Integrated seismic–CPTu analysis for engineering geological stratification of Quaternary deposits off Lianjiang, Fujian

As offshore wind power development has expanded towards deeper and more distant waters, accurately understanding the geotechnical characteristics of thick Quaternary unconsolidated sediments has become a major challenge in engineering geological investigations. Reliable stratigraphic classification of such deposits is essential for ensuring safe and effective foundation design, but traditional drilling-based methods face significant limitations in complex offshore environments. To address this issue, high-resolution seismic profiles are integrated with piezocone penetration test (CPTu) data from an offshore wind farm off Lianjiang, Fujian in this study. Within the range of penetration depth common to both methods, Quaternary deposits were classified into seven seismic units and twelve CPTu units. The correspondence between the units defined by these two methods was analysed, and sedimentary facies and systems tracts were interpreted on the basis of the fundamental principles of sedimentology and sequence stratigraphy. The results demonstrated that the integration of seismic and CPTu data effectively combines the strengths of both techniques, thereby providing reliable and efficient engineering geological stratification of late Quaternary deposits offshore Fujian. This integrated approach facilitates both generalised and detailed stratigraphic interpretations, accounting for not only the engineering properties of the deposits but also their geological age and genetic origin.