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桥梁孔径水力计算的目的是确定桥孔长度、雍水高度和桥梁河道冲刷深度。桥孔长度、雍水高度和桥梁河道的冲刷深度,在水流与输沙过程中是相互依存的,而成为一个整体。桥梁河道中水流与输沙之间的相互作用和平衡条件应做为桥孔水力计算的基础。本文中,建立了桥孔的一元水流模型,根据水流连续性方程和能量方程导出了桥孔水力学基本公式。该公式能够表达桥长、雍水和桥梁河道的冲刷三者之间的相互关系。冲刷与水流压缩之间的关系可应用一般冲刷公式来表示,这些公式是根据输沙和水流的连续性原理建立的。籍助电子计算机对桥梁雍水试验和公路桥梁孔径调查资料进行了数据处理,获得了不同桥孔流速系数公式。应用本文导出的各公式,当桥孔长度确定之后,桥梁河道的冲刷深度及其相应的雍水高度就可算出;反之,若确定了雍水高度和冲刷深度,则可算出需要的桥孔长度。最后文中给出了各种河床情况下的例题。
The purpose of hydraulic calculation of bridge aperture is to determine the length of bridge hole, the height of Yong water and the erosion depth of bridge river. Bridge length, Yong water height and bridge river erosion depth, in the process of water flow and sediment are interdependent, and become a whole. The interaction and equilibrium conditions between water flow and sediment transport in bridge channel should be the basis of hydraulic calculation of bridge hole. In this paper, a uniaxial flow model of bridge opening is established. Based on the continuity equation of water flow and the energy equation, the basic formulas of hydraulic flow in bridge opening are derived. The formula can express the relationship between bridge length, Yong water and erosion of bridge river. The relationship between erosion and flow compression can be expressed in terms of the general scour formula, which is based on the principle of continuity of sediment transport and flow. Computer assisted by the computer bridge Yong Yong water test and highway bridge borehole survey data were processed to obtain a different bridge orifice flow coefficient formula. Using the formulas derived in this paper, when the bridge length is determined, the erosion depth of bridge river and its corresponding Yong water height can be calculated. On the contrary, if the Yong water height and erosion depth are determined, the required bridge length can be calculated. The final text gives examples of various riverbed cases.