Assessment of Inherent Variability from SPT Data and Its Application to Shallow Foundations under Axial Loading

Resumo

This study proposes a practical framework for evaluating the inherent spatial variability of geotechnical parameters based on Standard Penetration Test (SPT) data. The approach includes the implementation and validation of numerical routines for calculating mean, standard deviation, probability distribution fitting, and the scale of fluctuation using vertical SPT profiles. The method is designed to support probabilistic and random field modeling in geotechnical applications. To illustrate the applicability of the developed routines, a case study is presented involving shallow foundations under axial loading. The geotechnical variability inferred from SPT data is incorporated into the bearing capacity assessment using random field theory. This allows for quantifying the influence of spatial variability on design parameters and failure probabilities. The study emphasizes the importance of adequate preprocessing of field data, including trend removal and normalization, and demonstrates how variability metrics—especially the scale of fluctuation—can be effectively integrated into reliability-based design approaches.