节段梁整孔拼装过程中大悬臂盖梁变形-内力双预控技术

Deformation and internal force double control technology for long cantilever crosshead during span erection

目前城市轨道越来越多采用节段拼装施工工艺,该工艺能够最大限度地不影响交通,减少了混凝土收缩徐变。同时,节段预制工厂化操作执行安全便捷,利于施工质量控制。施工进度快,桥梁下部结构和节段预制便能同时进行,较支架现浇法大大缩短了施工周期。但在城市施工中,不可避免出现跨越既有线路或河流等障碍物,需增加跨距越过障碍物,而这通常受到架桥机性能限制,需要采用其他方式架设,导致施工成本增大。若通过加长盖梁悬挑长度,使净跨距在架桥机架设工况内,则会大大降低施工成本。但由于架桥机站位于悬挑盖梁端部,对墩柱抗弯变形要求高,需增加临时措施,防止施工荷载对永久结构的不利影响。

Now more and more viaducts adopt segment erection in city.This method statement can not only not affect the traffic,but also reduce shrinkage and creep of segment.At the same time,segment casting in precast yard is more safety and convenient during operation,which is propitious to construction quality control.The construction progress is fast,the substructure and segment prefabrication of the bridge can be carried out at the same time,and the construction period is greatly shortened compared with the cast-in-place support method.But in urban construction,it can't avoid to across the road or rail or rivers and need increase the span to across the barrier,which limited by the performance of the bridge erecting machine and requires other erection methods,leading to the increase of construction costs.If the net span is in the erection condition by lengthening the cantilever length of the cover beam,the construction cost will be greatly reduced.However,because the bridge erecting machine station is located at the end of the cantilevered cover beam and requires high deformation resistance of the pier column,temporary measures should be taken to prevent the adverse effect of construction load on the permanent structure.