Non-contact Energy Flux Measurement of Impact Pile Driving

The increasing deployment of Offshore Wind Turbines (OWTs) necessitates larger steel monopiles, whose design currently includes additional steel to account for fatigue damage during installation. Traditional contact-based sensors, such as strain gauges and accelerometers, are challenging to deploy in offshore environments and are susceptible to damage under high stress. To overcome these limitations, a novel non-contact sensor system has been developed, utilizing the magnetomechanical effect to measure strain and an optical method to measure velocity. This paper presents the results of a test series using a full-scale impact hammer on a thin-walled steel pile, comparing the new system’s performance to a conventional Pile Driving Analyzer (PDA). Sources of error in the non-contact sensor measurements were identified, and post-processing techniques were applied to obtain acceptable time signals. Despite some residual errors, the system effectively captured strain and velocity behaviour. These findings demonstrate the feasibility of contactless monitoring for steel structures subjected to impact pile driving, representing a promising step toward more efficient and cost-effective monopile installations.