Utilização do pressiômetro de Ménard no estudo das areias carbonáticas do litoral Cearense

Abstract

This research investigates the stress-strain behavior of carbonate sands subjected to the Ménard pressuremeter test, aiming to determine representative geotechnical parameters for these atypical soils. The research was developed on marine sands with different carbonate contents, typical of coastal environments in Northeast Brazil, whose structure and cementation influence the mechanical response of the soil. The study is situated within the context of the expansion of offshore wind energy in the country, seeking to provide technical support for the safe and economical design of foundations on carbonate sandy soils. Ménard pressuremeter tests were carried out on the beaches of Moitas, in Amontada/CE, and on the beaches of Caiçara, Redonda and Retiro Grande, in Icapuí/CE. These tests allowed for the determination of deformability parameters (EM, E, G) and resistance parameters (σh0, Pf, Pl e φ’). The variation of these parameters with depth and carbonate content in the samples was analyzed to understand a possible influence of mineralogical composition on the stress-strain response of the soils. The parameters obtained were applied to estimate the bearing capacity and settlements of an offshore gravity wind turbine foundation, based on established analytical methodologies and comparisons with predictions derived from SPT soundings. The results preliminarily indicated that increasing the carbonate content tends to increase the initial stiffness and ultimate strength, reflecting in higher values of pressuremeter modulus and ultimate pressure. The bearing capacity predictions based on the pressuremeter test were, on average, lower than those obtained by SPT, highlighting the obtaining of more conservative predictions when using PMT tests on the investigated carbonate sands. It is concluded that the Ménard Pressuremeter is an effective tool in evaluating the deformability and strength of carbonate sands, especially for the design of offshore gravity foundations. Given the specific conditions of the region studied, this type of foundation proves to be technically viable for the installation of wind turbines. The study not only expands knowledge about the behavior of these soils, but also confirms the relevance of disseminating pressuremeter testing in regional and national geotechnical scenarios.