gravity base foundations for the thornton bank … · gravity base foundations for the thornton...

© DED

GRAVITY BASE FOUNDATIONS FOR THE THORNTON BANK OFFSHORE WIND FARM

CEDA DREDGING DAYS 2008, ANTWERP CEDA DREDGING DAYS 2008, ANTWERP -- Dredging facing SustainabilityDredging facing Sustainability

Authors: Kenneth Peire / Hendrik Nonneman / Eric BosschemPresentation: Kenneth Peire

13/11/2008 2© DED

1. Introduction

2. Project Development

3. Contract Strategy

4. Site Investigations

5. Design

6. Construction of the

GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds

9. Heavy lift, transport

and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

1.1. IntroductionIntroduction

2.2. Project DevelopmentProject Development

3.3. Contract StrategyContract Strategy

4.4. Site InvestigationsSite Investigations

5.5. DesignDesign

6.6. Construction of the Construction of the GBFGBF’’ss

7.7. Dredging of foundations PitsDredging of foundations Pits

8.8. Installation of foundations BedsInstallation of foundations Beds

9.9. Heavy lift, transport and offshore Heavy lift, transport and offshore

installation of the installation of the GBFGBF’’ss

10.10. Backfill of foundation PitsBackfill of foundation Pits

11.11. Ballast InfillBallast Infill

12.12. Scour protectionScour protection

13.13. GBF completion worksGBF completion works

14.14. ConclusionsConclusions

Paper PresentationPaper Presentation

13/11/2008 3© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

IntroductionIntroduction

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 4© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

� Offshore wind farm foundation structures to date:

- Cylindrical steel monopiles (North Sea & Baltic Sea)

- Gravity base foundations (Baltic Sea) in sheltered &

relatively protected waters

- Jackets, tripods, suction anchors for pilot projects of 1-2 WTGs

� WTGs: 2MW – 2,3MW – 3MW – 3,6MW

� Thornton Bank:

- First large scale commercial offshore application of

5MW WTGs

- First North Sea GBF as WTG support structure

- 30 km from coast

- Water depths up to 30m

Introduction

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 5© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

Project DevelopmentProject Development

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 6© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

� 60 wind turbines 5 MW, phase I: 6 wind turbines

� Installed capacity 300 MW

� Annual generation 1000 GWh

� Annual consumption of 600.000 inhabitants

� Avoided CO2 emission: 450.000 tonnes/year ~ forest 90.000 ha

C-Power NV is a Belgian company established for the development and implementation of a distant offshore wind farm on the Thorntonbank.

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 7© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

Shareholders:

Project Lenders: Owner’s Engineer: Certification Bodies:

The Client: C-POWER

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

� Dedicated area for offshore wind turbines

A number of other uses have already been licensed within the BCS.The area available for new wind farms is therefore severely limited.

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 9© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

Contract StrategyContract Strategy

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 10© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

Contractors:

THV SEAWIND (Belgium):Marine and Electrical Infrastructure

Non integrated Joint Venture with Dredging International NV as JV sponsor/leader

Wind Turbines

Marine cables

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 11© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

THV SEAWIND (Belgium):Marine and Electrical Infrastructure

Non integrated Joint Venture with Dredging International NV as JV sponsor/leader

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 12© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

DI/SCALDIS�Marine Installation of GBF’s

Tideway� Installation GBF foundation layer

DI�Dredging activities

DI/DBM�Scour protection around GBF’s

Marine Infrastructure Marine Infrastructure (Dredging International NV)(Dredging International NV)

DI/BDC/DBM�Backfill/ Infill of GBF’s

CFE/MBG�Construction of GBF’s

COWI�Design GBF’s

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 13© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

REPOWER (Germany):

Manufacturing & commissioning

of Wind Turbines

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 14© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

� Rated power: 5 MW

� Rotor diameter: 126 m

� Hub height offshore: 94 m

�� Rated power:Rated power: 5 MW5 MW

�� Rotor diameter:Rotor diameter: 126 m126 m

�� Hub height offshore:Hub height offshore: 94 m94 m

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 15© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

Nacelle

� weight: 315 tons

� dimensions: 18 x 6 x 6 m

Nacelle Nacelle

�� weight:weight: 315 tons315 tons

�� dimensions:dimensions: 18 x 6 x 6 m18 x 6 x 6 m

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 16© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

HubRotor BearingsGearboxConverter Onboard-Crane

Transformer Generator Yaw System

In the wind turbine the power that is generated is transformed to a voltage level of 33,000 volts (33kV).The electric components of the REPOWER 5MW turbine are located in the rear part of the nacelle.

