基于增量动力分析的混凝土重力坝抗震性能分析

A study of seismic performance of concrete gravity dam based on incremental dynamic analysis

基于性能的抗震设计理念,利用增量动力分析法(IDA)结合所建立的混凝土重力坝模型,根据分位分析结果评估重力坝抗震性能。以Koyna重力坝为例,分别建立以无质量地基法和附加质量法的传统模型和以黏弹性边界法和流固耦合法建立的坝体-地基-库水相互作用抗震分析模型。选取16条地震记录作为输入,选取地面峰值加速度作为地震强度指标、坝顶相对位移作为结构性能指标,以此为基础作IDA曲线。将两种模型分位分析结果进行对比,结果表明:针对不同保证率的地面峰值加速度(PGA),新模型总体安全冗余度高于传统模型10%～20%,以传统方法建立的抗震分析模型的计算结果偏于保守,Koyna大坝的极限抗震能力约为0. 45g,其功能保障水平约为0. 34g; IDA方法也将为今后大坝抗震设计提供一种新的思路。

Based on the performance of the seismic design concept for the concrete dam, the incremental dynamic analysis method （IDA） is adopted to evaluate the seismic performance of the gravity dam according to the resuhs of the sub-analysis. Taking the Koyna gravity dam as a case study, the traditional model with massless foundation and added mass method and the seismic dam-foundation-reservoir interaction model with the viscous spring boundary and fluid-solid coupling method are respectively developed in this study. 16 earthquake records are taken as the ground inputs; the ground peak acceleration is selected as the earthquake strength index and the relative displacement of the crest as the structural performance index. Then, the IDA curves are plotted and the resuhs of the two models are compared. The research results show that the new model has a high overall safety redundancy for the PGA with different guarantee rates, which is about 10% - 20% higher as compared to the traditional model. And the calculation resuhs of the seismic analysis model established by the traditional method are conservative ; the uhimate seismic capacity of the Koyna dam is about 0.45g, and its function guarantee level is about 0.34g. The traditional method is conservative and the incremental dynamic analysis method will also provide a new idea for the seismic design of dams in the future.