U.S. patent application number 13/243121 was filed with the patent office on 2012-01-19 for method of producing a tower foundation and tower adapter.
Invention is credited to Kenneth B. Leland, Joris Schiffer.
Application Number | 20120011801 13/243121 |
Document ID | / |
Family ID | 38294042 |
Filed Date | 2012-01-19 |
United States Patent
Application |
20120011801 |
Kind Code |
A1 |
Schiffer; Joris ; et
al. |
January 19, 2012 |
METHOD OF PRODUCING A TOWER FOUNDATION AND TOWER ADAPTER
Abstract
A method for producing a tower foundation is provided The method
includes providing a tower adapter having a cylindrical portion
extending in a longitudinal direction of the adapter and a first
lateral portion extending perpendicularly to the cylindrical
portion at a first end thereof, and having a plurality of first
through-holes, wherein the ratio of a maximum longitudinal
extension and a maximum lateral extension of the adapter is smaller
than or equal to 1 and providing an anchor and anchor bolts. The
method also includes forming a foundation including the anchor and
the anchor bolts, wherein the anchor bolts extend from the anchor
to an upper surface of the foundation and protrude from the upper
surface, and placing the adapter on the anchor bolts so that the
anchor bolts extend through and protrude from the first through
holes and a space is provided between an upper surface of the
foundation and a lower surface of the adapter.
Inventors: |
Schiffer; Joris; (Hannover,
DE) ; Leland; Kenneth B.; (Greer, SC) |
Family ID: |
38294042 |
Appl. No.: |
13/243121 |
Filed: |
September 23, 2011 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
11380937 |
Apr 30, 2006 |
8051627 |
|
|
13243121 |
|
|
|
|
Current U.S.
Class: |
52/742.16 ;
52/745.21 |
Current CPC
Class: |
E02D 27/425 20130101;
F03D 13/22 20160501; Y02E 10/728 20130101; E04H 12/085 20130101;
E02D 27/42 20130101; Y02E 10/72 20130101 |
Class at
Publication: |
52/742.16 ;
52/745.21 |
International
Class: |
E04H 12/00 20060101
E04H012/00; E02D 27/42 20060101 E02D027/42 |
Claims
1. A method for producing a tower foundation, comprising the steps
of: (a) providing a tower adapter having a cylindrical portion
extending in a longitudinal direction of the adapter and a first
lateral portion extending perpendicularly to the cylindrical
portion at a first end thereof, and having a plurality of first
through-holes, wherein the ratio of a maximum longitudinal
extension and a maximum lateral extension of the adapter is smaller
than or equal to 1, (b) providing an anchor and anchor bolts, (c)
forming a foundation including the anchor and the anchor bolts,
wherein the anchor bolts extend from the anchor to an upper surface
of the foundation and protrude from the upper surface, and (d)
placing the adapter on the anchor bolts so that the anchor bolts
extend through and protrude from the first through holes and a
space is provided between an upper surface of the foundation and a
lower surface of the adapter.
2. The method according to claim 1, wherein step (d) is
accomplished prior to step (c), and wherein the foundation is
formed with an upper surface being spaced from a lower surface of
the adapter.
3. The method according to claim 1, wherein the adapter is fixed by
fastening nuts to the anchor bolts protruding from the first
through-holes.
4. The method according to claim 1, wherein tubes for accepting
anchor bolts are provided, the tubes being attached to the anchor,
and wherein the foundation is formed so that the anchor bolts can
be exchangeably fixed to the anchor.
5. The method according to claim 4, wherein the anchor comprises
threaded blind holes, and wherein the anchor bolts are inserted
into the tubes and screwedly fixed to the anchor.
6. The method according to claim 4, wherein the anchor comprises
through-holes adapted for inserting anchor bolts, and wherein the
foundation is formed with a basement providing an access to the
through-holes of the anchor.
7. The method according to claim 1 further comprising: (e) pouring
grout to form a grout joint in the space provided between the upper
surface of the foundation and the lower surface of the adapter, and
(f) curing the grout joint.
8. The method according to claim 7, wherein the grout joint is
formed in a ring-shaped recess in the upper surface of the
foundation.
9. The method according to claim 7, wherein the grout joint is
formed in a shuttering built on the upper surface of the
foundation.
