哑铃型跨海桥梁围堰不规则波浪力试验研究

Experimental study of irregular wave force on dumbbell-shaped cofferdam for sea-crossing bridge

在跨海桥梁施工过程中,波浪力是作用在跨海桥梁施工期围堰的主要控制荷载,准确预测围堰波浪力将直接决定其施工安全。实际海浪是长短、高低不一的不规则波浪,对跨海桥梁围堰的波浪力也呈随机性变化。基于物理模型试验,系统测试不同结构吃水深度、有效波周期、有效波高及波浪入射角对哑铃型围堰不规则顺波向波浪力、横波向波浪力及垂向波浪力的影响,并与“单一最大波法”的规则波浪力进行对比。研究结果表明:与《港口与航道水文规范》中按H1%和平均周期的“单一最大波法”获得的规则波浪力相比,不规则波浪力普遍偏大,尤其波浪斜向入射时横波向不规则波浪力更不利。从波浪力功率谱图分析发现,随着入射角增加,顺波向波浪力高频成分的贡献增大,而垂向波浪力谱变化很小,二者谱峰频率均和入射波谱峰频率保持一致。

During the construction of sea-crossing bridges,wave force is the main controlling load acting on the bridge cofferdam.Accurate prediction of the wave force of bridge cofferdam directly determines the construction safety.The actual sea surface is obviously irregular wave with different lengths and heights,and the wave force on the bridge cofferdam also changes randomly.Based on the physical model test,influences of different structural draught,effective wave period,effective wave height and wave incident angles on the longitudinal,transverse and vertical wave forces for the cofferdam were tested.Irregular wave forces were compared with regular ones obtained from the“single maximum wave method”.The results show that:as compared with regular wave force obtained from the“single maximum wave method”with H1%and average wave period in the“Port and Channel Hydrological Code”,irregular wave force is generally of greater magnitude,especially in the transverse direction by oblique waves.According to wave force power spectrum,with the increase of incident angle,the contribution of high-frequency wave components increases for the longitudinal wave force,while few changes can be found from the shape of vertical wave force spectrum.The peak frequencies of the longitudinal and vertical wave forces are consistent with that of the incident wave spectrum.