TUBULAR FOUNDATION ELEMENT, ASSEMBLY AND METHOD FOR INSTALLING TUBULAR FOUNDATION ELEMENTS IN A GROUND FORMATION

Abstract

A tubular foundation element, in particular a pile e.g. a jacket pile, to be installed in a ground formation has at least one open end, typically both ends open, allowing a pile driver with an anvil to be inserted into the tubular foundation element. The tubular foundation element comprises a support at the inside thereof, which support is adapted to transmit energy from the anvil directly to the tubular foundation element, during installation of the tubular foundation element.

Claims

1. A tubular foundation element installed in a ground formation, the tubular foundation element comprising: an elongated member with at least one open end of size for a pile driver with an anvil to be inserted into the tubular foundation element, and a support at the inside of the tubular member, which support is configured to transmit energy from the anvil directly to the tubular foundation element, during installation of the tubular foundation element.

2. The tubular foundation element according to claim 1, wherein the support is located in the upper half of the tubular foundation element.

3. The tubular foundation element according to claim 1, wherein the tubular foundation element has a length in a range from 20 to 120 m, and wherein the support is placed at a distance from the at least open end, wherein the distance is in a range from 4 to 10 m.

4. The tubular foundation element according to claim 1, wherein the support comprises a flange secured to an inner surface of the tubular foundation element.

5. Tubular foundation element according to claim 1, wherein the support is substantially tapered towards a toe of the tubular foundation element remote from the open end in a longitudinal direction thereof.

6. The tubular foundation element according to claim 1, wherein the tubular foundation element has two open ends.

7. A method of installing a tubular foundation element in a ground formation, by a pile driver, the method comprising: providing a tubular foundation element with a support at the inside thereof, placing an anvil on the support, placing the pile driver on the anvil, and driving the tubular foundation element into the ground formation, wherein during installation the support transmits energy from the anvil directly to the tubular foundation element.

8. The method according to claim 7, wherein the support is provided in the upper half of the tubular foundation element.

9. The method according to claim 7, wherein the pile driver and/or anvil are held by the tubular foundation element during driving thereof.

10. The method according to claim 7, wherein the tubular foundation element is placed directly on the ground formation and, thereafter, is installed in the ground formation.

11. The method according to claim 7, wherein the anvil compresses soil material of the ground formation within the tubular foundation element during at least a part of an installation process of the tubular foundation element.

12. The method according to claim 7, further comprising placing a template having at least two guides for guiding a tubular foundation element at the ground formation.

13. The method according to claim 7, wherein water is relieved from the tubular foundation element during driving of the tubular foundation element into the underwater ground formation.

14. The tubular foundation element according to claim 1, further comprising a pile driver with an anvil configured to engage the support within the elongated member, and wherein the support at the inside of the tubular foundation element is configured to transmit energy from the anvil directly to the tubular foundation element, during installation of the tubular foundation element.

15. The tubular foundation element according to claim 14, further comprising a template having at least two guides configured to guide a tubular foundation element, which template is to be placed on the underwater ground formation.

16. The tubular foundation element according to claim 2, wherein the support is located in the upper quarter of the tubular foundation element.

17. The tubular foundation element according to claim 1, wherein the support is placed at a distance from the at least open end in a range from 7% to 30% of a total length of the tubular foundation element.

18. The tubular foundation element according to claim 1, wherein the support is placed at a distance from the at least open end in a range from 10% to 25% of a total length of the tubular foundation element.

19. The method according to claim 12, further comprising placing the template at the ground formation before the tubular foundation element is placed on the ground formation.

20. The method according to claim 7, wherein water is relieved from the tubular foundation element at least from a part between a ground formation and the support during driving of the tubular foundation element into the underwater ground formation.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Aspects of the invention will be explained in greater detail by reference to exemplary embodiments of the invention shown in the drawings, in which:

[0024] FIGS. 1 and 2 illustrate the different stages of installing a tubular foundation element in a ground formation; and

[0025] FIG. 3 illustrates an installation of a jacket leg in the tubular foundation element of FIGS. 1 and 2.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0026] In practice, installation of a jacket, e.g. for a wind turbine, starts with installing a number a jacket piles in a ground formation, e.g. an underwater ground formation. After installing the jacket piles, jacket legs of the jacket are placed within the jacket piles. A jacket leg extends in the upper part of a jacket pile. Grout may be added to the jacket pile, in particular the upper part of the jacket pile, in order to fixate the jacket leg with respect to the jacket pile.

[0027] To this end, FIG. 1 shows an embodiment of a tubular foundation element 1, in this embodiment a jacket pile 1 which might be installed in an underwater ground formation 4. The tubular foundation element 1 is placed on the surface of the underwater ground formation 4 and is held by a guide 3 of a template 6. In this example, the jacket pile 1 has a circular cross-section and a diameter in the range from 1.5 to 3.5 m.

[0028] The jacket pile 1 is provided with a support, in this embodiment a flange 2 provided at an inner wall of the jacket pile 1. The flange 2 is attached to the inner wall of the jacket pile 1 by, e.g. welding, bolting, or any suitable manner to attach the flange 2 to the inner wall of the jacket pile 1.