10. A method for configuring a tower adapter, said method
comprising: providing a tower adapter with a cylindrical portion
extending in a longitudinal direction of the tower adapter and a
first lateral portion perpendicular to the cylindrical portion; and
providing a plurality of first through-holes in the first lateral
portion, wherein the ratio of a maximum longitudinal extension and
a maximum lateral extension of the adapter is smaller than or equal
to 1.
11. The method according to claim 10, wherein providing a tower
adapter further comprises providing a tower adapter wherein the
maximum longitudinal extension of the adapter is smaller than or
equal to 2 m.
12. The method according to claim 10, wherein providing a tower
adapter further comprises providing a tower adapter with a weight
less than or equal to 10,000 kg.
13. The method according to claim 10, wherein providing a tower
adapter with a first lateral portion further comprises providing a
tower adapter with a first lateral portion having an outer portion
extending to the outside of the cylindrical portion and an inner
portion extending to the inside of the cylindrical portion, and
wherein the outer portion comprises at least one outer through-hole
and the inner portion comprises at least one inner
through-hole.
14. The method according to claim 10, wherein providing a tower
adapter further comprises providing a tower adapter with a second
lateral portion at a second end of the cylindrical portion which is
opposite to the first end, the second lateral portion extending
perpendicularly to the cylindrical portion and having a plurality
of second through-holes.
15. The adapter according to claim 14, providing a tower adapter
with a second lateral portion further comprises providing a tower
adapter with a second lateral portion having an inner portion
extending to the inside of the cylindrical portion, and wherein the
inner portion comprises the plurality of second through-holes.
16. The adapter according to claim 15, wherein providing a tower
adapter with a second lateral portion having an inner portion
further comprises providing a tower adapter with a second lateral
portion having an inner portion that has a spacing between the
inner portion of the first lateral portion and the inner portion of
the second lateral portion adapted to provide sufficient workspace
for establishing bolt connections through the first and second
through-holes.
17. The adapter according to claim 10, wherein providing a tower
adapter with a cylindrical portion further comprises providing a
tower adapter with a cylindrical portion that is a circular
cylinder.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This patent application is a divisional application of U.S.
patent application Ser. No. 11/380,937 filed on Apr. 30, 2006.
BACKGROUND OF THE INVENTION
[0002] This invention relates generally to a tower adapter, a
method of producing a tower foundation and a tower foundation. In
particular but not limited thereto, the present invention relates
to a tower adapter for a wind turbine tower, a method for producing
a foundation of a wind turbine tower, and a foundation of a wind
turbine tower.
[0003] Several technical installations require a tower or a mast to
which the installation is mounted. Non-limiting examples of such
installations are wind turbines, antenna towers used in
broadcasting or mobile telecommunication, pylons used in bridge
work, or power poles. Typically, the tower is made of steel and
must be connected to a foundation made of reinforced concrete. In
these cases, the typical technical solution is to provide a flange
with through-holes at the bottom of the tower. Anchor bolts are
inserted into the through-holes and are fastened with nuts.
Typically, the anchor bolts are connected to an anchor ring
embedded in the foundation. Normally, the concrete surface of the
foundation is relatively rough so that a grout joint is formed on
which the flange is placed.
[0004] However, the bottom part of the tower has to be placed on
the grout joint before the grout has finally cured. Therefore, a
certain curing time of the grout joint has to be awaited after
installing the bottom section of the tower until further sections
of the tower can be installed. Typically, the curing of the grout
takes at least 24 hours but may take even longer according to the
conditions at the construction site. During this curing time of the
grout joint, no further work can be done on the particular tower
construction site. For example, the bottom section of a wind
turbine tower is relatively large, typically about 10 m to 20 m
long, and accordingly also relatively heavy. Therefore, the bottom
section has to be transported in a horizontal position, e.g. to
comply with the maximum headroom of bridges. Furthermore, two
mobile cranes have to be used for lifting such a bottom section in
a vertical position and placing it on the grout joint. However,
after placing the bottom section on the grout joint the two mobile
cranes are of no particular use until the grout joint has finally
cured and further tower sections can be installed. Since mobile
cranes are very expensive, it is economically detrimental if they
are idle for longer times. Since the construction sites of wind
turbines are often remote, it is also often economically
detrimental to relocate the mobile cranes for the curing time of
the grout joint.
