DK2698476T3 - Process for the construction of an offshore structure and foundation for an offshore structure - Google Patents

Process for the construction of an offshore structure and foundation for an offshore structure Download PDF

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Publication number
DK2698476T3
DK2698476T3 DK13172594.7T DK13172594T DK2698476T3 DK 2698476 T3 DK2698476 T3 DK 2698476T3 DK 13172594 T DK13172594 T DK 13172594T DK 2698476 T3 DK2698476 T3 DK 2698476T3
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DK
Denmark
Prior art keywords
foundation pile
foundation
filling
pile
seabed
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Application number
DK13172594.7T
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Danish (da)
Inventor
Daniel Bartminn
Original Assignee
Rwe Innogy Gmbh
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Publication date
Application filed by Rwe Innogy Gmbh filed Critical Rwe Innogy Gmbh
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Publication of DK2698476T3 publication Critical patent/DK2698476T3/en

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Classifications

    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D27/00—Foundations as substructures
    • E02D27/32—Foundations for special purposes
    • E02D27/42—Foundations for poles, masts or chimneys
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D27/00—Foundations as substructures
    • E02D27/32—Foundations for special purposes
    • E02D27/42—Foundations for poles, masts or chimneys
    • E02D27/425—Foundations for poles, masts or chimneys specially adapted for wind motors masts
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02B—HYDRAULIC ENGINEERING
    • E02B17/00—Artificial islands mounted on piles or like supports, e.g. platforms on raisable legs or offshore constructions; Construction methods therefor
    • E02B2017/0056—Platforms with supporting legs
    • E02B2017/0073—Details of sea bottom engaging footing

