基于蠕变模型下隧道围岩蠕变变形规律研究

发布时间：2018-01-19 06:20

本文关键词： 隧道蠕变变形有限差分数值模拟新奥法　出处：《河北工程大学》2014年硕士论文　论文类型：学位论文

【摘要】：随着我国公路工程的快速发展，在软岩状况下修建的公路隧道越来越多，新奥法施工在软岩隧道修建中具有很大的优势，其认为围岩具有一定的承载能力，能够和支护结构协同工作，，形成共同的载体，既允许围岩存在一定的变形，从而最大限度的发挥围岩的自承能力，而合理的二次衬砌支护时机可以充分的调动支护体系，是新奥法施工成功的关键。在软岩状态下的修建隧道及地下工程时，围岩及支护结构应力和应变相对复杂，并变现出和时间有着很大的关系，具有较大的流变性，所以在软岩地区进行新奥法设计施工时不能仅仅采用弹塑性理论进行描述。本文以分水岭隧道为背景依托，在复变理论与保角变换相结合的基础上，引用了复杂隧洞断面任一点的位移表达式，从而结合现场监测数据反演得到分水岭隧道的burger模型参数。采用FLAC3D有限差分软件，在隧道开挖中考虑岩石的蠕变作用，分析了开挖后隧道的弹塑性变化，以及蠕变作用下隧道围岩、支护结构的应力和应变变化规律，并假定在不同时刻施加二次衬砌，分析隧道结构的变化情况，从而结合规范要求确定了分水岭隧道最佳二次衬砌时机。在burger模型基础上分析了隧道建成100年内围岩蠕变变化情况，以及二次衬砌在蠕变作用下的受力状态，从而得到隧道周围应力场和位移场分布规律。结果表明随着时间增长，隧道围岩逐渐趋于均匀化，但在洞口拱脚处出现应力集中现象，二次衬砌内拱脚部位弯矩和轴力也逐渐增大，所以要特别注意拱脚处的监测和加固。
[Abstract]:With the rapid development of highway engineering in China, more and more highway tunnels are built under the condition of soft rock. Can work with the support structure to form a common carrier, both allow the existence of certain deformation surrounding rock, so as to maximize the self-supporting capacity of surrounding rock. And reasonable secondary lining support timing can fully mobilize the support system, is the key to the success of the construction of the new Austrian method. In the soft rock state of the construction of tunnels and underground works. The stress and strain of surrounding rock and supporting structure are relatively complex, and the realization has a great relationship with time, and has great rheology. Therefore, the elastoplastic theory can not be used to describe the design and construction of the new Austrian method in soft rock area. Based on the background of watershed tunnel and the combination of complex theory and conformal transformation, the displacement expression of any point in the section of complex tunnel is quoted in this paper. The parameters of burger model of watershed tunnel are obtained by inversion of field monitoring data. The creep effect of rock is considered in tunnel excavation by FLAC3D finite difference software. The elastoplastic change of tunnel after excavation and the variation of stress and strain of surrounding rock and support structure under creep are analyzed, and the variation of tunnel structure is analyzed on the assumption that secondary lining is applied at different time. The optimal secondary lining time of watershed tunnel is determined according to the specification. On the basis of burger model, the creep change of surrounding rock in 100 years after completion of tunnel is analyzed, and the stress state of secondary lining under creep action is analyzed. The distribution of stress field and displacement field around the tunnel is obtained. The results show that with the increase of time, the surrounding rock of the tunnel tends to be homogenized, but the stress concentration occurs at the arch foot of the tunnel. The bending moment and axial force of the inner arch foot of the secondary lining also increase gradually, so special attention should be paid to the monitoring and strengthening of the arch foot.
【学位授予单位】：河北工程大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U451.2

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