强震作用下核安全壳结构参数时变特性及抗震裕度研究

Taking seismic margin and security protection of China's nuclear power engineering structures as an application background, the methods of shaking table model test, field measurement and numerical simulation will be utilized in this project to investigate the problems including characteristics of in the near-field ground motions in the field of nuclear island, nonlinear constitutive model and parallel computing seismic response analysis considering dynamic contact problem and viscous-spring artificial boundaries of nuclear containment, time-variant characteristics of physical parameters and modal parameter of nuclear containment, seismic margin of nuclear containment. Consequently, the damage mechanism and the time-varying process of parameters of the nuclear reactor building under strong earthquake can be revealed in this project. The results will provide a scientific basis for the construction of Earthquake Safety and Disaster Prevention and seismic performance evaluation of Chinese Nuclear Power Engineering. In connection with the scientific issues for the near-field strong ground motion, by the combination methods of HHT, short-time FFT and extended Kalman filter with mobile spectrum respectively, the characteristic parameters of ground motion are identified so that it can provide a reasonable ground motion parameters for seismic analysis of the nuclear island. Considering time-varying characteristics of parameters of nuclear containment as study objects, Nonlinear seismic response of nuclear containment parameters to change the law for the goal of near-field ground motions nuclear containment, nuclear safety shell material non-linear restoring force model, nuclear containment shaking table test, the following issues will be studied including nonlinear seismic response of nuclear containment under the input of near-field ground motions, nonlinear hysteresis curve model, shaking table model test, and then the time-varying charactieristics of the model parameters of the nuclear containment can be revealed, and furthermore the floor response spectrum of nuclear containment would be given. And then the site vibration testing of nuclear containment structure will be carried out, time-varying parameters of nuclear containment structure are identified by using the obtained data justnow on the structure. The quantitative relationship of the failure mechanism of structural damage and time-varying parameters of the structure would be summarized. In the end, a method of seismic margin assessment for nuclear containment can be proposed not to depend on the original information of structure.

以我国核电工程结构抗震裕度与安全评估为应用背景，采用模型试验、现场实测和数值模拟相结合的方法，研究核岛区近场强地震动特征、核安全壳非线性本构模型及考虑动接触问题和粘弹性边界的有限元并行计算、核安全壳物理及模态参数的时变特征及其关系、核安全壳抗震裕度，揭示在强震作用下核安全壳参数时变规律及破坏机理。针对近场强地震动的科学问题，采用HHT、短时FFT、扩展的卡尔曼滤波与移动谱结合识别其特征参数，为核安全壳抗震分析提供合理的地震动参数。以核安全壳抗震裕度评估为目标，研究近场强地震动作用下核安全壳的非线性反应，核安全壳振动台试验，核安全壳材料强度等物理与模态参数之间的关系，揭示核安全壳参数的时变规律与破坏机理，给出核安全壳结构在超设计基准地震事件作用下的抗震裕度。以某在役核电厂为依托，对其核安全壳进行现场振动测试，识别其参数时变特征，并对其进行抗震裕度评估，为我国核电厂安全运行提供技术支撑。

首先，在役核电厂在强烈地震作用下其抗震安全性以及接近或者已经达到服役期的核电厂是否可以延寿继续使用，需要对在役核电厂进行详细的抗震安全及抗震裕度评估，以此作为在役核电厂延寿或者评估其抗震能力的重要依据。再者，由于地震发生的概率和强度的不可预知性，对于在役核电厂可能会遭遇超过设计时所设定的地震水平，已有日本的福岛和柏崎刈羽两个核电厂遭遇超设计基准地震的印证。最后，发生强烈地震时，安全壳作为防止核电厂发生核泄漏的最后一道屏障，其抗震安全性及重要性不言而喻。本项目主要开展了如下研究工作：（1）利用几种时频分析方法对近几年诸如汶川、玉树、福岛等大地震中记录到的近断层强震记录进行时变特性分析，得到近断层地震动参数的时变特性以及强度衰减规律；（2）安全壳模态参数与材料强度及结构物理参数之间的关系研究，得出其动力特性与材料强度之间的变化关系；（3）超设计基准地震动作用下核安全壳物理和模态参数的时变特性以及抗震裕度研究；（4）核电厂结构三维动力分析粘弹性边界条件的研究，开发了一套适用于核电厂安全壳结构三维抗震分析的并行计算程序以及抗震裕度评估系统；（5）高温及地震荷载作用下核电厂安全壳结构抗震及承压性能研究，得出安全壳在多种荷载作用下的薄弱环节：（6）强震作用下核电厂安全壳结构隔震性能研究，得出采用摩擦摆隔震支座时安全壳结构的隔震效果及其设计方法；（7）核电厂安全壳结构参数识别及其确定安全壳结构损伤程度和位置的方法，该方法已经在高层框架结构中得以实施，并且可以对其损伤程度和损伤位置进行识别；（8）在役核电厂核安全壳的健康诊断及抗震裕度评估，对某在役核电厂进行现场试验，得到其振动特性及变形规律。