a tower wall preferably takes place, preferably by means of an air cushion. Then, arranging 1002 of the first section of the tension strand 400 in a first tension strand receptacle 213, 313 and anchoring of the first section of the tension strand 400 in a first anchoring unit 310, 310 take place first of all, and then arranging 1002 of a second section of the tension strand in a second tension strand receptacle 223, 323 and anchoring of the second section of the tension strand 400 in a second anchoring unit 220, 320 take place. Changing 1003 of a spacing between the first and second anchoring units 210, 220, 310, 320 by means of a lifting unit 240, 340 then takes place, and, in particular, a decrease 1004 in the spacing between the first and second anchoring unit 210, 220, 310, 320. The decrease in the spacing between the first and second anchoring unit 210, 220, 310, 320 is preferably at most 3 cm, in particular at most 1 cm. The spacing between the first and second anchoring unit 210, 220, 310, 320 is preferably decreased to such an extent that the tension strand 400 is relieved completely or virtually completely between the first and second anchoring unit 210, 220, 310, 320. Severing 1005 of the tension strand 400 then takes place between the first and second anchoring unit 210, 220, 310, 320, and an increase 1006 in the spacing between the first and second anchoring unit 210, 220, 310, 320 subsequently takes place. An increase in the spacing between the first and second anchoring unit 210, 220, 310, 320 is preferably at least 10 cm, in particular at least 50 cm. In particular, the increase in the spacing between the first and second anchoring unit 210, 220, 310, 320 serves to reduce or to eliminate the tension S in the tension strand 400 outside the apparatus 200, 300. Finally, a release 1007 of the anchoring of the tension strand sections in the anchoring units 210, 220, 310, 320 takes place, and the removing of the apparatus 200, 300 takes place.

[0071] A method for dismantling a prestressed concrete tower 102 of a wind power plant 100 preferably results if, after relieving of at least one tension strand 400, preferably a plurality of tensioning strands, in particular all the tensioning strands, by means of the apparatus 200, 300 and/or by means of the method 1000 for relieving a tension strand 400, the tension strand 400 or the tension strands are removed, in particular after severing, and/or tower segments are removed. For example, prefabricated parts of a concrete tower can be placed onto one another, with or without joint connection means. The prefabricated parts can then be removed successively, optionally after severing of the joints, in order to dismantle the tower.

[0072] The apparatuses 200, 300 make it possible for a tension strand 400 between the respective two anchoring units 210, 220, 310, 320 to be relieved and severed safely and in a controlled manner, and subsequently for the tension strand outside the apparatuses 200, 300, in particular outside the two anchoring units 210, 220, 310, 320, to be relieved. The risks and costs during the dismantling of externally prestressed structures, in particular concrete towers of wind power plants, can thus be reduced considerably, and the safety can be increased.