Avaliação Através de Métodos Determinísticos e Probabilísticos da Ruptura Geotécnica de Porto em Barcarena/PA

: Several geotechnical accidents recorded in recent years in the country have emphasized the importance of carrying out probabilistic analyzes in order to better understand the risk factors involved in the problems. This way, this work presents a probabilistic analysis of the slope stability of a pier under construction, located in the city of Barcarena / PA , which failed a few months after the constructions of a compacted landfill on soft soil to access it. In order to evaluate que possible causes of the failure, several cenarius were simulated using the software Slope, developed by Roc Science Inc, involving situations of tide fluctuation and fill loading, to calculate the probabilities of failures and their corresponding factors of safety. The deterministic factors of safety were in all situations very close to 1 or less. These results were not able to explain in a reasonable way how could the slope be stable for approximately 5 months. Such explanation was possible only based on the probabilistic analysis and the calculated probability of failure which showed that the most critical situation was in low tide with the fill load completely applied. In this situation the probability of failure was close to 60%, what means that the slope was very likely to fail, but not necessarily the failure would occur. Besides that, it may be concluded that the variation of the tide level, with its 6 hour time period between maximum and minimum levels, induces a process o fatigue within the slope which causes an elevation of the probability of failure along the time.