Description

Method for the construction of an offshore structure and foundation for an offshore structure
Method for installing an offshore construction with an anchoring structure and at least one foundation pile inserted into the subsoil beneath the sea bed, wherein at least a part of the structure within the foundation pile is affixed in the subsoil beneath the sea bed under load transfer, and grouted inside the foundation pile using a curable mass.
The invention further relates to the foundation of an offshore construction with at least an anchoring structure with at least a foundation pile inserted into the subsoil beneath the sea bed, wherein at least a part of the structure within the foundation pile is affixed in the subsoil beneath the sea bed under load transfer, and is inserted in the foundation pile and grouted. A method as well as a foundation of the aforementioned type is, for example, known from WO 2011/010937 A1 or GB 2476051 A. WO 2011/010937 A1 particularly relates to a method for controlling the load transfer between a structure and a foundation pile during the grouting of the structure in the foundation pile.
The structure described in WO 2011/010937 A1 comprises a support leg, for example, of a jacket foundation, which is grouted in a foundation pile in the subsoil beneath the sea bed. The support leg includes a bracket that is so attached to the support leg that the support leg can be inserted into the foundation pile to a proposed embedded length leading to the removal of the load of the structure above the bracket in the foundation pile until the support leg is grouted within the foundation pile, and until the grouting compound is cured. An adjustment or fine adjustment of the embedded length of the support leg is effected by means of shims that are placed between the bracket and the foundation pile.
Offshore foundations are often designed as pile foundations, wherein one or more piles are usually driven into the subsoil beneath the sea bed. After the piles, in the form of hollow piles, have been driven the planned depth into the subsoil beneath the sea bed, an anchoring structure, for example in the form of a so-called jacket foundation, is attached to the piles. The jacket foundation later receives a transition piece and a construction built on the transition piece. The support legs of the structure can be provided, for example, with so-called pile sleeves that are interspersed in the installation position of the foundation piles; alternatively, the support legs can be inserted in the foundation piles and be grouted with them.
Usually jacket foundations or other anchoring structures comprise a plurality of support legs, so that, in order to prepare the foundation, several piles are driven into the subsoil beneath the sea bed. Due to geological inhomogeneities in the subsoil beneath the sea bed, it is not always possible to drive the piles to exactly the same depth of penetration in the subsoil beneath the sea bed. To compensate for any differences in height, WO 2011/010937 A1 proposes, for example, a method to provide shims between the brackets on the support legs of the structure and the circumferential face of the foundation piles. The brackets cause the load of the structure to be removed in the foundation piles before the connection is grouted and the curable grouting compound dissipates the load in the subsoil beneath the sea bed.
The measure described in WO 2011/010937 to compensate for level differences that arise in the subsoil due to different penetration depths of the foundation piles, are only suitable for compensating for slight differences in level, e.g. by insertion/use of shims for measurement tolerances. Moreover, the retention of the structure by means of brackets, as is known in the prior art, has the disadvantage that complex pipe laying is required on the relevant support leg of the structure to introduce grout into the foundation pile. The annular space between the support leg and the foundation pile is, in fact, no longer readily accessible after the installation of the structure.
The invention is therefore based on the object of improving a method of the type mentioned in this respect.
The invention has a further object of providing a foundation of the above-mentioned type, with which the above-mentioned method is particularly simple to carry out.
The object underlying the invention is first achieved by a method for installing an offshore structure with an anchoring structure and at least a foundation pile set in the subsoil beneath the sea bed, wherein at least a part of the structure inside the foundation pile is fixed in the subsoil beneath the sea bed under load transfer, and is grouted within the foundation pile using a curable mass, wherein the method is characterised, in particular before the implanting of the structure, by the foundation pile being provided with a viable self-levelling filling up to a predetermined level, wherein the foundation pile is provided with a load-bearing, self-levelling filling up to predetermined level prior to inserting the structure, and wherein the structure is positioned on the filling in the subsoil beneath the sea bed and/or in the foundation pile under load transfer, and wherein the grouting compound is introduced after positioning the structure on the filling.
According to the invention, therefore, the so-called brackets (collars, cuffs, removable brackets) on the supporting legs of the structure are dispensed with altogether, and height adjustment is achieved by adjustment of the level of the filling within the foundation piles or a single foundation pile. This makes it possible to dispense with mechanical means on the supporting legs completely. The support legs can then be easily placed on the corresponding levelled filling. Load transfer is via the filling of the foundation pile.
Such an approach thus has the further advantage that it is not necessary to provide the support legs of the structure with pipes or other installations for the introduction of the grouting material. Rather, the annular space between the foundation pile and support leg on the side facing away from the sea bed is open so that a grouting compound can be introduced into the annulus via the open upper side.
Appropriately, a self-compacting flowable concrete or grouting compound is introduced into the foundation pile as the filling. The concrete is so flowable that the concrete is selflevelling, without it being necessary to compact the concrete with the usual additional vibration compaction measures.
Suitable underwater-curable flowable concretes are basically available on the market. The method according to the invention can, however, also be used with conventional vibrated, possibly reinforced, underwater concrete.
In the method according to the invention, one or more piles in the form of cylindrical steel pipes are driven into the subsoil beneath the sea bed. After driving in the foundation pile, they are drilled and/or flushed out and filled with a self-compacting self-levelling flowable concrete up to a level which defines the insertion or embedded length of the supporting leg of the structure inserted into the foundation pile. On insertion of several piles, these are usefully filled to the same level.
The support legs of the structure may be positioned on the cured filling, so that there is first a load transfer via the filling into the subsoil beneath the sea bed. Load transfer thus inevitably occurs via the cured filling and a friction and/or form fit via the foundation pile in the subsoil beneath the sea bed.
In a particularly advantageous variant of the method according to the invention, it is provided that the structure is pre-fixed within the foundation pile in the circumferential direction before grouting.