BRIEF DESCRIPTION OF THE INVENTION
[0005] In view of the above, a tower adapter is provided. The tower
adapter includes a cylindrical portion extending in a longitudinal
direction of the adapter, and a first lateral portion extending
perpendicularly to the cylindrical portion at a first end thereof
and having a plurality of first through-holes, wherein the ratio of
a maximum longitudinal extension and a maximum lateral extension of
the adapter is smaller than or equal to 1.
[0006] Furthermore, a method for producing a tower foundation is
provided, the method including the steps of: (a) providing a tower
adapter having a cylindrical portion extending in a longitudinal
direction of the adapter and a first lateral portion extending
perpendicularly to the cylindrical portion at a first end thereof,
and having a plurality of first through-holes, wherein the ratio of
a maximum longitudinal extension and a maximum lateral extension of
the adapter is smaller than or equal to 1, (b) providing an anchor
and anchor bolts, (c) forming a foundation including the anchor and
the anchor bolts, wherein the anchor bolts extend from the anchor
to an upper surface of the foundation and protrude from the upper
surface, (d) placing the adapter on the anchor bolts so that the
anchor bolts extend through and protrude from the first through
holes and a space is provided between an upper surface of the
foundation and a lower surface of the adapter, (e) pouring grout to
form a grout joint in the space provided between the upper surface
of the foundation and the lower surface of the adapter, (f) curing
the grout joint.
[0007] Also, a tower foundation is provided, the tower foundation
including an anchor, and tubes for accepting anchor bolts, the
tubes being attached to the anchor, wherein the foundation is
adapted so that the anchor bolts can be exchangeably fixed to the
anchor.
[0008] Further aspects, advantages and features of the present
invention are apparent from the dependent claims, the description
and the accompanying drawings.
[0009] According to a first aspect of the invention, a means for
connecting a foundation to a tower is provided. The connecting
means includes a hollow portion having a closed cross-section, and
a flange portion extending perpendicularly to the hollow portion at
a first end thereof and having a plurality of first bores, wherein
the ratio of the length of the hollow portion and a maximum
diameter of the connecting means is smaller than or equal to 1.
[0010] According to a further aspect of the present invention, a
foundation for a tower is provided. The tower foundation includes
an anchoring means, and duct means for accepting coupling means,
the duct means being attached to the anchoring means, wherein the
foundation is adapted so that the coupling means can be
exchangeably fixed to the anchoring means.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 shows a wind turbine to which the embodiments of the
present invention can be applied.
[0012] FIG. 2 is a plan top view of an adapter according to an
embodiment of the present invention.
[0013] FIG. 3 is a longitudinal cross-sectional view along line A-A
in FIG. 2.
[0014] FIG. 4 is a longitudinal cross-sectional view along line B-B
in FIG. 2.
[0015] FIGS. 5 to 8 show different steps of a method for producing
a tower foundation according to an embodiment of the present
invention.
[0016] FIGS. 9 and 10 show different steps of a method for
producing a tower foundation according to an alternative embodiment
of the present invention.
[0017] FIG. 11 is a perspective view of an anchor cage according to
an embodiment of the present invention.
[0018] FIG. 12 is a plan top view of the anchor cage shown in FIG.
9.
[0019] FIG. 13 is a cross-sectional view of an embodiment of the
anchor cage.
[0020] FIG. 14 is a cross-sectional view of another embodiment of
the anchor cage.
[0021] FIGS. 15 and 16 show different steps of a method for
producing a tower foundation according to an embodiment of the
present invention.
[0022] FIG. 17 is a cross-sectional view of a tower foundation
according to another embodiment of the present invention.
[0023] FIG. 18 is a cross-sectional view of an embodiment of the
anchor cage used in the embodiment shown in FIG. 14.
[0024] FIGS. 19 to 21 show different steps of a method for
producing a tower foundation according to another embodiment of the
present invention.
[0025] FIG. 22 is a cross-sectional view of a tower foundation
according to a further embodiment of the present invention.
