Análise comparativa de correlações empíricas aplicadas à estimativa da resistência ao cisalhamento a partir de ensaios CPTu

Abstract

Geotechnical investigation is a fundamental step in the design and safety assessment of engineering structures due to the inherent variability of the physical and mechanical properties of soils. In this context, the piezocone penetration test (CPTu) has become an important in situ investigation tool because it provides continuous geotechnical data throughout the soil profile. One of its main applications is the estimation of soil shear strength through empirical correlations. However, the literature presents numerous correlations developed from different experimental databases, geological settings, and mathematical formulations, which may lead to different estimates for the same soil. Therefore, this study aims to perform a comparative analysis of empirical correlations used to estimate shear strength from CPTu data, considering sandy and clayey soils under drained and undrained conditions. The study was based on CPTu data obtained from foundation soils underlying bauxite tailings storage facilities. Initially, the normalized CPTu parameters were determined to classify the soils according to the methodology proposed by Robertson (2016). Subsequently, empirical correlations compatible with the soil type and drainage conditions were applied to estimate shear strength. The results were compared using elevation-based profiles and box plots. The findings indicate that the agreement among the empirical correlations depends on the geotechnical behavior of the material, the drainage conditions, and the parameters incorporated into their formulations. Furthermore, no single correlation proved to be universally superior. Instead, the selection of an appropriate correlation should consider the characteristics of the deposit, the objectives of the analysis, and, whenever possible, validation against laboratory test results.