摘要
针对湿热地区桥梁因混凝土碳化加速引发钢筋锈蚀的严峻问题,本工作以西双版纳森林公园悬索桥为工程载体,通过现场实测揭示了关键风险:尽管桥塔构件碳化深度平均值(1.46~15.20 mm)均小于保护层厚度平均值(22.7~31.4 mm),且碳化深度/保护层厚度比值(0.1~0.6)评定标度(1~2级)显示当前影响轻微,但部分构件存在保护层厚度特征值(D_(ne))严重不足的问题:实际D_(ne)检测值为9.9~17.4 mm,相较于保护层厚度设计值(D_(nd)),两者的比值(D_(ne)/D_(nd))仅为0.50~0.87,按评定标准,此指标评定标度为4~5级,构成钢筋锈蚀的潜在重大威胁,凸显了“碳化未超标但保护层不足”削弱耐久性的核心矛盾。为此,创新地构建了多级协同防护体系:在材料层面,采用纳米SiO_(2)改性磷酸镁水泥(MPC)实现快速再碱化与微观强化,结合真空浸渍、电场辅助技术提升迁移型阻锈剂的渗透效果;在结构层面,实施分级裂缝修复,显著提升裂缝区抗碳化和抗渗性;在系统层面,构建基于BIM的数字孪生监测系统,集成微型长寿命pH传感器,实现混凝土内部环境实时监测与碳化速率预测,支撑主动防控与智能管养,并配套提出检测周期缩短至1年等优化策略。本研究阐明了湿热环境碳化-锈蚀机制与核心风险,提出的多级防护体系为提升类似环境桥梁结构耐久性与服役安全性提供了有效的理论依据和工程解决方案。
In response to the severe problem of steel bar corrosion caused by accelerated concrete carbonation in bridges located in hot and humid regions,this paper takes the suspension bridge in Xishuangbanna Forest Park as an engineering case and reveals key risks through on-site measurements:Although the average carbonation depth of the bridge tower components(1.46-15.20 mm)is less than the average thickness of the protective layer(22.7-31.4 mm),and the evaluation scale(Level 1-2)based on the ratio of carbonation depth to protective layer thickness(0.1-0.6)indicates that the current impact is slight.However,some components have a serious deficiency in the characteristic value of protective layer thickness(D_(ne)):the actual detected value of D_(ne)ranges from 9.9 mm to 17.4 mm;compared with the design value of protective layer thickness(D_(nd)),the ratio of the two(D_(ne)/D_(nd))is only 0.50 to 0.87.In accordance with the assessment criteria,the evaluation scale for this indicator is Grade 4 to Grade 5,which constitutes a potential major threat to steel bar corrosion.This highlights the core contradiction that"insufficient protective layer despite non-excessive carbonation"weakens durability.To address this,an innovative multi-level collaborative protection system has been constructed:At the material level,nano-silica(SiO_(2))modified magnesium phosphate cement(MPC)is used to achieve rapid re-alkalization and microstructural reinforcement,combined with vacuum impregnation and electric field-assisted technologies to enhance the penetration effect of migration-type corrosion inhibitors.At the structural level,hierarchical crack repair is implemented to significantly improve the carbonation resistance and impermeability of cracked areas.At the system level,a BIM-based digital twin monitoring system is built,integrating miniature long-life pH sensors to realize real-time monitoring of the internal concrete environment and prediction of carbonation rate,supporting active prevention and control as well as intelligent management and maintenance.Additionally,optimized strategies such as shortening the inspection cycle to 1 year are proposed.This study clarifies the carbonation-corrosion mechanism and core risks in hot and humid environments,and the proposed multi-level protection system provides an effective theoretical basis and engineering solution for improving the durability and service safety of bridge structures in similar environments.
作者
母昌辉
杨建荣
MU Changhui;YANG Jianrong(Department of Civil Engineering,Faculty of Civil Engineering and Mechanics,Kunming University of Science and Technology,Kunming 650500,China;Earthquake Engineering Researching Center of Yunnan,Kunming 650500,China)
出处
《材料导报》
北大核心
2025年第S2期306-311,共6页
Materials Reports
关键词
混凝土碳化
钢筋锈蚀
保护层厚度
耐久性
防护措施
concrete carbonation
steel bar corrosion
protective layer thickness
durability
protective measures
