Undrained shear strength of Finnish soft clays: A database perspective

The undrained shear strength (su) of clays is a governing parameter in several geotechnical engineering problems. However, su is not a unique parameter; it depends on factors like stress paths, loading rates, soil composition, and stress history. This complexity results in significant uncertainty in su determination, impacting construction and operational safety. Further, the selection of design su from a given test type shall reflect the anticipated field deformation mechanism for a specific structure. To address these uncertainties, global and local databases have emerged as powerful tools. They offer statistical correlations between measured su values and basic clay properties, thus reducing uncertainty. In this study, high-quality data from Southern Finland is compared with extensive databases, resulting in a robust statistical correlation for anisotropic undrained shear strength of Finnish soft clays. The proposed correlations are meant for preliminary analyses, where site-specific data is limited or unavailable. Overall, databases provide invaluable resources to assess local data reliability, reduce bias, and enhance confidence in infrastructure design and construction.