【摘要】 自振特征是核电厂结构动力分析首先应考虑的因素,它也是影响核电厂反应谱特征的关键因素之一。采用常规的自振特性分析方法(如Lanczos法等)只能以核电厂上部结构为模型进行计算求其固有频率,在复杂场地条件下,这样的计算结果通常与更符合实际的土-结构相互作用(SSI)模型计算结果存在较大差异。本文以SASSI用户手册中的典型压水堆核电厂土-结构动力相互作用模型为研究对象,采用时域显式有限元法结合透射人工边界方法及相应编写的三维显式有限元程序3DSSI,计算了同一上部结构,结合多工况局部复杂场地条件的核电厂SSI体系的单脉冲响应,并通过求传递函数幅值谱方法,获得各种工况下SSI体系的自振频率。依据计算结果,分别研究了核电厂上部结构、自由场及SSI体系的自振特征及其相互联系,并通过比较研究,讨论了局部复杂场地特性对核电厂SSI体系自振特性影响等问题,进而加深了对核电厂动力特征及动力安全区性的认知。更多还原

【Abstract】 Vibration frequency characteristic analysis is one of necessary considerations during the dynamic analysis of nuclear power plant(NPP).This is also one of key factors influencing the response spectrum of nuclear power plant.Conventional methods of modal analysis(such as Lanczos method,etc) are only used to calculate model and natural frequencies when the system is upper structure.The results obtained by using the conventional method are quite different from the calculations of soil-structure interaction(SSI) model,which is more consistent with the actual conditions of complex site.In this paper,a typical PWR nuclear power plant in SASSI user’s manual is used to study the frequency characteristics of soil structure dynamic interaction system.The lumped-mass explicit finite element with local transmitting artificial boundary method in time domain and the corresponding three-dimensional explicit finite element program 3DSSI are employed to compute the unite pulse responses of NPP SSI system under various local complex site conditions.Then,the results based on these pulse responses are used to calculate the free vibration frequencies of various case conditions of NPP SSI system by calculating the transfer function amplitude spectra.According to the calculating results above,a detailed discussion of vibration characteristics and their mutual relationship among NPP’s upper structure,free field and SSI system.Through the comparative study of the effects of the complex local site on NPP SSI system vibration characteristics,the understanding of the nuclear power plant dynamic characteristics and cognition of dynamic security become more profound.更多还原