Offshore structure

Abstract

An offshore structure having a foundation structure, wherein the foundation structure has at least a first and a second profile, the first profile is designed as a pile and the second profile is designed as a pile sleeve, the second profile encloses the first profile over a penetration length, wherein an interspace is formed between the first and the second profile, the interspace has a casting compound filling over the total penetration length, shear elements are provided on the first and/or the second profile, the shear elements extend into the interspace and effect an axial load dissipation into the casting compound filling, the shear elements are provided only over a first partial length of the penetration length, the first partial length is between 65 and 90% of the total penetration length and a second partial length is free of shear elements, wherein the second partial length forms the upper length of the penetration length in the installed position.

Claims

1. An offshore structure comprising: a foundation structure, wherein the foundation structure has at least a first and a second profile, wherein the first profile is configured as a pile and the second profile is configured as a pile sleeve, and the second profile encloses the first profile over a penetration length, wherein an interspace is formed between the first profile and the second profile, the interspace has a casting compound filling over the penetration length, wherein shear elements are provided on the first profile and/or the second profile, the shear elements extend into the interspace and effect an axial load dissipation into the casting compound filling, the shear elements are provided only over a first partial length of the penetration length, the first partial length is between 65% and 90% of the penetration length and a second partial length is free of shear elements, wherein the second partial length forms an upper length of the penetration length in an installed position, wherein (a) the first profile and/or the second profile have/has an adhesion-reducing coating over the second partial length on a side facing the interspace; and/or (b) a layer of an elastic material is provided between first profile and/or the second profile and the casting compound filling over the second partial length of the penetration length.

2. The offshore structure according to claim 1, wherein the second partial length has a length which is at least equal to a width of the interspace.

3. The offshore structure according to claim 1, wherein the casting compound filling comprises a first casting compound over the first partial length of the penetration length and a second casting compound over the second partial length of the penetration length, and the second casting compound has a higher tensile and/or a higher compressive strength than the first casting compound.

4. The offshore structure according to claim 3, wherein the second casting compound has a higher ductility than the first casting compound.

5. The offshore structure according to claim 1, wherein the casting compound filling is fibre-reinforced and/or strengthened over the second partial length of the penetration length.

6. The offshore structure according to claim 1, wherein the casting compound filling receives an insert component over the second partial length, wherein the insert component has a higher tensile and/or a higher compressive strength than the casting compound.

7. The offshore structure according to claim 6, wherein the insert component is selected from a group of insert components comprising prefabricated concrete elements, steel profiles and polymer construction materials.

8. The offshore structure according to claim 1, wherein the interspace is at least partially closed on an upper end side in the installed position.

9. The offshore structure according to claim 1, wherein the pile sleeve has an upper, inwardly projecting collar which partially covers an upper end side of the interspace in the installed position.

10. The offshore structure according to claim 1, in which the first profile or the second profile has fastened thereto a reinforcement which extends over the second partial length of the penetration length.

11. The offshore structure according to claim 1, wherein the shear elements are selected from a group comprising shear ribs and/or shear webs.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention is described below with reference to an exemplary embodiment illustrated in the drawings, in which:

(2) FIG. 1 shows a schematic illustration of a part of an offshore wind turbine having cast connections which have been created according to the principle of post-piling;

(3) FIG. 2 shows a schematic illustration of an offshore wind turbine having cast connections which have been created according to the principle of pre-piling;

(4) FIG. 3a shows a partial section through a cast connection of the foundation of the offshore wind turbine represented in FIG. 2, which schematically illustrates a shear stress as compressive stress of the cast connection;

(5) FIG. 3b shows a partial section through a cast connection of the foundation of the offshore wind turbine represented in FIG. 2, which schematically illustrates a shear stress as tensile stress of the cast connection;

(6) FIG. 4 shows a section through a cast connection according to the invention, which shows the arrangement of the shear elements; and

(7) FIG. 5 shows the section through the case connection of FIG. 4, further including certain additional features as illustrated.

DETAILED DESCRIPTION

(8) The invention relates to an offshore structure 1 and in particular to a cast connection on an offshore structure 1. The invention is described below with reference to an offshore structure 1 having a jacket foundation. As has already been mentioned at the outset, the principle of the cast connection according to the invention can be applied to different types of connections on offshore structures.

