Real-time monitoring of scour and sediment deposition evolution at bridges and offshore wind turbine foundations based on soil electromagnetic properties

This doctoral thesis describes the development of a novel methodology for monitoring the evolution of scour and sediment re-deposition processes in the vicinity of foundation structures. The system employs two different devices in the Amplitude Domain (AD): an off-the-shelf and a new low-cost prototype sensor that yields an economical, accurate and robust structural health monitoring solution. Measurement principles are based on the Reflection (off-the-shelf ADR sensor) and Transmission (new ADT sensor) characteristics of propagating electromagnetic waves affected by impedance mismatches. The study initially validated the capability of an off-the-shelf ADR sensor, with ring-shaped electrodes, to monitor scour and sediment re-deposition processes under various environmental media through experiments conducted under both ‘static’ scour and real-time flume conditions. A novel approach was developed that enabled discrimination between in-situ and re-deposited sediments at the foundation structure. A new impedance-based sensor consisting of strip electrodes was then developed based on the ADT measuring principle and characterised in terms of its ability to detect bed level variations. The sensor design process included electromagnetic field modelling to optimise the electrode geometry within models that simulated various surrounding permittivity conditions. Principles of the sensor’s operation were established through a theoretical analysis that provided further insight into the electrical behaviour of the instrument. Sensor optimisation and the assessment of the frequency that maximises its sensitivity were then investigated experimentally and its operation was validated using ‘static’ scour and open channel flume experiments under different environmental conditions (salinity, temperature and sediment) that will vary in a practical offshore installation environment. Results indicate that both prototype sensors can accurately measure scour and re-deposited sediment processes, potentially offering an accurate and low-cost alternative to existing scour monitoring instruments. Validation of the newly developed ADT sensor in a representative operational environment enables the instrument to be classified at Technology Readiness Level (TRL) 6.

Name dc:type.qualificationname

phd

Level dc:type.qualificationlevel

doctoral-pg

Grantor dc:publisher.institution

University of Strathclyde

Year dc:date.issued

2014

Author dc:creator

• Michalis, Panagiotis A.

Advisor dc:contributor.advisor

• Tarantino, A. (Alessandro)

DOI

10.48730/abkb-ks21

Identifier

T13954

OAI identifier oai:identifier

oai:strathclyde:jq085j97c