上承式坦拱桥台后“预顶”的设计研究

Design Research on the Pre-pushing behind Abutment of Top-Bear Arch Bridge

针对上承式坦拱桥台后存在较大水平推力而影响该类桥型应用发展的问题,对台后抗推体系进行研究,通过具体工程项目进行科研试验。依托的工程项目为五跨连续钢筋混凝土上承式坦拱桥,拱桥矢跨比均采用1/10。施工阶段在桥台承台及台后阻滑板之间利用千斤顶施加"预顶"力,使桥台桩向河心侧"预偏"、阻滑板向台后"预位移",同时改善拱圈受力性能、群桩抗水平推力能力以及减小阻滑板后期位移。通过采用了台后"预顶"技术以及桩周土二次注浆工艺,有效解决了在软弱地基上修建上承式坦拱桥水平推力大、位移大的难题,经工程实践和试验检验效果显著,为同类工程提供有益的参考。

The paper analyzed and researched the anti-thrust system behind abutment according to the problem of the influence on the application and development of such a type of bridge,for the larger horizontal pushing force behind the abutment of deck arch bridge,and this paper was based on the actual project of a five-span continuous reinforced concrete Top-Bear arch bridge,rise-span ratio 1/10.It was applied the prepushing force using jack between the abutment pile cap and the antislider behind abutment in the stage of construction,in order to make the abutment piles＇ riverheart pre-bias and the antislider pre-displacement behind abutment,so that this improved the arch ring mechanical behavior,pile group resistance to horizontal thrust and reduce the late displacement of the antislider.Through the use of pre-pushing technique behind abutment as well as secondary grouting process of soil around pile,the problem,which was the larger horizontal pushing force and displacement for building the Top-Bear arch bridge on soft foundation,was effectively solved,and The engineering practice and the experiment test effect is remarkable and provides a beneficial reference to similar projects.