Abstract:
Many researchers have studied the service behavior of piles with the intention of validating the limit state of foundations and establishing a method for predicting settlements. In addition, the challenge is even greater in soils with complex stratigraphy and large diameter floating piles. This case study will present three load tests in a soil with complex stratigraphy, with intercalated layers of sand and clay, typical of sedimentary soils on the Brazilian coast. The piles are of the friction continuous fligh auger (CFA)Â with a diameter of 1.00m (D = 1.00m) and a length of 15.00m (L = 15.00m) monitored at 5 different instrumentation levels, one at the tip and four monitoring levels at the shaft (-1.42m, -5.42m, -8.42m, -11.42m and -13.62m), thus differentiating the forces and displacements at the shaft and tip. In these tests, the aim was to advance with top displacements of at least 20% of the diameter in order to ensure total load mobilization of the pile, including tip resistance.
The results were used to validate finite element modeling, as well as triaxial and oedometer tests to adopt appropriate geotechnical parameters and compare with semi-empirical methods for pile strains. For modeling, the tangent modulus value proposed by Janbu (1963) was discussed with the aim of verifying the influence of varying this parameter with the confining stress on the estimation of settlement compared to load tests. This is possible due to the level of deformation adopted in the design Â