Static Load Tests in an Instrumented Rock Socket Barrette Pile

M. Musarra, F. Massad

Article

Soils and Rocks, São Paulo, 38(2): 163-177, May-August, 2015 | PDF


Abstract

The foundation for the new Petrobras headquarters building in Salvador, Bahia, northwest of Brazil, had barrette pile rock socketed units chosen as the best engineering solution, due to shallow top rock, given schedule and cost. Even though the soil strata was stiff to very stiff silt, the required design load was not able to be based on soil side resistance only, resulting in a rock socket design. A 300 kPa ultimate shear stress was assumed by the designers and static load tests were performed to verify this parameter. This paper evaluates the results obtained from the test without discussing the designer assumption. Rock socket shear stress verification was made possible by placing an expanded polystyrene block below the pile steel cage, eliminating any possible bottom resistance. Beyond the usual top instrumentation, electric retrievable extensometers were installed along the shaft to afford depth load transfer evaluation. This paper presents the results of the load tests as well as an application of analytical and semi-empirical methods available in the literature to prove their usefulness and effectiveness, revealing and confirming many aspects of field behavior.


Submitted on December 21, 2014; Final Acceptance on June 3, 2015; Discussion open until December 31, 2015.