摘要
池州长江公路大桥主桥为(3×48+96+828+280+100)m混合梁斜拉桥,4号主墩承台位于大堤压浸台的二级台阶迎水斜坡上,临近长江主航道,基坑开挖达10m,大堤侧与临江侧有较大不平衡土压力。针对此难题,通过围堰方案比选,采用锁口钢管桩加内支撑围檩结构围堰,锁口钢管桩采用刚度相对较大的820×10主钢管,钢围檩采用H型钢(沿管桩围堰四周设置2层),围堰结构受力合理。施工时,先安装第一层围檩,以第一层围檩为导向,采用DZ120振动锤施打钢管桩,控制垂直度,优化合龙工艺,完成钢管桩围堰施工。基坑土方开挖前,利用弃土修筑临江侧反压坡道,抵消不平衡土压力。基坑采用分层台阶法开挖,在枯水季节干挖土方。施工监测结果表明,围堰结构安全稳定,大堤结构安全,抗渗性能良好。
The main bridge of Chizhou Changjiang River Highway Bridge is a hybrid girder cable-stayed bridge with spans of 3×48,96,828,280,and 100 m.The pile cap of main pier No.4 is located on the waterfront slope of the second stair of pressure immersion bed of the embankment,close to the main shipping channel of the Changjiang River.The foundation pit was excavated down to 10 m,which exposes to unbalanced soil pressure between the embankment side and water side.To resolve this problem,the cofferdam formed of interlocked steel pipe piles and inner supporting wailing was selected via scheme comparison,which had rational load bearing behavior.The interlocked steel pipe piles are the?820×10 pipes with big stiffness and the steel waling is formed of H-shaped section steel(two layers of waling are installed along the circumference of the steel pipe pile cofferdam).During the construction,the first layer of waling was installed to serve as the guide for the construction of the steel pipe piles that were driven by DZ120 vibration hammer,along which the perpendicularity of the pile was controlled and the closure technique was optimized,till the completion of the construction of steel pipe pile cofferdam.Before the foundation pit excavation,the abandoned soil was used to build the river-side anti-pressure slope to counteract the unbalanced soil pressure.The foundation pit was excavated in layers and stair by stair,in the dry season,without interruption of water.The construction monitoring shows that the cofferdam is safe and stable,the embankment is safe,and the anti-penetration performance of the embankment is good.
作者
苏从辉
尚龙
SU Cong-hui;SHANG Long(Wuhan Bridge and Building Works Supervision Co.,Ltd.,Wuhan 430034,China;The Fourth Engineering Co.,Ltd.,CCCC Second Harbor Engineering Company,Wuhu 241000,China)
出处
《世界桥梁》
北大核心
2018年第5期32-35,共4页
World Bridges
关键词
斜拉桥
深基坑
围堰
锁口钢管桩
围檩
施工技术
cable-stayed bridge
deep foundation pit
cofferdam
interlocked steel pipe pile
waling
construction technique
