Study on Vertical Load Distribution of Pile Group–Liquefied Soil System under Horizontal Seismic Environment

The dynamic responses of pile–liquefied composite soils are complex, and the bearing capacities of single piles or pile groups in liquefiable soils remain unclear. For friction piles, the friction resistance determines the vertical bearing capacity of the pile. In a pile–soil system, it is very important to study the friction resistance changes in the pile during vibration. Based on a shaking table test, this study investigated the vertical bearing capacity of a pile foundation–liquefied soil system under simulated horizontal seismic forces, using the MIDAS GTS software. The load borne by the top of the pile was studied under a horizontal earthquake with a certain vertical load, different pile spacings, and different vibration times, along with the cumulative coefficient CCPF of the pile side friction. The distributions of the CCPF along the pile body of a single pile and pile groups with different pile spacings were analyzed at different vibration times. It was found that the CCPF intuitively reflected the distribution law of the pile side friction during vibration. When the CCPF at the bottom of the pile was equal to 1, the load on the top of the pile was equal to the average value of the total load. When the CCPF at the bottom of the pile was less than 1, the load on the top of the pile was less than the average value of the total load. When the CCPF at the bottom of the pile was greater than 1, the load on the top of the pile was greater than the average of the total load.