钻孔灌注桩开挖对紧邻既有桥梁影响研究

Study on the influence of bored pile excavation on the adjacent existing bridge

舟山市新城大桥改扩建工程新建提篮拱桥紧邻既有桥,由于钻孔灌注桩与既有桥桩基最近距离仅为6.3 m,为研究钻孔灌注桩开挖对既有桥桩基变形的影响,在钻孔灌注桩开挖过程中对既有桥的变形进行监测,并结合有限元对钻孔灌注桩开挖过程进行仿真模拟。实测数据分析表明:对于单根钻孔灌注桩开挖和多根钻孔灌注桩同时开挖这2种工况,测点横向位移最大值分别为1.96 mm和3.26 mm,纵向位移最大值分别为1.70 mm和2.57 mm,钻孔灌注桩开挖过程中除需考虑开挖带来的影响外,还应该考虑既有桥周围环境如台风、人群和车辆荷载的影响。数值计算结果与实测数据吻合较好,开挖不影响既有桥的正常运营,变形监测和数值计算为现场开挖提供了重要指导。本研究成果可为类似工程提供参考。

The newly-built basket arch bridge of the Zhoushan New Town Bridge reconstruction project is next to the existing bridge.The nearest distance between the bored pile and the existing bridge pile foundation is only 6.3 m.In order to study the influence of the excavation of the bored pile,the deformation of the existing bridge was monitored,and the finite element method was used to simulate the excavation of the bored pile.The analysis of the measured data shows that,the maximum lateral displacement of the measuring point is 1.96 mm and 3.26 mm,and the maximum longitudinal displacement is 1.70 mm and 2.57 mm respectively for the two conditions of single bored pile excavation and multiple bored pile excavation.In addition to the effects of excavation,the surrounding environment of the existing bridge such as typhoons,crowds and vehicle loads should be considered during the excavation of bored piles.The numerical calculation results are in good agreement with the measured data,and excavation does not affect the normal operation of the existing bridge,Deformation monitoring and numerical calculations provide important guidance for site excavation.The research results can also provide reference for similar projects.