一、桥位河段一元流水力模型 桥位河段的水流是三元流(图1),可简化为一元流水力模型(图2、图3)进行计算。 为简化计算可假定:桥位河段水流为缓流;桥孔收缩断面近似取在桥下出口断面;桥下冲刷完成后,桥下出口断面水位恢复到天然水位。采用符号见图3,即天然状态全断 First, the water flow model of the uniaxial flow in the bridge reach is the ternary flow (Fig. 1), which can be simplified into the uniflow hydraulic model (Fig. 2 and Fig. 3). In order to simplify the calculation, it is assumed that the water flow at the bridge reaches is slow flow; the contraction section of the bridge hole takes approximately the exit section under the bridge; after the bridge flushing is completed, the water level at the exit section under the bridge is restored to the natural water level. See Figure 3 using the symbol, that is, the natural state of the whole off