Caracterização geotécnica de areias carbonáticas do litoral cearense por meio de ensaios de piezocone

Abstract

This study presents a preliminary geotechnical characterization of the subsoil in two coastal areas of Ceará, characterized by the presence of calcareous sands, a material still scarcely studied within the Brazilian geotechnical context and whose behavior may differ significantly from that of quartz sands. Amid the advancement of renewable energy and the planned expansion of offshore wind power generation in northeastern Brazil, understanding the behavior of these deposits becomes essential to support energy infrastructure projects. The research employed piezocone penetration tests (CPTu) to characterize stratigraphy and estimate representative parameters of soil mechanical behavior, including strength and deformability, as well as to assess susceptibility of liquefaction, evaluate the applicability of traditional correlations in calcareous materials, and propose correlations for the studied sands. The analyses also included comparisons with SPT, seismic tests (SDMT), and PMT results, allowing for the examination of convergence among estimates and consistency between different in situ testing methods. The results demonstrated that stratigraphic profiles were consistently identified in both investigated subsoils, revealing predominantly sandy profiles with interbedded fine layers and local variations in relative density. The estimation of geotechnical parameters showed internal consistency among CPTu-based correlations; however, significant dispersion was observed when compared to other tests, with insufficient convergence to validate the applied correlations. Regarding liquefaction susceptibility, Moitas exhibited a higher liquefaction potential, whereas Requenguela showed lower susceptibility. Concerning the proposed correlations, the results indicated limited overall performance, highlighting the constraints of the available data set and pointing to the need for its expansion. Thus, the findings indicate that CPTu testing was suitable for preliminary characterization; however, it was not possible to fully assess the validity of classical correlations for the studied calcareous sands. Therefore, additional investigations are required to achieve a more comprehensive understanding of the material, thereby supporting future offshore wind projects along the coast of Ceará.