Impact of Shield Tunneling on Adjacent Pile Foundation in Sandy Cobble Strata

The assessment of the impact of urban area shield tunneling on adjacent pile foundations is essential to ensure the stability and integrity of the piled buildings. Sandy cobble strata has force transmission feature of strong dispersion; therefore the equilibrium state of original strata would be easily destroyed by shield tunneling. In this study, model tests referring to the Chengdu Metro Line 1 and using the Phi 520 mm EPB model shield machine are carried out to investigate the impact of shield tunneling on the existing pile foundation deformation and internal forces. Meanwhile, particle distinct element method is applied to analyze the soil particle movement feature surrounding the pile foundation from the micro view. Results showed that soil disturbance surrounding the pile foundation caused by shield tunneling makes the ground surface subsidence and pile foundation tilt, leading to the occurrence of stress concentration at the pile foundation base and nearby regions. Cutter head positive resistance and friction effect between shield machine and surrounding strata lead to the pile foundation three-dimensional movement and deformation during the shield tunneling.