Application of Pile Test Data for the Foundation Design of a Rail Viaduct at Carrum, Victoria-Paper

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The Carrum rail viaduct in Victoria is a 545 m, 19-span structure built to remove level crossings on the Frankston railway line. Its piers and abutments are supported by groups of 1.2 m diameter continuous flight auger (CFA) piles.<br /><br />Rather than rely solely on conventional empirical correlations, designers used high-strain dynamic pile test results from the nearby Seaford Road Bridge, where geological conditions are similar, to derive pile design parameters for Carrum. The design was informed by site investigations and a ground model divided into nine geotechnical domains, and was verified through installation-record reviews and dynamic testing during construction.<br /><br />The adopted test-based parameters produced estimated pile capacities about 30–40% greater than those calculated using published correlations. In total, 24 production piles were dynamically tested, and every tested pile exceeded its required design capacity. Shaft friction was below the design value in some tests, but higher-than-design end bearing compensated for the shortfall.<br /><br />Using the test data enabled the foundation design to be optimised, reducing the total number of piles by approximately 50% through fewer piles and shorter pile depths. The authors conclude that pile testing can reveal conservatism in empirical design methods and deliver substantial cost and schedule benefits. They also emphasise the value of coordinating geotechnical and structural design, and recommend further research to better relate local ground conditions and test energy to pile capacity.

Keywords

Carrum rail viaduct

Victoria

Frankston railway line

CFA piles

pile testing

dynamic pile test

geotechnical design

pile capacity

end bearing

shaft friction