Pile-Run Risk Assessment (PiRRA)

WHY

Pile-run is a critical risk in offshore wind foundation installation, referring to the sudden and uncontrolled penetration of a pile into the seabed during driving. It occurs when a pile rapidly descends through weak soil layers or when moving from a dense layer into a softer one, triggered by a sudden reduction in soil resistance. The pile continues to penetrate until it reaches a stiffer layer or until sufficient shaft friction develops to resist further movement. Such events can lead to major safety concerns, significant cost overruns, project delays, and increased construction uncertainty. Reliable assessment of pile-run risk is therefore essential to determine whether mitigation measures are required and, if so, to what extent.

Never witnessed a pile run? It is impressive. Have a look here.

Current industry practice largely relies on static assessment methods that compare the self-weight of the pile, or the pile plus hammer, with the Soil Resistance to Driving (SRD) derived from historical pile-driving data. While widely used, these methods do not adequately capture the dynamic nature of pile-run, particularly the rapid pile acceleration and the development of excess pore pressures in the soil during driving. Dynamic, energy-based prediction models offer a more realistic framework. Nonetheless, their predictions often show substantial discrepancies when compared to observed field behaviour.

As a result, there is a clear need for further research to improve pile-run prediction models by better accounting for key factors, such as pore pressure generation and dissipation, drainage conditions, and soil stratigraphy. This would improve the ability to predict and mitigate pile-run risks during installation.

WHAT

This project is the first step in a longer-term development effort. Its focus is on gathering insights from existing research and industry experience, bringing together what is already known on current approaches to pile-run risk analysis. We will subsequently define the scope and priorities for a future, larger research project aimed at developing advanced risk-assessment models.

The project aims to build a shared understanding of pile-run risks analysis in offshore wind farm construction, identify the most critical knowledge gaps, and create a solid starting point for further research and development. The work will be carried out in close collaboration with industry partners and technical experts, so that future risk assessment methods and mitigation measures are well aligned with the real challenges faced during offshore installation.

The project will include a structured review of current pile-run assessment approaches, covering empirical, static, and dynamic methods. Particular attention will be paid to where existing methods fall short and where improvements are needed. While energy-based approaches are promising in principle, they often rely on accurate predictions of Soil Resistance to Driving (SRD), which are difficult to obtain in practice due to uncertainties in soil behaviour and limited access to installation data. For this reason, alternative modelling directions will also be explored, such as explicitly accounting for pore pressure effects, more complex soil–structure interaction behaviour, and pile penetration through layered ground conditions; for example, scour protection over weak clay layers.

Rather than settling on a single solution too early, the project will remain open to different ideas and approaches. Based on the identified gaps, a clear roadmap will be developed for a follow-up R&D project to further advance pile-run risk assessment methods.

EXPECTED RESULTS

The project delivers a report that presents the current state of pile-run risk assessment, including the limitations of existing models identified through a literature review. It sets out the key knowledge gaps and open research questions that remain unresolved. The report also includes a roadmap for a larger R&D programme to advance dynamic pile-run prediction models, with improved representation of soil behaviour and the effective use of real-world pile-driving data.