Análise preliminar do desempenho de fundações do tipo monopile offshore em solos arenosos carbonáticos do litoral cearense através de modelos numéricos

Abstract

The expansion of offshore wind energy represents a strategic alternative for diversifying the Brazilian energy matrix, particularly in view of the high wind potential of the northeastern coastline. However, the implementation of these structures depends on an adequate assessment of the geotechnical behavior of marine soils, especially carbonatic sandy soils present on the Ceará Continental Shelf (CCS), which exhibit mechanical characteristics distinct from those of conventional quartz sands. In this context, this study aims to analyze the performance of offshore monopile foundations installed in carbonatic sandy soils along the Ceará coastline through three-dimensional numerical simulations. Initially, two carbonatic sands representative of the region were considered and characterized based on drained triaxial compression (CD) tests, whose results served as the basis for calibrating the constitutive parameters. The back-analysis of these tests was carried out using the PLAXIS 2D software, adopting the Hardening Soil (HS) constitutive model in order to adequately reproduce the stress-strain behavior of the soils. Subsequently, three-dimensional models were developed in PLAXIS 3D to simulate the soil–structure interaction of different monopile geometric configurations subjected to monotonic loading. The results allowed the evaluation of the influence of soil density state, embedment length, and L/D ratio on the lateral load-displacement behavior of the foundations. Finally, the performance of the monopiles was assessed according to the applicable normative criteria, considering both Serviceability and Ultimate Limit States. The results indicate that the carbonatic sands of the Ceará coastline show potential for the installation of offshore monopile foundations, provided that the geotechnical particularities of these soils are properly considered in the design process.