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21世纪以来,地铁作为一种城市快捷交通方式,获得了快速发展。地铁沿线成为地产开发的首选区域,越来越多的基坑工程出现于已建地铁隧道上方。基坑开挖将引起开挖面下一定范围土体产生卸荷回弹,使坑底已建地铁隧道上浮。因此,合理选择控制下方地铁隧道变形的设计、施工工艺,保证地铁安全,成为工程界必须解决的课题。以天津西站北广场上穿工程基坑开挖为背景,利用有限元分析软件ABAQUS分析了考虑时空效应的限时、分块开挖,以及抗拔桩、地基加固等措施以减小下部隧道变形的效果。对比发现数值模拟与理论计算结果基本一致,分析方法和结果可为类似工程提供有益的借鉴。
Since the 21st century, the subway has gained rapid development as an urban express transportation mode. Subway along the line become the preferred area for real estate development, more and more foundation pit project appeared in the subway tunnel has been built above. Foundation excavation will cause a certain range of excavation under the soil to produce unloading rebound, so that the bottom of the subway tunnel has been built floating. Therefore, a reasonable choice to control the deformation of the subway tunnel design, construction technology, to ensure the safety of the subway, the engineering community must be addressed. Taking the excavation of engineering pit in the north square of Tianjin West Railway Station as the background, finite element analysis software ABAQUS was used to analyze the time-limited, block excavation considering the time-space effect and the measures of anti-pile and foundation reinforcement to reduce the deformation of the lower tunnel Effect. The results show that the numerical simulation and the theoretical calculation are basically the same, and the analysis methods and results can provide useful reference for similar projects.