Currently, monopiles are the industry's first choice to support offshore wind turbines (OWTs) due to the complexities associated with fabrication, transportation and installation of various foundation solutions. These are, however, considered suitable for water depths up to ∼30–35 m, beyond which they become massive and complex to handle. Increasing the application range of monopiles without making them too large by adopting some suitable means may significantly impact the rapid growth of OWTs at intermediate water depths (∼50 m), where existing solutions such as jackets or concrete gravity foundations involve large capital expenditure. In this work, a novel approach of utilising pre-tensioned tethers along with a 6.0 m wide monopile was explored for 50 m water depth. Under an extreme load case, the stress ratio was found to be reduced from 1.17 to 0.44 when pre-tensioned tethers are used. Similarly, it was found that by adjusting parameters associated with the proposed concept, fatigue damage can be brought down from a very high value to 0.63 or less. The results thus show that the proposed approach can open new avenues to bring competitiveness to the cost of offshore wind energy at intermediate water depths.

中文翻译：

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用于较深水域海上风力涡轮机的预张紧系绳单桩研究

目前，由于各种基础解决方案的制造、运输和安装的复杂性，单桩是业界支持海上风力涡轮机 (OWT) 的首选。然而，这些被认为适用于深达〜30-35 m的水深，超过这个深度它们就会变得巨大且难以处理。通过采用一些合适的方法来增加单桩的应用范围而不使其太大，可能会显着影响单桩在中等水深（∼50 m）的快速增长，其中现有的解决方案（例如导管架或混凝土重力基础）涉及大量资本支出。在这项工作中，探索了一种利用预张紧系绳和 6.0 m 宽单桩的新方法，用于 50 m 水深。在极端负载情况下，使用预张紧系绳时，应力比从 1.17 降至 0.44。同样，我们发现，通过调整与所提出的概念相关的参数，疲劳损伤可以从非常高的值降低到 0.63 或更小。结果表明，所提出的方法可以开辟新的途径，为中等水深的海上风能成本带来竞争力。