Chengshi guidao jiaotong yanjiu (Jul 2024)
Grouting Reinforcement Method and Application for Existing Piles in Open-excavation Tunnel Under-passing Bridge Engineering
Abstract
Objective When constructing a new tunnel under-passing bridge with open-excavation method, it is crucial to protect the existing pile foundation system within the excavation pit. In the project of South Hubin Road Tunnel under-passing Guangqing Highway Bridge, the foundation pit excavation leads to the exposure of existing bridge piles, affecting the bridge overall stiffness and causing pier settlement. Grouting reinforcement is proposed to stabilize the pit bottom and the pile surrounding. It is aimed to investigate the impact of variation in the grouting reinforcement range (thickness and width) on bridge deformation. Method Using finite element software Midas GTS for three-dimensional modeling, the bridge pier top displacement and the axial force distribution along the pile shafts are compared under different grouting reinforcement ranges. The impact of changes in grouting reinforcement width and thickness around the piles on bridge deformation, and the effect of improving pile bearing capacity are analyzed. Based on numerical calculation results and deformation control requirements, a construction reinforcement plan is formulated, and the pier abutment settlement is monitored on-site during tunnel construction. Result & Conclusion Grouting reinforcement around the piles can effectively compensate for the loss of friction pile side friction resistance, improving the load transfer efficiency in the reinforced section and better distributing the load from the superstructure. Increasing the thickness of reinforcement around the piles can significantly improve pier top settlement and differential settlement between adjacent piers. On-site monitoring of tunnel grouting reinforcement construction shows that both bridge settlement deformation and differential settlement meet the control requirements.
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