三峡库区滑坡涌浪作用下桥墩波压特性研究

Wave pressure characteristics of bridge piers under landslide-generated surges in the Three Gorges Reservoir area

由于三峡库区的非开敞性,滑坡引起的涌浪衰减较慢,传播过程中可能对沿程桥墩产生巨大破坏。以涪陵长江二桥为依托,构建了比例尺为1∶70的库区河道水槽,试验模拟了滑坡涌浪对桥墩的作用。结果表明:桥墩上涌浪波压分为共振波压(P_(re))和脉动波压(P_(pu)),共振波压为涌浪冲击桥墩瞬间桥墩共振产生的高频振动波,频率为300.0~400.0 Hz;脉动波压为波浪作用过程产生的压力,频率为0.2~0.5 Hz;脉动波压在对岸桥墩上沿水深的分布近似为垂直分布,在同岸桥墩沿水深锯齿状减小,最大脉动波压分布在水面附近;共振波压沿水深分为单峰值、多峰值和无峰值3种,10万m^(3)以上大方量滑坡产生的共振波压为单峰值和多峰值分布,单峰值的峰值波压是水面波压的5.0倍,多峰值的峰值波压为水面波压的2.5倍~4.0倍,10万m^(3)以下滑坡产生的共振波压呈现无峰值分布;共振波压沿水深呈先增大后减小的“侧V”形;P_(re)/P_(pu)最大位置在距水面1/3水深位置,第二大位置在距水面1/5水深位置。该文提出了桥墩迎波面涌浪压力荷载计算模型,并针对三峡库区不同运行水位给出了相应水位条件下最大涌浪波压的计算公式。

Due to the non-openness of the Three Gorges Reservoir area,waves generated by landslide decay slowly,potentially causing significant damage to the bridge piers.A reservoir channel flume model with a scale of 1∶70 was constructed to simulate the impact of landslide-generated waves on the bridge piers.The results indicate:the wave pressure on the bridge piers is divided into the resonance wave pressure(P_(re))and pulsating wave pressure(P_(pu)).The P_(re)is of frequencies ranging from^(3)00.0-400.0 Hz and the P_(pu)is of frequencies between 0.2-0.5 Hz.The P_(pu)can be considered approximately as vertically distributed on the opposite bank,while it decreases in a saw-tooth pattern on the same bank,with the maximum pulsating wave pressure distributed near the water surface.The resonance wave pressure is categorized into the types of single peak,multiple peaks,and no peak.The P_(re)generated by a landslide of more than 100000 m^(3)is distributed with the types of single peak and multiple peaks.The P_(pu)with a volume less than 100000 m^(3)shows the type of no peak,with the form of a“side V”shape.The position of maximum P_(re)/P_(pu)is at one-third the depth from the water surface,and the second largest position is at one-fifth the depth.A calculation model for wave pressure load on the wave-facing side of the bridge piers was proposed,and the formulas for calculating the P max under different operating water levels in the Three Gorges Reservoir area were provided.