Bidirectional tests are an option for pile static load tests that have been growing significantly in Brazil in the last years. This work presents the procedures used in the interpretation of this test. In the bidirectional method generally one Expendable Static Cell (ESC) is installed near the pile toe (about 1/3 of pile length). The cell is pressurized by fluid (generally water), thus generating a load that is applied to the two parts of the pile. The test provides directly two load x displacement graphs, corresponding to the upper and lower parts of the pile. The load x settlement curve which the pile would present under a load applied to its top has to be constructed from these graphs. Different methods can be used to construct the top load x settlement curve, and the proposals of Silva (1983) and Massad (2015) are the most used in Brazil. In the interpretation of the test, a key parameter is the elastic shortening of the pile. If the pile is rigid, the method proposed by Silva (1983, 1986) can be used, but, if the pile is compressible, it is of the utmost importance to measure the elastic shortening.
Subjects: Bi-Directional Load Test, Static Load Test, Foundations Performance Control
Author: Felipe V. A. de Souza Cruz, Civil/Geotechnical Engineer, Marco A. G. Conte, Civil/Geotechnical Engineer, Renan Basso, Civil Engineer and Alessandra C. de Freitas, Professor of Civil/Geotechnical Engine
Publisher: DFI, EFFC