大跨简支钢箱梁顶推及高位落梁施工关键技术

Key Construction Techniques for Incremental Launching and High Falling Beam of Long‑Span Simply Supported Steel Box Girder

以长沙盼盼路上跨京港澳高速公路立交桥工程为依托,针对其桥下交通繁忙、顶推坡度大、落梁总高度高等难点,提出一种钢箱梁大坡度步履式顶推及高位落梁施工方法。钢箱梁拼装完成后,在预拼场先行施工部分桥面附属设施并配重,随钢箱梁同步顶推,从而减少后期桥上高空作业;在大坡度引桥上方进行钢箱梁顶推施工时,通过后支点循环分级升梁,调整钢箱梁线形;在临时支墩上进行高位落梁时,在钢箱梁底板上设置落梁吊挂系统,采用子、母双重循环方式,通过在步履机搁墩、步履机滑箱和置换墩之间反复“倒顶”,将高位落梁转换为连续分级低位落梁;通过分析各个工序转换时顶推及落梁系统的高程匹配与约束条件,建立适用于一般情况的系统高程计算式,给出合理的参数范围。

Based on the overpass project over Beijing-Hong Kong-Macao Expressway on Changsha Pan-Pan Road,this paper proposed a construction method of large-slope walking-type incremental launching and high falling beam of steel box girder given the difficulties in busy traffic under the bridge,large pushing slope,and great total height of falling beam.After the steel box girder assembly was completed,some bridge deck ancillary facilities were constructed in advance in the preassembly yard and the weight was allocated.The steel box girder was pushed synchronously,thereby reducing the aerial work on the bridge in the later stage.During the incremental launching construction of the steel box girder above the large-slope approach bridge,the alignment of the steel box girder was adjusted by cyclic grading of the rear fulcrum.When high falling beam was carried out on the temporary pier,the drop beam hanging system was set on the bottom plate of the steel box girder,and the child and mother double circulation mode was adopted.The high falling beam was converted into continuous graded low falling beam by repeatedly“top-down”method between the crawler shelf pier,the crawler slider,and the replacement pier.By analyzing the elevation matching and constraint conditions of incremental launching and falling beam systems in each process conversion,this paper established the system elevation calculation formula suitable for the general situation and gave a reasonable parameter range.