The level of filling within the foundation pile is suitably selected as a function of a planned embedded length of the structure within the foundation pile.
In the filling, Scheer elements in the form of plugs, ribs or similar projections may be embedded within the foundation pile, so that the filling has a form fit with the foundation pile in order to dissipate the load distribution via both the filling as well as via the foundation pile in the subsoil beneath the sea bed.
In a particularly advantageous variant of the method according to the invention, it is provided that the structure has an intermediate layer of an elastomeric material on the filling. In the case of a foundation with several piles, an elastomeric material can be used on the filling to compensate for slight differences in level after hardening of the filling. Instead of an elastomeric material, shims may also be placed on the filling before the structure is put in position.
In a particularly advantageous variant of the method according to the invention, it is provided that the structure is fixed and/or centred within the foundation pile before grouting by means of wedges to prevent relative movements occurring between the foundation pile and the structure during curing of the subsequently introduced grouting compound, for example, movements induced as a result of waves and/or the wind, with the result that a sufficient material connection would not be formed between the structure and the introduced grouting compound.
The object underlying the invention is further achieved by a foundation of an offshore structure with at least one anchoring structure and at least one foundation pile in the subsoil beneath the sea bed, wherein at least a part of the structure is inserted in the foundation pile in the subsoil beneath the sea bed under load transfer and grouted in this, wherein the foundation is characterised in that the part of the structure embedded in the foundation pile is retained alone within the foundation pile, i.e. that the structure according to the invention is free from the so-called brackets or similar means for load transfer via the face of the foundation pile.
In a useful variant of the foundation according to the invention, it is provided that the structure comprises at least one support leg standing on a concrete base within the foundation pile.
The foundation is appropriately designed as a jacket foundation, which has a plurality of supporting legs.
It is particularly advantageous if the supporting legs do not have retaining clips, collars or brackets.
The figures are as follows:
Fig. 1 shows a partial section through a structure of a foundation inserted in a foundation pile according to the invention,
Fig. 2 shows a view similar to Fig. 1, wherein the support leg of the structure is fixed provisionally within the foundation pile with wedges,
Fig. 3 shows a perspective view of a supporting leg of a structure centred by means of several wedges; the foundation pile is not shown for reasons of clarity, and Fig. 4 shows a view in the direction of the arrow shown in Fig. 3
In Fig. 1, 1 designates a support leg 1 as part of an anchoring structure of an offshore structure. For simplicity, the anchoring structure is hereinafter referred to as a structure. This structure is provided with several support legs 1 in the form, for example, of a so-called jacket foundation, which receives a transition piece and a building erected thereon, for example in the form of a tower with a wind power generator. The support leg 1 is inserted a predetermined length in a foundation pile 2, which is in the form, for example, of a steel pipe that is driven into the subsoil beneath the sea bed 3. After driving in the foundation pile 2, this is drilled or flushed out, i.e. via a planned length free outside the sediment/rock. Then, a filling 4 in the form of a flowable self-compacting concrete, grouting compound, sand or similar material is introduced into the foundation pile 2. As is schematically illustrated in Figure 1, the foundation pile 2 is provided with Scheer plugs 5 in the area in which it receives the filling 4, and which extend radially inwards into the foundation pile 2 and in the filling 4. The filling 4 is introduced into the foundation pile 2 up to a level that has been selected as a function of a planned embedded length of the support leg 1 within the foundation pile 2. Alternatively, on the basis of adequate knowledge of the existing soil, the support leg can also be positioned on the soil in the pile and the filling dispensed with.
For example, the jacket foundation can have a total of three support legs 1 as a structure, wherein each is received by a foundation pile 2. A filling 4 is then introduced in all three foundation piles 2 according to the planned level of the foundation and the planned embedded length of the supporting legs 1.
After hardening of the filling 4, the structure is so positioned that the support leg 1 or, in the case of several support legs, all support legs are posiitioned on the filling 4, so that the load of the structure above the filling 4 and the foundation pile 2 is dissipated in the subsoil beneath the sea bed 3.
The support leg 1, for example, is columnar in shape and is provided on its outside with Scheer ribs 6.
After the positioning of the structure, the annular space 7 between the support leg 1 and the foundation pile 2 is filled with a grouting compound 8 in order to produce a material connection between the support leg 1 and the foundation pile 2 so that load transfer takes place evenly via the entire construction into the subsoil beneath the sea bed 3.
The support leg 3 is usefully provided with a support base 9, which, as can be seen in Fig. 3 and 4, can be made of cross-shaped steel bars.
In order to obtain a pre-fixing of the support leg 1 within the foundation pile 2 and, where appropriate, centring of the support leg 1 within the foundation pile 2 before the grouting compound 8 is introduced, several wedges 10 are inserted in the annulus 7 between foundation pile 2 and the support leg 1 and can be removed again after curing of the grouting compound 8.
The wedges 10 may be suspended by a corresponding device which is shown only schematically in Fig. 3. These wedges 10 ensure that no relative movement may take place between the support leg 1 and the foundation pile 2 in the circumferential direction, as long as the grouting compound 8 is not yet cured and able to accept load.
The entire arrangement shown in the figures is underwater.
Concretes and similar grouting compounds which cure under water and are correspondingly flowable and thus self-levelling, are known in the prior art.
The fixing by means of the wedges 10 is primarily intended to prevent relative movements induced by waves or wind loading.
Positional fixing during curing can also be achieved and ensured without wedges. For this purpose, systematic tolerance-free support is needed. This can e.g. be achieved by means of hydraulic cushions inserted under the support leg. In four-legged or multi-legged jackets, a statically determined support on three points can be achieved so that only three support legs are positioned on the same level while the fourth (fifth ...) leg does not rest on the filling. The leg opposite the free leg is filled or weighted so that the overall centre of gravity accordingly lies within the three resting points. The filling is selected so that lifting forces induced by waves and/or wind loads are compensated. The fourth "free" leg is underpinned by an elastomer to prevent tilting in the event of temporarily occurring higher waves and/or wind loads. Lateral forces are absorbed by friction in the pile.
LIST OF REFERENCE NUMERALS 1 Support leg 2 Foundation pile 3 Subsoil beneath the sea bed 4 Filling 5 Scheer plug 6 Scheer ribs 7 Annulus 8 Grouting 9 Support foot 10 Wedges