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 17© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

Tower section (2 parts)

� weight (each): 120 tons

� dimensions: 37,5 x 6 diam.

Tower section (2 parts)Tower section (2 parts)

�� weight (each):weight (each): 120 tons120 tons

�� dimensions:dimensions: 37,5 x 6 diam. 37,5 x 6 diam.

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 18© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

Rotor Blade

� weight: 17.8 tons

� width: 4.6 m

� length: 61.5m

Rotor Blade

� weight: 17.8 tons

� width: 4.6 m

� length: 61.5m

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 19© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

ABB (Sweden):

Design and manufacturing of the marine cables

1 x 38.000 m of 150 kV cable 1 x 38.000 m of 150 kV cable

((diamdiam 22 cm, weight 81 kg/m) 22 cm, weight 81 kg/m)

6 x 500 m of 33 kV cable 6 x 500 m of 33 kV cable

((diamdiam 13,6 cm, weight 26 kg/m) 13,6 cm, weight 26 kg/m)

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 20© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

The TWO submarine cables (150kV) between the offshore transformer platform and the public 150kV grid on land are responsible for transporting the power that has been generated. For the submarine part of the route (about 36 km) the cables are buried in the sea bed.

22 cm22 cm

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 21© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 22© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

Site InvestigationsSite Investigations

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 23© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

Executed in 2004, covering all 6 turbine locations of Phase 1

�Geophysical:

- bathymetric (MBE) surveys

- side scan sonar (SSS)

- seismic surveys

- magnetometric surveys

�Geotechnical:

- borings with undisturbed sampling

- borings for pressure meter testing

- cone penetration tests with measurements of pore water pressures (CPTU)

- vibrocores, seabed CPTU’s

Site Investigations

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 24© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

Geological model, established on the basis of the seismic results, calibrated using the data from the geotechnical campaign:

�Coarse to medium dense sand with a gravelly horizon at the bottom, thickness 10 metres

�Stiff clay (tertiary layer), at the bottom a transition to more silty or sandy material, thickness 15 metres

�Dense sand, slightly silty to clayey, thickness 3 metres

�Very to extremely dense (aged) slightly silty to clayey fine sand with seams or pockets of clay, thickness 8 metres

�Stiff tertiary clay down to the end of the boreholes

Site Investigations

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 25© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

DesignDesign

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 26© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

�Design life: - Foundations: 30 years

- WTG components: 20 years

�Versatility of GBF structure towards WTG model

�Homogeneous very dense fine sand layer at +/- 28m below seabed

�Concerns w.r.t. driveability and monopile basic dimensions

� Increase of steel prices on world markets

After basic design stages, and following an extensive risk assessment and technical evaluation, the gravity base foundation concept was retained.

GBF Design

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 27© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

�Concrete caisson structures ballasted with infill

�Foundation level = 3,5m below RSBL

�RSBL: design seabed level that can be guaranteed during the lifetime (30 years)

�Foundation level from -21,50m TAW (D1) to -27.00m TAW (D5 & D6)

�Backfill up to RSBL

�Scour protection (engineered by owner / owner’s engineer)

� Installation tolerance for tilt: 0,25°

GBF Design

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 28© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

GBF Design - Dimensions

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 29© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

GBF Design - Dimensions

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 30© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

Physical modeling at DHI (Danish Hydraulic Institute)

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 31© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

Construction of Construction of GBFsGBFs

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 32© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

� “Halve Maan” construction site, east of entrance channel to Port of Ostend

� Site provided in concession to C-Power by Port of Ostend

� Quay wall provided by “Maritime Acces Division” (Ministry of Mobility & Public Works)

� Upgrading of site:

- design loads 10 ton/m²

- over 800 concrete piles driven into subsoil

- reinforced concrete “floor” of 0,75m thickness

- upgrading of quay wall to cater for mooring of the HLV Rambiz

� Construction at 6 locations:

