基于现场实验结果对倾倒泥沙扩散数值模型参数率定研究

Parameter determination of the numerical model for dumping sediment transport based on the field experimental results

倾倒区倾倒过程泥沙输运扩散数值模型理论较为成熟,但模型的一些相关参数给定范围较大,且一般由实验室静水或河口淡水实验获取,用于海洋倾倒区的泥沙模型有一定的局限性,使得模型预测结果波动范围也很大,具有较强的不确定性,模型参数亟需物理实验数据的率定和验证。2011-2014年在沙埕港临时性海洋倾倒区开展了3次倾倒物海洋倾倒实验,对现场实验结果数据分析论证后,建立倾倒过程二维泥沙输运扩散数值模型,用实验数据对模型中一些主要参数进行计算和率定。计算率定结果表明:沙埕港倾倒区倾倒过程初期疏浚泥絮团沉降速度可达3.0 cm/s,细沙颗粒充分混合后沉降速度减小,一般小于0.5 mm/s;悬沙紊动扩散系数Dx、Dy取45 m^2/s时计算悬浮物浓度增量曲线与实测结果吻合效果最佳,建议调试值域为30~50 m^2/s。模型参数率定后计算结果的客观性和准确性进一步提高,可为海洋倾倒区选划泥沙扩散模型参数的选取提供一定参考。

Sediment transport numerical model theory for ocean dumping site is relatively mature, but the range of some parameters in the model is given too wide, and some parameter values are obtained by sediment experiments in the laboratory hydrostatic or estuarine fresh water in general. Using them for the marine dumping area has some limitations, which makes the model prediction results not accurate and vary considerably, so some model parameters urgently need the determination and verification by field experiment data. We did three ocean dumping experiments at the temporary ocean dumping site of Shacheng Harbour during 2011-2014, and based on the field experiment data, we established an two-dimensional sediment transport and diffusion numerical model for the ocean dumping, using observation data of experiments to determine and calculate parameters for the model. The results show that： in the temporary ocean dumping site of Shacheng Harbour, the sedimentation rate of floccule dredged mud may be bigger than 3.0 cm/s at the beginning of the process of dumping, and the velocity of mix sand particles decreases, and generally is less than 0.5 mm/s. The calculate sediment concentration increment curve agreeswith the measured results best while the sediment turbulent diffusion coefficient Dx／Dy values 45 m2/s, so we suggest that the Dx／ Dy＇s debugging domain should be of 30～50 m2/s. After the parameter determination, the model prediction results are more objective and accurate, which can provide some reference for the parameter determination of sediment diffusion model in selecting marine dumping sites.