裸露穿河管道在压重块保护下的冲刷特性

水流冲刷引起河床变形的不确定性对水下穿越管道的安全运行造成威胁。为了探究裸露穿河管道在压重块保护措施下的冲刷特性,通过水槽模型试验,研究压重块长度、压重块布置间距、水流流速、河道水深等因素对管道周围河床地形和冲刷深度的影响。试验结果表明:水下穿越管道在压重块保护措施下的冲刷过程可分为冲刷坑形成、压重块迎流侧悬空、管道迎流侧悬空和冲刷平衡4个阶段;管道的最大冲刷深度与流速和压重块长度正相关,与水深和压重块布置间距负相关;采用量纲分析法得到了无量纲冲刷深度与压重块长度、压重块布置间距、弗劳德数之间的函数关系式。研究成果可为水下穿越管道压重块保护措施的设计、建造及运营维护提供重要的理论支撑。

Erosion Characteristics of Exposed River-crossing Pipe under the Protection of Heavy Block

The uncertainty of riverbed terrain changes caused by water scour poses a threat to the safe operation of river-crossing pipeline. In the aim of exploring the scour characteristics of exposed river-crossing pipelines under heavy block protection measures, a flume model test was carried out to investigate the influences of four factors, namely, length of heavy block, the spacing between heavy blocks, flow rate and water depth, on scour terrain and scouring depth of riverbed around the pipeline. The scouring process of underwater pipeline under the protection of heavy block can be divided into four stages: formation of scouring pits, suspension of heavy block on the upstream side, suspension of pipeline on the upstream side, and scour balance. The maximum scouring depth of pipeline is positively correlated with the flow velocity and the length of heavy block, but negatively correlated with the water depth and the spacing between heavy blocks. The functional relationship between the dimensionless scouring depth, the length of heavy block, the spacing between heavy blocks and Froude number is obtained by dimensional analysis method. The research findings could be a theoretical support for the design, construction, operation and maintenance of heavy block protection measures for underwater crossing pipeline.