超宽钢箱梁自锚式悬索桥顶推施工技术

Incremental Launching Construction Technology for Ultra-wide Steel Box Girder Self-anchored Suspension Bridge

为揭示超宽钢箱梁自锚式悬索桥顶推施工过程中钢主梁及临时墩受力变化规律,确保钢箱梁在顶推施工过程中结构安全性,以海南省琼海市乐城大桥为工程背景,运用MIDAS Civil桥梁专用分析软件,基于背景桥梁的设计构造、顶推施工方案及施工监控方案等,建立超宽钢箱梁顶推施工仿真模型,通过计算分析得到各工况下钢主梁位移及临时墩受力变化规律。分析结果表明:在不同施工工况下,钢导梁根部及钢箱梁最大组合应力的最大值发生在钢导梁处于最大悬臂,接近第一个临时墩时,而最小值则出现在箱梁和钢导梁吊装就位时,钢箱梁受力及线形控制较好;临时墩的支反力始终处于较大幅度的波动状态,在最大支反力工况下临时墩安全性及稳定性满足要求。通过对超宽钢箱梁步履式顶推施工过程进行有限元数值模拟分析并指导实际顶推施工可以保证超宽钢箱梁采用步履式顶推法的合理性。

To reveal the force variation of steel main beam and temporary pier during the top incremental launching construction process of ultra-wide steel box girder self-anchored suspension bridge,and to ensure the structural safety of steel box girder during the top incremental launching construction process,the Lecheng Bridge in Qionghai City of Hainan Province was taken as the engineering background.The MIDAS Civil bridge beam special analysis software was used.Based on the design and construction,top incremental launching construction plan,and construction monitoring plan of bridge,the simulation model for top incremental launching construction of ultra-wide steel box girder was established.Through calculation and analysis,the displacement of steel main beam and the force variation of temporary pier were obtained.The result indicates that under different construction conditions,the maximum combined stress at steel guide beam root occurs when the steel guide beam is in the maximum cantilever.When close to the first temporary pier,the minimum value occurs when the box beam and steel guide beam are lifted in place.The stress and line shape control of steel box beam are good.The support reaction force of temporary pier always fluctuates significantly,and the safety and stability of temporary pier meet the requirements under the maximum support reaction condition.By conducting finite element numerical simulation analysis on construction process of walking top push for ultra-wide steel box girders,and guiding actual top push construction,the rationality of using walking top push method for ultra-wide steel box girders can be ensured.