Análises de resposta sísmica e estabilidade de taludes no planejamento e projeto de estruturas submarinas

Abstract

The assessment of local seismic effects in deep water areas of oil production development represents an important step in proposing strategies to mitigate geological hazards. Among other factors that affect the ground motion in a specific site, deep soil deposits and topographic irregularities have the potential to modify the motion on the surface. Based on the results of numerical simulations validated by centrifuge tests, the influence of the combined effects of stratigraphy and topography on the ground motion amplification was evaluated. In addition, the strength and stability conditions of an area selected as of interest on the continental margin of southeastern Brazil were evaluated considering the soil amplification. The site response analyzes were combined in a Geographic Information System to estimate the landslide susceptibility. A better understanding of the physical phenomena that govern site effects in complex morphological situations was obtained, quantifying such effects from a low acceleration amplitude earthquake. It was found that site effects are not only related to the geomorphological complexity, but also to local stratification. The slope stability mapping can be used to optimize the positioning of subsea production and mooring systems, in addition to pipeline routes, to avoid areas most susceptible to failure where possible and assist in the design of structures based on a better understanding of potential hazards. This is important in rugged relief areas, notably with the presence of canyons.