Design optimization method of jacket foundations in shallow-overburden regions: from rock-socketed to non-rock-socketed

Thin soil overburden and shallow bedrock in offshore areas of southeastern China often necessitate rock-socketed piles, which increase construction complexity and cost. This study proposes a jacket-geometry optimization strategy to enable non-rock-socketed piles. A finite-element model was used to assess pile bearing capacity, natural frequencies, ultimate strength, and fatigue performance. At the initial base width Lbase of 30 m, the rock-socketed jacket satisfied all design criteria, whereas removing the socketed pile segments caused the non-rock-socketed scheme to fail the frequency and pile-capacity requirements. The jacket base width was, therefore, increased parametrically. Increasing Lbase improved the natural frequency and reduced pile compressive and uplift loads but also increased fatigue damage and structural mass. For the investigated site, Lbase=33 m was the only evaluated non-rock-socketed configuration satisfying all criteria. The results provide practical guidance and decision support for offshore wind foundation design in shallow overburden regions.