Avoiding Damage due to Piling Vibrations (AD-PVIB)

WHY

During both impact and vibratory piling, vibrations occur in equipment and mechanical components on installation vessels. So far, only limited damage has been observed from piling operations, but there are signs that damage increases as pile sizes grow. The risk of damage can affect lifting tools, pile grippers, piling templates, hoses, deck equipment, cranes, anodes, vessel structures, engines, and even propulsion systems.

Impact hammers and vibro-hammers generate waves that travel through the piles, soil, water, and air into the vessel. However, the frequency and amplitude of the vibrations are not yet well understood.

As a result, the industry faces two risks:

• Underestimating the problem could lead to serious incidents in critical systems or unplanned downtime during installation due to damage or accelerated wear.
• Overcompensating by taking unnecessary or overly expensive precautions.

WHAT

The complete study has two parts: a preparation phase and an execution phase. This project covers the first phase.

First, we speak with industry partners individually about specific cases and collect any available measurement data. We will then generalise the input and use it as the basis for the analysis.

Next, we will identify the relevant load paths as a starting point for each case. We will map out the full load path – from the vibration source to the most affected part. Together with the partners, we will assess key components using load limits or failure indicators like acceleration, stress, deformation, and shock response. We will also consider assessment methods used onshore, such as building standards based on root main square (RMS) velocity.

We will look at the different analysis methods available for each load path. If needed, we will suggest improvements to these methods or theories and list the software that exists or is required for each method. With the stakeholders, we will decide which load paths should be studied further in the second phase. This will depend on their impact on key components and the shared interests of the stakeholders.

Finally, we will describe different ways of measuring structural loads and responses. We will advise which sensors to use based on the needed frequency range and the purpose of the measurements. We will also suggest specific measurement campaigns to help us better understand the physical effects and support future model testing.

EXPECTED RESULTS

The results of the first phase (inventory phase) of the project are:

• Identification of relevant load paths from impact hammering or vibration during pile installation.
• Identification of critical components and their load limits.
• Suggestion of analysis techniques for load paths.
• Prioritisation of load paths for follow-up research.
• Guidelines for selection of sensor types for specific measurements.
• Report identifying knowledge gaps and a plan for implementation of the second phase of the study.