【摘要】：近年來,隨著我國公路建設規(guī)模的日益擴大,高速公路不可避免地要經(jīng)過一些特殊地基,如斜坡湖相軟土地基等。斜坡湖相軟土地基在路基橫斷面方向和沿路線縱向均具有坡度,因此其土層的成層情況更為復雜,土體具有較強的空間變異性。目前關于路堤荷載作用下斜坡湖相軟土地基的變形及穩(wěn)定性研究,大多數(shù)將其看作平面應變問題進行研究,盡管有些是進行三維有限元數(shù)值模擬,但是縱向長度只取單位長度,這樣并不能體現(xiàn)沿路線縱向地基土坡度對斜坡湖相軟土地基的變形及穩(wěn)定性的影響。鑒于此,本文結(jié)合云南某高速公路工程,運用大型通用有限元軟件ABAQUS分別建立了路堤荷載作用下斜坡湖相軟土地基的二維和三維有限元數(shù)值分析模型,對路堤荷載作用下斜坡湖相軟土地基的變形特征進行分析,并與實測結(jié)果進行對比,驗證了模型的準確性;在此基礎上,基于有限元強度折減法,建立了多種工況下的斜坡湖相軟土地基的二維和三維數(shù)值分析模型,對其穩(wěn)定性進行分析;最后通過正交試驗對路堤下斜坡湖相軟土地基的變形影響因素顯著性進行了研究,主要研究成果如下:1.運用有限元法建立路堤荷載作用下斜坡湖相軟土地基的二維和三維數(shù)值分析模型,并結(jié)合現(xiàn)場實測沉降數(shù)據(jù),初步論證了斜坡湖相軟土地基的變形應采用三維數(shù)值分析模型進行研究;在此基礎上,對斜坡湖相軟土地基的沉降和側(cè)向位移變形規(guī)律進行了分析。2.基于強度折減法,將湖相軟土層厚度、雜填土厚度、湖相軟土尖滅度、沿路線縱向坡度作為斜坡湖相軟土地基穩(wěn)定性的主要影響因素,利用數(shù)值模擬手段,分別探討了各因素對斜坡湖相軟土地基二維和三維穩(wěn)定性的影響。3.運用非線性有限元法建立了路堤荷載作用下水平湖相軟土地基、水平普通地基、地表為水平的斜坡普通地基和地表為水平的斜坡湖相軟土地基四種工況下的數(shù)值分析模型,分析了各種工況下地基表面豎向位移以及坡腳處側(cè)向位移的變形規(guī)律。4.將湖相軟土層厚度、雜填土厚度、彈性模量比、湖相軟土尖滅度和沿路線縱向坡度五個因素作為影響斜坡湖相軟土地基變形的主要影響因素,通過正交試驗,對各因素對斜坡湖相軟土地基的縱向差異沉降、豎向位移和側(cè)向位移的顯著性進行了分析。
[Abstract]:In recent years, with the increasing scale of highway construction in China, expressway inevitably has to pass through some special foundations, such as slope lake soft soil foundation and so on. The slope lake soft soil foundation has the slope in the subgrade cross section direction and along the route longitudinally, so the stratification condition of the soil layer is more complex, and the soil has strong spatial variability. At present, most of the researches on deformation and stability of sloping lake soft soil foundation under embankment load are carried out as plane strain problems. Although some of them are simulated by three-dimensional finite element method, the longitudinal length is only taken as unit length. This does not reflect the influence of the longitudinal soil slope along the route on the deformation and stability of the sloping lake soft soil foundation. In view of this, the two-dimensional and three-dimensional finite element numerical analysis models of sloping lacustrine soft soil foundation under embankment loading are established by using large-scale general finite element software ABAQUS combined with a highway project in Yunnan Province. The deformation characteristics of sloping lake soft soil foundation under embankment load are analyzed and compared with the measured results to verify the accuracy of the model. Two and three dimensional numerical analysis models of slope lacustrine soft soil foundation under various working conditions are established, and its stability is analyzed. Finally, the influence factors of slope lake soft soil foundation deformation under embankment are studied by orthogonal test. The main research results are as follows: 1. Two and three dimensional numerical analysis models of slope lake soft soil foundation under embankment loading are established by using finite element method, and field measured settlement data are combined. This paper preliminarily proves that the deformation of slope lacustrine soft soil foundation should be studied by three dimensional numerical analysis model, on the basis of which, the settlement and lateral displacement deformation of slope lake soft soil foundation are analyzed. 2. Based on the strength reduction method, the thickness of lacustrine soft soil, the thickness of mixed fill, the sharp extinction of lacustrine soft soil and the longitudinal slope along the route are taken as the main influencing factors of the stability of the sloping lacustrine soft soil foundation, and the numerical simulation method is used. The effects of various factors on the two and three dimensional stability of sloping lake soft soil foundation are discussed respectively. Using nonlinear finite element method, the numerical analysis models of horizontal lake soft soil foundation, horizontal ordinary foundation, horizontal slope ordinary foundation and slope lake soft soil foundation under embankment load are established. The deformation law of the vertical displacement of the ground surface and the lateral displacement at the foot of the slope under various working conditions are analyzed. 4. Five factors, such as the thickness of lacustrine soft soil, the thickness of mixed fill, the ratio of elastic modulus, the peak extinction of soft soil and the longitudinal slope along the route, are taken as the main factors affecting the deformation of the soft soil foundation of the slope lacustrine facies, and the orthogonal test is carried out. The significance of longitudinal differential settlement vertical displacement and lateral displacement of slope lake soft soil foundation is analyzed.
【學位授予單位】：北京交通大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：U416.1

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