钢箱梁顶推法顶推反力对桥墩桩基的影响分析——上海浦东新区某跨线桥工程案例分析

Analysis of the Effect of the Push Force on the Pier’s Piles When Using Incremental Launching Method to Build Steel Box Girder Bridge—A Case Study on an Incremental Launched Bridge in Eastern Shanghai

摘要: 顶推法架设钢箱梁在桥梁建设中广泛应用。但是顶推法会对桥梁下部结构产生巨大的水平反力，而该水平反力往往在设计阶段未予以考虑，而在采用顶推法工艺时又常被忽视，这给工程安全埋下隐患。因此，选择顶推法时，需要采取科学方法全面评估顶推反力对桥梁桩基的影响及其承载能力，确保结构安全。本文针对软土地基上的矮墩直桩情况，提出了桥梁基桩顶推力作用下内力和变形的简化计算方法，并以上海浦东新区创新中路某跨线桥工程作为案例进行了实例验证，同时就计算结果和现场实测结果进行了对比分析。本文可为分析类似工程提供借鉴。

Abstract: Incremental launching method is becoming increasingly popular to build steel box girder. But this method shall often exert huge lateral load, which is usually beyond the consideration of the designer, on the underground structures such as pile foundation on which the sliding tracks are placed. As such, for the safety of its underground structure, it is necessary to wholly appraise the effect of push force on piles before launching. Aiming at pile foundation with low cap at soft ground and based on frame theory, this paper has presented a simplified method to analyse the behaviour of piles subject to lateral load. In the end, as a case history, the foregoing methods are applied in analysing a project of incrementally launched bridge, and a comparison between theoretical calculation and site measurement has been carried out. This simplified method can be a reference for other similar projects.