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Offshore Pile Testing Campaign Wikinger
Pile driving analysis, static and dynamic load tests in 40m water depth
Jan Fischer, Fichtner Water & Wind GmbH, Hamburg, Germany
Rob van Dorp, Allnamics BV, Den Haag, The Netherlands
Wikinger OWF
Developer Iberdrola Renewables Deutschland GmbH
The Windfarm Turbine: 70 Adwen AD 5-135 (5 MW, Rotor-, 135 m) Project Capacity: 350MW Foundation: Jackets Water depth: 36 m to 42 m
Pile testing campaign Execution: Bilfinger Marine & Offshore Systems GmbH Date: 2014/2015
Installation Company: Boskalis and Volker Stevin Start: spring 2016
Slide 2 Offshore Pile Testing Campaign Wikinger l Jan Fischer & Rob van Dorp l Geotechniekdag 2015
Location
Slide 3 Offshore Pile Testing Campaign Wikinger l Jan Fischer & Rob van Dorp l Geotechniekdag 2015
Pile testing campaign
Slide 4 Offshore Pile Testing Campaign Wikinger l Jan Fischer & Rob van Dorp l Geotechniekdag 2015
General Only very little information exists about the skin friction and toe resistance behavior of typical Baltic Sea soils as glacial till and chalk.
Why Gain soil data information for driveability studies and for bearing capacity calculations
How Extensive offshore pile testing campaign including pile driving analysis (PDA), dynamic load tests (DLT) and pull out static load tests (SLT-T)
Source: ECSMGE 2015, Barbosa et al.
Special Task: Testing underwater, in depths of approx. 40 m
Fichtner / Allnamics
Slide 5 Offshore Pile Testing Campaign Wikinger l Jan Fischer & Rob van Dorp l Geotechniekdag 2015
Drivability predictions / hammer selection
Producing the deep sea operation sensors, cables etc. (for PDA and DLT)
Development of method statements for the different investigation phases
Pile driving analysis / dynamic load tests (at altogether six piles)
Signal matching (using AllWave-DLT)
Back calculation (simulation) of the pile driving using the results from the pile driving protocols and the dynamic load tests
Execution of the static tension pull out test (SLT-T) in terms of correct application of the different load steps
Interpretation of the static tension pull out test
Restrike dynamic load tests including signal matching
Interpretation of the soil setup on the basis of the results from the different phases
etc.
Phase I
Installation of nine piles at three different locations, including pile driving analysis (PDA) and dynamic load testing (DLT)
Slide 6 Offshore Pile Testing Campaign Wikinger l Jan Fischer & Rob van Dorp l Geotechniekdag 2015
Location Water depth
[m MSL]
Diameter
[m]
Pile
length
[m]
Penetration
depth at the end
of driving
[m BSF]
WK-a 40.0 1.37 21.8 16.8
WK-b 38.2 1.37 35.7 30.7
WK-c 36.6 1.37 36.0 31.0 MV Lone: DP2 Vessel by SAL
Test piles:
Phase I - Equipment
Slide 7 Offshore Pile Testing Campaign Wikinger l Jan Fischer & Rob van Dorp l Geotechniekdag 2015
Triplex Template (Pile guiding frame)
Pile Hammer (MENCK MHU 800S)
Phase I - Video
Slide 8 Offshore Pile Testing Campaign Wikinger l Jan Fischer & Rob van Dorp l Geotechniekdag 2015
Instrumentation
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• Two equipped test piles per location (for SLT and DLT)
• Two separate sets per pile
• Each set consisting of two strain transducers and two acceleration transducers
• Each 'pair' (strain and acceleration) placed diametrically opposed on the pile shaft
• Special deep sea sensors and cables
Data recorder (PDR)
Instrumentation
and testing
Phase II: Execution of one static tension pull out test (SLT-T) and one dynamic re-strike test (DLT) per test location. More than ten weeks after pile installation as part of Phase I
Phase II - Equipment
Slide 10 Offshore Pile Testing Campaign Wikinger l Jan Fischer & Rob van Dorp l Geotechniekdag 2015
Reference frame (SLT-T) Displacement measurement
Loading beam (SLT-T) Force application
Hammer (DLT)
Phase II - Video
Slide 11 Offshore Pile Testing Campaign Wikinger l Jan Fischer & Rob van Dorp l Geotechniekdag 2015
page 12
Slide 12 Offshore Pile Testing Campaign Wikinger l Jan Fischer & Rob van Dorp l Geotechniekdag 2015
Locking Tool
Loading Beam and Reference Frame
Phase II – SLT-T
page 13
Slide 13 Offshore Pile Testing Campaign Wikinger l Jan Fischer & Rob van Dorp l Geotechniekdag 2015
Phase II – SLT-T
Phase II – Results
Slide 14 Offshore Pile Testing Campaign Wikinger l Jan Fischer & Rob van Dorp l Geotechniekdag 2015
0.0
0.2
0.4
0.6
0.8
1.0
1.2
0 0.2 0.4 0.6 0.8 1 1.2
norm
aliz
ed d
ispla
cem
ent [-
]
normalized Force [-]
Statische Probebelastung
Load-Displacement
Static tension pull out test (SLT-T)
0.0
0.2
0.4
0.6
0.8
1.0
1.2
0.0 0.2 0.4 0.6 0.8 1.0 1.2
no
rma
lize
d fo
rce
[-]
normalized time [-]
Allnamics strain gauges (mean value)
Load cells (cumulative value)
-0.4
-0.2
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
0 10 20 30 40 50 60
norm
aliz
ed forc
e [-]
time [ms]
DLT restrike
Strain transducer 1Strain transducer 2Acceleration trancducer 1 (v*Z)Accerleration trancducer 2 (v*Z)
Restrike dynamic load test
Summary
Slide 15 Offshore Pile Testing Campaign Wikinger l Jan Fischer & Rob van Dorp l Geotechniekdag 2015
• The entire offshore testing campaign can be considered a huge success, especially since tests of this nature had not been performed before
• During the execution of the work in Phase I and Phase II, all tests could be carried out with high accuracy and high quality data
• The obtained test results led to a detailed understanding of the skin friction and toe resistance values for large diameter offshore pipe piles in typical Baltic Sea soils, i.e. glacial till and chalk
What is next • On the basis of the obtained test results, the installation of the wind turbine
piles was predicted by us
• The results were used e.g. for pile driving fatigue calculations, as an important value for the pile design
Thank you for your attention
Fichtner Water & Wind GmbH
Hammerbrookstrasse 47b D-20097 Hamburg Tel. +49 40 300673 – 0
jan.fischer@fww.fichtner.de www.fww.fichtner.de
Allnamics BV
Waterpas 98 NL-2495 Den Haag
Tel. +31 (0)882556264
vandorp@allnamics.eu www.allnamics.eu
FICHTNER WATER & WIND
FICHTNER WATER & WIND
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