[0026] FIG. 23 is a cross-sectional view of a tower foundation
according to an even further embodiment of the present
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0027] Reference will now be made in detail to the various
embodiments of the invention, one or more examples of which are
illustrated in the figures. Each example is provided by way of
explanation of the invention, and is not meant as a limitation of
the invention. For example, features illustrated or described as
part of one embodiment can be used on or in conjunction with other
embodiments to yield yet a further embodiment. It is intended that
the present invention includes such modifications and
variations.
[0028] FIG. 1 shows a wind turbine to which the embodiments of the
present invention can be advantageously applied. However, it should
be understood that the present invention is not limited or
restricted to wind turbines but can also be applied to tower
structures used in other technical fields. In particular, the
various embodiments of the present invention may also be applied to
antenna towers used in broadcasting or mobile telecommunication or
to pylons used in bridge work. Therefore, although the aspects of
the invention will be exemplified with reference to a wind turbine,
the scope of the present invention shall not be limited
thereto.
[0029] The wind turbine 100 shown in FIG. 1 comprises a tower 110
bearing a machine nacelle 120 on its top end. A rotor including a
rotor hub 130 and rotor blades 140 is attached to one side of the
nacelle 120. The tower 110 is mounted on a foundation 150.
Typically, the tower foundation 150 is made of reinforced
concrete.
[0030] FIG. 2 is a plan top view of an adapter 1000 according to an
embodiment of the present invention. Such an adapter can be used to
form a connection between the lower section of the tower 110 and
the foundation 150. In other words, the adapter is a connection
means for attaching the lowest tower section to the foundation. The
adapter 1000 shown in FIG. 2 has a circular ring-shaped form.
However, it should be understood that the adapter 1000 may have any
other desired form and that the outer shape of the adapter is
adjusted to the cross-section of the tower 110. The adapter 1000
comprises a first lateral portion 1010 having a maximum lateral
extension D1. In the present case of the first lateral portion 1010
being circular and ring-shaped, the maximum lateral extension D1 is
equal to the outer diameter of the first lateral portion 1010.
However, it should be understood that the concept of a maximum
lateral extension not confined to circular shape but can be applied
also to other cross-sectional shapes of the adapter. For example,
for a square or rectangular cross-section the maximum lateral
extension is given by the diagonals of the square or rectangle. The
first lateral extension includes first through-holes 1020, 1030
which are arranged in a circumferential direction. The first
through-holes are grouped into outer through-holes 1020 located
adjacent the outer edge of the first lateral portion 1010 and inner
through-holes 1030 located adjacent the inner edge of the first
lateral portion 1010. The adapter 1000 further comprises a second
lateral portion 1042 located above the first lateral portion 1010
and also having a circular ring-shaped form. Second through-holes
1045 are formed within the second lateral portion 1042 in a
circumferential direction thereof.
[0031] For a better understanding of the configuration of adapter
1000, reference is made to FIG. 3 showing a longitudinal
cross-sectional view along line A-A in FIG. 2 and to FIG. 4 showing
a longitudinal cross-sectional view along line B-B in FIG. 2. The
cross-sectional view of FIG. 3 shows that the first lateral portion
1010, 1012 and the second lateral portion 1042 are disposed at
opposite ends of a cylindrical portion 1014, 1044. In the present
case, the cylindrical portion 1014, 1044 forms a circular cylinder
but also other cylinder types are allowed for cylindrical portion
1014, 1044 as long as they are conforming to the cross-sectional
shape of tower 110. The cylindrical portion 1014, 1044 is located
midway of the first lateral portion, thus dividing the lateral
portion into an outer portion 1012 extending to the outside of the
cylindrical portion and an inner portion 1010 extending to the
inside of the cylindrical portion. Accordingly, the lateral portion
1010, 1012 and the lower part of the cylindrical portion 1014, 1044
form a T-shaped flange. The outer through-holes 1020 are located
within the outer portion 1012 and the inner through-holes 1030 are
located within the inner portion 1010. The second lateral portion
1042 is located at the opposite end 1044 of the cylindrical
portion. In the present embodiment, the second lateral portion 1042
extends only inwardly of the cylindrical portion so that the second
lateral portion 1042 and the upper end 1044 of the cylindrical
portion form an L-shaped flange 1040. Thus, the vertical
cross-sectional shape of the adapter 1000 according to the present
embodiment can be described as a T-shaped flange 1010, 1012, 1014
being connected to an L-shaped flange 1042, 1044. However, it
should be understood that the second lateral portion may also have
an outwardly extending portion so that also the second lateral
portion is formed as a T-flange.