- foundation beams

- GBF weights: 2.800 – 3.000 t

Construction of GBF’s

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 33© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

Foundation piles

13/11/2008 34© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

Reinforced concrete “floor” with foundation piles

13/11/2008 35© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

GBF Base Plate with central soft infill pad (rockxolid / politerm 500)

13/11/2008 36© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

•• Total weight GBF: 2.800 Total weight GBF: 2.800 –– 3.000 ton3.000 ton

•• Height: between 38,5 and 44 m Height: between 38,5 and 44 m

•• Diameter foot: 23.50 mDiameter foot: 23.50 m

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 37© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

Conical section – formwork and reinforcement steel

13/11/2008 38© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 39© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 40© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 41© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 42© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

Dredging foundations pitsDredging foundations pits

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 43© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

� Foundation Pits dredged to +/- 7m below existing seabed

� Dredging level = 1,3m below foundation level

� Foundation Pits: - 50m x 80m at bottom

- slopes 1:8 / 1:5

- heading along mail current direction

� Bulk dredging / Precision dredging

� Medium loose to dense sands

� Disposal areas at +/- 300m distance, in between crests of sand dunes

� Subsequent re-use of dredged materials: - backfill

- ballast infill

� 90.000 m³ dredged on average per foundation pit

� Works executed by latest generation TSHD Brabo (11.650m³)

Dredging foundations Pits

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 44© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

Dredging of the loose top layer (sand dunes) & denser layers below

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 45© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

Removal of bottom layer shortly before placing foundation bed

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 46© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

Installation of foundation bedsInstallation of foundation beds

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 47© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

� Important interface with GBF Base Plate

� First step in assuring verticality installation tolerances

� Highly accurate installation specifications

� Installation by means of DP class 2 DPFV “Seahorse”

� Crushed rock loaded in Norwegian seafront quarry

� 2 layers: filter (0-63mm) & gravel (10-80mm)

� 2500 tons filter layer material / 1200 tons gravel layer material per foundation bed

Installation of foundation beds

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 48© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 49© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

Seahorse

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 50© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

Heavy lift, transport and offshore Heavy lift, transport and offshore

installation of the installation of the GBFsGBFs

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 51© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

�Onshore transport by SPMTs from construction location to quay wall

� Lift-off from quay wall by HLV Rambiz

� Lowering of GBF once HLV rambiz was clear from quay wall

�Further lowering in open waters, up to 10m below water table

�Final ballasting with water during lowering of GBF onto foundation bed, to increase stability by allowing sufficient and equal suspension of crane hooks

Heavy lift, transport and offshore installation of the GBFs

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 52© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

�Weight management system during construction (DNV, ISO standards)

- material weighing & listing

- 3D volume scans

�Physical weighing prior to lift-off (accuracy 0,5%)

�During engineering phase:

- physical modeling (DHI)

- numerial modeling (MARIN)

�Dedicated current measurements on site during installation to compare against modeling


1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 53© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

Detail of a lifting lug

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 54© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

Hydraulic pin release

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 55© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 56© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 57© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 58© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 59© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 60© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 61© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 62© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

Transport & installation of the gravity foundations

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 63© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 64© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

� Purpose-built lifting frame

� Purpose designed lifting lugs

� Purpose-built hydraulic pin release mechanism for diverlessinstallation

� Positioning:

- LRK GPS antennas in each crane boom

- electronic inclination measurements on top of GBF

- 4 echosounders near base plate to assess lowering operation

� Results:

- average offsets from target centre: 0,5m

- average inclination of GBF installed: 0,10°


1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 65© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

Backfill of foundation pitsBackfill of foundation pits

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 66© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 67© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

Backfill

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 68© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

Multi Purpose Pontoon Thornton I

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 69© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

�Filling of dredged foundation pits after GBF installation

� Important contribution to geotechnical stability (primarily against overturning)

�Erosion protection required to guarantee presence of backfill during design life

�Sands re-dredged from nearby disposal areas

�Backfill level up to RSBL

�Extent covering full surface of foundation Pits

�+/- 60.000 m³ per foundation Pit

Backfill of foundation pits

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 70© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

�Sand D50 > 200µm, silt content < 2%

�Specifications met by using sand that was dredged twice

�Dredging & pumping by TSHD “Jade River” (3.300m³)

