中美桥梁墩台局部冲刷深度预测方法比较分析

Comparative analysis on prediction method for local scour depth of bridge piers and abutments in China and America

针对中美两国规范中桥梁墩台局部冲刷深度预测方法及公式进行较为系统地归纳和整理.然后,结合实际桥墩洪水冲刷监测数据以及实验室中某桥台局部冲刷试验的数据,对不同的墩台局部冲刷深度预测方法进行了比较分析.研究结果表明,在非黏性土河床条件下,中国规范所得最大冲刷深度值小于实测结果且小于美国规范计算值,美国规范所得最大冲刷深度值则较实测结果偏大;在黏性土河床条件下,相较于最大冲刷深度预测值,时效最终冲刷深度预测方法所得结果与实测结果更为接近,该方法同时还能够反映冲刷深度随桥梁服役时间变化发展的过程.美国规范Froehlich方程得到的桥台冲刷深度的预测值更接近实验室的测量数据,中国规范计算式和美国规范HIRE方程得到的桥台冲刷深度预测值相对较大,但对于目前桥梁工程基础埋深设计而言为偏安全.

the prediction methods and formulas of local scour depth for bridge piers and abutments in Chinese and American specifications were summarized and organized in this study.Then,combined with the flood scour monitoring data of the real bridge piers and the local scour test data of an abutment in the laboratory,the different methods to predict local scour depth of piers and abutments are compared and analyzed.The results show that,under the condition of non-cohesive soil riverbed,the maximum scour depth obtained by the Chinese specification is less than the practical measured value,and the calculated value is less than that obtained by the American specification,which is larger than the practical measured value.Under the condition of cohesive soil riverbed,compared with the predicted value of maximum scour depth,the results obtained by the time-dependent scour depth prediction method are much closer to the measured results.In addition,time-dependent scour depth prediction method can also reflect the development process of scour depth with the service time of the bridge.The predicted value of abutment scour depth obtained by the Froehlich equation in American specification is closer to the test data in laboratory,while the predicted value of abutment scour depth obtained by the equations in Chinese specification and the HIRE equations in American specification is relatively large,However,this larger value is relatively safe for the current foundation buried depth design of the bridge engineering.