Local scour around bridge abutments under ice covered conditions.

摘要

Local scour refers to the sediment transport around hydraulic structures by flowing water. Excessive scour around the abutment can potentially cause damage to the bridge, which may also result in catastrophic consequences. Abutment scour refers to the local scour generated by the flow passing around bridge abutments. One of the challenging problems for hydraulic engineers is the prediction of maximum scour depth around abutments and pier foundations so that proper provisions can be made in the design and construction to mitigate the consequences. Despite significant research efforts to improve the understanding of scour related problems, abutment scour is still among the more complex and challenging problems. Over the past few decades, local scour around bridge abutments has received wide attention, and many researchers have contributed various studies on the topic. The current state knowledge on local scour still has insufficiently understood aspects, for example, ice accumulation has never been addressed in the abutment scour research. The impacts of ice cover has never been conducted. To fill this gap, the present research is conducted. The ice cover can change the channel morphology and flow field. It is well known that river ice affects the vertical and lateral distribution of flow in a channel. Additionally, because river ice affects the flow conditions, it potentially influence sediment transport. Hence, the scour around abutments is affected. In the present research, a series of large flume experiments are conducted. By adding different simulated ice covers in the flume, ice-covered flow can be generated. By comparing the scour profiles and maximum scour depth around two commonly used abutments in three non-uniform sediments, the ice cover impacts have been investigated. A significant increase can be noticed by adding ice cover. With the increase in ice cover roughness, the maximum scour depth increase correspondingly. Meanwhile, semi-circular abutment can generate a relatively small scour hole. Further