# US 11,028,551 B2 · Foundation for a tower of a wind-turbine

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- Number: US 11,028,551 B2
- Document ID: US11028551B2
- Status: Granted
- Kind: B2
- Application number: 16/688,191
- Filed: 2019-11-19
- Published: 2020-05-21
- Granted: 2021-06-08
- Earliest claimed: 2018-11-19
- Assignees: Nabrawind Technologies, S.L.
- Applicants: Nabrawind Technologies, S.L.
- Inventors: Hely Ricardo Savii Costa; Ion Arocena De La Rúa; Eneko Sanz Pascual; Arantxa Esparza Zabalza
- Web page: https://patentgrep.com/patent/US11028551B2

## CPC

- E02D 27/425: {specially adapted for wind motors masts (wind motors per se F03D1/00)}
- E02D 5/223: {Details of top sections of foundation piles (E02D5/54 takes precedence)}
- E02D 5/34: Concrete or concrete-like piles cast in position {; Apparatus for making same (E02D5/50 takes precedence; moulds E02D5/665; placing, removing moulds E02D7/00 - E02D11/00; placing the concrete E02D15/04)}
- E02D 11/00: Methods or apparatus {specially adapted} for both placing and removing sheet pile bulkheads, piles, or mould-pipes (features relating to placing only E02D7/00, to removing only E02D9/00 {; placing apparatus which without special provisions, can be operated to remove, e.g. vibrating drivers E02D7/00})
- F03D 13/22: {Foundations specially adapted for wind motors}
- E02D 2250/0023: Cast, i.e. in situ or in a mold or other formwork
- F03D 13/20: Arrangements for mounting or supporting wind motors; Masts or towers for wind motors
- F05B 2240/9121: on a lattice tower
- Y02E 10/72: Wind turbines with rotation axis in wind direction
- Y02E 10/728: Onshore wind turbines
- E02D: FOUNDATIONS; EXCAVATIONS; EMBANKMENTS (specially adapted for hydraulic engineering E02B); UNDERGROUND OR UNDERWATER STRUCTURES {(tunnels, tunnelling, mining E21)}
- F03D: WIND MOTORS
- F05B: INDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

Foundation for a tower of a wind turbine with at least three columns. The foundation includes a reinforced concrete pile corresponding to each of the tower columns. According to one embodiment the pile includes a bolt cage and a main reinforcement formed by a cylindrical framework made up of horizontal rings interconnected by vertical bars. The bolt cage is arranged inside the main reinforcement radially at a distance of less than 0.1 meters. Each of the piles resides in a hole formed in the ground. Concrete is not poured into the holes until the main reinforcements and bolt cages are placed therein and aligned with one another.

## Claims

### Claim 1

A foundation for a tower of a wind turbine, the tower including three columns that each has a bottom end flange, the foundation comprising:
a reinforced concrete pile for each of the three columns, the reinforced concrete pile residing in a hole in the ground and comprising:
a main reinforcement formed by a first plurality of horizontal rings and a first plurality of vertical bars attached to one another forming a first cylindrical framework, the main reinforcement being arranged near a periphery of the pile;
a bolt cage arranged inside an upper portion of the first cylindrical framework, the bolt cage including a plurality of vertically oriented threaded bars positioned a radial distance of less than 0.1 meters away from the cylindrical framework; and
concrete in which the main reinforcement and bolt cage are encased, each of the plurality of vertically oriented threaded bars having an upper end portion that protrudes upward from a top surface of the concrete that is configured to pass through the bottom end flange of the column, the positioning of the bolt cage in relation to the main reinforcement inside the concrete enabling tensile loads generated by the tower to be transferred from the bolt cage to the main reinforcement and from the main reinforcement to the concrete.

### Claim 2 (depends on 1)

The foundation according to claim 1, further comprising a secondary reinforcement formed by a second plurality of horizontal rings and a second plurality of vertical bars attached to one another forming a second cylindrical framework, the second cylindrical framework being located encased in the concrete inside the first cylindrical frame work.

