马鞍山长江公铁大桥主航道桥中塔下横梁施工关键技术  

Key Construction Techniques for Lower Crossbeam of Central Pylon of Main Navigation Channel Bridge of Maanshan Changjiang River Rail-cum-Road Bridge

作　　者：刘爱林[1,2] 徐敏 王伟 LIU Ailin;XU Min;WANG Wei(China Railway Major Bridge Engineering Group Co.,Ltd.,Wuhan 430050,China;State Key Laboratory of Bridge Intelligent and Green Construction,Wuhan 430034,China;Hefei Railway Hub Engineering Construction Headquarters(Ning′an Railway Co.,Ltd.),Hefei 230011,China)

机构地区：[1]中铁大桥局集团有限公司,湖北武汉430050 [2]桥梁智能与绿色建造全国重点实验室,湖北武汉430034 [3]合肥铁路枢纽工程建设指挥部(宁安铁路有限责任公司),安徽合肥230011

出　　处：《世界桥梁》2024年第4期29-34,共6页World Bridges

基　　金：国家十四五重点研发计划项目(2022YFB3706405)。

摘　　要：马鞍山长江公铁大桥主航道桥Z4号中塔采用空间四肢A形钢-混组合塔,横向两塔肢间设下横梁,下横梁间设3道系梁,纵向两塔肢间不设置横梁。下横梁采用支架法分层浇筑施工。下横梁施工支架采用落地式钢管支架配套模板体系,受力性能满足要求;通过有限元计算比选下横梁混凝土分层浇筑方案并进行优化,采取(5.5+2.5)m分层方案,上、下层混凝土分别分为2块、3块分层分块浇筑;通过低温升、易泵送、高抗裂的C60混凝土研制、下横梁与塔柱倒弧结合面抗裂措施优化、分块间接缝构造形式及施工工艺优化、下横梁与系梁混凝土浇筑施工组织优化、混凝土温度智能化监控、预应力束张拉时机控制等混凝土防裂措施,有效解决了下横梁大体积混凝土易开裂的难题。The central pylon Z4 of main navigation channel bridge of Maanshan Changjiang River Rail-cum-Road Bridge is a spatial A-shaped steel-concrete composite structure that has four legs,every two legs standing oppositely to each other along the bridge width are connected by a lower crossbeam,and there are three tie beams in between the two lower crossbeams.No crossbeams are installed between pylon legs along the bridge length.The lower crossbeams were cast in layers on ground scaffolds that consists of steel tubes and are fitted with a formwork system.Numerical simulation was conducted to compare and optimize the layered casting plans of the lower crossbeam,and the selected plan was to cast the concrete in two layers of 2.5 m(upper layer)and 5.5 m(lower layer)thick,and the upper and lower layers were in turn divided into two and three blocks to facilitate the casting.A series of measures were taken to effectively control the cracking of the inverse arc interface of lower crossbeam and pylon legs as well as the concrete body of the lower crossbeam,including sustaining an environment with minor temperature variation,using C60 concrete that is easy to be pumped and highly cracking resistant,optimizing the inverse arc connection between lower crossbeams and pylon legs and the joints between concrete blocks,streamlining the construction process and casting organization of the lower crossbeams and tie beams,adopting intelligent concrete temperature monitoring,and choosing appropriate timing of prestressing tendons tensioning.

关 键 词：斜拉桥 钢-混组合塔 下横梁 施工支架 分层分块浇筑法 混凝土防裂措施 施工技术 

分 类 号：U448.27[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] U445.4