Análise da confiabilidade de projeto de fundação por estaca escavada, a partir de metodologia semiempírica aplicada em caso real de obra

Abstract

The safety assurance in Civil Engineering projects is not based on scenarios where the risk of ruin is non-existent. Even the Brazilian Association of Technical Standards (ABNT) advocating the use of safety coefficients, several relevant aspects and uncertainties are not considered, that have a fundamental influence on the reliability of a foundation project, such as soil heterogeneity. Cintra and Aoki (2010) advocate the use of a probabilistic approach, in which the ruin probability inherent to each foundation project is determined, and evaluated to what extent the risks are considered acceptable for that scenario. In this perspective, the present work makes a reliability analysis of the foundation project executed in Block 31 of the work of the Convergence Center of the Federal University of Rio de Janeiro, in Cidade Universitária, located on Ilha do Fundão, north zone of the city of Rio de January. The analyzed design has 50 stakes of the continuous propeller type, with diameters of 60 and 80 centimeters, and three probes of simple of recognition, from which the capacities of the loads of the piles were estimated, using semiempirical methodology. Through the concept of probability of ruin, the reliability of that foundation project was evaluated, comparing three design methodologies for admissible loads proposed by Cintra and Aoki (2010), and analyzed the efficiency of safety factors in ensuring that risks are in an acceptable range. The results of the probabilistic approach indicate Methodology 1 as the most appropriate to the analyzed project, which evaluates the catalog load of the stake to be dimensioned. In addition, the results allow to conclude that semiempirical methodologies for the determination of the load capacity are sensitive to the variability of the subsurface layers. Even with the adoption of security and correction coefficients, such practices are insufficient to ensure a probability of acceptable ruin, and hence the safety and economic viability of a project.