Wave Flume Test and Simplified Algorithm for Freak Wave Forces on a Dumbbell-Shaped Bridge Structure
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摘要:
为研究畸形波浪参数对新型哑铃型桥梁结构波浪力的影响,开展一系列波流水槽模型试验. 首先,分析谱峰频率、频率范围及聚焦位置对哑铃型桥梁结构周围的波面时程图及波峰的影响;其次,阐明上述波浪参数对结构畸形波浪力时程图及波浪力峰值的影响规律;最后,基于经典绕射理论,提出适用于新型哑铃型桥梁结构畸形波浪力谱的简化计算方法. 研究结果表明:谱峰频率、聚焦位置及频率范围对结构周围的波面位移影响均较小,差异均小于3%. 谱峰频率和聚焦位置对哑铃型桥梁结构畸形波浪力有较大影响,当谱峰频率从0.6 Hz增加到1.1 Hz时,顺波向波浪力呈先增后减的变化趋势,变化幅度最高达11.0%,垂向浮托力则下降了57.0%;当频率范围从0.5 Hz增加到0.8 Hz时,顺波向波浪力下降了2.1%,垂向浮托力增大了5.9%;当聚焦位置从结构物的迎浪侧移动到背浪侧时,引起的结构顺波向波浪力变化幅度小于5%,垂向浮托力变化幅度小于3%. 经过试验数据和理论分析结果的对比表明,基于绕射理论提出的简化算法可有效计算畸形波作用下哑铃型桥梁结构的波浪力谱模型.
Abstract:In order to study the effects of freak wave parameters on the wave force of a new dumbbell-shaped bridge structure, a series of wave flume model tests were conducted. Firstly, the influences of peak frequency, frequency bandwidth and focusing position on wave elevation time history and wave crest around the dumbbell-shaped bridge were analyzed. And the influences of the wave parameters mentioned above on the freak wave force time history and the statistical peak value were investigated. Finally, based on the classical diffraction theory, a simplified calculation method for the freak wave force spectrum on the new dumbbell-shaped bridge structure was proposed. The results show that the peak frequency, focusing positions and frequency bandwidth have little influence on the wave elevation around the dumbbell-shaped bridge structure with a small difference of less than 3%. The peak frequency and focusing positions have great influence on the freak wave force of dumbbell-shaped bridge structure. When the peak frequency increases from 0.6 Hz to 1.1 Hz, the horizontal wave force increases first and then decreases with a maximum range of 11.0%, while the vertical wave force decreases by 57.0%. When the frequency bandwidth increases from 0.5 Hz to 0.8 Hz, the horizontal wave force decreases by 2.1% and the vertical wave force increases by 5.9%. When the focusing position moves from the surge side of the structure to the back/opposite side, the change amplitude of horizontal wave force is less than 5%, and that of vertical wave force is less than 3%. The comparison of experimental data and theoretical analysis proves that the simplified algorithm based on the diffraction theory can effectively estimate the wave force spectrum of dumbbell-shaped bridge structure under freak waves.
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Key words:
- dumbbell-shaped bridge structure /
- freak waves /
- wave forces /
- wave flume tests /
- diffraction theory
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表 1 试验工况
Table 1. Test conditions
工况 Amax/m Δf/Hz fp/Hz λ/m 1 0.04 0.5~1.2 0.8 28.5 2 0.06 0.5~1.2 0.8 28.5 3 0.08 0.5~1.2 0.8 28.5 4 0.10 0.5~1.2 0.8 28.5 5 0.06 0.6~1.1 0.8 28.5 6 0.06 0.6~1.2 0.8 28.5 7 0.06 0.5~1.3 0.8 28.5 8 0.06 0.5~1.2 0.6 28.5 9 0.06 0.5~1.2 0.7 28.5 10 0.06 0.5~1.2 0.9 28.5 11 0.06 0.5~1.2 1.0 28.5 12 0.06 0.5~1.2 1.1 28.5 13 0.06 0.5~1.2 0.8 28.2 14 0.06 0.5~1.2 0.8 28.8 15 0.08 0.5~1.2 0.8 28.2 16 0.08 0.5~1.2 0.8 28.8 17 0.10 0.5~1.2 0.8 28.2 18 0.10 0.5~1.2 0.8 28.8 -
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