冰盖下组合桥墩的局部冲刷特性及水力特性

Local scour and hydraulic characteristics of composite piers under ice sheet

为研究冰盖对组合桥墩局部冲刷及其周围流场分布的影响,基于动床冲刷试验,在不同覆盖条件下,分析了不同水流条件和桥墩尺寸对组合桥墩局部冲刷的影响,建立了预测明渠水流与冰盖流条件下组合桥墩最大冲刷深度的经验方程,并通过ADV测量了墩前的流场。结果表明:组合桥墩的冲刷模式与串列桥墩相似,最大冲刷深度始终出现在墩正前方;经验方程中来流水深、来流流速、桥墩尺寸、冰盖糙率均与最大冲刷深度呈正相关关系;在粗糙冰冰盖流条件下,墩前的垂向流速最大,导致其最大冲刷深度总是大于同等条件下的明渠水流和光滑冰盖流。

In order to study the influence of ice sheet on the local scour of composite piers and the distribution of flow field around them,the influence of different flow conditions and pier sizes on the local scour of composite piers was analyzed under different cover conditions based on the scour test of moving bed.The empirical equation for predicting the maximum thrust depth of composite pier under the conditions of open channel flow and overburden flow was established,and the flow field in front of the piers was measured by ADV.The results show that the scour pattern of composite pier is similar to that of tandem pier,and the maximum scour depth always appears in front of the pier.The depth of incoming flow,incoming flow velocity,pier size and ice sheet roughness are positively correlated with the maximum scour depth.In the rough ice-overburden flow condition,the maximum vertical velocity in front of the pier is the highest,resulting in greater maximum scour depth than that of open channel flow and smooth ice flow under the same condition.