依据洋山港区多年(2006~2016年)的水文泥沙、水深等资料,在深入地分析洋山港四期工程海域水沙环境基础上,采用数学模型的方法对四期港区增深方案进行了研究,结果显示:(1)洋山港区属非正规浅海半日潮型,平均潮差2.76 m,潮汐强度中等;四期港区水域,涨、落潮水流呈明显的往复流运动,涨潮平均流速为0.63 m/s,落潮平均流速为0.69 m/s;(2)四期港区水域含沙量季节变化与整个洋山海域是一致的,季节变化明显,冬、春季节含沙量较高,夏、秋季节含沙量较低,多年垂线平均含沙量约为1.4 kg/m3;底质泥沙颗粒中值粒径一般在0.012~0.029 mm之间,平均为0.019 mm,主要为粘土质粉砂;(3)四期港区水域总体上呈现出冲刷的态势,长时间累计净冲刷强度接近2.0 m.目前的水动力和泥沙环境及地形冲淤特征对四期港区的开发处于有利状态;(4)四期港区工程建成后,潮流性质没有发生变化,泊位、港区和航道水域水流归槽明显,水流更加平顺;对洋山港海域各汊道潮量变化没有明显影响;7万t和12万t两个方案建设后,港池与航道总淤积量为500~600万m3左右.%Based on the measured data of hydrology, sediment and water depth from 2006 to 2016, water sediment environment and terrain changes in Yangshan Deep-water Port Phase IV project were analyzed, and deepening scheme of harbor district was studied using the method of mathematical model.The results show:(1)the Yangshan harbor tide belongs to the informal neritic semidiurnal tide and the intensity of tidal medium with the average tidal range 2.76 m;the tidal currents are the reciprocating movement,the average flood and ebb flow velocity are about 0.63 m/s and 0.69 m/s respectively;(2)the seasonal change of suspended sediment concentration shows high values in winter and low values in summer,the annual mean concentration is about 1.40 kg/m3, and the average diameter of the seabed surface sediment is from 0.012 m to 0.029 mm with the average value 0.019 mm;(3)terrain change of Phase IV project waters generally shows a tendency of scour,and the cumulative scour rate is about 2.0 m/a;at present,the hydrodynamic sediment environment and erosion and deposition characteristics are favorable to the development and construction of Phase IV project waters;(4)after Phase IV project,the feature of the tidal currents has not changed,water flow returning into channel in the area of berth,harbor and waterway is obvious,and the water flow is more smooth;tidal volume changes of each branch have no significant effect;after the two schemes(70 000 tons and 120 000 tons),total sedimentation of basin and channel is around 5~6 million m3.
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