钱塘江河口过江隧道河段最大冲刷深度的数值模拟

2-D Movable-bed Mathematical Model on the Maximum Erosion Depth of the Riverbed nearby the Tunnel across the Qiantang Estuary

针对钱塘江河口水流泥沙运动及河床冲淤变化的实际情况,从平面二维非恒定水流运动方程、不平衡泥沙输移方程及河床变形方程出发,建立了钱塘江河口平面二维动床数学模型。以钱塘江河口的典型实测水流、泥沙及河床冲淤的实测资料对模型的潮位、流速、含沙量及河床冲淤变形进行了率定和验证计算。在此基础上开展了钱塘江河口过江隧道河段在极端洪水作用下河床最大冲刷深度的数值模拟,预测结果与动床物理模型及地质详勘的成果基本一致,进一步表明了动床数学模型的可靠性,预测成果可为过江隧道的合理埋设提供参考依据。

According to 2-D unsteady flow equations, sediment continuity equations and riverbed deformation equations, two -dimensional sediment mathematical models have been developed in this paper. The model has been calibrated by using hydrographic field data as well as data on historical morphological changes in the Qiantang Estuary. After the calibration the model was used to investi gate the maximum scour depth caused by an exceptional flood in the river reach near the cross-section of the tunnel across the Qiantang Estuary. Finally, thiis paper presents the riverbed erosion depth nearby the tunnel under the frequency of one percent flood, and the predicted result agrees very well with that of physical model and geologic drilling data. It showed that the mathematical model is basically reasonable and the scientific basis was offered to lay this tunnel.