Comportamento de radiers estaqueados assentes em solos arenosos

Abstract

It is observed in the last decades, the search of the optimization of pile foundations from the analysis of the benefit that the contact of the pile cap or raft with the ground can confer to increase the load capacity and stiffness. Contribution that is not inserted in the design of the foundation system by the traditional methodology of pile group. Thus, in the present dissertation an analysis of the behavior of a foundation conceived by the pile group methodology was carried out, in light of the piled raft, through numerical modeling. The study work is from Instituto Cérebro, located in the Central Campus of the Federal University of Rio Grande do Norte (UFRN), Natal-RN. Theoretical and experimental studies, highlighting pioneering and more recent searchs on the theme of this work, were used as subsidies to present the state of the art of foundations in piled raft. The study foundation consists of bored piles of the continuous flight auger, composed of lengths of 15, 17 and 20 m and diameters of 250, 400 and 500 mm. For the analysis of the behavior of this foundation, the numerical program PLAXIS 3D Foundation, based on the Finite Element Method (FEM). To verify if the program was handled correctly, the verification of the software was done through comparative analysis of cases previously studied by other researchers. The program input data and back-analysis of soil geotechnical parameters were subsidized by Standard Penetration Test (SPT), carried out in the field according to the procedures recommended by NBR 6484/2001 and static load tests (PCE), carried out according in NBR 12131/2006. The local subsoil, which was modeled assuming its elastic behavior perfectly plastic, is formed by layers of fine and medium sand, little compact silt, until reaching the impenetrable. The water level was not detected in any of the 13 boring performed. It was observed in the results obtained that the interaction of the pile cap with the soil increased the load capacity and stiffness of the system. The pile cap presented up to 21% contribution in receiving the efforts applied in the foundation. In addition, it has been observed that the load capacity of the piled raft foundation system is not confined to the algebraic sum of the isolated resistances of the pile cap and pile(s). Considering these results, it can be concluded that the methodology of foundation in piled raft is configured as a positive foundation technique for the city of Natal for medium-sized buildings.