锥体海洋平台结构冰荷载的离散单元分析

Analysis of ice load on conical structure with discrete element model

在冰区油气开发中,锥体结构可以有效降低冰力,避免强烈的冰激振动,是目前渤海油气平台的主要结构形式。为研究海冰与锥体结构的相互作用过程,文章建立了适用于模拟海冰破碎特性的离散单元模型。该模型将海冰离散为若干个具有粘接-破碎功能的颗粒单元,并通过海冰弯曲试验确定了单元间的粘接强度;然后对海冰与锥体结构的作用过程进行了数值计算,获得了相应的动冰荷载及冰振响应;在此基础上讨论了不同锥角影响下冰荷载及结构振动响应的变化规律。结果表明,水平方向冰荷载及结构冰振响应随锥角的增加明显增加,而竖直方向冰荷载则显著降低。该离散单元模型还可进一步应用于不同类型抗冰结构的冰荷载分析,有助于解决冰区结构物的抗冰结构设计和冰致疲劳分析。

In oil/gas exploitations of ice covered cold regions, the conical structure can reduce ice force and avoid intense structure vibration. It is applied most widely in the Bohai Sea recently. In order to investigate the interaction between ice cover and conical structure, a discrete element method is established to mod-el the sea ice breaking characteristics. The ice cover is dispersed into a series of bonded spherical elements.The bonding strength among ice particles is determined with the flexural test of sea ice. The interaction between the ice cover and the conical structure is simulated with the discrete element method to determine the dynamic ice load and structure vibration. Moreover, the influence of conical angle is discussed based on the simulated results. The ice load and the ice-induced structure response in horizontal direction increase obviously with the increase of cone angle, while the ice load in vertical direction decreases significantly.This discrete element method can also be applied to simulate ice loads of other type structures, and to be aided for the design of ice-resistance structure and the analysis of ice induced structure fatigue.