【作者】 姚霄雯；

【导师】 蒋建群；

【作者基本信息】 浙江大学 ， 水工结构工程， 2013， 博士

【摘要】 近年来,一批200米甚至300米级的混凝土高拱坝在我国西部强震区陆续建成或正在设计之中。这些高拱坝作为复杂的大型混凝土结构体系,其在地震作用下的响应具有较大的随机性和不确定性,因此有必要从概率的角度对高拱坝在不同强度地震作用下的结构响应和安全性能进行评估。本文尝试将地震易损性分析方法引入高拱坝的动力设计,发展一种基于性能的高拱坝抗震安全评价方法,研究具有重要的理论意义和应用价值。论文的主要内容和成果包括以下几个方面：(1)在高拱坝动力分析模型方面,从材料非线性和横缝接触非线性两方面进行了详细分析。对于混凝土材料非线性,将规范中的应力应变曲线与混凝土塑性损伤模型相结合,揭示了塑性损伤对拱坝动力响应的影响；对于拱坝横缝接触非线性,应用了动接触力模型,并针对缝间抗震构造对该模型提出了改进。(2)结合混凝土损伤模型与横缝接触力模型对某高拱坝建立了三维有限元模型,分析了不同横缝数量或不同缝间抗震构造对拱坝动力响应的影响,验证了横缝及缝间抗震构造的设置能在不同程度上影响高拱坝在强震下的坝体应力、横缝开度、拱坝变形等动力响应特征。(3)通过一系列不同强度地震下的拱坝动力时程分析,研究了结构响应的不确定性问题。以高拱坝坝顶位移和横缝变形为典型响应参数,建立了高拱坝概率地震需求模型,并在此基础上比较了15种不同地震动强度指标与高拱坝响应的相关性,提出了三种改进的地震动强度指标。(4)根据拱坝响应随地震强度的变化趋势,提出了以响应拐点作为界限值的拱坝性能划分准则,并结合上述概率地震需求模型,采用高拱坝地震易损性分析方法,提出了不同地震动强度指标下针对拱坝顶部位移以及横缝变形的地震易损性曲线。(5)结合高拱坝的地震危险性分析结果与地震易损性曲线,提出了基于性能的高拱坝抗震安全评估方法,最终得到在设计基准期内拱坝响应针对不同性能等级的安全概率,并对高拱坝在极震下的性能目标准则提出了建议。通过对抗震加固优化后高拱坝抗震性能的对比分析验证了所提方法的合理性和适用性。更多还原

【Abstract】 Recently, a series of arch dams with the height of200-300meters are under construction or will be constructed in the severe seismic regions in western part of China. The high arch dam is such a complicated concrete structural system that the seismic responses are full of great randomness and uncertainty. It’s necessary to evaluate the seismic safety performance of high arch dams from the perspective of probability. In this study, seismic fragility analysis method is introduced to the seismic design of high arch dams. Also, a performance-based safety assessment of high arch dams is developed. The study includes:(1) Both material nonlinearity and joint contact nonlinearity are considered for the dynamic model of high arch dam. For the concrete material nonlinearity, the stress-strain curves in the code are combined with the concrete plastic damage model, demonstrating the effect of plastic damage to the dynamic response of concrete dams. For the joint contact nonlinearity, dynamic contact force model is applied and also modified for the consideration of seismic constructions set between the joints.(2) The three dimensional finite element model of a high arch dam is developed with the consideration of concrete damage model and joint contact model. The seismic responses for the arch dam models with different joint numbers or different seismic constructions between joints are analyzed. The results verify that contraction joints and the constructions between them can affect the arch dam stresses, joint opening and arch dam deformation when the dam is subjected to strong earthquakes.(3) The uncertainty of arch dam seismic response is analyzed by means of a series of dynamic time-history analyses under different magnitude earthquakes. The probabilistic seismic demand models of high arch dam are established with the response parameter of the crest displacement and the deformation of contraction joints. Furthermore, the correlation between15earthquake intensity measures and the dam response are compared, and3revised intensity measures are presented.(4) According to the variation tendency of the arch dam responses with the seismic intensity, the inflection points are utilized as the limit states of the arch dam performance. On the basis of the probabilistic seismic demand models and the limit states, the seismic fragility analysis method for high arch dam is applied. Also, the fragility curves for the crest displacements and joint deformations of arch dam are presented. (5) Combined the seismic fragility curves of the arch dam and the seismic hazard analysis in the dam region, a performance-based seismic safety assessment method is proposed for the high arch dam. The safety probabilities of arch dam in the design reference period for different performance levels are calculated. Also, the performance objective of high arch dams under maximum credible earthquake is suggested. In addition, the seismic safety of the high arch dam after seismic reinforcement and optimal design is assessed and compared to illustrate the rationality and applicability of the above-mentioned seismic safety assessment.更多还原