海冰与直立结构相互作用的离散单元数值模拟

DISCRETE ELEMENT MODELLING OF INTERACTION BETWEEN SEA ICE AND VERTICAL OFFSHORE STRUCTURES

在冰区油气开发中,海冰会导致海洋结构的强烈振动,并对结构累积疲劳损伤、上部油气管线和设备,以及操作人员健康构成很大的威胁。在海冰与直立海洋结构的相互作用中,冰荷载的幅值和频率一直是海冰工程研究的重要内容。该文针对海冰与直立海洋结构作用中的破碎过程,建立了海冰的离散单元模型。它将海冰离散为若干个规则排列且具有粘接-破碎功能的颗粒单元,并通过海冰单轴压缩试验对单元间的粘接强度进行确定;在此基础上对直立海洋平台结构的作用过程进行了数值计算,获得了不同桩径下的冰荷载和结构冰振响应,为冰区平台结构设计和现役海洋结构的疲劳寿命评估提供了参考依据。

In the exploitation of oil and gas in ice-covered regions, sea ice can cause strong vibration of offshore structures, result in accumulated fatigue damage of structures and threat the safety of upper pipelines and facilities and the health of staff. It is important to determine the magnitude and frequency of ice load on offshore structures in sea ice engineering. In this study, a discrete element model was developed to simulate the interaction between sea ice and vertical structures. The sea ice cover was dispersed （DEM） into spherical elements with a bonding-breaking function. The bonding strength between particles was determined through the uniaxial compression test of sea ice. The interaction between ice cover and vertical offshore structures was simulated with DEM, and the ice loads on vertical structure with various pile diameters were obtained. This investigation will benefit the rational design of new offshore structures and the fatigue life estimation of existing structures in ice-covered regions.