响堂铺2号大桥钢槽梁顶推施工导梁落梁方案分析

科学的导梁落梁方案，对于确保钢桥安全顶推施工具有重要意义。响堂铺2号大桥采用步履式顶推施工法，下侧临时支架为非对称式布置。为确保主梁跨线施工的安全性，采用MIDAS/Civil有限元软件建立钢桥的顶推模型，通过前一施工阶段监测数据验证数值模型，在此基础上以顶推过程中主梁应力分布为参照标准，对比两种施工落梁方案，确定最优的导梁落梁方案。研究结果表明，三跨钢桥顶推施工中，导梁落梁应分阶段落梁，第一阶段一次性落梁，第二阶段分布式落梁；非对称式支架落梁时，各阶段中结构峰值应力多集中于导梁根部桁架处，导梁应有加固处理与实时监测等预防措施。

Guide Beam Falling Scheme of Steel Channel Beam Jacking Construction

Scientific guide beam falling scheme is of great significance to ensure the safety of steel bridge jacking construction. Xiangtangpu No.2 Bridge adopts walking jacking construction method, and the temporary support on the lower side adopts asymmetric arrangement. In order to ensure the safety of incremental launching construction, MIDAS/Civil software is used to establish finite element models for two incremental launching construction schemes respectively. On the basis of the correctness of the finite element model verified by the monitoring data of the preceding construction stage, through the numerical simulation and result comparison of each stage when the guide beam falls, it is found that the selection of the scheme has a great influence on the structural stress value and deflection value. In view of this phenomenon, it is concluded that when the guide beam falls on the asymmetric temporary support, the first stage should choose the construction scheme of large cantilever one-time jacking, and the second stage should choose the construction scheme of step-by-step falling beam. Through this kind of staged and different falling beam schemes, the structural internal force and the risk of falling beam can be effectively reduced. Compared with the field data, the stress value and deflection value of the main beam structure calculated by the model are basically consistent with the measured values obtained from the construction site, and the errors are also within a reasonable range. It not only proves the reliability of the finite element model and the rationality of on-site monitoring, but also saves time for the project to improve its time efficiency while ensuring the safe construction of the bridge. It also provides a theoretical basis for future related guide beam falling, numerical simulation and on-site monitoring.