水位下降对均质土石坝坝坡稳定的影响分析

发布时间：2018-05-04 13:22

本文选题：水位下降 + 有限元法　；参考：《石河子大学》2014年硕士论文

【摘要】：在水工建筑物中，土石坝是最常见的一种，它具有对地质条件要求低、造价低、结构简单，施工管理也比较方便等的优点，因此较常采用。在我国，过去已建成很多土石坝，从事土石坝方面研究的人也逐渐增多。在土石坝的研究中，其安全是最重要的，而对土石坝安全的最大威胁则是渗流导致的破坏，所以土石坝的渗流应该引起社会的关注。由此，渗流的研究和控制是土石坝研究中的一个重要的课题，直接影响到土石坝的安全和造价。查阅国内外有关土石坝的资料发现，许多坝坡破坏和溃决的土石坝过程，多数是由渗流控制方面的不足引发的。我国在过去50年代到70年代修建的中小型水库中，土石坝占了很大一部分比例，由于当时的经济和技术条件都非常有限，许多土石坝都是在边勘测、边设计和边动工的情况下竣工的。经过很多年的冲刷、腐蚀，这些水库已经属于“病险水库”，所以对这些水库重新评估、综合评估以及除险加固是当务之急。对土石坝过程的渗流分析是非常必要的，同时对在渗流作用下土石坝的边坡稳定性分析都是必不可少的，本篇论文采用了加拿大中仿科技公司的GEO-STUDIO软件中的SEEP/W与SLOPE/W模块分别对大坝体内的非稳定渗流分析和稳定渗流情况下的边坡稳定进行分析。由于前人对水位下降时，坝坡稳定的变化规律研究不深，尤其是定量研究，所以本文针对此问题进行了研究，通过分析在库水位降落时，，土石坝的失稳破坏案例，总结分析了土石坝的破坏机理，同时简单介绍了有关水位下降时，土石坝的边坡稳定的研究方法和一些研究进展。本文假设库水位瞬间下降，建立了模型，利用有限元法对土石坝坝坡稳定进行了数值模拟分析，同时定量研究了坝坡稳定的各个影响因素。结果显示：坝坡安全系数K与坝体材料摩擦角φ成线性相关关系，同时也与水位下降幅度ΔH和坝坡坡率m成线性相关关系。根据上述几个因素各自对安全系数K的影响特点，计算分析并通过公式拟合，得到坝体材料摩擦角φ、水位降落幅度ΔH、坝坡坡率m各因素与坝坡稳定系数K的函数关系。本文通过工程实例建立实例模型，利用数值模拟的有限元方法，分析研究土石坝坝体内的渗流场，分别研究了渗透系数、水位下降速度和库水位的下降幅度三个因素对渗流场的影响规律，得出水位下降容易形成指向上游的逆向渗流，对上游坝坡的稳定及其不利的结论，同时渗透系数、水位下降速度和库水位的下降幅度三个因素都影响着土石坝上游坝坡的渗流逸出点位置，同时也影响着逸出点渗透坡降与浸润线位置的变化。
[Abstract]:Among hydraulic structures, earth-rock dam is the most common one. It has the advantages of low requirements for geological conditions, low cost, simple structure and convenient construction management, so it is often used. In China, many earth-rock dams have been built in the past, and the number of people engaged in earth-rock dams is increasing gradually. In the research of earth-rock dam, its safety is the most important, and the biggest threat to the safety of earth-rock dam is the damage caused by seepage, so the seepage of earth-rock dam should be paid attention to by the society. Therefore, the research and control of seepage flow is an important subject in earth-rock dam research, which directly affects the safety and cost of earth-rock dam. According to the data of earth-rock dams at home and abroad, it is found that most of the processes of dam failure and collapse are caused by the lack of seepage control. In the past 50's to 70's, the earth-rock dam accounted for a large proportion of the small and medium-sized reservoirs built in our country. Because of the very limited economic and technical conditions at that time, many earth-rock dams were being surveyed on the side. Completed with design and construction. After many years of erosion and corrosion, these reservoirs are already "dangerous reservoirs", so it is urgent to re-evaluate, synthesize and reinforce these reservoirs. The seepage analysis of earth-rock dam is very necessary, and it is necessary to analyze the slope stability of earth-rock dam under seepage. In this paper, the SEEP/W and SLOPE/W modules of GEO-STUDIO software of Canadian Zhongshi Science and Technology Company are used to analyze the unsteady seepage in the dam and the slope stability under the condition of steady seepage respectively. Because the previous researches on the stability of dam slope are not deep, especially the quantitative study, this paper studies this problem, and analyzes the failure cases of earth-rock dam when the water level is falling. In this paper, the failure mechanism of earth-rock dam is summarized and analyzed. At the same time, the research methods and some research progress on slope stability of earth-rock dam when the water level drops are briefly introduced. In this paper, the model is established on the assumption that the reservoir water level drops instantly, and the stability of earth-rock dam slope is numerically simulated and analyzed by using finite element method. At the same time, the factors influencing the stability of embankment slope are quantitatively studied. The results show that the safety factor K of dam slope is linearly correlated with friction angle 蠁 of dam body material, and it is also linearly correlated with the drop of water level 螖 H and slope ratio m. According to the influence characteristics of the above factors on the safety factor K, the functional relations between the friction angle of dam material 蠁, the fall amplitude of water level 螖 H, the slope ratio m and the stability factor K of dam slope are obtained by calculating and analyzing and fitting by formula. In this paper, an example model is established through an engineering example, and the seepage field in earth-rock dam body is analyzed by using the finite element method of numerical simulation, and the permeability coefficient is studied respectively. The effect of three factors on the seepage field is obtained. It is concluded that the descending water level is easy to form the reverse seepage to the upstream, to the stability and disadvantage of the upstream dam slope, and at the same time to the permeability coefficient. There are three factors which affect the location of seepage escape point of upstream dam slope of earth-rock dam and the change of seepage slope and infiltration line.
【学位授予单位】：石河子大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TV641.22

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