Nonlinear numerical study of structure-soil-structure interaction effects between conventional and three-dimensional base-isolated nuclear power plants

Abstract

The three-dimensional (3D) isolation technology holds immense potential in the field of nuclear power plants (NPPs) due to its proficiency in mitigating vertical seismic impacts. In practice projects, multi-unit NPPs are a common form. As the site conditions become increasingly complex, the structure-soil-structure interaction (SSSI) effects are crucial in seismic assessments of NPPs. This study endeavours to meticulously simulate the scenarios where adjacent nuclear units are subjected to super-strong earthquakes. A novel time-domain coupled model and its computational procedure for nonlinear SSSI seismic analysis are proposed, and system models of ten NPPs are established to analyze the seismic responses of NPPs in firm rock and hard soil sites, and the impact of SSSI on the dynamic responses of conventional and 3D base-isolated NPPs is investigated in detail. Key findings illustrate that the SSSI effects on both conventional and 3D base-isolated NPPs are dependent on specific site conditions and inherent structural properties. For both conventional and 3D base-isolated NPPs, the floor response spectra and acceleration responses of a single NPP cannot fully envelope the scenarios where SSSI effects are considered. Furthermore, SSSI effects exert a more substantial influence on conventional NPPs compared to 3D base-isolated NPPs, with heightened effects at sites characterised by lower shear-wave velocities. These results furnish theoretical underpinnings for the seismic evaluation of multi-unit NPPs and the practical implementation of 3D base isolation in NPPs.