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ABSTRACT The existence of groundwater inevitably influences the seismic response of a nuclear power plant (NPP) through soil–structure interaction (SSI). This study investigates the effect of groundwater on the seismic response of NPP. First, we propose a novel methodology that (i) utilizes the wave potential theory and transfer‐matrix method to derive the analytical solution for free‐field response in layered permeable dry soil–saturated soil–impermeable bedrock system; (ii) extends the generalized saturated porous medium model to describe permeable dry soil, saturated soil, and impermeable bedrock, and discretizes it using explicit finite element method, which enables the simulation of dynamic coupling between diverse media within a unified computational framework; (iii) makes use of the multitransmitting boundary to input the free field and to absorb the outgoing scattered waves; (iv) enables the efficient SSI analysis through a hybrid partitioned algorithm combined with asynchronous parallel computation. Then, the proposed method is verified using a simple model. Finally, seismic response analyses of the CAP1400 NPP, resting on a layered half‐space, are conducted by both the proposed method and an approximation method in ASCE 4‐16. The groundwater table is varied to investigate its effect on structural response. Results show that groundwater has a limited effect on structural displacements but a noticeable influence on acceleration responses. Specifically, as the groundwater table rises, the structural dynamic responses tend to decrease. Moreover, as the site soil becomes softer (i.e., with a reduction in shear modulus), the influence of groundwater on structural responses becomes more pronounced. Comparisons between results from the two methods demonstrated that the approximation method yields marginally larger values, potentially leading to overly conservative seismic safety designs.
Gao et al. (Mon,) studied this question.