Tower Loading Risk Assessment
Scottish and Southern Electricity Networks
SSEN Future Networks Team
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Innovation Funding Incentive
Corrosion of steelwork in tower foundations has been a concern for some time as many steel overhead towers are more than fifty years old. The project will investigate the use of non-intrusive techniques to ascertain the strength and integrity of both underground steel and concrete components of the tower foundations of a representative sample of the Scottish and Southern overhead power distribution network.
The investigation will be undertaken on the foundations of approximately 120 overhead towers to assess the feasibility of two complimentary techniques.
Polarisation Resistance Measurements to obtain an instantaneous value of the steel foundation corrosion rate that is based on the consideration of the electromechanical mechanisms involved in corrosion. These measurements will provide information on the state of the tower foundations and aid in identifying foundations that are most likely to have suffered significant corrosion damage.
Transient Dynamic Response to assess the integrity of both pre-cast and cast in situ concrete piles and foundations. The method is based on measuring the frequency and amplitude response of a concrete foundation based on an impulse wave being passed through it The response contains information which is related to the integrity of the concrete foundation.
The Transient Dynamic Response techniques have not been used by UK DNO companies to assess tower foundations, but other types of business have found them to be useful for assessing concrete foundations.
The project objectives are:
- To undertake an initial investigation of 120 overhead tower lines using both techniques
- To assess the feasibility and benefits of using this approach to assess all overhead tower assets
- To analyse the data gained from the site surveys to provide a subset of towers where further investigation is recommended
- To undertake witnessing of tower foundation excavation works where further investigation is recommended
- To provide an assessment of the viability and effectiveness of the use of non-invasive assessments of tower foundations using Polarisation.