长距离并行基坑施工对临近地铁隧道的影响

杨鹏

中铁工程设计咨询集团有限公司济南设计院，山东 济南  250001

摘要：为研究长距离并行基坑施工对临近地铁隧道的影响，以济南市历下区某临近地铁隧道施工的基坑项目为依托，采用有限差分软件FLAC^3D建立三维模型，分析基坑施工过程中引起的地铁隧道竖向、水平向位移及应力变化，并将分析结果与现场监测结果进行对比。结果显示：随着电力沟基坑逐步开挖，盾构管片顶部开始产生隆起变形，管片竖向应力迅速增大，当开挖至坑底时，盾构管片顶部的最大竖向位移为2.67 mm，且在地铁隧道拱肩位置处产生应力集中，最大压应力为2.29 MPa，管片最大水平位移为1.84 mm；当基坑回填后，管片竖向和水平变形均有所减小；污水管基坑和雨水管基坑施工对地铁隧道的影响较小。基坑施工对地铁隧道的影响均在安全控制标准范围内。

关键词：长距离并行基坑；盾构隧道；位移；应力；FLAC^3D

Influence of long-distance parallel foundation pit construction onnearby subway tunnels

YANG Peng

Jinan Design Institute ,China Railway Engineering Consultants Group Co.,Ltd., Jinan 250001,China

Abstract:To study the influence of long-distance parallel foundation pit construction on nearby subway tunnels, large-scale finite difference software FLAC^3Dis applied to establish a model based on the construction of a foundation pit project near the subway tunnel in Lixia District, Jinan City. The vertical and horizontal displacement and stress changes during the whole process of foundation pit construction are analyzed, then the results are compared with the field monitoring data. The results show that with the partial excavation of the power ditch foundation pit, the top of the shield segment begins to heave, and the vertical stress of the segment increases rapidly. When the excavation reaches the bottom of the pit, the maximum vertical displacement of the top of shield segment is 2.67 mm. When the stress concentration occuring at the shoulder of the subway tunnel, the maximum compressive stress is 2.29 MPa, and the maximum horizontal displacement of the segment is 1.84 mm. When the foundation pit is backfilled, the vertical and horizontal deformation of the segment are reduced. The construction of sewage pipe foundation pit and rainwater pipe foundation pit has relatively small impact on the subway tunnel. The impact of the foundation pit construction on the subway tunnel is within the scope of safety control standards.

Keywords: long-distance parallel foundation; shield tunnel; displacement; stress;FLAC^3D