Numerical Examination of EPB Shield Tunneling–Induced Responses at Various Discharge Ratios

This study investigated earth pressure balance (EPB) shield tunneling–induced responses in terms of muck pressure, machine parameters, and surface settlements using an efficient numerical scheme that couples PFC3D and FLAC3D software. Tunneling cases with different discharge ratios in the chamber were conducted using PFC3D, and the surrounding ground was modeled in FLAC3D. The results showed that the muck pressures near the bulkhead vary periodically during shield tunneling and have negative relations with the discharge ratios. Pressure differences between the left and the right sides in the shield chamber, and at different longitudinal positions, were found to be subject to the discharge ratio in the chamber. Furthermore, negative relations between the discharge ratio and both the thrust in the shield and the torque in the cutterhead were observed during excavation. Finally, it was found that positive ground loss has a larger effect on surface settlement than its negative counterpart.