双曲拱桥复合套拱加固方法及应用

针对传统双曲拱桥加固存在的新旧混凝土结合受力不明、施工平台搭设复杂等问题,在双曲拱桥下部结构安全储备充足、需更换拱上填料的条件下,提出双曲拱桥复合套拱加固方法,即在原拱圈上新增拱肋、横系梁及加厚拱板,形成框架式受力结构,实现双曲拱桥加固。应用时,首先封闭桥面交通,拆除旧桥面及附属设施、旧拱上填料;其次在裸露的主拱圈上增设主拱肋及横系梁,根据配重需要设置拱背加厚区;然后在主拱圈及新增结构上浇筑轻质拱上填料;最后进行桥面系及附属设施施工。该方法无需拱下支架,对桥下交通影响小,安全性高,不改变桥梁外观,尤其适用于文物桥梁维修改造。在南京长江大桥双曲拱桥S56跨涉铁工程中应用该技术,有效提高了结构承载力和整体性,工期缩短约67%,综合成本降低约26%。

Method to Strengthen Two-Way Curved Arch Bridge by Adding a Composite Cover to Original Arch

The strengthening of the traditional two-way curved arch bridge faces the challenges of unknown load bearing behaviors of the combined new and old concrete and the difficulties in erecting the construction platform.When the safety margin of the substructure of a two-way curved arch bridge is sufficient and the filling material of the arch need to be replaced,a method to strengthen the two-way curved arch bridge by adding a composite cover to the original arch is proposed.New arch ribs and transverse tie beams are added to the original arch ring and the walls of the arch ring are thickened to form a latticed load-bearing structure,so as to realize the strengthening of the two-way curved arch bridge.During the strengthening process,the traffic on the deck is closed first,and the old deck,auxiliary facilities and filling stuff of the old arch are dismantled.Then,main arch ribs and transverse tie beams are added to the exposed main arch ring,and a thickening zone in the arch back should be reserved,according to the condition of the counterweights.Light filling stuff is cast to the main arch ring and the newly-added structure.And the last step is to construct the deck system and auxiliary facilities.By using this method,no scaffoldings are needed to be built under the arch,with minimal influence on the traffic below the bridge.The method is safe and will not change the appearance of the bridge,which is especially feasible to the retrofit of historical bridges.The method has been used to the S56 span of the two-way curved arch bridge of Nanjing Changjiang River Bridge that crosses railways,the load bearing capacity and integrity of the structure have been effectively improved and the construction time was cut by 67%,and the overall costs were cut by about 26%.