Claims (11)

FREMGANGSMÅDE TIL KONSTRUKTION AF EN OFFSHORE-STRUKTUR OG FUNDAMENT TIL EN OFFSHORE-STRUKTURPROCEDURE FOR THE CONSTRUCTION OF A OFFSHORE STRUCTURE AND FOUNDATIONS FOR A OFFSHORE STRUCTURE 1. Fremgangsmåde til fundering af en offshore-konstruktion med en forankringsstruktur og mindst én funderingspæl (2), der indsættes i undergrunden under havbunden (3), hvor mindst en del af strukturen i funderingspælen (2) fastgøres i undergrunden under havbunden (3) under belastningsoverførsel, og støbes inde i funderingspælen (2) under anvendelse af en hærdbar masse, kendetegnet ved, at funderingspælen (2) inden indsættelsen af strukturen forsynes op til et forudbestemt niveau med en bæredygtig, selvnivellerende fyldning (4), at strukturen på fyldningen (4) under belastningsoverførsel afsættes i havbunden (3) og/eller i funderingspælen (2), og at støbemassen (8) indsættes efter afsætningen af strukturen på fyldningen (4).A method of foundation of an offshore structure with an anchor structure and at least one foundation pile (2) inserted into the subsurface below the seabed (3), at least part of the structure of the foundation pile (2) being fixed to the subsurface below the seabed (3) during load transfer, and cast inside the foundation pile (2) using a curable mass, characterized in that the foundation pile (2) is provided up to a predetermined level with a sustainable, self-leveling padding (4) prior to insertion of the structure, (4) during load transfer is deposited in the seabed (3) and / or in the foundation pile (2) and the casting mass (8) is inserted after depositing the structure on the filling (4). 2. Fremgangsmåde ifølge krav 1, kendetegnet ved, at der som fyldning (4) indsættes en selvnivellerende, flydende beton i funderingspælen (2).Method according to claim 1, characterized in that as a filling (4) a self-leveling liquid concrete is inserted into the foundation pile (2). 3. Fremgangsmåde ifølge et af kravene 1 eller 2, kendetegnet ved, at strukturen inden støbningen for-anbringes i funderingspælen (2) i periferiretning.Method according to one of Claims 1 or 2, characterized in that the structure is placed in the foundation post (2) in the circumferential direction before casting. 4. Fremgangsmåde ifølge et af kravene 1 til 3, kendetegnet ved, at niveauet af fyldningen (4) i funderingspælen (2) vælges afhængigt af en planlagt indlejringslængde af strukturen i funderingspælen (2).Method according to one of claims 1 to 3, characterized in that the level of the filling (4) in the foundation pile (2) is selected depending on a planned embedding length of the structure in the foundation pile (2). 5. Fremgangsmåde ifølge et af kravene 1 til 4, kendetegnet ved, at fyldningen (4) i funderingspælen (2) opviser indlejring af klippeelementer i form af dyvler, ribber eller lignende fremspring.Method according to one of claims 1 to 4, characterized in that the filling (4) in the foundation pile (2) exhibits embedding of cutting elements in the form of dowels, ribs or similar projections. 6. Fremgangsmåde ifølge et af kravene 1 til 5, kendetegnet ved, at strukturen afsættes på fyldningen (4) ved hjælp af midlertidig positionering af et elastomert materiale.Method according to one of claims 1 to 5, characterized in that the structure is deposited on the filling (4) by temporary positioning of an elastomeric material. 7. Fremgangsmåde ifølge et af kravene 3 til 6, kendetegnet ved, at strukturen inden anbringelsen af støbemassen fikseres og/eller centreres foreløbigt inde i funderingspælen (2) ved hjælp af kiler (10).Method according to one of claims 3 to 6, characterized in that the structure is fixed and / or temporarily centered within the foundation pile (2) by means of wedges (10) prior to the application of the casting mass. 8. Fundering af en offshore-konstruktion med mindst én funderingspæl (2), der indsættes i undergrunden under havbunden (3), hvor i det mindste en del af strukturen indsættes i funderingspælen (2) i undergrunden under havbunden (3) under belastningsoverførsel, og støbes inde i samme, kendetegnet ved, at den del af strukturen, der indlejres i funderingspælen (2), kun er opfanget i funderingspælen (2).8. Foundation of an offshore structure with at least one foundation pile (2) inserted into the subsurface beneath the seabed (3), at least part of the structure being inserted into the foundation pile (2) in the subsurface below the seabed (3) during load transfer, and molded within the same, characterized in that the part of the structure embedded in the foundation pile (2) is only intercepted in the foundation pile (2). 9. Fundament ifølge krav 8, kendetegnet ved, at strukturen har mindst ét støtteben (1), som står på en betonsokkel inde i funderingspælen (2).The foundation according to claim 8, characterized in that the structure has at least one support leg (1) which stands on a concrete base inside the foundation pile (2). 10. Fundament ifølge et af kravene 8 eller 9, kendetegnet ved, at det er udformet som jacket-fundament, der har flere støtteben (1).Foundation according to one of Claims 8 or 9, characterized in that it is designed as a jacket foundation having several support legs (1). 11. Fundament ifølge et af kravene 8 til 10, kendetegnet ved, at støttebenene (1) ikke har holdeklammer.Foundation according to one of claims 8 to 10, characterized in that the support legs (1) do not have clamps.
DK13172594.7T 2012-08-14 2013-06-19 Process for the construction of an offshore structure and foundation for an offshore structure DK2698476T3 (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE102012016092.5A DE102012016092A1 (en) 2012-08-14 2012-08-14 Procedure for establishing an offshore structure and foundation for an offshore structure

