Geotechnical characterization of seabed sediments in Jintang Strait using CPTU and laboratory tests

The characterization of subsurface soils in marine tunnel projects is critical for their safety, design, construction, and maintenance. The cone and piezocone penetration tests (CPT and CPTU) are widely used in-situ tests for soil classification and property determination. However, most CPTU-based correlations were originally developed for onshore deposits, limiting their applicability in offshore environments. This study presents a comprehensive case investigation along the Jintang Strait, where extensive CPTU measurements were combined with laboratory and complementary field tests to assess soil classification methods and establish site-specific correlations. The analysis of the extensive dataset confirms the potential of CPTU for delineating soil stratigraphy and evaluating engineering properties, while also revealing the limitations of commonly adopted empirical correlations and coefficients. Meanwhile, CPTU soundings arranged along the strait cross section provide valuable insights into the spatial distribution of sediments. the Site-specific correlations between CPTU and soil properties, with particular emphasis on strength and small-to-large deformation characteristics, are established and verified against existing recommendations. These findings emphasize the importance of site-specific calibration and provide practical guidance for CPTU-based geotechnical characterization in marine environments.