[0032] The adapter 1000 has a maximum longitudinal extension H1,
which may also be called the height of the adapter. According to an
embodiment of the present invention, the ratio of the maximum
longitudinal extension H1 and the maximum lateral extension D1 is
smaller or equal to 1, more specifically in the range of 0.1 to
0.5, even more specifically in the range of 0.15 to 0.3. In other
words, the adapter 1000 is at least as wide as it is high and,
typically, is wider than it is high. For example, the diameter D1
is in the range of 3000 mm to 5000 mm for wind turbine towers and
the height of the adapter is about 1000 mm resulting in an aspect
ratio, i.e. height-to-diameter ratio, of 0.2 to 0.33. Typically,
the height of the adapter is smaller or equal to 2 m, more
specifically 800 mm to 1500 mm, even more specifically, 800 mm to
1200 mm. Furthermore, the weight of the adapter is typically
smaller than or equal to 10,000 kg, more specifically 5,000 kg,
even more specifically, 2500 kg. Therefore, the adapter 1000 is
relatively small and can be handled even by a single small mobile
crane. Especially, the adapter may be transported in an upright
position on a truck since it does not exceed the maximum headroom
of bridges. Since the adapter can be handled by a single small
crane, the costs are considerably reduced compared to conventional
construction necessitating two larger cranes.
[0033] The longitudinal cross-sectional view shown in FIG. 4 shows
that the second through holes 1045 are formed in the second lateral
portion 1042 of the L-shaped flange 1040. A spacing H2 is provided
between the upper surface of the inner portion 1010 of the first
lateral portion and the lower surface of the inner portion of the
second lateral portion 1042. This spacing is dimensioned to provide
sufficient workspace for workers establishing bolt connections
through the first and second through-holes 1030, 1045,
respectively.
[0034] The use of the adapter 1000 will now be explained with
reference to FIGS. 5 to 8 showing different steps of a method for
producing a tower foundation according to an embodiment of the
present invention. FIG. 5 shows a cross-sectional view of a tower
foundation 150 made of reinforced concrete. Foundation 150 is made
according to well-established methods for reinforced concrete
construction. An anchor ring 310 is embedded in foundation 150.
Anchor bolts 350 are fixed to anchor 310 by nuts 370. Typically,
the anchor bolts 350 are fixed to anchor ring 310 and are placed
together with the reinforcement within the formwork of the
foundation. Then, concrete is poured into the formwork and the
foundation 150 is formed. Furthermore, a ring-shaped recess 1200 is
formed within an upper surface of the foundation 150. The anchor
bolts 350 have a sufficient length so that they extend from the
anchor ring 310 to the upper surface of the foundation and protrude
therefrom. Particularly, the recess 1200 is formed such that the
anchor bolts extend from a bottom surface of the recess, i.e. the
recess 1200 is located above and aligned with the anchor ring 310.
Next as shown in FIG. 6, grout is poured into the recess 1200 to
form a grout joint 1210. The length of the anchor bolts 350 is such
that they also protrude from an upper surface of the grout joint
1210. In a next step, the adapter 1000 is aligned with the
foundation 150 such that the first lateral portion 1010, 1012 faces
the upper surface of the foundation and that the second lateral
portion 1042 is disposed at a distal end of the adapter. Then, the
first through-holes 1020, 1030 of the adapter 1000 are aligned with
the anchor bolts 350 protruding from the grout joint 1210. However,
the grout joint may also be formed by a formwork technique in that
a shuttering is built on the upper surface of the foundation 150
and the grout is poured into the shuttering. Also in this case, the
anchor bolts 350 are sufficiently long to protrude from an upper
surface of the grout joint.
