红树林防护溃坝态海啸波冲击集装箱消能试验研究

Experimental study on energy dissipation of container impacted by dam-break-like tsunami flow under mangrove protection

近年来海啸灾害频繁发生,对海工建筑物造成巨大损失。在以往的海啸事件中,红树林对海啸具有一定的消减作用。基于溃坝原理生成海啸波,进而研究红树林对海啸波消减作用及红树林防护下的海啸冲击集装箱的变迁表征。对闸门处溃坝研究结果表明,溃坝过程包含突然下降、相对稳定、缓慢下降三个阶段,且蓄能水位越高溃坝发生得越剧烈。海啸波冲击搬运集装箱可分为初始冲击、加速、匀速三个阶段,其动力成因包含了冲击力和浮力。红树林消减海啸波的流态表明尾涡重叠产生的紊动水流是消能的主因,合理密植、对称排布、交错排布有利于海啸波能的消减。此外,三角形交错红树林排布、海啸波强度减小、集装箱重度增加、以及海岸坡度增加均有利于减小集装箱的变迁距离。基于试验数据提出了红树林消波系数计算公式,本试验中红树林消波系数范围为0.02至0.42。

Tsunami disasters occurred frequently in recent years, causing huge damages to marine structures. Previous tsunami events suggest that mangroves have a certain mitigation effect on tsunami flow. Based on the dam break method, the tsunami flow was simulated in this study. The mitigation effect of mangroves on tsunami was investigated, and the container movement due to tsunami was also explored. The dam break experiment at the sluice gate shows that the dam break process includes the sudden drop stage, the quasi-steady stage, and the slow decrease stage. Higher storage water results in a faster dam break. The container movement due to tsunami flow includes the initial impact stage, the speeding up stage, and the constant speed stage. The impact and buoyant forces contribute its movement. The flow pattern of the tsunami wave attenuation due to mangrove forest indicates that the turbulent flow generated by the superposition of the trailing vortices is the main cause of energy dissipation, and the reasonable dense planting, symmetrical arrangement and staggered arrangement are beneficial to the reduction of tsunami wave energy. In addition, the distribution of triangular staggered mangroves, the reduction of tsunami flow intensity, the increase of container weight, and the increase of coastal slope are all beneficial to reducing the movement distance of containers. Based on the experimental data, a formula for calculating the tsunami attenuation coefficient of mangroves was proposed. In this study, the tsunami attenuation coefficient of mangroves ranged from 0.02 to 0.42.