基于多介质、多尺度离散元方法的冰载荷数值冰水池

极地船舶与海洋工程结构冰载荷的确定是其结构抗冰设计、冰区安全运行和结构完整性管理的重要研究内容. 当前快速发展的高性能计算技术和多介质、多尺度数值方法为准确、高效地计算结构冰载荷提供了有效的途径, 其中以离散元方法为代表的数值方法取得了出色的研究成果. 为此, 本文针对目前极地船舶与海洋工程结构对冰载荷及力学响应的工程需求, 同时考虑国内外对海冰、工程结构与流体相互耦合的多介质、多尺度数值方法研究现状, 对极地船舶与海洋工程数值冰水池的概念、框架、开发技术以及基于离散元方法的软件实现与工程应用进行了论述. 数值冰水池在船舶与海洋工程结构冰载荷确定方面具有可靠性、经济性、快速性、扩展性和情景化等显著优势. 本文工作借鉴数值水池的研究思路, 以典型船舶和海洋平台结构冰载荷及结构力学响应的离散元计算为例, 探讨了数值冰水池研究的可行性和工程应用前景, 阐述其与理论分析、现场测量和模型试验研究相结合的必要性. 以上研究有益于中国在极地船舶与海洋工程领域形成具有独立知识产权的数值计算分析平台, 对中国极地海洋强国的战略实施具有很好的启发和指导意义. 

NUMERICAL ICE TANK FOR ICE LOADS BASED ON MULTI-MEDIA AND MULTI-SCALE DISCRETE ELEMENT METHOD

The investigation of ice loads on polar ships and offshore engineering structures is very important for anti-ice structure design, safe operation and structural integrity management in ice-covered regions. Recently, the rapid developments on high-performance computing techniques and multi-media, multi-scale numerical methods provide an effective improvement on the determination of ice loads on polar ships and offshore engineering structures. The numerical methods represented by the discrete element method (DEM) achieved excellent contributions on the ice load predictions. Therefore, considering the engineering demands to forecast ice loads and mechanical responses of polar ships and offshore structures, and also based on the present state-of-the-art of the multi-media and multi-scale numerical methods for coupling of sea ice, engineering structures and fluid, the concept, frame and technique of numerical ice tank are discussed based on DEM simulations. The numerical ice tank has significant advantages in reliability, economy, rapidity, expansibility and scenario in determining the ice load on hulls and offshore engineering structures. Based on the concept and experience of numerical tank, this paper illustrates the feasibility and engineering application prospects of numerical ice tank with the DEM simulations on ice loads and structural mechanical responses of typical ship and offshore platform. The computational parameters in DEM simulations were calibrated with the mechanical properties of sea ice obtained with physical experiments. The ice loads on ship hull and jacket platforms simulated with DEM were compared with the model tests and filed measurements. Finally, the interaction between ice cover and structures of model tests in ice tank are repeated numerically with DEM. With the numerical ice tank, ice loads on ships and offshore structures can be simulated with DEM under various ice conditions on different scales. The necessity of combination of theoretical analysis, field measurement and model test with the numerical ice tank is also elaborated. The research above can be aided to develop the numerical software for ice load determination for polar ships and offshore engineering structures, and to promote the implementation of the polar ocean strategy in China.