Review of Piling Works at Carrington and Ardnacrusha

GDG was requested by international consulting firm ESBI to undertake independent foundation designs for two major projects at Ardnacrusha and Carrington. GDG was commissioned to review the design and performance of CFA piles installed to resist axial static compression loads at the Carrington Combined Cycle Power Plant in Manchester. GDG was also requested to perform a technical review of piling works at the site of the construction of a new 110 kV substation building at Ardnacrusha power station, County Clare. 111 CFA piles were installed at the site in some challenging ground conditions.

Scope of Work:
 

Carrington Combined Cycle Power Plant:

1. Review the original foundation design with particular reference to the behaviour of axially loaded compression piles.
2. The review focused on the axial pile behaviour in both the ultimate and serviceability limit state.
3. The methods adopted to derive the ultimate shaft friction and unit end bearing were assessed.
4. The load-settlement model used to predict the pile settlements was reviewed.
5. Recommendations regarding the level of conservatism in the pile design methodology were provided.
6. The available static load test data was interrogated to determine the likely mobilisation of shaft and base loads.
7. The load-settlement behaviour was compared to semi-empirical settlement models.
8. The load-test was compared to the original design assumptions and recommendations were given about the accuracy of the original analysis.

Ardnacrusha Power Station:

1. Foundation design review
2. A review of integrity test results including investigating the cause of anomalies.
3. A statement on the reliability of dynamic pile testing as a means of proving the performance of piles with unknown and non-uniform cross-section.
4. An opinion as to whether the piles are serviceable.