Case study: Merkur Offshore Wind Farm


Category:
Renewable Energy
Client: DEME Offshore
Project: Merkur Offshore Wind Farm
Location: Germany

Merkur offshore wind farm

The project

Merkur is a 396MW capacity wind farm located 35KM off the coast of Germany in the North Sea. As one of Germany’s largest offshore wind farms, it has the potential to generate up to 1,750 GWh each year which is enough to supply 500,000 German homes. The G-Octopus team were engaged by civil engineering company, DEME Offshore, to use their expertise in Pile Driving Monitoring (PDM) to confirm the foundation pile capacity of the installed offshore substation (OSS) platform.

Our challenge

The G-Octopus team were tasked with a great challenge at the Merkur offshore wind farm site. They were commissioned to provide underwater Pile Driving Monitoring services during the installation of four driven skirt piles of the Merkur OSS jacket as well as four restrike tests. The piles were to be approved in real-time on site according to Eurocode requirements. In order to do this, the team were able to draw on their experience and expertise to devise novel offshore pile testing procedures.

Our solution

In order to carry out underwater PDM, specific waterproof underwater sensors, cables and instruments are required, all of which were supplied by G-Octopus team. And to avoid any project delays, the piles were prepared and all sensors were installed by our team of experts while they were on board the cargo barge.

Once the instrumented piles was ready for upending, experts from the G-Octopus team were on hand to monitor the driving of the four skirt piles and record the blow count until the end of the drive, providing real-time information including force and acceleration responses of the piles to the DEME Offshore team.

After 90 hours, the team then carried out dynamic pile load testing on two of the four piles to evaluate the increase in pile axial capacity (“set-up”). Using the data generated, the team performed signal matching analyses using CAPWAP® software to disclose pile static bearing capacity on selected signals at the time of restrike.

The impact

Despite storm damage to some equipment, all four monitored piles were driven down to the tolerance regarding target penetration. The required test results were provided to our client (DEME Offshore) quickly, ensuring there was zero time lost on barge and the project remained on track. And as requested, we were able to green-light the final pile installation and deliver verification of the pile capacity according to Eurocode 7 and DIN 1054:2010-12 standards.

Services Included:

  • Underwater pile driving monitoring
  • Preliminary verification of end of initial driving (EOID) results
  • Re-strike test
  • Final verification of pile design capacity

Pile Information:

Length: 82.3 m
Thickness:
60 -75 mm
Diameter: 2.43 m

Equipment Used:

  • PDA 8G
  • Pile Driving Analyzer
  • Underwater Strain transducer
  • Underwater Piezo-Electric (PE) accelerometers
  • Deck cable.

 

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