發(fā)布時間：2018-11-10 12:20

【摘要】：盾構(gòu)施工技術(shù)由于對周圍環(huán)境影響小,而被廣泛應(yīng)用于城市地下工程的施工。在盾構(gòu)隧道施工過程中,需要通過對開挖面前方土體施加一定的支護壓力來保證隧道開挖面的穩(wěn)定性。因此,如何確定開挖面所需要的極限支護壓力成為了確保盾構(gòu)隧道開挖面穩(wěn)定的關(guān)鍵問題。目前已有的盾構(gòu)隧道開挖面穩(wěn)定性方面的研究大都采用線性破壞準(zhǔn)則,但是許多實際工程問題和土工試驗數(shù)據(jù)表明,巖土介質(zhì)服從非線性破壞準(zhǔn)則,而線性破壞準(zhǔn)則只是其中的特例。本文基于巖土材料的非線性破壞特征,采用非線性莫爾-庫倫破壞準(zhǔn)則對盾構(gòu)隧道開挖面的穩(wěn)定性開展研究,主要工作內(nèi)容如下：(1)利用FLAC二次開發(fā)平臺VC++將非線性莫爾-庫倫破壞準(zhǔn)則嵌入到FLAC自帶的本構(gòu)模型的源程序中,實現(xiàn)了對FLAC數(shù)值模擬軟件的二次開發(fā),通過將已有數(shù)據(jù)和數(shù)值計算的結(jié)果進行對比,驗證了上述研發(fā)過程的有效性,同時分析了非線性參數(shù)對開挖面極限支護壓力的影響；(2)基于退化的非線性莫爾-庫倫破壞準(zhǔn)則,依據(jù)極限平衡理論,利用淺埋隧道開挖面楔形體破壞模型,得到了開挖面極限支護力理論求解公式。選取具體算例,將數(shù)值模擬得到的淺埋隧道開挖面極限支護力與極限平衡理論解進行比較,以驗證基于非線性莫爾-庫倫破壞準(zhǔn)則數(shù)值模擬結(jié)果的正確性；(3)采用線性與非線性破壞準(zhǔn)則,通過劃定的六個不同超載區(qū)以及自定義的超載主要影響區(qū)探究了地表超載對隧道開挖面穩(wěn)定性的影響。最后,結(jié)合盾構(gòu)隧道開挖面失穩(wěn)實例,應(yīng)用數(shù)值模擬法以及楔形體模型求解開挖面極限支護壓力,將求得的極限支護壓力數(shù)值解和理論解與實測土倉壓力進行對比,進一步檢驗了基于非線性莫爾-庫倫破壞準(zhǔn)則進行數(shù)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.
【學(xué)位授予單位】：長沙理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：U455.43
，

本文編號：2322460