Numerical investigation of the seismic bearing capacity of offshore skirted foundations installed in sand using finite element limit analysis

Abstract. Within the scope of offshore infrastructure, skirted foundations have emerged as an innovative technical solution, offering significant advantages in optimizing the bearing capacity of structures. These foundations not only enhance resistance to vertical loading but also provide more effective control over settlements, ensuring greater stability and durability of marine structures. This study leverages Finite Element Limit Analysis (FELA) to conduct an in-depth assessment of the bearing capacity of a strip skirted foundation installed in sandy soil, subjected to seismic conditions. By employing a pseudo-static approach, the analysis meticulously examines several critical parameters, such as the embedment depth of the foundation (Ds), the internal friction angle of the sand (φ), and the horizontal seismic coefficient (kh). These variables are rigorously analyzed to understand their impact on the overall behavior of the foundation under dynamic loads. The results, derived from detailed numerical analyses, highlight the effectiveness and resilience of a strip skirted foundation in sandy soil, particularly under seismic loading. The effects of seismic forces have been precisely quantified using the Bearing Capacity Ratio (BCR), which shows a significant improvement when vertical skirts are incorporated into the foundation design. Additionally, the study reveals that variations in the horizontal seismic coefficient (kh) and the embedment depth (Ds) significantly influence the BCR. To provide a broader context, these results have been compared with previous studies available in the scientific literature, thereby validating the findings and contributing to the existing body of knowledge on the subject.