### Claim 3 (depends on 2)

The foundation according to claim 2, wherein the plurality of vertically oriented threaded bars of the bolt cage are positioned a radial distance of less than 0.1 meters away from the second cylindrical framework.

### Claim 4 (depends on 2)

The foundation according to claim 2, wherein the secondary reinforcement has a first length, and a portion of the bolt cage encased in the concrete has a second length, the first length being greater than the second length.

### Claim 5 (depends on 2)

The foundation according to claim 2, wherein the main reinforcement and the secondary reinforcement are attached by joining ties arranged between the vertical bars of the main reinforcement and the vertical bars of the secondary reinforcement.

### Claim 6 (depends on 1)

The foundation according to claim 1, wherein the bolt cage includes a lower collar encased in the concrete through which the plurality of vertically oriented threaded bars pass, the first cylindrical framework being attached to the lower collar of the bolt cage by ties.

### Claim 7 (depends on 1)

The foundation according to claim 1, wherein the bolt cage comprises an upper collar located outside the concrete through which the plurality of vertically oriented threaded bars pass, the upper collar configured to be attached to the bottom end flange of the column.

### Claim 8 (depends on 7)

The foundation according to claim 7, wherein the upper collar comprises through holes arranged 60 degrees part from one another and configured to receive leveling elements that extend between the piles.

### Claim 9 (depends on 1)

The foundation according to claim 1, wherein the bolt cage has a length in a range between 0.8 and 2 meters and the main reinforcement has a length in a range between 20 and 40 meters.

### Claim 10

A method of constructing a foundation, the method comprising:
forming first, second and third vertical holes in the ground, each of the first second and third vertical holes having a depth;
inserting a first, second and third main reinforcement respectively inside each of the first, second and third vertical holes, each of the first, second and third main reinforcements being formed by a plurality of horizontal rings and a plurality of vertical bars attached to one another forming respective first, second and the third cylindrical frameworks that respectively extend around a contour of the first, second and third vertical holes, each of the first, second and third main reinforcements having a length that extends along an entire depth of the respective first, second and third vertical holes;
installing a first, second and third bolt cage inside an upper portion of the respective first, second and third main reinforcements, each of the first, second and third bolt cages respectively including a first, second and third upper collar, the first, second and third bolt cages being arranged such that each of the first, second and third upper collars protrude from a level of the ground;
with the use of first, second and third leveling elements extending between the first, second and third upper collars and arranged 60 degrees from one another, arranging the first second and third bolt cages so that the first, second and third upper collars are level with one another; and
after the first, second and third upper collars are level with one another, pouring concrete into each of the first, second and third vertical holes to encase the first, second and third main reinforcement and first, second and third bolt cage inside the respective first, second and third vertical holes.

### Claim 11 (depends on 10)

The method of constructing a foundation according to claim 10, further comprising:
coupling the first, second and third bolt cages respectively to the first, second and third main reinforcements by respective first, second and third ties;
inserting together the first main reinforcement and first bolt cage into the first vertical hole;
inserting together the second main reinforcement and second bolt cage into the second vertical hole; and
inserting together the third main reinforcement and third bolt cage into the second vertical hole.

### Claim 12 (depends on 11)

The method of constructing a foundation according to claim 11, wherein each of the first, second and third bolt cages respectively includes first, second and third lower collars, the method comprising coupling the first cylindrical framework to the first lower collar by use of the first tie, coupling the second cylindrical framework to the second lower collar by use of the second tie and coupling the third cylindrical framework to the third lower collar by use of the third tie.

### Claim 13 (depends on 10)

The method of constructing a foundation according to claim 10, further comprising inserting first, second and third secondary reinforcements respectively inside the first, second and third main reinforcement prior to the pouring of the concrete.

### Claim 14 (depends on 10)

The method of constructing a foundation according to claim 10, further comprising coupling each of the first, second and third secondary reinforcements respectively to the first, second and third main reinforcement by use of one or more ties and simultaneously inserting the first main reinforcement and first secondary reinforcement into the first vertical hole, simultaneously inserting the second main reinforcement and second secondary reinforcement into the second vertical hole, and simultaneously inserting the third main reinforcement and third secondary reinforcement into the third vertical hole.

