本文選題：隧道穩(wěn)定性　切入點：極限分析有限元法　出處：《湖南大學(xué)》2015年碩士論文

【摘要】：穩(wěn)定性問題的研究對于隧道設(shè)計、施工以及理論研究均有重要的指導(dǎo)意義。目前,采用傳統(tǒng)的滑移線法、極限平衡法和極限分析法研究該課題時存在諸多困難,如難以有效考慮復(fù)雜的幾何邊界、荷載以及非均質(zhì)材料等問題。而常用的有限元數(shù)值方法在研究隧道穩(wěn)定性問題時,需要進行大量的迭代計算,極為耗時且不易收斂。相比而言,極限分析有限元法是解決上述問題的有效途徑。其實質(zhì)是采用數(shù)值分析方法求解極限問題,可考慮不同的力學(xué)參數(shù)與復(fù)雜工況,并避開了復(fù)雜的應(yīng)力-應(yīng)變增量迭代過程,直接針對最終的極限狀態(tài)進行處理,無需假定破壞模式即可進行穩(wěn)定性計算,利用計算機自動搜索出連續(xù)體破壞時的極限荷載及速度場或應(yīng)力場,具有計算穩(wěn)定、高效、易收斂等特點。為此,本文采用極限分析有限元法,對不同參數(shù)條件下隧道穩(wěn)定性問題進行深入探討,具體研究工作如下:(1)從介紹塑性極限理論的基本原理開始,對極限分析有限元法數(shù)值方法的基本內(nèi)容進行系統(tǒng)的闡述,涉及單元離散化、數(shù)學(xué)規(guī)劃模型的建立及其優(yōu)化求解、計算機實現(xiàn)過程等內(nèi)容。(2)基于某些合理的計算假定,建立一個可考慮多種因素影響的計算模型;針對不同參數(shù)條件下的隧道穩(wěn)定性問題,利用極限分析有限元法進行計算分析,得到穩(wěn)定系數(shù)的相關(guān)計算圖表和經(jīng)驗計算公式,并探討方形隧道的穩(wěn)定性影響因素和破壞模式的形態(tài)特征及其演變規(guī)律,為實際工程提供參考。(3)參照Terzaghi地基承載力計算公式,對關(guān)于黏聚力、超載和重力的支護反力分項系數(shù)N'c、N's、N'γ分別進行數(shù)值計算,整理形成相應(yīng)的計算圖表,并對圓形隧道破壞的形態(tài)特征和演變規(guī)律進行總結(jié)。(4)結(jié)合云陽山隧道開挖過程中圍巖與支護結(jié)構(gòu)的大變形和冒頂坍塌的工程實例,采用極限分析有限元法分析隧道圍巖發(fā)生失穩(wěn)破壞時的形態(tài)特征和破壞范圍,獲取隧道周邊圍巖需要進行重點加強的區(qū)域,驗證本文方法的實用性和有效性。
[Abstract]:The study of stability is of great significance for tunnel design, construction and theoretical research. At present, there are many difficulties in using the traditional slip line method, limit equilibrium method and limit analysis method to study the problem. For example, it is difficult to effectively consider the complex geometric boundary, load and heterogeneous materials, while the commonly used finite element numerical method needs a large number of iterative calculations to study the stability problem of the tunnel. In contrast, the finite element method of limit analysis is an effective way to solve the above problems. The essence of the finite element method is to use numerical analysis method to solve the limit problem, which can take into account different mechanical parameters and complex working conditions. The complex stress-strain increment iteration process is avoided, and the ultimate limit state is processed directly, and the stability can be calculated without assuming the failure mode. In this paper, the finite element method of limit analysis is used to automatically search the limit load, velocity field or stress field of continuum failure, which has the characteristics of stable calculation, high efficiency and easy convergence. The problem of tunnel stability under different parameters is discussed in depth. The specific research work is as follows: (1) starting with the introduction of the basic principle of plastic limit theory, the basic contents of finite element method for limit analysis are systematically expounded. It involves the discretization of units, the establishment of mathematical programming model and its optimization solution, the process of computer realization, etc.) based on some reasonable calculation assumptions, a calculation model which can take into account the influence of many factors is established. Aiming at the tunnel stability problem under different parameters, the finite element method of limit analysis is used to calculate and analyze the stability coefficient. The paper also discusses the influencing factors of stability of square tunnel, the morphological characteristics of failure mode and its evolution law, which provides a reference for practical engineering. (3) with reference to the calculation formula of bearing capacity of Terzaghi foundation, the cohesion force is discussed. The partial coefficients of support reaction of overload and gravity are calculated numerically respectively, and the corresponding calculation charts are formed. Combined with the engineering examples of large deformation and roof collapse of surrounding rock and supporting structure during the excavation of Yunyang Mountain Tunnel, the paper summarizes the morphological characteristics and evolution law of circular tunnel failure. The finite element method of limit analysis is used to analyze the morphological characteristics and failure range of the surrounding rock in the tunnel, and the area where the surrounding rock around the tunnel needs to be strengthened is obtained, which verifies the practicability and validity of the method in this paper.
【學(xué)位授予單位】：湖南大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：U451

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