O-Cell methodology supporting pile design optimisation in Angola-PPT Presentation

PPT Presentation

Pdf Summary

The presentation describes the use of bi-directional Osterberg Cell (O-Cell) load testing to optimise pile design for the Terminal Oceânico project at Barra do Dande, about 30 km north of Luanda, Angola. The development includes a 1.7 km pier and two mooring areas, supported by 323 cased bored piles founded in limestone and claystone.<br /><br />Four full-scale pile tests were conducted to validate and refine the foundation design. O-Cells installed within the piles applied loads simultaneously upward against shaft resistance and downward against base resistance and lower shaft resistance. Because the system requires no above-ground reaction structure, it was particularly suitable for testing over water and in the project’s remote setting.<br /><br />The piles were 700 mm in diameter and 31–43 m long. Test assemblies were designed for target loads of 5.5 MN and 9.0 MN. Loading schedules were extended beyond the original targets to gather additional geotechnical information, reaching approximately 8.0 MN and 14.9 MN.<br /><br />The tests improved understanding of the soil strata and pile-bearing capacity, complementing site investigation and laboratory results. They confirmed that the O-Cell method could meet the client’s testing requirements efficiently under challenging site conditions. Findings enabled pile design optimisation, with reductions of up to 40% in pile length—specifically, in the rock-socket length. This reduced the duration, cost and environmental impact of the most difficult and expensive drilling work.

Keywords

Osterberg Cell

O-Cell load testing

pile design optimization

bi-directional loading

Terminal Oceânico

Barra do Dande

foundation testing

cased bored piles

rock-socket reduction

geotechnical investigation