Research on the Influence of Post-Construction Consolidation Settlement of High-Fill Loess Sites on the Bearing Performance of Foundation Piles

Owing to the consolidation of the fill material, the pile foundations in high-fill sites are subjected to downward Negative Skin Friction (NSF), which can impact the safe serviceability of the foundations. This study employs the secant modulus method to establish the settlement curve of the soil and subsequently introduces a time parameter to account for the consolidation settlement of the soil around the piles. Based on the load transfer method, a calculation and analysis model for NSF in pile foundations situated in high-fill loess sites, considering the time effects of soil consolidation, is developed. The force states of the piles are categorised into nine types based on the boundary conditions at the pile tip and the relative displacement between the pile and soil. By controlling the differential equations of the pile displacement, analytical solutions for the pile settlement, axial forces, and side friction resistance under different loading conditions are derived. Case studies validate the correctness of the proposed solutions. The results indicate that with a constant pile top load, as the consolidation settlement of the surrounding soil progresses, the displacement at the pile top increases, and the distribution pattern of axial forces within the pile exhibits significant changes. Furthermore, the post-consolidation of the surrounding soil has a notable impact on the bearing capacity of the pile foundation. The findings of this study provide valuable insights into the negative skin friction problem associated with pile foundations due to consolidation settlement in high-fill loess sites, as well as the assessment of the bearing capacity of these foundations.