Abstract Water jet-driving technique has been shown as a viable practice for driving prefabricated piles in resistant soil layers. However, this technique is also associated with the reduction of load capacity of piles. Along these lines, the use of reams in prefabricated concrete piles improves their mechanical performance. The main objective of this research was to study the efficiency of reams on water jet-driven concrete piles; to this extent, pile loading tests and mini-cone tests were carried out before and after the driving of the piles. In addition, numerical modelling with the finite element method (FEM) was applied to study the stress-strain behavior. By means of the numerical modelling, it was possible to identify the stress and strain distribution at the tip, shaft, and reams of the piles; this allowed the understanding of the contribution of these elements in the total load capacity. Results have shown that the reams directly contribute for load capacity, with increases up to 40% when compared to conventional piles. Laboratory tests and numerical modeling proved to be fundamental tools to understand the mechanisms behind the contribution of reams to the load capacity of piles.

Abstract In recent years several dam failures have been reported throughout the world, generating a social concern on mine tailings. Along these lines, it became essential to understand the mechanical behavior of these materials in order to refine current design technologies and prevent more tragedies. In this context, this research had two main goals: (i) to analyze bauxite tailings mechanical behavior through isotropically consolidated-undrained triaxial tests and consolidation tests; and (ii) to compare triaxial tests and numerical simulations results. Confining stresses of 75kPa, 150kPa, and 300kPa were applied in the triaxial tests. Numerical modelling was performed through ABAQUS software, in which three different failure criteria were analyzed, Mohr-Coulomb Model (MCM), Drucker-Prager Model (DPM), and Modified Cam-Clay Model (MCCM). Results indicated that all studied criteria showed satisfactory results, however, DPM was the best criterion to simulate bauxite tailings mechanical behavior and respective strength parameters.