�Controlled spreading of sands into foundation pits by purpose-built spraying barge “Thornton 1”

� 300m self-floating line between “Jade River” and “Thornton 1”


1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 71© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

� 12m wide diffuser spray pipe

�Controlled layer pattern

�Fixed height of spray pipe above seabed, automatic correction for tidal levels

�Pre-defined spraying tracks, hauling speeds based on survey data (MBE) and on-line velocity and concentration measurements

�Fully automated dynamically controlled tracking by dedicated computer system regulating the 6 hydraulic winches

�Anchors (7/12 ton flipper delta) at strictly pre-defined locations


1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 72© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 73© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 74© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 75© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

Ballast InfillBallast Infill

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 76© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 77© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

Hydraulic Infill

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 78© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 79© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

� Ballasting to ensure sufficient weight, primarily against horizontal sliding of GBF

� +/- 2.000 m³ infill required per GBF

� Infill Materials:- Sand (15,80 kN/m³ above water / 19,24 kN/m³ below

water)- Magna Dense (heavy infill for GBF D6 – dry bulk density

27.50 kN/m³)

� Hydraulic infill (infill tower on Thornton 1, supplies by Vlaanderen XXI)

� Dry infill (following hydraulic infill and entirely for D6, with both sand & magnadense)

Ballast Infill

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 80© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

�For structural reasons, hydraulic infill was required at reduced rates (100m³/hr. sand) compared to dredging standards (e.g. backfilling of foundation pits with small TSHD at 2.500m³/hr. sand)

�Requirement to maintain mixture density below 13 kN/m³

�Dedicated infill tower o/b “Thornton 1” to bridge height difference and considering 4m tidal fluctuations

�Dry infill works: separate activity, performed from jack-up platform that was used later on for levelling & grouting of transition piece + other completion works on GBF

Ballast Infill

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 81© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

Vlaanderen XXI

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 82© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

Scour ProtectionScour Protection

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 83© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 84© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

Scour protection

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 85© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

Scour Protection

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 86© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

�Extent determined on the basis of physical modeling

- 2,5 D and 3D deemed appropriate

- outcome of hydraulic design was verified against geotechnical design

- iterative process

�Diameter of circular scour protection system (armourlayer): 44m (D1 – D3) up to 58m (D6)

�Filter layer: quarry run 0-120mm

Armour layer: mixture of 5-40kg (20%) and 40-200kg (80%)

�Filter layer thickness: 0,6m

Armour layer thickness: 0,7m

Scour protection

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 87© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

�Materials transported by truck to stockpile and loading quay in port of Zeebruges

�Execution using “Thornton 1” in fallpipe mode

�Fully automated process based on surveys and rock volumes on conveyor belt

�Rock supplies by “Vlaanderen XXI”

Scour protection

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 88© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

GBF completion worksGBF completion works

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 89© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

Anchor cage

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 90© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

� Levelling of transition flange within inclination tolerance of 0.25°

- Actual levelling not required considering achieved accuracy of installation

- Fine-tuning of #6 flange sections performed by WTG supplier (contractual interface)

- Grouting of volume between concrete top level of GBF

and transition flange by high strength non-shrink grout

- Operations performed from jack-up platform

� Further GBF completion works performed from jack-up platform

- Remaining (dry) ballast infill using big bags

- Installation of top sections of access ladders

- Lowering of water table within GBF down to MSL

GBF completion works

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 91© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

ConclusionsConclusions

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

13/11/2008 92© DED

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

�Gravity Base Foundation concept as WTG support structure has proven to be a viable option for deployment in deeper North Sea waters.

�Flexibility of GBF concept is less sensitive to a particular WTG model.

�Multidisciplinary project at all levels resulting in a matrix ofinterfaces.

�Marine construction works to realise the GBFs are largely based on extensive experience gained in dredging and related indutries.

Conclusions

1. Introduction




5. Design


GBF’s

7. Dredging of

foundations Pits

8. Installation of

foundations Beds


and offshore

installation of the

GBF’s

10.Backfill of

foundation Pits

11.Ballast Infill

12.Scour protection

13.GBF completion

works

14.Conclusions

gravity base foundations for the thornton bank … · gravity base foundations for the thornton...

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