Volume 42, N. 2, May-August 2019 | PDF(4 downloads)
Although the dynamic load test technique has been developed for a long time, it became very popular in Brazil over the last 20 years (especially after the publication of Brazilian Standard NBR6122, in 2010). However, the site quality control of driven piles in respect to the resistant capacities remains with the practical application of the so-called “dynamic formulas”. Most of the established formulations use a key parameter of the driving event: the driving system efficiency, whose calibration is performed with dynamic monitoring. However, assuming a single value for the efficiency in order to extrapolate it to non-tested piles of the site requires a much more careful analysis of the test than that which has been carried out in practice. The aim of this paper is to discuss the issues involving the efficiency assessment based on the dynamic test and to propose an alternative method of estimating the effective energy during driving through measurements of set and elastic rebound. The method application was verified in comparison with 692 dynamic test records (526 in concrete and 166 in steel piles) of twelve sites spread across seven different locations in Brazil.