冰盖下桥墩局部冲刷新型防冲组合结构试验研究

河流冰盖的形成改变了桥墩周围的水力特性，导致桥墩局部冲刷加剧。基于动床冲刷，在冰盖及明流条件下进行了螺纹式减冲索与钩环式护圈组合的新型防冲结构室内模型试验，探究其对桥墩局部冲刷的防冲效果。试验结果表明：新型防冲组合结构改变了桥墩的局部冲刷模式，延缓了冲刷过程；通过极差分析与方差分析可知，螺纹直径为6.0 mm、螺纹角为15°、螺纹排数为3的新型防冲组合结构的防护效果最优；与无防护工况相比，在粗糙冰盖条件下新型防冲组合结构桥墩最大冲刷深度减小了59.03%；螺纹式减冲索增大了桥墩表面的粗糙度，可以更好地削弱下潜流和分离墩前迎面水流，从而达到有效防冲的目的。

Experimental study on a novel anti-scouring composite structure for local erosion of bridge piers under ice-covered conditions

The presence of the river ice cover changes the hydraulic properties around the bridge piers, resulting in increased local scour of the bridge piers. Based on moving bed scour, an indoor model test of a novel anti-scouring structure combining threaded scour-reducing cables and hooked-collar was conducted under ice-covered and open flow conditions to explore the anti-scouring effect of the novel structure on local scour of bridge piers. The test results show that the novel anti-scouring composite structure changes the local erosion mode, and slows down the erosion process of the bridge pier. According to the range analysis and variance analysis, the optimal novel anti-scouring composite structure is consist of a thread diameter of 6.0 mm, a thread angle of 15°and 3 rows of threaded cables; compared with no protection, the maximum scour depth of the bridge piers is reduced by 59.03% under rough ice-covered condition. The threaded anti-scouring cables can increase the surface roughness of the pier, which is conducive to weakening the undercurrent and separating the oncoming water flow in front of the pier to achieve the purpose of effective anti-scouring protection.