地震载荷下核岛动力响应数值模拟

Numerical simulation of dynamic response of nuclear island under seismic load

核电作为清洁型能源具有广阔的发展前景,研究核电站的地震响应具有重要意义。建立了AP1000核岛的有限元模型,进行模态分析获取核岛的振动形态。用无限元模拟远场地基,有限元模拟近场地基,并考虑基础埋置及土与结构相互作用,开展了不同地基条件下的核岛地震响应分析。结果表明:随着地基刚度的增加,核岛节点的响应加速度幅值增大,而加速度反应谱峰值对应的周期减小,核岛节点应力增大,但其相对位移减小;考虑土与结构相互作用之后,软弱地基的响应加速度峰值大幅减小,地基加速度反应谱峰值对应的周期增加,土与结构相互作用对此类地基上核岛的地震输入有较大影响;对于坚硬岩石地基,土与结构相互作用对地震输入的影响可以忽略。

As clean energy, nuclear power has shown broad prospects for development, so it is of great importance to investigate response of nuclear power plant under seismic loading. Firstly, finite element model of the AP1000 nuclear island is built to perform modal analysis for obtaining vibration modes of nuclear island. Then, by using infinite element to simulate the far field ground and finite element to characterize the near field ground, the seismic responses of nuclear island on different ground conditions are studied with the foundation embedment and soil-structure interaction effect considered. Results show that as foundation stiffness becomes larger, the response acceleration of nuclear island increases, while the period corresponding to peak spectral acceleration of nuclear island decreases. At the same time, the node stress of nuclear island increases but its relative displacement reduces. By considering soil-structure interaction, peak value of response acceleration of soft foundation diminishes while the period corresponding to peak spectral acceleration of foundation rises, which implies that soil-structure interaction has significant influence on seismic input of nuclear island on the soft ground. For hard rock foundation, the influence of soil-structure interaction on seismic input can be ignored.