Abstract Glacial ice features in the northern and central Barents Sea may threaten ships and offshore structures. Particularly, small glacial ice features, which are difficult to detect and manage by concurrent technologies, are of concern. Additionally, small glacial ice features are more susceptible to wave-driven oscillatory motions, which increases their pre-impact kinetic energy and may damage ships and offshore structures. This paper is part of three related papers. An initial paper (Monteban et al., 2020) studied glacial ice features’ drift, size distribution and encounter frequencies with an offshore structure in the Barents Sea. The following two papers (Paper I and Paper II) further performed glacial ice impact studies, including impact motion analysis (Paper I) and structural damage assessment (Paper II). This paper (Paper I) studies the wave-driven motion of small glacial ice features and their subsequent impact with a given offshore structure. The aim here is to develop a numerical model that is capable of efficiently calculating the relative motion between the ice feature and structure and to sample a sufficient amount of impact events from which statistical information can be obtained. The statistical information entails the distributions of the impact location and associated impact velocities. Given the distributions of the impact velocities at different locations, we can quantify the kinetic energy for related impact scenarios for a further structural damage assessment in Paper II (Yu et al., 2020). In Paper I, a numerical model that separately calculates the wave-driven oscillatory motion and the mean drift motion of small glacial ice features is proposed, implemented and validated. Practical and fit-for-purpose hydrodynamic simplifications are made to simulate and sample sufficient impact events. The numerical model has been favourably validated against existing numerical results and experimental data. A case study is presented where a 10 m wide glacial ice feature is drifting under the influence of surface waves towards an offshore structure. The case study shows that if an impact happens, the overall impact location and impact velocity can be best fitted by the Normal and Weibull distributions, respectively. Additionally, the impact velocity increases with impact height. Moreover, the impact velocity increases and the impact range is more dispersed in a higher sea state. It is also important to notice that the approaches and methods proposed in this paper adhere to and reflect the general requirements stated in ISO19906 (2019) and NORSOK N-003 (2017) for estimating the design kinetic energy for glacial ice impacts.

中文翻译：

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冰川冰影响：第一部分：波浪驱动的运动和小的冰川冰特征影响

摘要 巴伦支海北部和中部的冰川冰特征可能威胁到船舶和海上结构。特别是，难以通过并发技术检测和管理的小型冰川冰特征值得关注。此外，小的冰川冰特征更容易受到波浪驱动的振荡运动的影响，这会增加它们的冲击前动能，并可能损坏船舶和海上结构。本文是三篇相关论文的一部分。最初的一篇论文（Monteban 等人，2020 年）研究了冰川冰特征的漂移、尺寸分布和与巴伦支海近海结构的相遇频率。以下两篇论文（论文一和论文二）进一步进行了冰川冰撞击研究，包括撞击运动分析（论文一）和结构损伤评估（论文二）。这篇论文（论文 I）研究了小型冰川冰特征的波浪驱动运动及其对给定离岸结构的后续影响。这里的目的是开发一个数值模型，该模型能够有效地计算冰特征和结构之间的相对运动，并采样足够数量的撞击事件，从中可以获得统计信息。统计信息包含撞击位置和相关撞击速度的分布。鉴于不同位置的冲击速度分布，我们可以量化相关冲击场景的动能，以便在论文 II（Yu 等人，2020）中进行进一步的结构损坏评估。在论文 I 中，提出、实施和验证了一个分别计算波浪驱动的振荡运动和小冰川冰特征的平均漂移运动的数值模型。进行了实用且适合目的的流体动力学简化，以模拟和采样足够的冲击事件。该数值模型已经根据现有的数值结果和实验数据进行了有利的验证。介绍了一个案例研究，其中 10 m 宽的冰川冰特征在表面波的影响下向近海结构漂移。案例研究表明，如果发生撞击，整体撞击位置和撞击速度可以分别通过正态分布和威布尔分布进行最佳拟合。此外，冲击速度随冲击高度而增加。而且，冲击速度增加，冲击范围在更高的海况下更加分散。同样重要的是要注意，本文中提出的方法和方法遵循并反映了 ISO19906（2019）和 NORSOK N-003（2017）中规定的用于估算冰川冰冲击设计动能的一般要求。