砂质河床桥墩局部冲刷深度预测

Equilibrium Depth Prediction of Local Scour around Piers in Sandy Riverbed

桥墩局部冲刷深度的准确预测对跨河桥梁设计有重要的影响,是决定桥墩基础埋置深度的关键因素。该文基于桥墩局部冲刷机理分析及能量平衡理论,建立了适用于砂质河床窄墩深流型、过渡型和宽墩浅流型流场的局部冲刷平衡深度的预测方程。通过与实验数据对比,分别得到清水冲刷和动床冲刷时不同流场类型所处的深宽比范围。选取代表性实验数据对方程的适用性进行了验证。与已有预测方程的误差对比分析表明,根据流场类型分别建立冲刷深度预测方程,能有效提高预测的精度。

Accurate prediction of the local scour depth has an important influence on the design of the bridge across the river,which is the key factor to determine embedded depth of the pier foundation.According to the theory of energy balance and the analysis of scour mechanism,the prediction equations of equilibrium scour depth in the sandy riverbed for narrow piers in deep flow,transition piers and wide piers in shallow flow were established.Compared with the experimental data,the depth-to-width ratio ranges of different flow field types under the conditions of clear-water scour and moving-bed scour are obtained respectively.The experimental data were selected to verify the applicability of the equations.A comparative analysis of the errors with existing prediction equations shows that the establishment of scour depth prediction equations according to the type of flow field can effectively improve the prediction accuracy.