邻近高速铁路桩板路基的轨道交通基坑隔离桩参数优化分析
何舒琦王炳龙项瑞聪
Optimization Analysis of Isolation Pile Parameters for Rail Transit Foundation Pits near High-speed Railway Pile-slab Subgrade
HE ShuqiWANG BinglongXIANG Ruicong
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作者信息:上海市轨道交通结构耐久与系统安全重点实验室， 201804， 上海
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Affiliation:Shanghai Key Laboratory of Rail Infrastructure Durability and System Safety, 201804, Shanghai, China
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关键词:
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Key words:
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DOI:10.16037/j.1007-869x.20230469
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中图分类号/CLCN:TU473.1+2; U443.16+1
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栏目/Col:土建工程
摘要:
［目的］邻近高速铁路路基的深基坑施工会对既有路基结构产生不利影响。在基坑外侧设置隔离桩作为工程实践中常用的防护加固措施，可以有效控制基坑开挖引起的周边环境变形。因此，研究隔离桩设计参数对基坑变形控制效果的影响具有重要意义。［方法］依托上海轨道交通市域线机场联络线1号风井基坑工程，通过有限元软件进行数值模拟，选取隔离桩桩长、与地下连续墙距离、桩间距、桩径以及桩身刚度等5个关键设计参数，采用正交试验设计方法构建18种工况组合，以隔离桩对高速铁路桩板路基的承载板水平位移、承载板沉降、桩顶水平位移的控制效率，以及对高速铁路桩板路基的桩基水平位移最大值的放大效率作为评价指标，定量分析各设计参数对路基变形指标的影响，并提出隔离桩设计参数优化建议。［结果及结论］隔离桩能有效控制路基浅层桩基的水平位移，同时也会放大深层桩基的水平位移；隔离桩与地下连续墙距离对各评价指标的影响程度均较大，在保证邻近高速铁路路基安全的前提下，应适当增加隔离桩与地下连续墙距离。
Abstracts:
［Objective］ Deep foundation pit construction adjacent to high-speed railway subgrades can adversely affect the stability of existing subgrade structure. As a commonly used protective reinforcement measure in engineering practice, isolation piles installed outside the foundation pit can effectively control the deformation of the surrounding environment caused by foundation pit excavation. Therefore, studying the influence of isolation pile design parameters on foundation pit deformation control is of great significance. ［Method］ Based on the construction of No.1 ventilation shaft excavation for Shanghai Suburban Railway Airport Link Line, numerical simulations are conducted using finite element software. Five key design parameters are selected including isolation pile length, distance from the underground diaphragm wall, pile spacing, pile diameter, and pile stiffness. An orthogonal experimental design method is employed to construct 18 working condition combinations. The control efficiency of isolation piles on the horizontal displacement and settlement of high-speed railway pile-slab subgrade bearing slabs, as well as the horizontal displacement of pile top, and the amplification efficiency of the maximum horizontal displacement of the above pile-slab subgrade piles are used as evaluation indicators. The influence of each design parameter on subgrade deformation is quantitatively analyzed, and optimization recommendations for isolation pile design parameters are proposed. ［Result & Conclusion］ Isolation piles can not only effectively control the horizontal displacement of shallow subgrade pile foundation, but also amplify the horizontal displacement of deep subgrade pile foundation. The distance between isolation piles and underground diaphragm wall significantly affects all evaluation indicators. To ensure the safety of adjacent high-speed railway subgrade, it is recommended to appropriately increase the distance between isolation piles and underground diaphragm wall.
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