软土深基坑施工对邻近地铁的影响与有限元分析

The impact of soft soil deep foundation pit construction on adjacent metro and its finite element analysis

随着城市化进程的加速发展,杭城地铁网覆盖越来越广泛,已延伸至周边区县,在设计和施工方面对处在地铁保护范围内的工程建设项目提出了更高的要求,特别是在地下室施工阶段,如何安全高效地完成地下室的开挖和回填显得尤为重要。本文介绍了杭州市富阳城区内的一个深基坑项目,周边环绕着地铁隧道盾构区间、城市道路、居民小区,分布着各类城市管线,周边环境很复杂,同时基坑开挖面处于深厚软土地层,开挖时对周边地铁盾构区间的影响尤为显著,因此基坑支护设计采用了“围护桩+带伺服预应力型钢支撑”的方案。为了验证该方案的合理性,在项目施工完成后对地铁隧道盾构区间内的隧道结构沉降数据进行了分析,同时通过有限元模拟基坑开挖对地铁隧道的影响,对比隧道结构的水平位移,二者变化结果相近,且均在规范允许范围内。为此,本支护方案可以适用于类似的工程项目,为各位岩土工程师们提供参考借鉴。

With the accelerating urbanization,the coverage of Hangzhou Metro network has become increasingly extensive,extending to surrounding districts and counties.Higher requirements have been put forward in the design and construction of engineering construction projects within the protection scope of the subway,especially in the basement construction stage.It is particularly important to ensure the safety and efficiency in excavation and backfilling of basement.This article introduces a deep foundation pit project in the urban area of Fuyang District,Hangzhou City.The surrounding environment is complex,featuring metro shield tunneling sections,urban roads,residential communities,and various urban pipelines.The excavation surface of the foundation pit is also located in a deep soft soil layer,making the impact on the adjacent metro shield tunnel sections particularly significant.Therefore,the foundation pit support design here adopted a support system scheme of“retaining piles+servo prestressed steel support”.In order to verify the rationality of this scheme,the settlement data of the tunnel structures within the metro shield tunneling sections were analyzed after the project’s completion.Additionally,finite element simulations were conducted to assess the impact of the excavation on the metro tunnels.The horizontal displacement of the tunnel structure was analyzed,and the results from the field test and numerical simulation were similar,both within the allowable range required by the specifications.Consequently,this type of support scheme can be applied to similar engineering projects,providing a reference for geotechnical engineers.