Centrifuge modelling of monopiles for offshore wind turbines

DTU Civil Engineering, Technical University of Denmark

Monopile

06/10/2011Ph.D projekt af Rasmus T. Klinkvort 2009-20122

(http://www.ramboll-wind.com/, 2010)(http://www.dongenergy.com ,2010) (Byrne & Houlsby, 2006)

DTU Civil Engineering, Technical University of Denmark

Research method

06/10/2011Ph.D project by Rasmus Klinkvort 2009-20123

Prototype model

Numerical model

Scaled model

Constitutive law

Scaling law

Calibration&

Verification

DTU Civil Engineering, Technical University of Denmark

Research method

06/10/2011Ph.D project by Rasmus Klinkvort 2009-20124

Prototype model

Numerical model

Scaled model

Constitutive law

Scaling law

Calibration&

Verification

DTU Civil Engineering, Technical University of Denmark

Dimensional analysis of a laterally loaded pile in sand

• For a laterally loaded pile

06/10/2011Ph.D project by Rasmus Klinkvort 2009-20125

( )

=

==

',,,,'

),,,,,,,(',',,,,,,

503

87654321

50

ϕγ

ππππππππϕγ

dd

dL

de

duf

dH

fFdLeduHfF

DTU Civil Engineering, Technical University of Denmark

Centrifuge modelling

06/10/2011Ph.D project by Rasmus Klinkvort 2009-20126

DTU Civil Engineering, Technical University of Denmark

Centrifuge modelling

06/10/2011Ph.D project by Rasmus Klinkvort 2009-20127

Scale effect – Modelling of models

DTU Civil Engineering, Technical University of Denmark

Scale effect

06/10/2011Ph.D project by Rasmus Klinkvort 2009-20128

DTU Civil Engineering, Technical University of Denmark

Installation effect

06/10/2011Ph.D project by Rasmus Klinkvort 2009-20129

DTU Civil Engineering, Technical University of Denmark

Non-Linear stress distribution

06/10/2011Ph.D project by Rasmus Klinkvort 2009-201210

DTU Civil Engineering, Technical University of Denmark

The non-linear stress distribution effect

06/10/2011Ph.D project by Rasmus Klinkvort 2009-201211

DTU Civil Engineering, Technical University of Denmark

Centrifuge modelling

06/10/2011Ph.D project by Rasmus Klinkvort 2009-201212

Stress level effect

DTU Civil Engineering, Technical University of Denmark

Stress level effect

06/10/2011Ph.D project by Rasmus Klinkvort 2009-201213

DTU Civil Engineering, Technical University of Denmark

Stress level effect

06/10/2011Ph.D project by Rasmus Klinkvort 2009-201214

DTU Civil Engineering, Technical University of Denmark

Modelling technique

06/10/2011Ph.D project by Rasmus Klinkvort 2009-201215

Prototype model

Numerical model

Scaled model

Constitutive model

Scaling laws

Calibration&

Verification

DTU Civil Engineering, Technical University of Denmark

Monotonic tests e=15d, L=6d & d=1-?m

06/10/2011Ph.D project by Rasmus Klinkvort 2009-201216

DTU Civil Engineering, Technical University of Denmark

Monotonic tests e=8.25d, L=6d & d=1-?m

06/10/2011Ph.D project by Rasmus Klinkvort 2009-201217

DTU Civil Engineering, Technical University of Denmark 06/10/2011Ph.D project by Rasmus Klinkvort 2009-201218

DTU Civil Engineering, Technical University of Denmark

Cyclic loading of monopile

06/10/2011Ph.D project by Rasmus Klinkvort 2009-201219

DTU Civil Engineering, Technical University of Denmark

Cyclic loading of monopile ζb=0.35, ζc=-0.5

06/10/2011Ph.D project by Rasmus Klinkvort 2009-201220

DTU Civil Engineering, Technical University of Denmark

Accumulation of deflection – 10 000 cycles

06/10/2011Ph.D project by Rasmus Klinkvort 2009-201221

1000 cycles capture the trend

Fatique limit state 107

cycles

DTU Civil Engineering, Technical University of Denmark

Cyclic p-y curves, e=15d, L=6d & d=1-?m

06/10/2011Ph.D project by Rasmus Klinkvort 2009-201222

06/10/201123 Ph.D project by Rasmus T. Klinkvort 2009-2012

ConclusionsCentrifuge modelling of monopiles: Stress distribution Load eccentricity/Pentration depth... Development of initial subgrade reaction÷ Diameter effect÷ (Size of Stiffness)

Cyclic tests: Accumulation of deflection/rotations Increase in stiffness Damping in the soil÷ Accumulation of porepresure