Application of Ordinary Kriging for Modeling the Shallow Marine Sediment Distribution in Offshore Wind Foundation Design: A Case Study in the South Vietnam Continental Shelf

Abstract

This study applies geostatistical modelling to characterize the spatial variability of shallow marine sediments for offshore wind turbine foundation design. The primary objective is to estimate near-surface sediment property variations in areas with limited site investigation data, thereby supporting risk-informed engineering and foundation optimization. A case study was conducted in the MC area, offshore Vietnam, using cone penetration test (CPTu) and borehole data to derive sediment parameters—cone resistance (qc), sleeve friction (fs), and pore pressure (u2)—and classify soil type through the soil behaviour type index (Ic). Ordinary Kriging interpolation and variogram modelling were employed to quantify spatial correlation and anisotropy of key parameters. Results reveal four principal soil zones: soft clay, silty clay, silty sand, and dense sand, exhibiting clear vertical and lateral transitions controlled by depositional and post-depositional processes. qc values increase from <2 MPa near the seabed to >35 MPa below 50 m, while u2 ranges from -0.6 to +0.5 bar, reflecting progressive sediment compaction and drainage evolution. Variogram analysis produced spherical models with horizontal ranges of 450–550 m and anisotropy ratios near 2.0, indicating strong east–west continuity aligned with paleo-channel trends. Kriged maps highlight weaker, compressible zones in depositional basins and stiffer, well-drained sands along channelized structures. These findings demonstrate that integrating CPTu-based parameters with Kriging provides a robust, data-efficient framework for early-stage geotechnical assessment in offshore wind developments. The spatial model enhances understanding of ground variability, improves foundation selection, and reduces design uncertainty where site investigation coverage is sparse.