摘要
宜昌伍家岗长江大桥主桥为主跨1160 m的双铰钢箱梁悬索桥。该桥江南侧锚碇处基岩埋深较深,地下水位较高,采用直径为85 m的浅埋式扩大基础,持力层为中粗砂卵砾石,高15 m。基坑采用放坡开挖+咬合桩相结合的支护方案,咬合桩嵌入中风化岩层不小于3 m。基底以下设50 cm厚混凝土垫层,为降低基础不均匀沉降对桥梁结构的影响,基底采用钢管法注浆与原土体形成复合地基。结合项目建设条件对江南侧锚碇基坑开挖支护结构、地基承载力、地基沉降进行验算,结果均满足规范要求。所采用的锚碇基础及地基设计方案,较大程度降低了施工难度、缩短了施工工期、节省了工程造价,具有较好的经济效益和社会效益。
The main bridge of Wujiagang Changjiang River Bridge in Yichang is a two-hinge steel box girder suspension bridge with a main span of 1160 m.At the site of the south anchorage,the deep bedrock and high ground water level restrict the selection of the foundation types.The adoption of a shallow foundation,specifically a tailored 85-m diameter spread foundation,was finally determined,which could take advantage of the 15-m deep bearing stratum of medium coarse gravels.The foundation pit was excavated by sloping,assisted by secant piles shoring system.The driven depth of the secant piles into the moderately-decomposed rocks should be over 3 m.The foundation base is fitted with a 50 cm-thick concrete cushion.To reduce the influence of uneven settlement of foundation on the bridge structure,the foundation base was grouted via steel pipes to compositely act with the surrounding soil.The shoring system for the excavation of foundation pit as well as the bearing capacity and settlement of the ground were computed,which were all proved meeting the requirements.The type of foundation selected and the subgrade design facilitated the construction,shortened the construction time and saved costs,leading to good economic and social benefits.
作者
肖德存
王碧波
易伦雄
王凌鹏
XIAO De-cun;WANG Bi-bo;YI Lun-xiong;WANG Ling-peng(China Railway Major Bridge Reconnaissance&Design Institute Co.,Ltd.,Wuhan 430050,China)
出处
《桥梁建设》
EI
CSCD
北大核心
2021年第5期95-100,共6页
Bridge Construction
基金
中国中铁股份有限公司科技研发开发计划项目(2015-重点-50)。
关键词
悬索桥
锚碇
浅埋式扩大基础
放坡开挖
咬合桩
持力层
地基沉降
复合地基
suspension bridge
anchorage
shallowly-buried spread foundation
sloping in excavation
secant pile
bearing stratum
foundation settlement
composite foundation
