既有隧道改造为地铁的施工力学效应研究

Research on Mechanical Behavior of Construction in Transforming the Existing Tunnel into Subway

研究目的:哈尔滨利用既有人防隧道工程改造为地铁在我国尚属首次,隧道的改造采用了单侧扩挖与双侧扩挖的施工方式,结合数值分析与现场监测,对施工过程中的应力分布状态与拱顶、地表沉降状况展开研究,为隧道的安全施工提供理论指导和决策依据。研究结论:结合现场结构和施工工艺,借助监控量测和数值模拟手段,分析了施工过程中应力场的分布与地表沉降规律,得到以下结论:(1)单双侧扩挖施工造成的地表、拱顶沉降小于规范要求,证实施工方法是合理的;(2)应力最大值的出现位置:单侧扩挖出现在破除边墙的一侧靠近拱顶部位(最大值为2.65 MPa),双侧扩挖出现在破除边墙处和仰拱边墙交界处(最大值达到2.79 MPa);(3)单侧扩挖与双侧扩挖对隧道结构的沉降影响有明显的差异,具体表现在结构的最大沉降值及产生部位均有不同;(4)通过对比发现,两种施工方法对地表沉降的变化影响不大;(5)该研究成果能够为城市地铁建设积累经验,对类似项目的施工具有较高的指导价值。

Research purposes： It is the first attempt in our country to transform the existing civil air defense engineering into subway. Unilateral and bilateral excavation are being used in the reconstruction of the original tunnel. In order to provide theoretical guidance and decision - making basis for the tunnel construction safety, combined with numerical analysis and field monitoring, we study the stress distribution and arch, surface settlement status in the whole progress. Research conclusions： Based on the structure, construction technology, monitoring, measurement and numerical simulation, we analysis the distribution of stress field and the law of surface settlement in the construction process, and get the following conclusion ： （ 1 ） The surface and vault settlement caused by unilateral or bilateral excavation is less than the standard, so it is reasonable construction procedure. （2）We discussed the phenomenon of stress concentration in the process of implementation of two kinds of construction methods, and determined the corresponding location of the maximum stress occurs. （3） It has significant differences on the settlement of tunnel structure which mainly performs in the position of the maximum settlement value occurs. （4） The study found, by contrast, that the construction method has little influence on the change of surface settlement. （5） So the research results can accumulate experience for the city subway construction and provide higher guidance value to the similar projects.