Caracterização geomecânica de um solo residual compactado de gabro no Nordeste Brasileiro

Abstract

The study aims to assess, in an integrated manner, the geotechnical aspects of a gabbroic residual soil located in Northeastern Brazil, focusing on its physical, chemical, hydraulic, and mechanical properties. The research covers the gabbroic body situated in the São João do Sabugi Intrusive Suite, where 20 different points were evaluated, totaling 21 collections with varied characteristics. The study area corresponds to approximately 12.8% of the municipality of Jardim de Angicos, in the state of Rio Grande do Norte. Tests were conducted to determine the physical, chemical, hydraulic, and mechanical properties of the soil. The observed physical characteristics varied widely, making it impossible to establish a generalized pattern for the samples, which ranged from low-cohesion soils to high-plasticity clays. The grain size analysis also suggests potential translocation of clay minerals. Chemical analyses, performed using XRD, XRF, and SEM, indicated the presence of expansive clay minerals, such as montmorillonite, in addition to the formation of chlorite, highlighting an advanced and gradual degree of weathering in the region. Regarding hydraulic properties, the samples exhibited low permeability, on the order of 10⁻⁷ cm/s. In terms of mechanical properties, triaxial compression tests revealed ductile materials, with no characteristic strength peaks and continuous hardening behavior throughout the test. The consolidation test showed expansive characteristics of approximately 3.96%. The gabbroic residual soil in the studied area presents significant variation in its physical and mechanical properties, notably the presence of expansive clay minerals and low permeability. These factors suggest that the use of this soil in geotechnical works must be carefully planned, considering its variability, expansive potential, and ductile behavior. The low permeability also indicates that the soil may be suitable for projects requiring infiltration control, such as earth dams. However, the diversity of observed characteristics reinforces the need for further studies, especially in other areas with gabbroic bodies, to evaluate geotechnical variability in different contexts. This study expands the understanding of gabbroic soils and provides important insights for their use in geotechnical works, contributing to the understanding and planning of applications in conditions similar to those found in Northeastern Brazil.