芜湖长江公铁大桥2号墩围堰气囊法下水设计

为给双壁钢套箱围堰气囊法下水施工组织设计提供理论支撑,以商合杭铁路芜湖长江公铁大桥2号主墩圆端形双壁钢套箱围堰为例,研究双壁钢套箱围堰气囊法下水的设计方法。结合围堰拼装场地地形条件进行坡道与气囊布置并进行后端地笼计算。将围堰下水过程分解为多个工况进行静力计算,在计算过程中考虑气囊受力不均对围堰角度的修正。运用能量守恒原理简便求解围堰下水时的初速度和围堰入水后的漂移长度。采用该方法指导芜湖长江公铁大桥2号主墩围堰下水,过程顺利、可控,证明该方法正确可行。该方法可同时适用于圆形、矩形、哑铃形等各类双壁钢套箱围堰气囊法下水设计。

Design of Airbag Launching for Cofferdam of Pier No.2 of Wuhu Changjiang River Rail-cum-Road Bridge

To find theoretical support for the design and implementation of airbag launching for the double-walled steel box cofferdam,the double-walled steel box cofferdam with round corners for pier No.2 of Wuhu Changjiang River Rail-cum-Road Bridge on the Shangqiu-Hefei-Hangzhou Railway is cited as an example,to study the design methods for airbag launching of the double-walled steel box cofferdam.The slopes and airbags were arranged and distributed to suit the geological condition of the cofferdam assembly yard,and the rear reinforcement cages were calculated.To facilitate the static calculation,the launching process of the cofferdam is detailed into multiple loading conditions.In the calculation process,the effect of uneven load distribution among airbags on the angle modification of cofferdam is considered.The initial launching speed and drifting distance after the cofferdam dipped into the water were gained based on the energy conservation principle.The method has been used to guide the launching of the cofferdam of pier No.2 of Wuhu Changjiang River Rail-cum-Road Bridge.The cofferdam was smoothly launched into the river and the whole process was under control,proving that the method is correct and feasible.The method can be applied to the airbag launching design for double-walled steel box cofferdams of different shapes,including the round,rectangular and dumbbell-shaped ones.