Modelos para interação vertical riser-solo para análise global de risers em catenária

Abstract

As subsea production goes deeper, the evaluation of riser loads gets more complex, due to unsolved questions such as representative models to treat its interaction with seabed. The touchdown point (TDP) is a hot spot, where duly assessed loads and curvatures yield more reliable fatigue life predictions. Soil model plays an important role and simplified abstractions of the riser-soil interaction may overestimate the riser curvature at TDP. Different soil models have been proposed over years, many of them based on linear and nonlinear springs, which cannot depict many phenomena in riser-soil interaction. Therefore, more recent researches have focused on p-y curves calibrated by experimental works, from which two families arise: non-degradable and degradable soil model. The former has been applied in commercial softwares, whereas the latter has not. The degradation model accounts for the plastic deformation of soil under cyclic loads, along with other features such as consideration of soil-water mixing, erosion and soil consolidation, which may drive trench formation. By using the global analysis SITUA/Prosim and a routine implementing the degradable soil model, three case studies were run, which showed good agreement with literature and expectations.