With the development of underground space and uplift resistance issues arising during urbanization

the application of uplift pile technology in high water table clay areas

such as the southeast coastal regions

has become increasingly prevalent. However

conventional drilling techniques face significant challenges

including difficulty in achieving the required side resistance due to the mud cake effect and challenges in expanding the bottom hole. To address these challenges

a novel calculation method for the uplift bearing capacity of constrained grouting pile groups

accounting for disturbance effects

has been proposed. Taking the ⑤1 layer of grey clay in Shanghai as a case study

a clay and sand elastic-plastic-disturbed state concept(CASM-DSC) model was developed to accurately simulate the mechanical behavior of the soil around the pile. Numerical simulations were performed using a user-defined material constitutive (UMAT) subroutine to analyze the disturbance effects of the foundation soil around the pile and the influence of expansion size. The simplified calculation method for the uplift resistance of grouted and expanded steel pipe piles

as proposed in previous research

was revised. The results indicate that drilling excavation significantly reduces the side resistance of clay soils and influences the mechanical performance of the pile-soil interface. The disturbance coefficient and range exhibit a quadratic relationship with stress state and a linear reduction trend

respectively

in the foundation soil. At varying expansion lengths

the ultimate uplift bearing capacity of the model pile exhibits a “V” shape characteristic as length increases. Additionally

the expansion process alters the distribution of side force and axial force along the pile. Field tests at the Xuhui Binjiang site in Shanghai confirmed the effectiveness and applicability of the simplified calculation method

with a calculation error controlled within 15%. This provides reliable theoretical support and a practical calculation method for pile foundation engineering design.