深水大流速倾斜岩面河床不等高双壁钢围堰综合施工技术研究

Research on Comprehensive Construction Technology of Unequal High Double Wall Steel Cofferdam at River Bed with High Velocity and Inclined Surface in Deep Water

以石梯巴河特大桥12#、13#主墩基础双壁钢围堰施工为背景,分析了工程的难点,重点对深水大流速倾斜岩面河床条件下双壁钢围堰的结构设计、安全沉降以及封底混凝土结构设计与施工进行研究。通过采用不等高双壁钢围堰的设计,利用既有栈桥设置双壁钢围堰就位的限位架,结合吊车的使用,成功使不等高双壁钢围堰准确就位;同时运用桩基约束模型,在封底混凝土薄弱区域加强配筋,突破常规的封底混凝土采用素混凝土结构这一理念,减小封底混凝土厚度,节约了混凝土垢工工程量。该项综合技术的使用,施工质量优良,各项指标均满足设计要求,加快了施工进度,节约钢材约40t,节约投资约32万元,取得良好的社会、经济效益,可为类似工程提供参考。

Based on the construction of double wall steel cofferdam for the 12# and 13# main pier foundation of Shitiba River Bridge, the difficulties of the project are analyzed. The structural design, safe settlement and the design and construction of the bottom sealing concrete structure of the double wall steel cofferdam under the condition of the inclined rock surface riverbed with large velocity in the deep water are studied. By adopting the design of double wall steel cofferdam with unequal height, using the limited position frame of the double wall steel cofferdam located in the existing trestle, and combined with the use of the crane, the double wall steel cofferdam with unequal height is successfully placed, and the pile foundation constraint model is used to strengthen the reinforcement in the weak area of the bottom sealing concrete and break through the conventional bottom sealing with plain concrete. The concept reduces the thickness of the bottom sealing concrete and saves the amount of concrete masonry. By using this comprehensive technology, construction quality is excellent, and all the indicators meet the design requirements with speeding up the construction progress, saving about 40 t of steel, retrenching about 320 thousand yuan, and achieving good social and economic benefits. It can provide a reference for similar projects.