The determination of the axial bearing capacity of large-diameter steel pipe piles is a crucial aspect of the design of pile foundations. However

the existing methods for calculating the axial bearing capacity of pile foundations are mostly based on the test results of closed-ended piles or small-diameter steel pipe piles

and these methods are not applicable to large-diameter steel pipe piles. Based on the existing pile foundation bearing capacity calculation methods based on cone penetration tests

a modified method is proposed. By comprehensively considering the Poisson's effect

soil plugging effect

and side resistance degradation

an expression for the pile side friction resistance is derived. Meanwhile

the base resistance is divided into two parts: annular resistance and inner shaft resistance

and the proportional relationship between cone-tip resistance and these two resistances is established. The modified method is used to calculate the axial bearing capacity of large-diameter steel pipe piles in an actual offshore engineering project

and the results are compared with those obtained using six commonly used existing methods. The results show that compared with the existing methods

the modified method is more accurate

especially in terms of the prediction accuracy of pile side friction resistance. Additionally

sensitivity analyses of key parameters

including pile diameter

pile length

plug length ratio

and cone tip resistance

demonstrate that the soil plug effect significantly influences the calculation of the vertical bearing capacity of large-diameter steel pipe piles in both non-cohesive and cohesive soils. The research results can provide theoretical guidance for the calculation of the axial bearing capacity of large-diameter steel pipe piles.