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DE (1) DE102012016092A1 (en)
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Families Citing this family (7)

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Publication number Priority date Publication date Assignee Title
DE102012014828A1 (en) * 2012-07-27 2014-01-30 Repower Systems Se Dissolved structural structure for a wind energy plant and method for producing a dissolved structural structure for a wind energy plant
DE102014220782A1 (en) * 2014-10-14 2016-04-14 Rwe Innogy Gmbh Foundation system for the foundation of an offshore structure, procedure for the foundation of an offshore structure and offshore construction with an appropriate foundation system
CN105369821B (en) * 2015-12-10 2017-08-22 国网浙江省电力公司温州供电公司 A kind of transmission line of electricity steel pipe pile foundation anti-side pressure device
DE102017118375A1 (en) * 2017-08-11 2019-02-14 Innogy Se Offshore construction
DE102017123935A1 (en) * 2017-10-13 2019-04-18 Rosen Swiss Ag Sealing arrangement for a connection of two fasteners of an offshore structure and method for producing the same
DE102019103070A1 (en) * 2019-02-07 2020-08-13 Innogy Se Process for forming a connection between two pipe segments of different widths and a connection made accordingly
GB2609841B (en) * 2021-03-08 2024-04-03 China Three Gorges Corp Monopile foundation using cemented vibroflotation pile to reinforce soft soil foundation for use in offshore wind power generation, and construction method

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Publication number Priority date Publication date Assignee Title
JPH11323962A (en) * 1998-05-13 1999-11-26 Kohan Kenzai Kk Fitting accuracy adjusting tool and accurately fitting method using this fitting accuracy adjusting tool
NO339381B1 (en) 2009-07-22 2016-12-05 Owec Tower As Method and apparatus for controlling power transmission between a structure and its foundation during installation
GB2476051B (en) * 2009-12-08 2016-07-27 Atkins Ltd A structure for supporting a wind turbine

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DE102012016092A1 (en) 2014-02-20
EP2698476A1 (en) 2014-02-19

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