路堤下斜坡湖相软土地基的稳定性及变形研究

发布时间：2018-10-18 16:12

【摘要】：近年来,随着我国公路建设规模的日益扩大,高速公路不可避免地要经过一些特殊地基,如斜坡湖相软土地基等。斜坡湖相软土地基在路基横断面方向和沿路线纵向均具有坡度,因此其土层的成层情况更为复杂,土体具有较强的空间变异性。目前关于路堤荷载作用下斜坡湖相软土地基的变形及稳定性研究,大多数将其看作平面应变问题进行研究,尽管有些是进行三维有限元数值模拟,但是纵向长度只取单位长度,这样并不能体现沿路线纵向地基土坡度对斜坡湖相软土地基的变形及稳定性的影响。鉴于此,本文结合云南某高速公路工程,运用大型通用有限元软件ABAQUS分别建立了路堤荷载作用下斜坡湖相软土地基的二维和三维有限元数值分析模型,对路堤荷载作用下斜坡湖相软土地基的变形特征进行分析,并与实测结果进行对比,验证了模型的准确性;在此基础上,基于有限元强度折减法,建立了多种工况下的斜坡湖相软土地基的二维和三维数值分析模型,对其稳定性进行分析;最后通过正交试验对路堤下斜坡湖相软土地基的变形影响因素显著性进行了研究,主要研究成果如下:1.运用有限元法建立路堤荷载作用下斜坡湖相软土地基的二维和三维数值分析模型,并结合现场实测沉降数据,初步论证了斜坡湖相软土地基的变形应采用三维数值分析模型进行研究;在此基础上,对斜坡湖相软土地基的沉降和侧向位移变形规律进行了分析。2.基于强度折减法,将湖相软土层厚度、杂填土厚度、湖相软土尖灭度、沿路线纵向坡度作为斜坡湖相软土地基稳定性的主要影响因素,利用数值模拟手段,分别探讨了各因素对斜坡湖相软土地基二维和三维稳定性的影响。3.运用非线性有限元法建立了路堤荷载作用下水平湖相软土地基、水平普通地基、地表为水平的斜坡普通地基和地表为水平的斜坡湖相软土地基四种工况下的数值分析模型,分析了各种工况下地基表面竖向位移以及坡脚处侧向位移的变形规律。4.将湖相软土层厚度、杂填土厚度、弹性模量比、湖相软土尖灭度和沿路线纵向坡度五个因素作为影响斜坡湖相软土地基变形的主要影响因素,通过正交试验,对各因素对斜坡湖相软土地基的纵向差异沉降、竖向位移和侧向位移的显著性进行了分析。
[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.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U416.1

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