钱江新城二号港水处理工程泥沙沉降分析

Sedimentation Analysis of Hangzhou CBD Secondary Port Water Treatment Project

钱江新城二号港水处理工程是将钱塘江原水进行净化处理后引入市区河网,以改善城市水环境质量。由于钱塘江原水受河口水文泥沙条件影响,含沙量较大且颗粒级配不均,对水处理工程的规模设计及工艺选择等带来较大的困难。为此,对引水口的水文泥沙特性进行了统计分析,并对水处理工程设计中的预沉池沉沙效果进行了数值模拟。结果表明:引水口水体的含沙量具有明显的年际、月际及日间变化特点,丰水年的含沙量高于平、枯水年,夏、秋季节高于春、冬季节,涨潮时段高于落潮时段;引水口水体多年平均含沙量约为0.078 kg/m3,进入内河的多年平均泥沙总量约为8 000 t,其中,若仅在落潮时段配水,进入内河的泥沙总量将降低30%以上;经模拟计算,设计预沉池中的含沙量沿程降幅约为28%,预沉后进入排灌站的水体含沙量约为0.073 kg/m3。

The Hangzhou CBD Secondary Port water treatment project is a purification effort of the Qiantang River water before it flows into the urban river system. Affected by the complex hydro-sedimentary conditions in the estuary, the sediment concentration in water is large and the particle size is uneven, which caused difficulty in determining the scale and selecting the technology for the project. Statistical analysis of hydro-sedimentary characteristics and numerical simulation of sedimentation effect were conducted. The results of the sediment concentration showed obvious annual, monthly and daily trends. The sediment concentration in high water period was higher than in normal water and low water periods, the sediment concentration in summer and autumn was higher than in spring and winter, and the sediment concentration at high tide was higher than at low tide. The average annual sediment was 0. 078 kg/m^3, the total sediment in the inland river was 8 000 t. If water was taken at low tide, the total sediment concentration would be reduced by at least 30%. Using simulation, the sediment concentration in the settling basin was 28% lower, the sediment concentration in water into pump station was about 0.073 kg/m^3 after settlement.