Seismic response of pile-supported embankment in unequal thickness liquefiable soil with V shape underlying stratum

In this study, a series of shake table tests were conducted on saturated sand soil foundations to investigate the seismic response of pile-supported railway embankments under equal and unequal thickness heterogeneous liquefiable soil conditions. The model's failure process, the variations of excess pore water pressure, the bending moments of the pile, and the acceleration response under different seismic intensities were analyzed in detail. Test results showed that the pore pressure increased with the increase of seismic intensity, and the liquefaction phenomenon occurred in the loose sand layer under 0.2 g dynamic excitation. The growth rate and peak value of excess pore water pressure in unequal thickness liquefiable soil terrain were greater than that in equal thickness soil conditions. The maximum bending moment of the pile body exhibits an inverted S-shaped distribution. In unequal thickness soil conditions, the edge piles experience higher bending moments compared to those in terrains with the same thickness. Additionally, the position of the maximum negative bending moment distribution for the central pile underwent a noticeable downward shift. During the loading process, the amplification effect of acceleration was greater in the loose sand layer than in the gravel soil layer, and more significant at the center of the foundation or the subgrade in unequal thickness liquefiable soil conditions. Therefore, the influence of terrain factors on the rise of pore pressure and the distribution of pile bending moments was nonnegligible in the seismic design of pile-supported embankment.