VIBROJET®

There are three criteria for driving piles offshore. These are:

  • Drivability; pile has to reach target depth in dense sand and stiff clays

  • Environmental impact; noise needs to be below a certain limit

  • (Lateral) bearing capacity; pile needs to be a foundation for a wind turbine

 

Adding water injection to the inside of the pile together with vibro installation will cause:

  • The drivability to increase, in our SIMPLE I field tests, the piles were installed on average 4x faster and 2x deeper than conventional methods.

  • The environmental impact to decrease, because less harmful noise will be created during installation in comparison with conventional methods.

  • The (Lateral) bearing capacity will stay the same, because water is only injected on the inside of the pile and almost all (Lateral) bearing capacity is obtained on the outside of the installed pile.

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HOW IT WORKS

To install a monopile foundation, a vibrating system is installed at the monopile that reduce the resistance of the soil at the bottom tip and the outside of the pile.

Water is injected with a Jet gun upwards on the inner side of the pile wall to lubricate the pile-soil interface.

In this way, and by realizing a fluid bed in the monopile, the resistance of the soil is temporarily reduced to such an extent that the monopile foundation penetrates the soil to target depth under its own weight.

In addition, the jet gun is applied to go through clay layers by jetting it. The monopile foundation install process of this highly innovative system is managed by an advanced control system that measures real-time conditions at various key points.

 
KEY BENEFITS
  • Silent. No costly noise mitigations required which also appear ineffective and not future proof.

  • Future proof – larger monopiles. Validated in tests, Vibrojet® has proven to scale up more effectively than current method and other alternatives that could be considered.

  • Gentle method, no fatigue damage à  over 10% cost reduction of the monopile construction.

  • Faster installation. It is 5-6x faster than a vibration system only, reach much deeper levels and is also faster than current hydraulic hammer method.

  • Install costs. Similar or lower install costs depending on size of the monopile.