摘要
沪通长江大桥主航道桥为（140＋462＋1 092＋462＋140）m双塔连续钢桁梁斜拉桥,29号主墩采用沉井基础,沉井顶平面尺寸为86.9m×58.7m、高115m。由于29号主墩位处粉砂层较厚,水流作用下这部分泥砂易被冲刷,对沉井着床过程中的局部冲刷大,为确保沉井平稳安全着床,对29号主墩位处河床进行预防护。29号主墩河床预防护体系包括反滤层、防护层和棱体结构,其分别由1-6mm、3-10cm和6-10cm级配的碎石组成,抛填高度分别为1,1,2m;其中防护层抛填范围由沉井壁向外延伸25m。现场河床预防护抛填施工时,根据抛填试验确定的虚拟网格图,采用定位船、抓斗船、料斗及导管等设备进行定点抛填,先抛填反滤层,再抛填防护层和棱体结构。采取预防护技术后,29号主墩河床防冲刷效果明显,沉井着床定位后,沉井平面位置和姿态基本未发生变化。
The main ship channel bridge of the Hutong Changjiang River Bridge is a double-pylon continuous steel truss girder cable-stayed bridge with span arrangement（140＋462＋1 092＋462＋140）m.The foundation for the main pier No.29 of the bridge is the open caisson,the dimensions of the caisson top are 86.9m×58.7mand the caisson height is 115 m.Because the silty sand stratum at the pier is deep and the stratum is prone to scouring under the action of water current,the local scouring of the riverbed at the pier in the process of landing the caisson onto the riverbed can be severe.To ensure that the caisson could be stably and safely landed onto the riverbed,the riverbed was hence pre-protected.The pre-protection system for the riverbed included the inverted filter layer,protection layer and prism structure,respectively composed of the 1-6mm,3-10cm and 6-10cm grading crushed stones and the riprapping depth is respectively 1,1and 2m,of which the riprapping range of the protection layer extended 25 moutwards from the caisson wall.At the time the riverbed was pre-protected by the riprapping,the virtual grids were determined according to the riprapping tests,the positioning barge,grab barge,material hoppers and ducts were all used to riprap at the fixed points.The inverted filter layer was riprapped first,the protection lay was then and the prism structure was finally.With the application of the riverbed pre-protection technique,the protection effect of the riverbed at the pier was evident and after the caisson was landed onto the riverbed and positioned,the plan position and posture of the caisson almost had no changes.
出处
《桥梁建设》
EI
CSCD
北大核心
2015年第6期84-88,共5页
Bridge Construction
基金
中国铁路总公司科技研究开发计划项目(2013G001-A-2)~~
关键词
公路铁路两用桥
斜拉桥
沉井
冲刷
反滤层
防护层
抛填施工
桥梁施工
rail-cum-road bridge
cable-stayed bridge
open caisson
scouring
inverted filter layer
protection layer
riprapping construction
bridge construction