[0035] Next, the adapter 1000 is placed on the grout joint 1210 so
that the anchor bolts 350 extend through the first through-holes
1020, 1030 formed in the first lateral portion 1010, 1012. The
length of the anchor bolts 350 is sufficient so that the anchor
bolts 350 still protrude from an upper surface of the first lateral
portion 1010, 1012. Typically, placing the adapter 1000 on the
foundation is done by means of a mobile crane. The adapter 1000 is
lifted by the crane and moved over the upper surface of the
foundation 150. After the first through-holes 1020, 1030 of the
adapter are aligned with the anchor bolts 350, the crane lowers the
adapter until the adapter is placed on the grout joint 1210. After
placing the adapter on the grout joint, the adapter 1000 is fixed
to the grout joint 1210 by fastening nuts 360 to the protruding
upper ends of the anchor bolts 350. In this step, a desired
prestress can be applied to the bolt connection 310, 350, 360, 370.
Finally, the grout of the grout joint 1210 cures while the adapter
1000 is assembled to the anchor assembly. After the curing of the
grout joint 1210, a lower tower section can be mounted to adapter
1000 as shown in FIG. 8. The lower tower section 110 has a flange
portion 116 adapted to fit with the second lateral portion 1042 of
the adapter 1000. Furthermore, the flange portion 116 of the tower
section 110 also has through-holes which are aligned with the
second through-holes 1045 formed in the second lateral portion
1042. A bolt connection is established between adapter 1000 and
tower 110 by inserting bolts 1050 into the through-holes formed
within the flange portion 116 and the second lateral portion 1042.
The bolts 1050 are fastened by upper and lower nuts 1060, 1070,
respectively. Thus, a firm connection between the adapter 1000 and
the tower 110 is established.
[0036] An alternative method according to an embodiment of the
present invention for producing the tower foundation including the
adapter is now described with reference to FIGS. 9 and 10. Therein,
it is shown that the foundation 150 is produced so that a space
1220 is provided between an upper surface of the foundation and a
lower surface of the adapter. In the example shown in FIG. 9, the
spacing is formed as a recess so that the bottom of the recess
forms the part of the upper surface of the foundation 150 to which
the adapter 1000 is spaced. The adapter 1000 may be held in the
spaced condition by filler plates (not shown) on which it is
placed. Further to holding adapter 1000 in a spaced condition, the
filler plates are also used to level adapter 1000. IN a second
step, grout is poured into the space 1220 to form a grout joint
1210 between the concrete foundation 150 and the adapter 1000. The
embodiment shown in FIGS. 9 and 10 includes a grout joint 1210
being formed in a recess of the foundation. However, according to
another embodiment of the present invention the grout joint is
formed on the entire upper surface of the foundation 150. For this
purpose, a formwork has to be built on the upper surface of the
foundation 150. Then, grout is poured to form a grout joint between
the upper surface of the foundation and the adapter. According to
an even further embodiment of the present invention, the adapter
1000 and the anchor 310 may be assembled prior to forming the
foundation. In this case, the preassembled anchor/adapter assembly
can even be put into the excavation pit together with the
reinforcement prior to pouring the concrete. The anchor/adapter
assembly should then be protected against displacement during
concrete pouring. The foundation will thus be formed with a
preassembled anchor/adapter assembly. However, also in this case a
spacing must be provided in which the grout joint can be formed
after producing the concrete foundation. After the foundation
including the adapter is formed, a bottom section of the tower can
be mounted to the adapter in a similar manner as described install
the tower and with reference to FIG. 8.
[0037] Due to its configuration, especially due to its aspect
ratio, the above-described adapter according to an aspect of the
present invention can be handled by a single small mobile crane.
Therefore, the foundation including the adapter can be produced
without need of a two huge mobile cranes. Since small mobile cranes
are less expensive than huge mobile cranes and can also be
relocated more easily, the adapter according to an aspect of the
present invention allows saving of financial and time resources
during the construction of a tower. In particular, the expensive
two huge mobile cranes are only required after producing the
foundation for mounting of the tower sections. Thus, idle time of
these expensive cranes is avoided. Furthermore, sample cubes of the
grout are produced at the construction site and tested in a nearby
laboratory. These sample grout cubes have to be again tested before
putting the wind turbine to operation. Only if the sample cubes
pass the test, the wind turbine can be put to operation. However,
it might take several days or even weeks before the sample cubes
have sufficiently cured and pass this final test. Since the
above-described adapter allows to produce the foundation including
the adapter well ahead of the tower construction, sufficient time
can be awaited before the tower construction crew starts with the
tower construction. Thus, it is possible that the crew may put the
wind turbine to operation directly after installing the tower.
