强地震作用下混凝土重力坝抗震性能及稳定性分析

发布时间：2018-09-09 08:44

【摘要】：随着我国经济的高速发展,对能源的供应需求在不断增大。我国西部地区水力资源约占全国总量的70%,为了合理利用这些水能资源,我国在西部地区正在建设或将要建成一系列世界级的高混凝土重力坝。然而坝址地震频发且烈度较高,重力坝坝体一旦遭到破坏,将会产生灾难性的后果。因此,为了确保重力坝的安全,本文采用有限元动力分析方法,以某水电站混凝土重力坝溢流坝段作为研究对象,对高强度地震下混凝土重力坝的动力特性及其抗震安全性进行了深入的研究和探讨。主要做了以下几个方面的研究工作:1、建立有限元模型,对重力坝进行模态分析,分别求出了空库和满库的固有频率,分析坝体的自振特性,获取其自振周期以及结构的振型。2、采用新的地震动参数,运用振型分解反应谱法和时程动力法分别对重力坝进行抗震计算,分析了各工况下坝体关键部位的地震动位移和地震动应力分布规律。重点分析了应力集中的部位(包括坝踵、坝趾、上下游折坡处、近水面和坝顶),研究了该混凝土重力坝对地震的响应规律;确定结构的薄弱部位,并提出有效可行的抗震加固措施。为指导大坝及其系统的抗震安全运行和工程管理提供科学依据。3、运用混凝土塑性损伤模型模拟结构的非线性特性,对典型坝段进行模拟,分析在地震峰值加速度不断增加时坝体屈服区域的发展方向,以及混凝土重力坝的破坏过程和破坏形态,对不同烈度地震作用下坝体裂缝的出现位置、出现范围与裂缝发展趋势进行描述。找出了坝段在强震作用下抗震关键部位和薄弱环节。得到了混凝土重力坝在强震作用下的非线性破坏形式,较为真实的反映出坝体的响应。4、对基础进行了稳定性验算,基于振型分解反应谱法计算结果以及基于时程动力法计算结果,对坝体沿建基面的抗震稳定安全进行了深入的探讨研究。本论文的工作紧密结合工程实际,以具体工程为研究背景,其研究成果对设计及类似工程具有较大的参考和借鉴价值。同时,高地震烈度下混凝土重力坝的动态反应是非常复杂的问题,其动力分析中一些问题的处理还有待不断的深入研究。
[Abstract]:With the rapid development of our economy, the demand for energy supply is increasing. In order to make rational use of these hydropower resources, a series of world-class high concrete gravity dams are being constructed or will be built in the western part of China. However, the earthquake occurred frequently and the intensity is high. Once the gravity dam body is destroyed, it will have disastrous consequences. Therefore, in order to ensure the safety of gravity dam, the finite element dynamic analysis method is used to study the overflow section of concrete gravity dam of a hydropower station. The dynamic characteristics and seismic safety of concrete gravity dams under high intensity earthquakes are studied and discussed. This paper mainly studies the following aspects: 1, establishes the finite element model, carries on the modal analysis to the gravity dam, calculates the natural frequency of the empty reservoir and the full reservoir, and analyzes the natural vibration characteristics of the dam body. The natural vibration period and the vibration mode of the structure are obtained. The seismic calculation of gravity dam is carried out by using the new parameters of ground motion, using the mode decomposition response spectrum method and the time-history dynamic method, respectively. The distribution law of ground motion displacement and ground motion stress in key parts of dam body under various working conditions are analyzed. The stress concentration parts (including dam heel, dam toe, upstream and downstream slope break, near water surface and dam top) are analyzed, the response law of the concrete gravity dam to earthquake is studied, and the weak part of the structure is determined. And put forward effective and feasible seismic reinforcement measures. In order to provide scientific basis for seismic safety operation and engineering management of dams and their systems, the concrete plastic damage model is used to simulate the nonlinear characteristics of structures, and the typical dam segments are simulated. This paper analyzes the development direction of dam yield area when the peak acceleration of earthquake increases, the failure process and failure form of concrete gravity dam, and the location of cracks in dam body under the action of different intensity earthquakes. The scope of occurrence and the trend of fracture development are described. The key points and weak links of seismic resistance of dam section under strong earthquake are found out. The nonlinear failure form of concrete gravity dam under strong earthquake is obtained, which reflects the response of dam body. Based on the results of the modal decomposition response spectrum method and the time-history dynamic method, the seismic stability of the dam along the foundation surface is studied. The work of this paper is closely combined with engineering practice, and the research results are of great reference value to design and similar projects. At the same time, the dynamic response of concrete gravity dam under high seismic intensity is a very complex problem, and the treatment of some problems in its dynamic analysis needs to be studied deeply.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TV642.3

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