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中文核心期刊

水位变化对正倒锥体冰载荷影响的离散元分析

INFLUENCE OF WATER LEVEL ON ICE LOAD ON UPWARD-DOWNWARD CONICAL STRUCTURE BASED ON DEM ANALYSIS

  • 摘要: 在海冰与锥体海洋结构的相互作用过程中,潮汐水位变化时海冰作用于锥体结构的位置改变对冰载荷具有显著影响.本文采用具有粘结破碎功能的离散元方法计算海冰与锥体作用的破坏过程.同时考虑海冰上下表面温度差异对海冰强度的影响,将离散元计算冰载荷及海冰破坏模式与渤海现场实测数据进行对比验证.离散元结果表明,海冰与正锥和倒锥碰撞时均发生弯曲破坏,且冰载荷均随水线处锥径的增大而增大.在水线处锥径相同的情况下,正锥冰载荷大于倒锥冰载荷,而正锥作用下海冰的断裂长度则较小.基于离散元计算结果和渤海现场观测资料分析了海冰与正锥、倒锥作用时冰载荷和断裂长度差异的主要原因.海冰与正倒锥交界线处作用时,一般发生弯曲破坏.当冰层中心高度与正倒锥交界线的高度相同时,海冰才会发生局部挤压破碎,但冰荷载并没有明显升高.由此可见,倒锥体结构可有效降低冰载荷从而具有较好的抗冰性能.以上研究表明离散元方法可确定海冰与锥体结构作用时的海冰破碎规律和冰载荷特性,为海洋工程结构的抗冰设计提供参考依据.

     

    Abstract: During the interaction between the sea ice and the conical structure, the ice load is affected by the position of the sea ice acting on the conical structure when the tidal water level changes. In this study, the discrete element method (DEM) with the bond and failure model is adopted to simulate the breaking process of sea ice acting on the conical structure. In DEM simulations, the influence of the ice temperature at the top and bottom surface of ice cover on the ice strength is considered. The ice load and the failure mode of ice cover simulated with DEM are compared well with the field data in the Bohai Sea. The DEM results indicate that the bending failure of ice cover occurs when it acts on the upward or downward cone. For both of the upward and downward cone, the ice load increases with the increase of the cone diameter at water level, but the ice load on upward cone is larger than that of downward cone. Meanwhile, the breaking length of ice cover on upward cone is smaller than that on the downward cone. The reasons for the difference of ice load and breaking length between upward cone and downward cone are analyzed based on the DEM results and the filed observation in the Bohai Sea. Moreover, when the sea ice interacts with the interface of upward and downward cone, bending damage generally occurs. When the height of the ice cover center is very close to the height of the upward-downward cone interface, the local ice crushing occurs, but the ice load does not increase significantly. Therefore, the downward conical structure has better performance of ice resistance with effectively reducing the ice load. The DEM can be adopted to understand the mechanism of ice cover failure process, and provide reference for the anti-ice design of structures in cold ocean engineering.

     

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