[0038] Another aspect of the present invention is now described
with reference to FIG. 11 showing a perspective view of an anchor
cage 300 according to an embodiment of the present invention. The
anchor cage 300 includes an anchor ring 310 to which hollow tubes
320, 330 are fixed. The anchor cage 300 may be prefabricated or
assembled at the construction site by welding the tubes 320, 330 to
anchor ring 310. The tubes are arranged in a circumferential
direction of the anchor ring 310 and are grouped into outer tubes
320 and inner tubes 330. Each tube is configured to receive an
anchor bolt 350. Furthermore, each tube has a length H3 which is
adjusted so that the tubes 320, 330 will extend from the anchor
ring 310 up to an upper surface 155 of a foundation 150 in which
the anchor cage 300 will be embedded. The plan top view of the
anchor cage shown in FIG. 12 reveals that the anchor ring 310 has
an outer diameter D1 and a width W which both are adapted to either
an adapter 1000 or a lower tower section 110. It should be
understood that, similar to the case of the adapter 1000, the
circular ring shape of anchor ring 310 is merely an example. In
particular, anchor 310 may have any desired shape, especially it
may have a square, rectangular or ellipsoidal shape. Furthermore,
anchor 310 is not necessarily ring-shaped but may also be solid.
Although anchor 310 is shown as an integrally formed piece in FIG.
11, it should be understood that anchor 310 may also have two,
three, four, or even more parts which are assembled at the
construction site. For example, anchor 310 may be ring-shaped and
consist of two half-circles or four quarter-circles.
[0039] FIG. 13 shows a cross-sectional view of an embodiment of the
anchor 310. Therein, the anchor 310 includes a blind hole 340 which
is provided with a female thread. The threaded lower end of an
anchor bolt 350 is screwedly fixed to anchor 310. Furthermore, a
tube 320/330 is attached to anchor 310 and encircles the blind hole
340. The tube 320/330 is configured to receive the anchor bolt 350.
Furthermore, the anchor bolt 350 is guided by the tube 320/330.
[0040] FIG. 14 shows an alternative embodiment of the anchor 310.
Therein, the anchor 310 includes a through-hole 340 which is
provided with a female thread. The threaded lower end of an anchor
bolt 350 is screwedly fixed to anchor 310. The lower end of the
threaded through-hole 340 is sealed with a closing plate 315.
Closing plate 315 may be fixed to anchor 310 at the construction
site or may be preassembled. Furthermore, a tube 320/330 is
attached to anchor 310 and encircles the through-hole 340. The tube
320/330 is configured to receive the anchor bolt 350. Furthermore,
the anchor bolt 350 is guided by the tube 320/330.
[0041] Next, the use of anchor cage 300 in a method for producing a
tower foundation according to an embodiment of the present
invention is described with reference to FIGS. 15 and 16. FIG. 15
shows a cross-sectional view of a first embodiment wherein a
foundation 150 embedding an anchor cage 300 as described above has
been produced. In particular, the anchor cage with the anchor bolts
mounted thereto is put into the formwork for the foundation
together with the reinforcement. The anchor cage 300 is fixed so
that it is not displaced during concrete pouring. Then, concrete is
poured to form the foundation 150. Since the tubes 320, 330 extend
from anchor 310 up to an upper surface 155 of the foundation, they
preserve channels so that anchor bolts 350 are not in contact with
the concrete. The anchor bolts 350 have a length so that they
protrude from the upper surface 155 when being screwedly fixed to
anchor 310. Typically, the anchor bolts 350 are centered within the
tubes 320, 330 by means of a tapered ring (not shown). Due to the
centering, the anchor bolts 350 will have no contact to a flange of
a tower section or an adapter mounted thereto. For example, a
bottom section 110 of a tower has a T-flange 115 with through-holes
formed therein. The through-holes are aligned with the anchor bolts
350 protruding from the upper surface 155. Due to the centering of
the anchor bolts 350, the anchor bolts have no direct contact with
the flange. Then, the bottom section 110 is placed on the
foundation 150 so that the anchor bolts 350 extend through the
through-holes of the T-flange 115. Finally, the bottom section 110
is secured by nuts 360.