### Claim 15 (depends on 14)

The method of constructing a foundation according to claim 14, further comprising:
inserting the first bolt cage between the first main reinforcement and first secondary reinforcement;
inserting the second bolt cage between the second main reinforcement and second secondary reinforcement; and
inserting the third bolt cage between the third main reinforcement and third secondary reinforcement.

### Claim 16 (depends on 15)

The method of constructing a foundation according to claim 15, wherein:
the first main reinforcement, first secondary reinforcement and first bolt cage are attached to one other outside the first vertical hole and thereafter simultaneously inserted into the first vertical hole;
the second main reinforcement, second secondary reinforcement and second bolt cage are attached to one other outside the second vertical hole and thereafter simultaneously inserted into the second vertical hole; and
the third main reinforcement, third secondary reinforcement and third bolt cage are attached to one other outside the third vertical hole of the ground and thereafter simultaneously inserted into the third vertical hole.

### Claim 17 (depends on 15)

The method of constructing a foundation according to claim 15, wherein:
the first bolt cage includes an upper collar, a lower collar and a first plurality of vertical threaded bars that extend between the upper and lower collars of the first bolt cage, the first bolt cage being arranged such that the first plurality of vertical threaded bars are spaced a distance of less than 0.1 meters away from each of the first main reinforcement and first secondary reinforcement;
the second bolt cage including an upper collar, a lower collar and a second plurality of vertical threaded bars that extend between the upper and lower collars of the second bolt cage, the second bolt cage being arranged such that the second plurality of vertical threaded bars are spaced a distance of less than 0.1 meters away from each of the second main reinforcement and second secondary reinforcement; and
the third bolt cage including an upper collar, a lower collar and a third plurality of vertical threaded bars that extend between the upper and lower collars of the third bolt cage, the third bolt cage being arranged such that the third plurality of vertical threaded bars are spaced a distance of less than 0.1 meters away from each of the third main reinforcement and third secondary reinforcement.

### Claim 18 (depends on 10)

The method of constructing a foundation according to claim 10, further comprising removing the first, second and third leveling elements extending between the first, second and third upper collars after a setting of the concrete.

### Claim 19 (depends on 10)

The method of constructing a foundation according to claim 10, wherein each of the first, second and third main reinforcements includes a lower half portion and an upper half portion, the method further comprising:
partially introducing the lower half of the first main reinforcement into the first vertical hole and then coupling the upper half of the first main reinforcement to the lower half of the first main reinforcement outside the first vertical hole,
partially introducing the lower half of the second main reinforcement into the second vertical hole and then coupling the upper half of the second main reinforcement to the lower half of the first main reinforcement outside the second vertical hole,
partially introducing the lower half of the third main reinforcement into the third vertical hole and then coupling the upper half of the third main reinforcement to the lower half of the third main reinforcement outside the third vertical hole.

### Claim 20 (depends on 10)

The method of constructing a foundation according to claim 10, wherein:
the first bolt cage includes an upper collar, a lower collar and a first plurality of vertical threaded bars that extend between the upper and lower collars of the first bolt cage, the first bolt cage being arranged such that the first plurality of vertical threaded bars are spaced a distance of less than 0.1 meters away from the first cylindrical framework;
the second bolt cage including an upper collar, a lower collar and a second plurality of vertical threaded bars that extend between the upper and lower collars of the second bolt cage, the second bolt cage being arranged such that the second plurality of vertical threaded bars are spaced a distance of less than 0.1 meters away from the second cylindrical framework; and
the third bolt cage including an upper collar, a lower collar and a third plurality of vertical threaded bars that extend between the upper and lower collars of the third bolt cage, the third bolt cage being arranged such that the third plurality of vertical threaded bars are spaced a distance of less than 0.1 meters away from the third cylindrical framework.