复合土工膜心墙堆石坝应力变形分析

发布时间：2018-07-04 13:23

本文选题：复合土工膜 + 堆石坝　；参考：《兰州交通大学》2014年硕士论文

【摘要】：复合土工膜心墙堆石坝是水工结构中的重要坝型之一，因其筑坝材料取材方便、机械化施工简单、施工周期短、成本低等特点以及复合土工膜心墙良好的适应变形能力、耐酸碱性能、抗冲蚀、抗老化、防渗性能好等优点，迄今为止已被广泛运用于水利水电工程中。然而，复合土工膜心墙堆石坝的应力变形问题也将成为其设计施工的核心问题。本文简单介绍了堆石坝的特点、土工膜防渗体的研究现状，根据已有的研究成果,通过比较选取邓肯-张E B模型作为堆石体的本构模型，采用土工栅格单元和Goodman单元模拟了复合土工膜和接触面，论证了振型分解反应谱法在堆石坝地震反应分析中的应用。基于土理论和传统有限元法，以白龙江某复合土工膜心墙堆石坝为例，建立三维有限元模型，并结合MIDAS/GTS大型岩土分析软件，对竣工期、正常蓄水期以及正常蓄水期加8度地震作用三种工况下坝体和复合土工膜心墙的应力变形进行了模拟，计算了无膜情况下坝体的应力和变形，并分析了复合土工膜对坝体应力变形的影响。通过分析得出：竣工期，坝体和复工土工膜的应力、变形都很小基本呈对称分布，且都表现为受压不会出现拉伸破坏，坝体最大应力出现在坝底，位移主要表现为沉降变形，，且最大沉降发生在坝体三分之二处，而复合土工膜不仅受自重的影响，还依附于坝体的变形，其变形量比坝体的大；正常蓄水期，在水压力作用下，应力和变形不再呈对称分布，基本发生在水压力作用面附近。坝体和复合土工膜都在水位以上部位向上游移动表现为拉应力，水位以下依然受压，且向下游移动。无论是竣工期还是正常蓄水期，坝体和复合土工膜小主应力都表现为受压，只有大主应力出现了局部受拉，坝体发生在底部，而复合土工膜发生在与山体连接的部位。加8度地震作用后，拉应力区范围扩大，坝体拉应力主要分布在堆石区主要部位，复合土工膜依然出现在与相邻构件连接的部位，变形在水平方向坝体连同心墙整体移向下游，而竖直方向都出现了上抬现象。无膜情况下，坝体跟有膜情况下的应力变形规律基本一样，只是应力和变形都增大。由此可见：三种工况下，坝体和复合土工膜都从初始的受压状态依次出现了拉应力，地震作用下受拉区范围扩大，且拉应力增大。复合土工膜在连接部位出现了明显的应力集中现象；变形由最初的整体沉降变形过渡到局部水平再转化为整体水平及上抬状态，且膜的变形除了自身的变形外主要依附于坝体的变形。跟无膜情况相比较，复合土工膜不仅起到防渗作用，而且对坝体的应力变形有很大的改善，很大程度上抑制了坝体的应力和变形。
[Abstract]:The composite geomembrane core wall rockfill dam is one of the important dam types in hydraulic structure. Because of its advantages of convenient material selection, simple mechanized construction, short construction period and low cost, the composite geomembrane core wall has good adaptability to deformation. So far, it has been widely used in water conservancy and hydropower engineering because of its advantages of acid and alkali resistance, erosion resistance, aging resistance and good impermeability. However, the stress and deformation of composite geomembrane core wall rockfill dam will also become the core problem in its design and construction. In this paper, the characteristics of rockfill dam and the research status of geomembrane impervious body are briefly introduced. According to the existing research results, Duncan Zhang E B model is selected as the constitutive model of rockfill. The composite geomembrane and contact surface were simulated by using geo-grid element and Goodman element, and the application of mode decomposition response spectrum method in seismic response analysis of rockfill dam was demonstrated. Based on soil theory and traditional finite element method, a 3D finite element model of a composite geomembrane core wall rockfill dam in Bailongjiang is established, and the completion period of the dam is analyzed with Midas / GTS large-scale geotechnical analysis software. The stress and deformation of dam body and composite geomembrane core wall under three working conditions of normal storage period and normal storage period plus 8 degree earthquake are simulated, and the stress and deformation of dam body without film are calculated. The influence of composite geomembrane on stress and deformation of dam is analyzed. Through analysis, it is concluded that the stress and deformation of the dam body and the rework geomembrane are all symmetrical distribution basically in the period of completion, and they all show that there will be no tensile damage under compression, the maximum stress of the dam body appears at the bottom of the dam, and the displacement is mainly shown as settlement deformation. The maximum settlement occurs at 2/3 of the dam body, and the composite geomembrane is not only affected by the deadweight, but also attached to the deformation of the dam body, which is larger than that of the dam body, and in the normal water storage period, under the action of water pressure, Stress and deformation are no longer symmetrically distributed and occur near the surface of water pressure. Both the dam body and the composite geomembrane move to the upper reaches of the water level under tensile stress, and are still under pressure below the water level, and move downstream. The small principal stresses of dam body and composite geomembrane appear as compression, only the large principal stress appears local tension, the dam body occurs at the bottom, and the composite geomembrane occurs in the part connected with the mountain body, no matter in the completion period or in the normal water storage period. After adding 8 degrees earthquake, the range of tensile stress zone is enlarged, the tensile stress of dam body is mainly distributed in the main part of the rockfill area, the composite geomembrane still appears in the position connected with the adjacent members, and the deformation is moved downstream along with the core wall in the horizontal direction. And the vertical direction all appeared up the phenomenon. In the case of no film, the stress and deformation of the dam is basically the same as that of the film, except that the stress and deformation increase. It can be seen that under the three conditions, the tensile stress of dam body and composite geomembrane appears successively from the initial state of compression, and the range of tensile zone is enlarged and the tensile stress increases under earthquake action. The composite geomembrane shows obvious stress concentration phenomenon in the connection, and the deformation changes from the initial integral settlement deformation to the local level and then to the whole horizontal and uplift state. Besides its own deformation, the deformation of the film is mainly attached to the deformation of the dam body. Compared with the case without film, the composite geomembrane not only plays an anti-seepage role, but also improves the stress and deformation of the dam body greatly, and greatly inhibits the stress and deformation of the dam body.
【学位授予单位】：兰州交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TV641.41;TV31

【参考文献】