Research on Vertical Bearing Characteristics of Single Pile in Complex Interactive Karst Area

This study investigates the vertical bearing characteristics of single-pile foundations in complex karst areas, focusing on the influence of underlying cavities, eccentric cavities, and beaded cavities. Using both indoor model tests and numerical simulations with ABAQUS/CAE 2020, the load–settlement behavior, pile axial force, and side friction distribution under these conditions are explored. The results reveal that the presence of eccentric cavities (eccentricity 2.5 d) significantly enhances the ultimate bearing capacity by 53% compared to concentric cavities. In contrast, beaded cavities reduce the bearing capacity by 12% due to increased pile instability and larger settlements. The study also examines the effects of backfilling on the bearing characteristics, finding that backfilling underlying cavities increases the ultimate bearing capacity by 111.8% and prevents shear failure of the cavity roof. Backfilling beaded cavities improves stability by reducing top settlement and increasing the ultimate bearing capacity by 4.5%. The novelty of this research lies in the comprehensive consideration of both eccentric and beaded cavities, which are often overlooked in existing studies. These findings provide valuable insights for the design of pile foundations in karst regions, offering practical guidance on how to mitigate the adverse effects of cavities and optimize foundation stability.