[0042] Since an anchor bolt 350 is not embedded in the concrete but
is guided within a hollow tube 320/330, it may be exchanged by
loosening nut 360 and unscrewing the bolt from the anchor 310.
Thus, an exchangeable bolt connection for a tower foundation is
established. Whenever an anchor bolt 350 is damaged or broken, it
can be readily replaced by just unscrewing it. Furthermore, also
inspection of the bolts is facilitated since they may be taken out
or an inspection device may be lowered into the hollow tube.
Furthermore, anchor bolts 350 may be provided with a plastic shim
inside the tubes.
[0043] Another embodiment of a tower foundation according to
another embodiment of the present invention is shown in FIG. 17.
Therein, a foundation 150 is formed with a basement 700. The
basement 700 includes a subgrade or bottom plate 710 and a basement
ceiling 720. The basement ceiling 720 includes a basement entrance
730, e.g. a manhole, which provides access to the basement 700.
Furthermore, an anchor 310 and hollow tubes 320, 330 are embedded
in the foundation 150 in a similar fashion as in the
above-described embodiment. However, the configuration of the
anchor 310 is different in this embodiment as can be seen from FIG.
18 showing a cross-sectional view the anchor cage used in the
present embodiment. Therein, it can be seen that the anchor 310 has
a through-hole 340 instead of a blind hole. Accordingly, an anchor
bolt 350 may extend through anchor 310 into a space 740 provided
below anchor 310. In particular, the basement is formed such that
it provides access to the through-holes formed in anchor 310 in
that it provides a workspace 740. Workspace 740 is dimensioned
sufficiently large so that a worker can work on anchor 310 and may
establish a bolt connection or fasten nuts on a bolt extending
through anchor bore 340. Therefore, the anchor bolts 350, which are
typically installed prior to the formation of the foundation, have
to be fixed in their position. This is typically done by using a
molding tool.
[0044] Next, a method for producing a tower foundation as described
above is explained with reference to FIGS. 19 to 21. First, a tower
foundation as shown in FIG. 17 is produced by known reinforced
concrete construction. In particular, anchor 310 and tubes 320, 330
are positioned within the formwork together with the reinforcement
and, then, concrete is poured into the formwork. After that, a
bottom section 110 of a tower is placed on the upper surface of the
foundation. Anchor bolts 350 are inserted into through-holes formed
in a T-flange portion 115 of the tower section 110 and into the
tubes 320, 330. The anchor bolts 350 are secured with upper nuts
360 and lower nuts 370 to establish a bolt connection. For securing
the lower nuts 370, access to the protruding anchor bolts 350 is
provided from the basement 700 by workspace 740.
[0045] Since an anchor bolt 350 is not embedded in the concrete but
is guided within a hollow tube 320/330, it may be exchanged by
loosening upper and lower nuts 360, 370. Thus, an exchangeable bolt
connection for a tower foundation is established. Whenever an
anchor bolt 350 is damaged or broken, it can be readily replaced by
just loosening the upper and lower nuts 360, 370. Especially, even
broken bolts can be readily replaced since one part of the bolt may
be taken out from above and one part may be taken out from the
workspace 740. Furthermore, also inspection of the bolts is
facilitated since they may be taken out or an inspection device may
be lowered into the hollow tube. Furthermore, anchor bolts 350 may
be provided with a plastic shim inside the tubes.
[0046] Furthermore, the various above described aspects and
embodiments of the present invention may be combined with another.
FIG. 22 is a cross-sectional view of a tower foundation according
to a further embodiment of the present invention. This embodiment
combines the exchangeable bolt connection of the embodiment shown
in FIG. 16 with the adapter 1000 of the embodiment shown in FIG. 2.
FIG. 23 is a cross-sectional view of a tower foundation according
to an even further embodiment of the present invention. This
embodiment combines the exchangeable bolt connection of the
embodiment shown in FIG. 21 with the adapter 1000 of the embodiment
shown in FIG. 2. By combining the exchangeable bolt connection with
the adapter, an even further improvement is achieved.
[0047] While the invention has been described in terms of various
specific embodiments, those skilled in the art will recognize that
the invention can be practiced with modification within the spirit
and scope of the claims.
* * * * *