流变模型和渗透系数对心墙堆石坝变形影响的研究

发布时间：2018-09-11 06:42

【摘要】：心墙堆石坝具有就地就近取材、适应不同变形、施工方法灵活、施工速度快、便于维修加高等优点,是坝工界优先考虑和广泛采用的坝型,尤其在我国近二十年来,一大批已建、在建和拟建的两百米(及以上)心墙堆石坝发展迅猛。与此同时,也存在着许多亟待解决的工程技术问题,其中,高心墙堆石坝变形的研究就成为其中的关键问题之一。非线性有限元方法的应用为堆石坝变形计算提供了有效的求解手段,其中流变模型(包括各种指数型、对数型等)的研究影响着土体长期变形计算,也解决了工程中许多关键技术难题,为我国堆石坝设计理论的发展作出了贡献。但流变模型的对比应用工作仍不充分,实际工程中选择流变模型仍很困难,因此对各模型展开综合比较和应用将具有重要意义。同时,心墙渗透性能空间变化对瞬时变形的影响并没有引起足够的重视。在广泛阅读国内外相关文献的基础上,针对流变模型、长期变形参数的反演分析方面,本文选取了目前国内堆石坝长期变形计算中常用的两种流变模型:三参数模型和对数模型,首先,从理论上对两者进行了对比。其次,基于前人开展的室内试验和类比同类工程拟定了流变模型参数,以小浪底斜心墙堆石坝工程实例建立了有限元模型,讨论了以上两种流变模型在反映堆石料应力变形特性方面各自所具有的特点,评述了对数流变模型在反映堆石体长期变形特性方面的实用优越性。但模型初定参数的计算值与实测值偏差较大,因此,有必要通过反演分析确定模型参数,最后,通过反演分析确定模型参数的计算结果与实测值吻合的较好,可被用来预测长期变形。针对心墙渗透系数的研究,本文从心墙渗透性能空间变化对瞬时变形影响这一因素出发,并结合如美心墙堆石坝所取得的室内压缩试验和渗透系数试验,考察了心墙渗透性能空间变化对变形预测的影响。经过以上计算分析发现:对数流变模型计算的长期变形与实测值在位移发展趋势上相符较好,基于反演参数进行的长期变形计算,可用于已建心墙堆石坝位移的预测和安全评判;心墙渗透性能空间变化能更准确地预测坝体瞬时变形。
[Abstract]:The core wall rockfill dam has the advantages of getting materials locally, adapting to different deformation, flexible construction method, fast construction speed and convenient for maintenance and heightening. It is a dam type that has been given priority and widely adopted by the dam engineering circles, especially in the past twenty years in China. A large number of core rockfill dams, which have been built, are under construction and are to be built, are developing rapidly. At the same time, there are many urgent engineering technical problems, among which, the study of deformation of high core rockfill dam becomes one of the key problems. The application of nonlinear finite element method provides an effective method for calculating the deformation of rockfill dams. The study of rheological models (including various exponential types, logarithmic types, etc.) affects the calculation of long-term deformation of soil. It also solves many key technical problems and contributes to the development of the design theory of rockfill dams in China. However, the comparison and application of rheological models are still insufficient, and it is still very difficult to select rheological models in practical engineering. Therefore, it is of great significance to carry out comprehensive comparison and application of each model. At the same time, the influence of the spatial variation of the permeability of the core wall on the instantaneous deformation has not been paid enough attention to. On the basis of extensive reading of relevant literature at home and abroad, the inversion analysis of rheological model, long-term deformation parameters, In this paper, two kinds of rheological models commonly used in the long-term deformation calculation of rockfill dams in China are selected: the three-parameter model and the logarithmic model. Firstly, the two models are compared theoretically. Secondly, the rheological model parameters are drawn up on the basis of laboratory tests and analogous similar projects carried out by predecessors, and the finite element model is established with the example of Xiaolangdi inclined core rockfill dam. The characteristics of the above two rheological models in reflecting the stress-deformation characteristics of rockfill are discussed, and the practical advantages of logarithmic rheological models in reflecting the long-term deformation characteristics of rockfill are reviewed. However, the calculated values of the initial parameters of the model deviate greatly from the measured values. Therefore, it is necessary to determine the model parameters by inversion analysis. Finally, the calculated results of the model parameters are in good agreement with the measured values by the inversion analysis. It can be used to predict long-term deformation. According to the research of permeability coefficient of core wall, this paper starts from the factor that the spatial change of permeability property of core wall affects the instantaneous deformation, and combines the indoor compression test and permeability coefficient test obtained from the core wall rockfill dam. The effect of spatial variation of permeability on deformation prediction was investigated. Through the above calculation and analysis, it is found that the long-term deformation calculated by the logarithmic rheological model is in good agreement with the measured values in the trend of displacement development, and the long-term deformation calculation based on the inversion parameters is carried out. It can be used to predict and evaluate the displacement of rockfill dam with built core wall, and the spatial variation of permeability property of core wall can predict the instantaneous deformation of dam body more accurately.
【学位授予单位】：华北电力大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TV641.41;TV698.11

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