Large debris transported by flood affects scour features at bridge piers and increases the risks of structural failure. Geometric characteristics of the debris and the relative position of the pier with respect to the river bank are important parameters for the scour process. The interaction between the water flow and debris accumulation increases the shear stress, turbulence and consequently enhances the scour depth at the pier. This paper aims at analyzing such effects on scour evolution at bridge piers. To this end, two series of tests were carried out under clear water condition with different debris geometries and percentage blockage ratios. Experimental evidences showed that the pier position only influences scour evolution and equilibrium morphology for low water depths. Conversely, its effect becomes negligible for scour at bridge piers with debris accumulation and higher water depths. Useful practical relationships have been derived, with satisfactory prediction capability of the scour evolution for all the tested configurations.

中文翻译：

---

杂物堆积对岸旁桥墩冲刷演化的影响

洪水输送的大碎片会影响桥墩的冲刷特性，并增加结构破坏的风险。碎片的几何特征和码头相对于河岸的相对位置是冲刷过程的重要参数。水流与碎屑堆积之间的相互作用增加了剪应力，湍流，因此增加了码头处的冲刷深度。本文旨在分析这样对桥墩冲刷演变的影响。为此，在清水条件下以不同的碎屑几何形状和堵塞率百分比进行了两个系列的测试。实验证据表明，码头位置仅影响低水深的冲刷演变和平衡形态。反过来，对于杂物堆积和较高水深的桥墩冲刷，其影响可忽略不计。已经得出了有用的实用关系，对于所有测试的配置，其冲刷演变具有令人满意的预测能力。