大跨轻窄悬索管道桥雷诺数效应及管道覆冰气动性能研究

Pipeline suspension bridges for oil and gas transportation are characterized by narrow widths, low stiffness, light weights, bluff aerodynamic shapes and low damping, and their wind-resistant performance is an issue of great concern. However, the related researches need further improvements. The previous wind resistance design always ignored the influences of Reynolds number effect and the ice accretion on aerodynamic parameters and performances of stiffening girders, which could bring catastrophic accidents. To address these two issues, the aerodynamic parameters of typical stiffening girders will be comprehensively investigated, and the effect of ice accretion on aerodynamic parameters will be comprehensively studied through section model tests, and the previous unreasonable design parameters will be rectified. Using full aeroelastic bridge model tests, the wind-induced nonlinear responses of pipeline suspension bridges at various states will be investigated, in which the geometric nonlinear effect that ignored in section model test will be considered. With consideration of the Reynolds number effect and various nonlinear effects, an analytical framework for 3-D aerostatic, buffeting and flutter analysis will be developed, by which the influences of self-excited drag force, Reynolds number effect, ice accretion, and parameters of wind-resistant cables on flutter and buffeting will be thoroughly examined, and they are compared with those of wind tunnel tests. These will stress the unique feature and significance of this project. Research achievements can reveal the mechanisms of the effects of various factors on wind-resistant performance of pipeline suspension bridges. They can further provide scientific proofs for reasonably determining wind resistance design parameters, optimizing design scheme, and drafting wind-resistant specification for pipeline suspension bridges.

油气输运悬索管道桥具有窄、柔、轻、钝、低阻尼等特点，抗风问题极为突出，而目前研究较为滞后。以往抗风设计均未考虑圆形管道加劲梁气动参数的雷诺数效应和管道覆冰对加劲梁气动参数及结构抗风性能的影响，因此可能存在严重安全隐患。针对上述两个问题，首先通过节段模型测力和测振试验，对典型管道桥加劲梁和典型覆冰形状条件下气动参数展开全面研究，力求解决以往抗风设计参数取值不合理的问题；其次，通过全桥模型试验，研究多种工况下悬索管道桥三维静风响应和颤抖振特性，旨在考虑节段模型试验无法准确模拟的几何非线性效应；最后，发展计入雷诺数效应和多种非线性的风致响应精细化方法，进而明确窄钝加劲梁自激阻力、雷诺数效应、管道覆冰及抗风缆的影响，并与风洞试验结果进行对比分析，凸显本项目研究特色和意义。研究成果可揭示多种因素对悬索管道桥抗风性能的影响机制，进而合理确定抗风计算参数，优化抗风设计，为其抗风规范的制定提供科学依据。

管道悬索桥为承载管道(输送石油、天然气或水)跨越峡谷、河流等障碍的悬索结构。管道悬索桥具有窄、柔、轻、钝等特点，抗风问题突出。在雾凇和雨凇易发地区，管道桥可能遭遇覆冰灾害，引发其气动外形明显改变以致抗风性能下降。以往抗风设计均未考虑覆冰对加劲梁气动参数及结构抗风性能的影响，因此可能存在严重安全隐患。本课题在综合回顾已有研究成果的基础上，结合覆冰试验、风洞试验和有限元分析三种研究方法，对管道悬索桥覆冰特征、桥梁覆冰前后气动性能和不同设计参数对管道悬索桥气动性能的影响三个热点问题开展深入研究。首先，针对管道桥覆冰特征研究不足的问题，在冷冻降雨覆冰试验室开展了管道、风索拉索、桁架构件以及加劲梁节段模型在不同参数组合条件下的覆冰试验。研究了管道直径、型钢尺寸、降雨时间、倾角等对管道、风索拉索、型钢等覆冰的影响。且基于试验结果提炼了大直径管道和管道桥加劲梁覆冰模型，为覆冰条件下大直径管道和管道桥抗风研究提供基础。其次，针对以往覆冰圆柱研究雷诺数较低和鲜有考虑流场紊流度和表面粗糙度的影响的问题，基于测压和测力风洞试验，全面分析了雷诺数、覆冰形状、风攻角、紊流度和表面粗糙度对圆柱气动性能的影响，揭示了高雷诺数下覆冰对圆柱气动性能的影响规律，结果表明覆冰圆柱结构抗风设计中应考虑覆冰形状、表面粗糙度和流场紊流度的影响。最后，针对管道悬索桥抗风研究不足的问题，通过风洞测力试验、测振试验、全桥气弹模型试验和三维有限元分析，系统研究了典型管道悬索桥加劲梁覆冰前后的静气动特性和气动稳定性，全面分析了加劲梁和抗风缆的静风响应和抖振响应，总结了结构设计参数、流场特性、雷诺数和覆冰等条件的影响，研究成果可用于指导和优化管道悬索桥抗风设计，为补充相关抗风规范提供参考和借鉴。