大西客运专线岔口河特大桥(48+80+48)m连续梁施工线形控制技术

Linearity Control for the Construction of Continuous Girders of the Super-large Bridge with Spans(48+80+48)m on Datong-Xi'an PDL

采用悬臂浇筑法施工的大跨度预应力混凝土连续梁,由于箱梁在悬臂浇筑施工时受梁体自重、温度变化等因素影响而产生挠度,混凝土自身收缩、徐变也会使悬臂段线形发生变化。为使合龙后的桥梁成型及应力状态符合设计要求,达到合龙高程误差控制在(-5 mm,+15 mm)以内的要求,进行观测控制以便在施工中及时调整有关参数,为下节的模板安装提供数据预报,确定下节段模板高程,调整中线位置。结合大西客运专线岔口河特大桥跨G309国道(48+80+48)m连续梁工程施工实例,重点对悬臂浇筑连续梁线形控制进行了阐述。

Cantilever laying method is normally adopted for large-span prestressed concrete continuous beams.Because of the concrete dead weight and temperature variation,the girders deflect in the laying process.In addition,concrete shrinkage and creep also cause the change in linearity of the cantilever section.In order to make the closures of girders meet the design requirements with the closure elevation errors in the range of-5 mm to ＋15 mm,observation control can adjust elevation parameters in time,providing data forecast for the next section＇s template erection,to determine the template elevation of the next section and adjust the middle line.Based on Datong-Xi＇an passenger dedicated line Chakouhe river bridge continuous girders crossing G309 national highway with spans（48＋80＋48） meters,this paper explains the linearity control of continous girders by cantilever laying method.