The value of integrated design of offshore wind turbine foundationsKristoffer Skjolden SkauNorwegian Geotechnical Institute

Bergen 2019-09-12

NGI’s mission and marketsWe research and develop solutions for both industry and society, ensuring that we live, build and travel on safe ground

Services grouped into four markets─ Offshore energy─ Building, construction & transportation─ Natural hazards─ Environment

Offshore geotechnical engineering

Since 1970s Development of the required technology for the oil and gas adventure in Norway

From 2010 Offshore wind activitiesDesign, installation and monitoring of offshore wind foundations

NGI involvement in offshore wind

Work with all foundation types

Work with all foundation types

Work with all foundation types

NGI Oslo and Houston advanced Laboratories

Design and advanced analyses

Field testing and monitoring

Integrated designis a comprehensive holistic approach todesign which brings together specialisms usually considered separatelyDriven by :─ The real coupling of the processes and physical mechanisms governing the

design ─ The digitalization of data and workflows that replace old data storage and

manual workflows

Integrated design analysesREDWIN 1 developed the capabilities in modelling the physical interactions of the turbine. Integration of the physical mechanisms in the system

Site investigation and laboratory

testing

Soil parameters

Compute foundation response

Implement in integrated analyses

Integrated analyses to

determine OWT design

Design work flow

REDWIN

Integrated design analyses

Integrated design analysesREDWIN research project

Foundation type Applicable model Primary loading conditions

REDWIN model 1

Horizontal loading (but distributed 1D model can be applied to any DOF)

REDWIN model 2

Coupled Horizontal and

Moment loading

REDWIN model 3

Coupled Vertical, Horizontal and

Moment loading

REDWIN model 3

Coupled Vertical, Horizontal and

Moment loading

Integrated design analysesDesign is more than analysesREDWIN 2 takes an integrated approach to the complete foundation design processDigital and automated work flow replace manual work flow

Manual work flow Digital and automated work flow replace manual work flow

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Geophysical survey

Manual work flow

Manual work flow

Manual work flow D

L

t

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Manual work flow Manual work flow require simplificationsA few design casesOptimal design for the defined cases

D

L

t

D = 6L = 26

D = 5.5L = 24

Cluster 1 Cluster 2

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SUMO –SUper fast MOnopile design

orGeotechnical design

Structural design

Integrated designDigital and automated work flow replace manual work flowNot data reports, only data

From a point1D 2D 3DGeotechnical data is typically collected as a limited number of sparse 1D points in the ground model

CPTs and/or Engineering judgement can be used to scale soil parameters in 1D borehole

Inversion/Co-Kriging/ Machine learning can be used to scale to 2D

Interpolation or Geostatistics can be used to scale to 3D

(e.g. Linear, Spline, Kriging)

SUMO –SUper fast MOnopile design

orGeotechnical design

Structural design

SUMO - INFIDEP

Axisymmetric finite element with asymmetric loadingThe displacements are expanded from 2D to 3D with a Fourier series expansion

SUMO - INFIDEPAnalyses of PISA tests

SUMO – Sizing with INFIDEP

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Integrated designOptimal design across the site

D

L

t

D = 6L = 26

D = 5.5L = 24

……D = 4.9L = 18

D = 5.3L = 24

D = 5.5L = 23

D = 6.5L = 26

D = 5.8L = 24

D = 5.7L = 23

D = 5.6L = 22

A01 A02 A03 A04 B01 B02 B03 B04 C01

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Monopile design – spatial variability?

Pictures and figures are meant for illustration only

Integrated design

orGeotechnical design

Structural design

Integrated design – final remarks Integrated design is more than a buzzwordIt require new digital workflowsIt require cross-discipline thinking and collaborationOffshore wind is likely a front runner due to the number of structures and the focus on optimizationThe value is the ability to optimize; and the ability comes with reliable technical models and effective processes.

Thank you for your attention !