Study on the Influencing Factors of Vertical Bearing Capacity of Pile Foundation in Multi-Layer Cave

Pile foundations are widely employed in engineering to bolster structures and efficiently transmit loads to the underlying soil or rock. However, in karst terrains, the occurrence of multi-layered stone projections or caves can drastically affect the bearing capacity and stability of these pile foundations. In order to study the influencing factors of vertical bearing capacity of pile founda-tion in multi-layer karst cave environment, the bearing capacity test of pile foundation was carried out at the construction site. The results show that with the increase of external load eccentricity, the bearing capacity of pile foundation decreases obviously. Subsequently, we developed a finite element model for pile foundations in a double-layered karst area using the commercial general finite element software ANSYS. This model facilitated our analysis of the bearing capacity of concrete pile foundations under progressively increasing loads, accounting for variations in rock height, eccentricity, and elastic modulus. The findings reveal the following: (1) Under consistent external loading, the maximum displacement of pile foundations increases with eccentricity. (2) As concrete strength rises, the maximum displacement gradually decreases, while the corresponding peak stress remains approximately constant. (3) The height of karst caves significantly impacts the bearing capacity of pile foundations. Therefore, during construction, it is crucial to minimize or avoid traversing areas with high karst caves. In engineering applications involving multi-layered karst landforms, it is essential to assess the bearing capacity of pile foundations beforehand, paying particular attention to the effects of karst cave height, pile eccentricity, and concrete strength on the bearing capacity. This will enable the optimization of the design scheme, avoidance of high karst cave areas, and ensure the safety and stability of the structure.