四筒型基础气浮过程自振特性及运动响应研究

STUDY ON NATURAL VIBRATION CHARACTERISTICS AND MOTION RESPONSE OF FOUR-BUCKET FOUNDATIONS DURING AIR-FLOATING

针对多筒型基础气浮过程中的动力及运动响应问题,设计了筒间距为2.5倍筒直径的四筒型基础,通过比尺为1∶25的物理模型试验并结合数值模拟的方法,对结构在静水中的自振特性和规则波下运动响应的变化规律进行研究。研究结果表明:建立的数值分析模型能够较好地预测结构静水中自振特性以及波浪中运动响应的变化趋势;随着吃水的增加,该四筒型基础的有阻尼摇荡自振周期呈增大的趋势,而附加质量系数和阻尼比呈下降的趋势,结构摇荡运动的附加质量系数取值在1.4~1.7之间变化;吃水的增加能够改善结构的摇荡运动性能,但是增大了结构的垂荡响应以及接近纵摇角最大幅值的周期范围;水越浅,摇荡运动越大。

Aiming at the dynamic and motion characteristics of multi-bucket foundation during air-floating,a four-bucket foundation with a distance between the buckets of 2.5 times diameter is designed.A combination approach of physical model tests with a scale of1:25 and numerical models is adopted to investigate the natural vibration characteristics in still water and motion responses under regular waves.The results show that the natural vibration characteristics in still water and the change trend of motion responses in regular waves can be well predicted by numerical simulations.With the draft increasing,the damped natural vibration period increases,while the added mass coefficient and damping ratio decreases.The added mass coefficient varies between 1.4-1.7.Increasing draft can improve the oscillating motion performance of the structure,but it increases the heaving response and enlarges the periodic range of amplitude close to the maximum amplitude of pitching motion.The shallower the water,the greater the oscillating motion.