Installation of monopiles
Transcript of Installation of monopiles
DNV GL © 2016
Ungraded
25 April 2016 SAFER, SMARTER, GREENER DNV GL © 2016
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25 April 2016 Liv Hamre
INSTALLATION OF MONOPILES
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Analyses models
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INSTALLATION OF MONOPILES
DNV GL – This is us
Geotechnical Design Basis
Soil resistance to driving
Fatigue from driving
Vibro installation
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OFFSHORE WIND - COMBINING DNV GL COMPETENCES
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OUR GEOGRAPHICAL REACH IN RENEWABLES
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FOUNDATIONS
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Zhou
Jon
PhD students Other sections in marine structures
Erik
Dhruba
Jørn
Knut
Liv
Kristian
Robert
Siamak
Jens
Sébastien
David
Jan
Knut
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WIND FARM CERTIFICATION
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According to DNV GL-SE-0073
Project Certificate
Site Conditions Assessement
Design Basis Evaluation
Integrated Load Analysis
Support Structure Design Evaluation
Support Structure Manuf. Surveillance
Commissioning Surveillance
Transportation & Install. Surveillance
Final Evaluation
Project Characteristics Measurements
Project Certificate
Wind Turbine / RNA Manuf. Surveillance
Wind Turbine / RNA Design Evaluation
Other Installations Manuf. Surveillance
Other Installations Design Evaluation
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Type Certificate
Design B
asisD
esignInstal-lation
Com
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anufac-turing
In-service
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GEOTECHNICAL DESIGN BASIS
The Geotechnical Design Basis usually consists of:
– Geological Studies
– Bathymetric Investigations
– Geophysical Investigations
– Geotechnical Investigations
2014-09-09
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A cautious estimate of the characteristic strength would be a high value for the driveability calculations
The calculation models should preferably only be used for pile dimensions and soil conditions that they are based on
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PILE INSTALLATION
Soil Resistance to Driving, SRD, is calculated predict the installation challenges
High soil strength must be considered
Relevant soil models must be applied in the assessment of soil resistance to driving
Fatigue from driving shall be included in the pile fatigue evaluation
Noise assessments and mitigation measures may be required
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SOIL RESISTANCE TO DRIVING
Relevant published models: 1977 - Toolan & Fox 1981 - Semple & Gemeinhardt 1982 - Stevens et al 2001 - Alm & Hamre
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SOIL RESISTANCE TO DRIVING
1977 - Toolan & Fox Based on CPT Minimum of plugged and unplugged
resistance Remoulded shear strength
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SOIL RESISTANCE TO DRIVING
1981 - Semple & Gemeinhardt Based on static pile capacity
calculations including a “pile capacity factor” Suggest that the unit friction at a
given penetration decreases with the length of pile driven past this depth OCR is an important parameter
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SOIL RESISTANCE TO DRIVING
1982 – Stevens et al Based on static soil capacity
applying a pile capacity factor established from back-analyses Using both plugging and coring Include recommendation for
driving in rock
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SOIL RESISTANCE TO DRIVING
2001 – Alm & Hamre Based the friction fatigue concept
recommended by Jardine et al for axial pile capacity assessment Assuming coring pile Based on back-analyses from
several North Sea sites Pile diameters in the database is
30” to 108 “
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FATIGUE FROM DRIVING
According to DNV OS J101,
– DFF = 3 for WTGs and
– DFF = 10 for substations
Normally, the characteristic shear strength is applied
Planned interruptions in the driving operations must be included in the predictions
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VIBRO INSTALLATIONS
Noise from driving can be harmful to the environment and several countries are introducing limitation on noise emission
Vibro-driving is potentially a cost-effective and low-noise alternative to impact driving
Limited available information on prediction of resistance to installation
Research is ongoing with respect to lateral pile capacity for vibro installed monopiles compared to impact driven and drilled piles
Less impact on fatigue than impact driving
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Quad Kong, 12 m diameter pile in China (apevibro.com)
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SAFER, SMARTER, GREENER
www.dnvgl.com
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