考虑土⁃结构相互作用的安全壳隔震与支座数量优化∗

为了探究土-结构相互作用(SSI)对隔震的核电站安全壳在地震作用下隔震效果的影响,以及在此基础上对隔震支座数量设置的优化,选取CPR1000建立三维有限元模型,采用0.4g的LBNS地震波作用,通过ABAQUS有限元分析软件模拟计算在不同情况下,考虑SSI效应、不考虑SSI效应、隔震、非隔震,以及不同数量设置的铅芯橡胶隔震支座下的安全壳的地震加速度、位移响应。结果表明,对于非隔震安全壳,考虑SSI效应后最大加速度响应下降44.39%,最大位移响应增大了27.03%;而对于隔震结构,SSI效应影响相对较小,最大加速度及位移响应的变化分别为3.17%和10.73%。但在考虑位移响应下,SSI效应仍不可忽视。随着隔震支座设置数量增大,隔震层的刚度和阻尼增大,在考虑SSI效应下,安全壳的最大加速度响应近线性缓慢增大。而最大位移响应在数量100～300阶段迅速减小,在数量300～600阶段减速则趋于平缓。在数量达到300后,继续增加数量位移减小效果不明显,而加速度将有所增加。因此选取300作为较优的隔震支座数量设置。

Seismic Response of Base-isolated Nuclear Containment and Optimization for the Number of Isolation Bearings Considering Soil-Structure Interaction

This paper aims to analyze the behavior of the isolated containment vessel for the nuclear power plant under earthquake considering soil-structure interaction (SSI) and to optimize the number of isolation bearings. Therefore, a three-dimensional finite element model is established for CPR1000, and ABAQUS is used to simulate the seismic acceleration and displacement response under the LBNS seismic wave. The simulation conditions are: analysis with and without SSI, isolated and non-isolated structure, and different number of lead rubber bearings. For non-isolated containment, after considering the SSI effect, the maximum acceleration response decreases by 44.39%, and the maximum displacement response increases by 27.03%. For the isolated structure, the influence of SSI effect is relatively small, and the changes in maximum acceleration and displacement response are 3.17% and 10.73%, respectively. However, the SSI effect cannot be ignored when considering the displacement response. With the increase in the number of isolation bearings, the stiffness and damping of the isolation layer increases. As a result, the maximum acceleration response of the containment increases linearly. The maximum displacement response declines rapidly when the number of bearings decreases from 100 to 300. Then it slows down when the number rises above 300. That means the decrease of displacement response is not obvious at this stage, while the acceleration response will increase. Therefore, 300 is relatively the optimal number for isolation bearings.