基于非线性破坏准则的盾构隧道开挖面稳定性分析

发布时间：2018-11-10 12:20

【摘要】：盾构施工技术由于对周围环境影响小,而被广泛应用于城市地下工程的施工。在盾构隧道施工过程中,需要通过对开挖面前方土体施加一定的支护压力来保证隧道开挖面的稳定性。因此,如何确定开挖面所需要的极限支护压力成为了确保盾构隧道开挖面稳定的关键问题。目前已有的盾构隧道开挖面稳定性方面的研究大都采用线性破坏准则,但是许多实际工程问题和土工试验数据表明,岩土介质服从非线性破坏准则,而线性破坏准则只是其中的特例。本文基于岩土材料的非线性破坏特征,采用非线性莫尔-库伦破坏准则对盾构隧道开挖面的稳定性开展研究,主要工作内容如下：(1)利用FLAC二次开发平台VC++将非线性莫尔-库伦破坏准则嵌入到FLAC自带的本构模型的源程序中,实现了对FLAC数值模拟软件的二次开发,通过将已有数据和数值计算的结果进行对比,验证了上述研发过程的有效性,同时分析了非线性参数对开挖面极限支护压力的影响；(2)基于退化的非线性莫尔-库伦破坏准则,依据极限平衡理论,利用浅埋隧道开挖面楔形体破坏模型,得到了开挖面极限支护力理论求解公式。选取具体算例,将数值模拟得到的浅埋隧道开挖面极限支护力与极限平衡理论解进行比较,以验证基于非线性莫尔-库伦破坏准则数值模拟结果的正确性；(3)采用线性与非线性破坏准则,通过划定的六个不同超载区以及自定义的超载主要影响区探究了地表超载对隧道开挖面稳定性的影响。最后,结合盾构隧道开挖面失稳实例,应用数值模拟法以及楔形体模型求解开挖面极限支护压力,将求得的极限支护压力数值解和理论解与实测土仓压力进行对比,进一步检验了基于非线性莫尔-库伦破坏准则进行数值求解的可靠性。
[Abstract]:Shield construction technology is widely used in the construction of urban underground engineering because of its small impact on the surrounding environment. In the course of shield tunnel construction, it is necessary to apply certain supporting pressure to the soil in front of excavation surface to ensure the stability of tunnel excavation surface. Therefore, how to determine the limit support pressure of excavation surface becomes the key problem to ensure the stability of excavation face of shield tunnel. At present, most of the existing researches on the stability of excavation surface of shield tunnel adopt linear failure criterion, but many practical engineering problems and geotechnical test data show that the rock and soil medium is based on nonlinear failure criterion. The linear failure criterion is only one of the special cases. In this paper, based on the nonlinear failure characteristics of geotechnical materials, the stability of excavation surface of shield tunnel is studied by using nonlinear Mohr Coulomb failure criterion. The main work is as follows: (1) the nonlinear Mohr-Coulomb failure criterion is embedded into the source code of the constitutive model of FLAC using the FLAC secondary development platform VC, and the secondary development of the FLAC numerical simulation software is realized. The validity of the research and development process is verified by comparing the existing data with the numerical results. At the same time, the influence of nonlinear parameters on the ultimate support pressure of excavated face is analyzed. (2) based on the degenerate nonlinear Mohr-Coulomb failure criterion and the limit equilibrium theory, the solution formula of the ultimate support force of the excavated surface is obtained by using the wedge failure model of the shallow tunnel. In order to verify the correctness of the numerical simulation results based on nonlinear Mohr-Coulomb failure criterion, the numerical simulation results of the ultimate support force of shallow tunnel excavation surface and the limit equilibrium theory are compared. (3) by using the linear and nonlinear failure criteria, the influence of surface overload on the stability of tunnel excavation surface is investigated by using six different overload areas and the self-defined main influence areas of overload. Finally, with the example of shield tunnel face instability, the numerical simulation method and wedge body model are used to solve the limit support pressure of excavating face, and the calculated numerical solution and theoretical solution are compared with the measured soil chamber pressure. The reliability of numerical solution based on nonlinear Mohr-Coulomb failure criterion is further tested.
【学位授予单位】：长沙理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U455.43
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本文编号：2322460