The PISA design model is a procedure for the analysis of monopile foundations for offshore wind turbine applications. This design model has been previously calibrated for homogeneous soils; this paper extends the modelling approach to the analysis of monopiles installed at sites where the soil profile is layered. The paper describes a computational study on monopiles embedded in layered soil configurations comprising selected combinations of soft and stiff clay and sand at a range of relative densities. The study comprises (a) analyses of monopile behaviour using detailed three-dimensional (3D) finite-element analysis, and (b) calculations employing the PISA design model. Results from the 3D analyses are used to explore the various influences that soil layering has on the performance of the monopile. The fidelity of the PISA design model is assessed by comparisons with data obtained from equivalent 3D finite-element analyses, demonstrating a good agreement in most cases. This comparative study demonstrates that the PISA design model can be applied successfully to layered soil configurations, except in certain cases involving combinations of very soft clay and very dense sand.

中文翻译：

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PISA设计模型在层状土壤中单桩中的应用

PISA设计模型是用于分析海上风力涡轮机应用的单桩基础的程序。该设计模型先前已针对均质土壤进行过校准；本文将建模方法扩展到对土壤剖面分层位置安装的单桩进行分析。这篇论文描述了关于埋在分层土壤构造中的单桩的计算研究，包括在一定的相对密度范围内软，硬粘土和沙子的选定组合。该研究包括（a）使用详细的三维（3D）有限元分析对单桩行为进行分析，以及（b）的计算采用PISA设计模型。3D分析的结果用于探索土壤分层对单体桩性能的各种影响。通过与从等效3D有限元分析获得的数据进行比较，可以评估PISA设计模型的保真度，这在大多数情况下都表明了很好的一致性。这项比较研究表明，PISA设计模型可以成功地应用于分层土壤构造，除非在某些情况下涉及非常软的粘土和非常稠密的沙子的组合。