[0029] In an embodiment, the flange 2 may be provided with openings (not shown) in order to let water out from the lower part of the jacket pile 1 below the flange 2. It is therewith prevented that the water pressure within the lower part of the jacket pile 1 exceeds a predetermined value as a result of driving the jacket pile 1 by means of the driver 4, in particular a hydraulic driver, which driver delivers blows to the flange 2. In this embodiment the blows are delivered directly to an upper side, i.e. top surface of the flange 2.

[0030] In other embodiments, openings (not shown) might be provided in the tubular foundation element 1 and/or in an anvil 8 to let water out from the lower part of the tubular foundation element 1 below the support 2.

[0031] As can be seen in FIG. 3, when the jacket pile 1 is installed in the underwater ground formation 4, the flange 2 is below the surface of the underwater ground formation 4.

[0032] As can be seen in FIG. 2, a driver 7 with an anvil 8 is placed on top of the support 2, such that energy is transmitted from the anvil 8 directly to the tubular foundation element 1, during installation of the tubular foundation element 1. The driver 7 and the anvil 8 deliver blows to the flange 2 and therewith to the tubular foundation element 1 to install the tubular foundation element 1 in the underwater ground formation 4. At a predetermined point during installing of the tubular foundation element 1, the flange 2 and the anvil 8 reach the surface of the underwater ground formation 4.

[0033] Installing of the tubular foundation element 1 continues and the flange and in particular the anvil 8 delivering blows to the flange 2 of the tubular foundation element 1 deliver blows to the soil material within the tubular foundation element. As a result, the soil material 5 within the tubular foundation element 1 is compressed and becomes more dense, at least the soil material directly below the anvil 8 and the flange 2.

[0034] It is noted that the driver 7 with the anvil 8 can be hosted by a hoisting device such as a crane (not shown), which crane is for example placed on a surface vessel, such as a jack-up barge (not shown). The driver may be a hydraulic driver, e.g. one out of the IHC Hydrohammer S-series connected to a power pack on board of a surface vessel (not shown).

[0035] In practice the length B of the legs of the jacket in FIG. 3 may be 5 m. In the installed state, the tubular foundation element 1 may extend a distance D above the surface of the underwater ground formation 4, which distance D in this example is 1.5 m. The length C is in this example in a range from 4 to 10 m, in particular in a range from 6 to 8 m, and/or in a range from 7% to 30%, in particular in a range from 10% to 25% of the total length of the tubular foundation element 1.

[0036] Due to the anvil 8 with the driver 7 forcing the soil material to move downwards during driving of the tubular foundation element 1, it is not required to empty the part of the tubular foundation element 1 above the flange 2 after installation. As a result of compressing the soil material within the tubular foundation element 1, the soil material is more dense and is a good match for the grout used to fixate the jacket leg 9 relative to the jacket pile 1, i.e. grouting is improved.

[0037] In this embodiment, the jacket leg 9 comprises welding beads 10, which may contribute to the fixation of the jacket leg 9 to the tubular foundation element 1. The jacket leg 9 is inserted partly into the tubular foundation element 1 as indicated with arrow A.

[0038] As a further result, the compressed soil material is more dense. Due to the more dense soil material, mixing of the grout and the soil material is prevented or reduced, which leads to a reliable fixation of the jacket leg to the tubular foundation element 1.

[0039] Further advantages of the tubular foundation element as presently provided are as follows. The tubular foundation element 1 is installed in the ground formation by driving within the tubular foundation element 1. As a result thereof, the tubular foundation element 1 acts as a noise reducing element. As a further result, the diameter of the tubular foundation element 1 is not enlarged during driving. Thus the tubular foundation element 1 may be installed without additional structural elements at the outside of the foundation element and/or without adjusting the guide 3 of the template 6.

[0040] A further advantage is a low center of gravity due to the pile driver 7 being inserted in the tubular foundation element 1 during driving thereof.

[0041] Moreover, since the anvil 8 is placed on the support 2 during driving of the tubular foundation element 1, energy delivered to the support by, i.a. the anvil 8 is transmitted to the wall of the tubular foundation element. The transmitted energy is in particular transmitted downwards, i.e. via the wall of the tubular foundation element 1, in particular from the support 2 towards the toe of the tubular foundation element. As a result, the part of the tubular foundation element 1 contributing to the generation of noise is reduced.

[0042] It should be appreciated, however, that these embodiments may not be construed as limiting the scope of protection for the present invention.

[0043] It is noted that the drawings are schematic, not necessarily to scale and that details that are not required for understanding the present invention may have been omitted. The terms upward, downward, below, above, and the like relate to the embodiments as oriented in the drawings, unless otherwise specified. Further, elements that are at least substantially identical or that perform an at least substantially identical function are denoted by the same numeral.

[0044] The invention is not restricted to the above-described embodiments, which can be varied in a number of ways within the scope of the claims. It is, for example possible that a noise mitigation system is used during installing of the tubular foundation element. The noise mitigation system comprises a tubular sleeve, which can be placed around the tubular foundation element during driving thereof. The tubular sleeve reduces the noise produced during driving of the tubular foundation element. The noise mitigation system may be used in combination with a template as described above.

[0045] In a further embodiment, the tubular foundation element is composed of multiple parts, in particular cylindrical parts, which are placed on top of each other. One of the parts comprises a support, which might have a length in a range from 5-25 cm, in particular in a range from 10 to 15 cm.