城市轨道交通新建路基对邻近既有桩筏结构路基水平变形的影响
王长丹散骞骞王炳龙周伟陈凯祥
Influence of Newlyconstructed Urban Rail Transit Subgrade on Horizontal Deformation of Adjacent Existing Pileraft Structure Subgrade
WANG ChangdanSAN QianqianWANG BinglongZHOU WeiCHEN Kaixiang
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作者信息:1.同济大学道路与交通工程教育部重点实验室， 201804， 上海
2.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:The Key Laboratory of Road and Traffic Engineering of the Ministry of Education, Tongji University, 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.2023.12.007
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中图分类号/CLCN:U213.1+5; U238
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栏目/Col:研究报告
摘要:
目的：城市轨道交通新建线路并行或接轨既有线路时，往往需要在邻近既有线路新建路基。新建路基的加载会产生地基附加应力，这将导致土体发生沉降及水平位移，从而使得既有线路路基发生变形，同时可能会造成既有线路基发生后续固结变形，进而危害列车运营安全。因此，需要研究邻近既有线路新建路基对既有城市轨道交通桩筏结构路基水平变形的机制和主要影响因素，以保障轨道交通路基建设的安全。方法：以软土地区某邻近新建线路路基工程既有城市轨道交通线路桩筏结构路基为例，采用有限元数值模拟与离心模型试验的方法，研究新建路基加载对邻近既有路基水平变形的影响。结果及结论：在新建路基荷载作用下，邻近地层水平位移随地层深度先增大后减小，其最大值发生在地表以下4 m位置。新建路基与既有路基相邻坡脚间的地层水平位移同距既有路基坡脚距离呈指数关系递增。在邻近加载作用下，既有路基各排桩均向背离新建路基方向产生水平偏移，水平变形量值随着与邻近加载距离增大以及深度的增大而减小，水平变形差异主要位于上中段桩体。靠近加载位置桩基可以有效地阻拦邻近加载在地基中产生的水平土压力和水平位移的发展。
Abstracts:
Objective: When newlybuilt urban rail transit lines are parallel or connected to existing lines, it often necessitates the construction of a new subgrade adjacent to the existing line. The loading of the new subgrade will generate additional stress on the foundation, causing deformation and horizontal displacement of soil mass, which may result in existing line subgrade deformation and then the subsequent consolidation deformation, posing a risk to the safety of train operation. Therefore, it is crucial to study the mechanism and main influencing factors of existing urban rail transit pileraft structure subgrade horizontal deformation caused by the construction of adjacent existing line newlybuilt subgrade, to ensure the safety of rail transit subgrade construction.Method: Based on the pileraft structure subgrade of an existing urban rail transit line adjacent to the newlybuilt subgrade project in soft soil area as example, the influence of adjacent newlybuilt subgrade loading on the horizontal deformation of existing subgrade is studied by using finite element numerical simulation and centrifugal model test.Result & Conclusion: Under newlybuilt subgrade loading, the horizontal displacement of adjacent strata first increases and then decreases with the depth of strata, and the maximum value occurs at 4 m below the surface. For the newlybuilt subgrade and existing subgrade slope toes, the horizontal displacement of adjacent strata between them increases exponentially with their distance. Under the action of adjacent loading, each row of piles of in the existing subgrade experiences horizontal displacement away from the newlybuilt subgrade. The magnitude of horizontal deformation decreases with increasing distance from the adjacent loading and the depth, with the main differences in horizontal deformation occurring in the upper and middle sections of the pile body. Pile foundations near the loading point can effectively inhibit the development of horizontal earth pressure and horizontal displacement caused by adjacent loading in strata.
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