Around 80% of offshore wind turbines (OWTs) are founded on deep seabeds using large-diameter monopiles that reach a length up to 60 m. In a race to seek cost-effectiveness, tripod foundations made with suction caissons represent a promising solution. The deformation mechanism induced by cyclic lateral loading on the tripod bucket embedded in sand reveals recovery of dynamic stiffness with the number of cycles that influences the subsequent dynamic response of the structure–foundation complex. This ‘self-healing’ and the coupled increase of settlement rate are caused by uneven change in soil fabric and density among the buckets. However, the capability of the recently developed constitutive models to predict this effect is limited. To address this issue, a series of centrifuge tests are herein back-analysed with a three-dimensional finite-element model. The implicit approach has been implemented using an advanced rate-independent hypoplastic model coupled with the conventional intergranular strain theory. The model captures the magnitude of the peak and residual cumulative rotation. The results indicate that the push–pull mechanism turns into a horizontal translation, with active wedges formed behind the pulled bucket. After about 100 cycles, due to significant redistribution of mean stresses, wedges are formed around both pushed and pulled buckets.

中文翻译：

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海上风力涡轮机三脚架基础的性能：数值研究

大约 80% 的海上风力涡轮机 (OWT) 建立在深海床上，使用长度可达 60 m 的大直径单桩。在追求成本效益的竞赛中，用吸力沉箱制成的三脚架地基代表了一种有前途的解决方案。由嵌入沙子的三脚架铲斗上的循环横向载荷引起的变形机制揭示了动态刚度的恢复，循环次​​数影响了结构-基础复合体的后续动态响应。这种“自我修复”和沉降率的耦合增加是由桶间土壤结构和密度的不均匀变化引起的。然而，最近开发的本构模型预测这种效应的能力是有限的。为了解决这个问题，一系列离心机试验在这里用三维有限元模型进行反分析。隐式方法已使用先进的与速率无关的发育不良模型与传统的晶间应变理论相结合来实施。该模型捕获峰值和剩余累积旋转的幅度。结果表明，推拉机构转变为水平平移，在拉斗后面形成了主动楔。大约 100 次循环后，由于平均应力的显着重新分布，在推动和拉动的铲斗周围都会形成楔形。结果表明，推拉机构转变为水平平移，在拉斗后面形成了主动楔。大约 100 次循环后，由于平均应力的显着重新分布，在推动和拉动的铲斗周围都会形成楔形。结果表明，推拉机构转变为水平平移，在拉斗后面形成了主动楔。大约 100 次循环后，由于平均应力的显着重新分布，在推动和拉动的铲斗周围都会形成楔形。