多岛屿、多汊道环境下大型深水港建设中的水沙问题

Hydrodynamic and sedimentation problems in construction of large-scale deepwater harbor located at the area with many islands and branch channels

洋山港海域多岛屿、多汊道,是由大、小洋山两条岛链围成的喇叭口型的海域,潮汐水道以落潮流为主、高含沙量、强潮流,泥沙运动主要以悬沙为主。通道内潮流基本为东南-西北向往复流,潮流平均流速在1.0 m/s,最大流速都在2.0 m/s以上,含沙量在1.0 kg/m3以上。根据其海域边界特点,利用任意三角形网格建立了能较好拟合洋山港海域边界的二维潮流泥沙及地形冲淤变化数学模型。应用2006年4月实测水文泥沙及地形冲淤资料进行了验证,验证结果表明,该海域潮位及定点同步垂线流速、流向、含沙量过程的计算值与实测值吻合良好,洋山港海域通道内地形冲淤变化情况和实测值接近,较好地复演了洋山港一、二期工程建设后海域流场、含沙量场和地形变化。

Yangshan deepwater harbor locates in the bell-mouth shaped sea area enclosed by Dayangshan and Xiaoyangshan island chains,having many islands and branch channels dominated by mainly ebb current.The cyclic tidal flow with a mean velocity of 1.0 m/s is the major dynamic force for maintaining the stability of the way and the sediment in flow is always under the combined action of waves and tidal currents.The seabed evolu-tion is arisen by suspended sediment transport.The suspended sediment concentration is over 1.0 kg/m3.A 2-D mathematical model for flow and suspended sediment transport considering the actions of wave,tidal flow,as well as the sediment and evolution of sea bed for this kind of surrounding with many islands and branch channels is established.The validity of the model is verified by the observation data obtained in Apr.,2006,including the tidal flow and suspended sediment concentration in the vicinity of the harbor.The verification of calculation shows the calculated values are in good agreement with the measured data.The field of tidal currents,suspended sediment concentration and the deformation of seabed can be successfully simulated.