盾构隧道开挖斜穿地裂缝的数值模拟分析

摘要

为探索地铁穿越地裂缝时隧道围岩与衬砌结构的变形和应力变化规律,本文以实际工程为基础,通过合理简化土层,采用理想弹塑性模型,通过控制生死单元的方法对盾构隧道进行分步开挖数值模拟.获得施工过程中围岩与衬砌的位移与应力.结果表明,地裂缝是隧道开挖时最危险的部位,对隧道的破坏起决定性作用.在裂缝处围岩洞室沉降出现了较大变化,易造成隧道的坍塌;在地裂缝处隧道两侧围岩与管片衬砌两侧均形成了应力集中,易使隧道洞室侧壁与管片衬砌发生剪切破坏.最后提出了保证地裂缝处围岩稳定性的处理方法,为同类工程提供参考.%Through the numerical simulation method, based on the real engineering background, the soil layer is determined as three layers by reasonable simplification, and the cracks are treated as weak surface.Using the ideal elastic-plastic model, the drucker-prager criterion,and the shield tunnel was excavated and simulated by controlling the life and death unit. The displacement and stress of sur-rounding rock and lining in the construction process are analyzed.The analysis results show that the crack is the most dangerous part of tunnel excavation and play a decisive role in tunnel′s failure. There is a large change in the settlement of the caverns at the cracks,which is easy to cause the col-lapse of the tunnel. The stress concentration is formed on both two sides of the tunnel and the sides of the lining of the tunnel wall,which can cause the shear damage.It is recommended to use the method of preset and increase strength to ensure the stability of excavation, which gives references to the sim-ilar engineering projects.