CAP1400 nuclear island structure is an advanced and novel nuclear power plant structure. In order to explore the seismic response characteristics of CAP1400 nuclear island structure on soft rock sites, a three-dimensional refined nonlinear seismic response analysis model was established for a soft rock foundation-nuclear island structure system using ABAQUS software. The influences of the input ground motion intensity and the frequency spectrum characteristics on the acceleration, relative displacement, and floor response spectrum, as well as the critical shear wave velocity of nonbedrock sites for CAP1400 nuclear island structure, were proposed. The results suggested that the increasing amplitude of the peak acceleration and relative displacement of nuclear island structure decreased as the soft rock site entered a nonlinear state, and the high-frequency components of the input ground motion became more abundant. Specifically, the earthquake response was the largest at the cooling water tank on the top of the shield building, which was the focus of the seismic research on nuclear island structure. Due to the influence of the ground motion frequency spectrum characteristics and the nonbedrock site effect, the peak acceleration, peak relative displacement, and acceleration response spectrum of the nuclear island structure showed different changing trends for the near-field and far-field ground motions. Based on the influence of the site shear wave velocity on the seismic response of nuclear island structure, it was recommended that the critical shear wave velocity of nonbedrock sites for CAP1400 nuclear island structure should be 1250 m/s, and the nuclear island structure-foundation dynamic interaction could be ignored at this time. The research conclusions could provide some technical support and theoretical basis for the construction and seismic performance research of CAP1400 and other nuclear power plants.

中文翻译：

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软岩场地CAP1400核岛结构的非线性地震反应特征

CAP1400核岛结构是一种先进的新型核电站结构。为了探讨CAP1400核岛结构在软岩场地上的地震反应特征，利用ABAQUS软件建立了软岩地基-核岛结构系统的三维精细化非线性地震反应分析模型。提出了输入地面运动强度和频谱特性对CAP1400核岛结构的加速度，相对位移和地面响应谱以及非基岩场的临界剪切波速度的影响。结果表明，随着软岩场地进入非线性状态，峰值加速度的增大幅度和核岛结构的相对位移减小。输入地面运动的高频分量变得更加丰富。具体而言，在盾构建筑物顶部的冷却水箱处，地震响应最大，这是对核岛结构进行地震研究的重点。由于地震动频谱特征和非基岩场地效应的影响，核岛结构的峰值加速度，峰值相对位移和加速度响应谱在近场和远场地震动方面表现出不同的变化趋势。根据场地剪切波速度对核岛结构地震响应的影响，建议CAP1400核岛结构非基岩场地的临界剪切波速度应为1250 m / s，而此时核岛结构-地基动力相互作用可以忽略。研究结论可为CAP1400等核电站的建设和抗震性能研究提供一定的技术支持和理论依据。