Based on the wave-propagation mechanisms in saturated porous media and saturated frozen porous media, this study develops a composite geological model consisting of bedrock, a saturated soil layer, and a saturated frozen soil layer, and systematically derives an analytical solution for the seismic wavefield under incident plane P waves. By introducing the Helmholtz decomposition, the displacement field is decoupled into scalar and vector potentials, so that the solution strictly satisfies interlayer boundary conditions of stress continuity and displacement compatibility. In this way, a set of analytical equations is established to characterize energy-transfer behavior in the wavefield. The theoretical model clarifies elastic wave propagation paths in the three-phase coupled system and their control over the response characteristics of surface ground motion. Numerical simulations are then performed to analyze the influence of saturated soil thickness, medium temperature, and contact and cementation parameters in the saturated frozen soil on site seismic ground motion. The results show that the displacement amplification coefficient differs significantly depending on whether a saturated soil layer is present. When such a layer exists, the displacement amplification coefficient is generally larger, and the vertical amplification coefficient increases with increasing saturated soil thickness. At the same time, the horizontal displacement amplification coefficient decreases as medium temperature, cementation, and contact parameters increase. The vertical amplification coefficient decreases with increasing contact parameters, but increases with increasing medium temperature and cementation.
Liu et al. (Mon,) studied this question.