盾构隧道下穿软弱土层既有人行天桥桩基设计探讨

Discussion on Design of Shield Tunneling under Pile Foundation of Existing Footbridge in Weak Soil Layer

摘要:

地铁盾构隧道下穿软弱土层既有人行天桥钢筋混凝土桩基，设计中采用扩大基础对人行天桥桩基进行被动托换，同时在有限的桥下空间采用松木桩加固扩大基础底部软弱土层，结合加强盾构管片配筋、设置地面临时托换支架等措施，确保盾构机直接切削桩基通过后，地面天桥满足正常使用条件、高含筋量混凝土管片的强度及刚度均满足要求。该综合处理方式避免了人行天桥的拆除和二次新建，产生了显著的经济及社会效益。

Abstract:

In the design of the subway shield tunneling under the reinforced concrete pile foundation of the existing footbridge in weak soil layer, the passive underpinning is carried out for the pile foundation of footbridge by expanding the foundation, and at the same time, the pine pile is used to reinforce the weak soft layer at the bottom of the expanded foundation in the limited space under the bridge. Combined with the measures of strengthening the reinforcement of shield segment and setting up the temporary ground underpinning support, After the shield machine directly cuts the pile foundation for tunneling, it is ensured that the ground footbridge meets the normal use, and the strength and rigidity of high-reinforced concrete segment all meet the requirements. The integrated treatment method avoids the demolition and secondary construction of the footbridge, and has great economic and social benefits, which provides a good reference for similar projects.