钢桥大气腐蚀微环境与长寿基因

Atmospheric corrosion micro-environment and longevity genes of steel bridges

为探究钢桥不同构件腐蚀速率差异原因,通过文献综述、桥例分析和数值模拟等方法,研究了影响大气腐蚀速率的环境因素。利用构件表面温度、表面湿润时间及表面污染物沉积量表征钢桥微环境,明确了微环境是决定钢桥大气腐蚀速率的关键因素,灰尘、雨、露等通过影响钢桥微环境间接影响大气腐蚀速率;对比了桥位环境和钢桥微环境的监测方法及监测结果,发现了桥位环境与构件微环境的差异、构件之间微环境的差异,厘清了桥位处建筑物与地形、污染源、结构特征、构件劣化对微环境的影响机制,明晰了微环境在钢桥全生命周期的演化特征,即微环境在设计中赋予、施工中造就、运营中恶化、养护中优化;设计阶段确保构件可检、可达、可养,并采用疏通构造、阻隔构造、除湿装置,施工阶段减少板件制造的初始缺陷、避免构件之间的拼接误差,均可改善微环境,减缓腐蚀速率,延长构件的服役寿命,为结构注入长寿基因。

In order to explore the reasons for the different corrosion rates of different steel bridge components,the environmental factors affecting atmospheric corrosion rates were studied by literature review,bridge case analysis and numerical simulation.The micro-environment was characterized by temperature,wetting time and pollutant deposition of the components surface.It was clarified that micro-environment was the key factor determining the atmospheric corrosion rate,and dust,rain and dew indirectly affected the atmospheric corrosion rate by affecting the micro-environment.By comparing the monitoring methods and results of the bridge site environment and the steel bridge micro-environment,the differences between the bridge site environment and the component micro-environment,and the differences between the components micro-environment were found.The influence mechanism of buildings and topography,pollution sources,structural characteristics and deteriorated components on the micro-environment was clarified.The evolution characteristics of micro-environment in the whole service life of steel bridges were clarified,that was,micro-environment was given in design,created during construction,deteriorated in service,and optimized in maintenance.Ensuring that the components are inspectable,reachable,maintainable,and adopting the dredge structure,barrier structure,dehumidification device in the design stage,as well as reducing the initial defects of plate manufacturing and avoiding the splicing error between components in the construction stage,can improve the micro-environment,slow down the corrosion rate,extend the service life of components,and inject longevity genes into the structure.