桥墩影响下冰塞水位变化规律的试验
Impact of bridge piers on ice jam stage variation:An experimental study
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摘要: 采用聚乙烯颗粒为天然冰模拟材料,对桥墩影响下的冰塞水位变化规律进行了探索性试验研究.试验发现,有桥墩时,冰塞演变可分为冰塞越过桥墩和未越过桥墩两种情况;冰塞动态演变过程中,桥墩附近冰塞底部存在冲刷现象,由此产生的冲刷输冰流量会引发较为复杂的冰塞水位演变过程.研究表明,有桥墩条件下,水力及来冰量条件对平衡冰塞时的水位增值影响规律与无桥墩时基本一致;水流条件和来冰流量相同条件下,当冰塞能越过桥墩达到平衡时,墩径较大时水位增值也较大,在断面阻塞程度相同条件下,双墩水位增值大于单墩.Abstract: In the vast northern regions, ice jam can be easily formed during winter times, which can further result in ice jam flooding. Due to the presence of bridge infrastructures, the flow field can also be complicated. To study the impact of bridge pier on ice jam, the present study was conducted. By using experimental approach, the mechanism of backwater height variation was measured. It shows that the presence of bridge pier significantly changes the backwater height during ice jam. The ice jam evolution can be classified as "before pier" and "after pier" conditions. Erosion on ice jam around bridge piers can also be noted, which further complicate the ice jam stage development. It is also found that with or without bridge pier, the mechanism of backwater height shows similar trend under different flow conditions and ice discharge. However, with a larger diameter, the backwater height variation is larger under the same flow and ice conditions. With the same blockage ratio, double piers can results in a higher backwater height increase comparing to a single pier.