龙潭长江大桥主缆除湿系统送气管道开孔方案研究  

Perforation Scheme for Airflow Conduits of Main Cable Dehumidification System of Longtan Changjiang River Bridge

作　　者：陈巍 赵军 万田保[3] 陈柳灼 沈锐利[4] CHEN Wei;ZHAO Jun;WAN Tianbao;CHEN Liuzhuo;SHEN Ruili(College of Civil Engineering&Architecture,China Three Gorges University,Yichang 443002,China;Jiangsu Fasten Steel Cable Co.,Ltd.,Jiangyin 214445,China;China Railway Major Bridge Reconnaissance&Design Institute Co.,Ltd.,Wuhan 430056,China;School of Civil Engineering,Southwest Jiaotong University,Chengdu 610031,China)

机构地区：[1]三峡大学土木与建筑学院,湖北宜昌443002 [2]江苏法尔胜缆索有限公司,江苏江阴214445 [3]中铁大桥勘测设计院集团有限公司,湖北武汉430056 [4]西南交通大学土木工程学院,四川成都610031

出　　处：《桥梁建设》2024年第5期77-84,共8页Bridge Construction

基　　金：湖北省自然科学基金项目(2024AFB171);防灾减灾湖北省重点实验室(三峡大学)开放基金项目(2023KJZ21)。

摘　　要：龙潭长江大桥主桥为(615+1560+552)m单跨悬吊钢箱梁悬索桥,主缆由126股127丝平行钢丝索股组成,高强钢丝直径为6 mm、标准抗拉强度为1960 MPa,采用内部通干空气的新型除湿系统进行主缆防腐保护。该除湿系统由送气设备、送气管道、排气夹、监测气夹等组成,通过埋置在主缆截面中央的送气管道输送干空气。为确定送气管道的合理开孔方案,验证新型除湿系统的除湿效果,开展送气管道沿程干空气压力分布及主缆足尺模型除湿试验,并进行实桥现场检测。结果表明:龙潭长江大桥主缆送气管道沿程按45 m左右的间距设置出气接头,每个出气接头上开设6个直径为4 mm的出气孔,可满足边、中跨主缆全长范围的干空气输送需求;新型除湿系统可实现主缆截面的干空气全覆盖,随着干空气持续送气除湿,主缆内部各测点的相对湿度均能降低至50%以下,该除湿系统可达到预期除湿效果;实桥现场检测结果验证了送气管道制作和安装的精确性及开孔方案的合理性。The main bridge of Longtan Changjiang River Bridge is a suspension bridge featuring a suspended main span of 1560 m and two side spans of 615 m and 552 m,with the stiffening girder in the suspended main span consisting of steel boxes.Each of the two main cables contains 126 strands,and a single strand is composed of 127 parallel steel wires of 6 mm diameter and a nominal tensile strength of 1960 MPa.The bridge is fitted with a dehumidification system for main cable corrosion protection,which consists of air blowers,airflow conduits,exhaust clamps and humidity monitors.Dried air flows through the conduits embedded in the center of the main cable to take away the damp,thereby delaying the corrosion of the steel wires.This study investigates the dry air pressure distribution along the airflow conduits and presents the test results of the dehumidification system on a main cable mockup,as well as the selection of an effective perforation scheme for the airflow conduits.In the Longtan Changjiang River Bridge,exhaust sleeves are spaced 45 m in the airflow conduits,and each exhaust sleeve contains 6 circular air outlets of 4 mm diameter to achieve effective dehumidification protection for the main cables in the center span.The dehumidification system supplies dry air that is sufficient to cover the full cross-section of the main cables,with the sustained supply of dry air,the relative humidity at each monitored points inside the main cables drops below 50%,indicating that the dehumidification system achieves the expected dehumidification effect.The engineering practice in the Longtan Changjiang River Bridge proves the manufacture and installation accuracy of the airflow conduits,and the effectiveness of the perforation scheme.

关 键 词：悬索桥 主缆防腐 除湿系统 送气管道 开孔方案 主缆足尺模型 除湿试验 除湿效果 

分 类 号：U448.25[建筑科学—桥梁与隧道工程] U443.38[交通运输工程—道路与铁道工程] U445.7