Abstract: Based on the Biot’s three-phase medium theory, a two-dimensional layered site model of saturated frozen soil overlying bedrock is constructed to analyze the characteristics of seismic ground motion under plane SV wave incidence. The governing equations are decoupled via Helmholtz vector decomposition, and an analytical solution is derived by enforcing interlayer boundary conditions and employing the transfer-matrix method. The reliability of the solution procedure is validated through comparison with published results. On this basis, a systematic parametric study is conducted to investigate how incident frequency and angle, porosity, medium temperature, cementation and contact parameters, as well as the thickness of the surface saturated frozen layer influence the amplification of surface displacement. The results show that the amplification of seismic motion in layered saturated frozen sites is overall stronger than in homogeneous sites, with particularly pronounced amplification near the critical incident angle. Increases in porosity and temperature typically enhance horizontal displacement amplification, whereas the vertical displacement demonstrates notable structure-dependent and nonlinear behavior across various layering configurations. The cementation and contact parameters substantially modulate the stiffness of the soil skeleton, thereby altering both the magnitude and spatial distribution characteristics of surface displacement amplification; variations in the thickness of the surface frozen layer induce clear periodic fluctuations in the amplification factor. This study elucidates the mechanism of seismic ground-motion amplification in cold-region layered saturated frozen sites under SV wave incidence and provides theoretical support for site-effect assessment and earthquake-resistant design of relevant engineering in cold regions.

Key words: saturated frozen soil, layered site, ground motion, SV wave, analytical solution