【作者】 朱德武；

【导师】 刘先珊； 刘新荣；

【作者基本信息】 重庆大学 ， 土木工程， 2011， 硕士

【摘要】 随着我国交通建设的快速发展,软岩地区的隧道及地下工程越来越多。由于流变是软岩的重要力学特征,许多软岩隧道大变形都与流变特征有密切关系。目前,进行隧道设计时常采用弹塑性本构模型对隧道围岩进行描述,而实际上软岩隧道具有较明显的流变特性,因此考虑软岩的流变特性对于隧道支护问题具有重要的意义。本文以重庆市桃树垭隧道为依托工程,通过现场监控量测、室内试验研究及数值模拟相结合的方法,探讨施工过程中的大变形灾害,研究了该隧道施工力学特性、初期支护及二次衬砌合理支护时机及考虑时间效应的隧道开挖面空间约束效应。论文的研究工作和成果如下:①针对国内外软岩蠕变特性的资料进行研究,对软岩蠕变试验及影响隧道大变形灾害因素进行总结,并对桃树垭隧道施工期间发生灾害进行分析。②从桃树垭隧道施工现场采取岩样,进行室内单轴压缩试验,从而获得全应力—应变曲线。基于五级加载条件下的单轴蠕变试验,获得了不同加荷等级单轴应变—时间曲线,分析了蠕变曲线随着不同加载应力水平的变化规律。根据蠕变曲线特征来选择蠕变本构模型,并采用Origin7.0软件进行蠕变参数拟合。③根据桃树垭隧道现场状况建立计算模型,分别采用弹塑性本构模型及蠕变本构模型进行模拟分析,结合现场监控量测成果进行对比,选择能较好描述现场围岩变形特征的本构模型。通过FLAC^3D的数值模拟研究,分析并探讨了具有蠕变特性的软岩隧道的初期支护及二次衬砌的合理支护时机。④以FLAC^3D软件作为分析工具,对桃树垭隧道建立三维数值计算模型,进行施工力学行为的模拟,对隧道围岩及支护结构进行分析,并选择一个典型断面的围岩随着开挖面的空间效应及时间效应进行分析,探讨了开挖面的空间约束作用。更多还原

【Abstract】 With the rapid development of traffic construction in our country,tunnel construction and underground engineering is increasing In soft rock area. Because rheological is an important mechanics characteristic of the soft rock,large deformation in soft rock tunnels always has close relationship with the rheological characteristic.At present,In tunnel design the elastic-plastic constitutive model is often adopted to describe surrounding rock,however,the soft rock tunnels have obviously rheological properties In fact. So considering the rheological properties of soft rock has the vital significance for tunnel support problems. This paper relies on the peach-nek-tunnel engineering In Chongqing,disguises the large deformation disaster in the tunnel construction process by the method of combining site monitoring, the indoor experiment and numerical simulation,and researched the construction mechanic characteristics of this tunnel,the reasonable time for the primary support and the second lining and the space constraints effect of tunnel excavation face considering time effect. The research work and results are as follows:①Research the domestic and foreign material of soft rock creep properties,summarized soft rock creep test and the affecting factors of tunnel large deformation disaster,and analyzed the disasters that took place during the peach-nek-tunnel construction.②Drilled rock sample from the peach-nek-tunnel construction site,do indoor rock uniaxial compression test, thus obtained the stress-strain curve. Based on the uniaxial creep test under five loading levels conditions,produced the uniaxial strain– time curve under different loading levels,and analyzed the changing rule of the creep curves with different stress levels of loading. According to creep curve characteristics to choose the creep constitutive model,and adopted Origin7.0 software to fit the creep parameters.③According to peach-nek-tunnel site condition established calculate model, used elastic-plastic constitutive model and creep constitutive model to simulated and analyze respectively, combined site monitoring results contrast to contrast,chose the constitutive model that can describe deformation characteristics of surrounding rock mass from the site closely. Use FLAC^3D software as an analytical tool to analyze and discuss the reasonable supporting opportunity of primary support and secondary lining for soft rock tunnels that have creep characteristics. ④Use FLAC^3D software as an analytical tool to establish the 3D model of peach-nek-tunnel, and simulated the mechanical behavior of the tunnel surrounding rock and support structure during construction period, and select a typical cross section of the surrounding space to analyze the excavation surface effects and time effects, discusses the space constraints effect of excavation face .更多还原