(9) The offshore structure 1 comprises for example a tower structure 2, a transition piece 3, a so-called jacket 4 and an anchoring of the jacket 4 in the seabed 5 in the form of piles 6 and pile sleeves 7.

(10) The offshore structure 1 illustrated in FIG. 1 has been founded by so-called pre-piling, i.e. the piles 6 have been driven into the seabed 5 using a template and a corresponding tool. The piles sleeves 7, which are fastened to the jacket 4, have been placed on the driven-in piles 6, with the latter penetrating the pile sleeves 7. A curable casting compound 11, for example a fibre concrete or the like, has been cast into an interspace 8 or annular space between the piles 6 and the pile sleeves 7.

(11) Another variant of the pile foundation is illustrated in FIG. 2. This variant of the foundation is generally referred to as post-piling. Here, the pile sleeves 7 are first driven into the seabed 5. The feet of the jacket, which are each designed as piles 6, are inserted into said sleeves. The interspace between the pile 6 and the pile sleeve 7 is likewise filled with a curable casting compound.

(12) The axial forces introduced into the seabed via the jacket 4 are dissipated into the piles 6 (FIG. 1) or into the pile sleeves 7 (FIG. 2) via the casting compound.

(13) FIGS. 3a and 3b show the typical loading of the casting compound 11 with the introduction of tensile or compressive forces for example via the pile 6 in a foundation, as is shown in FIG. 2. The loading direction is indicated by the arrows 9 depicted in FIGS. 3a and 3b.

(14) In FIG. 3a, the inner profile is a cylindrical pile 6, whereas the outer profile, which encloses the inner profile, forms the pile sleeve 7. The interspace 8 is filled with a casting mortar or a hydraulically setting casting compound 11. With the introduction of compressive forces as shear stress, as illustrated for example in FIG. 3a, there appear diagonal compression lines 10 between the pile 6 and the pile sleeve 7 which under certain circumstances have the effect that the casting compound 11 is pressed out upwardly from the interspace 8. The movement tendency of the casting compound 11 is indicated by the arrows 13.

(15) The applicant has observed that in particular the interaction of the compression lines 10 with the underside of shear ribs 12 or shear elements of some other design generates oppositely diagonally extending reaction forces which result in the casting compound 11 becoming brittle and being driven upwardly out of the interspace 8, as is indicated by the arrows 13. In particular, the loss of the casting compound 11 escaping from the enclosure of the profiles ultimately causes a failure of the cast connection. FIG. 3a shows the loading profile with introduction of axial compressive forces, whereas FIG. 3b illustrates the loading profile with introduction of axial tensile forces.

(16) FIG. 4 shows a partial longitudinal section through a cast connection according to the invention. The formation of the cast connection (grouted joint) in the form of two cylindrical steel profiles as pile 6 and pile sleeve 7 which penetrate one another corresponds to the configuration according to FIGS. 3a and 3b. The pile 6 and the pile sleeve 7 penetrate one another over a penetration length L.sub.total, which corresponds to the casting length or the height of the casting compound 11 situated in the interspace 8. The penetration length L.sub.total is subdivided into a first partial length L1 and into a second partial length L2, with the second partial length L2 being the upper partial length in the installed position of the pile sleeve 7 and the first partial length L1 forming the lower partial length.

(17) Shear elements, for example in the form of shear ribs 12 or other geometries, which project into the interspace 8 and are enclosed by the casting compound 11, extend over the first partial length L1 of the penetration length on the side of the pile sleeve 7 that faces the interspace 8 and on the outer side of the pile 6 that faces the interspace 8. According to the invention, the partial length L2 of the penetration length is free of shear elements. The shear ribs 12 are provided only in the region of the first partial length L1 of the penetration length. The height of the second partial length L2 corresponds approximately to one to two times the width of the interspace 8 (0.5×(inside diameter of pile sleeve minus outside diameter of pile)).

LIST OF REFERENCE SIGNS

(18) 1 Offshore structure 2 Tower structure 3 Transition piece 4 Jacket 5 Seabed 6 Pile 7 Pile sleeves 8 Interspace 9 Arrows 10 Compression lines 11 Casting compound 12 Shear ribs 13 Arrows L1 First partial length L2 Second partial length L.sub.total=L1+L2