Bi-Directional Static Axial Pile Load Test: Garca River Bridge

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The paper presents a bidirectional static axial load test on a 1.4 m diameter, 20 m deep bored pile for the Garcia River Bridge in Brazil. Constructed offshore in running water, the pile had a working load of 8,000 kN and was tested to 16,632 kN—approximately twice its working load.<br /><br />Three hydraulic expansion cells were installed in the reinforcement cage, 7 m above the pile toe, before concreting. After a 28-day curing period, the cells were pressurized, pushing the pile upward and downward. This allowed the test to measure upper shaft resistance separately from the combined resistance below the cells (lower shaft friction and end bearing), as well as pile displacement. Results can also be used to develop an equivalent top-loaded load–settlement curve.<br /><br />The test reached its target load in 5 hours and 20 minutes, with the full load held for one hour. The pile met the specified performance requirements, and the authors report that installation and testing were completed in less than 48 hours. The method required relatively little equipment and manpower, avoided the substantial reaction setup often needed for conventional offshore tests, and provided results quickly.<br /><br />Key limitations are that the test pile must be selected and prepared before concreting, preventing random selection after construction has begun. Installation also requires changes to the reinforcement cage, which may concern project stakeholders, and specialized equipment and qualified personnel are needed. The paper concludes that bidirectional testing was effective for this challenging offshore project, while noting that its advance-planning and specialist requirements may affect its wider adoption.

Keywords

bidirectional static load test

bored pile

offshore bridge foundation

axial load test

hydraulic expansion cells

pile settlement

shaft resistance

end bearing

Brazil construction

Garcia River Bridge