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城市核心区隧道基坑施工不可避免地对邻近建筑桩基产生影响,特别是桩基位于基坑壁时,基坑施工风险和保护难度更大。渝中连接隧道穿越重庆核心区渝中半岛,其周边高楼林立,明挖段基坑壁紧靠桩基。依托此工程,从技术、经济、社会影响等方面,对桩基托换、地圈梁+扩大基础加固、异形钢板+预应力锚索的桩基加固保护等方案进行了综合分析比较,在传统桩基托换方案无法实施的情况下,提出采用异形钢板+预应力锚索的桩基加固保护方案。通过三维有限元数值模拟,分析了施工过程岩土体位移、桩基变形、桩基应力、钢板与锚索应力等发生和发展规律。结果表明,该保护方案可以有效控制桩基变形和应力,能够确保施工过程建筑物的安全。本项目方案可为类似工程设计施工提供有益借鉴。
The construction of the foundation pit of urban core area inevitably affects the pile foundations in adjacent buildings. Especially when the pile foundation is located on the foundation pit wall, the risk of foundation pit construction and the protection are more difficult. Yuzhong connecting tunnel through the core area of Chongqing Yuzhong Peninsula, its surrounding tall buildings, Ming dug foundation pit wall close to the pile. Relying on this project, from the aspects of technology, economy and social impact, comprehensive analysis and comparison are made on the pile foundation underpinning, the geo-girder + expanded foundation reinforcement and the pile foundation reinforcement and protection of profiled steel plates and prestressed anchor cables. In the traditional Under the condition that the pile foundation underpinning scheme can not be implemented, a scheme of pile foundation reinforcement using profiled steel plate and prestressed anchor cable is proposed. Through three-dimensional finite element numerical simulation, the occurrence and development of rock and soil displacement, pile deformation, pile stress, steel plate and anchor cable stress during construction are analyzed. The results show that the protection scheme can effectively control the deformation and stress of pile foundation and ensure the safety of the building during construction. The project scheme can provide useful reference for similar project design and construction.