Investigation of the dynamic discharge of cuttings in slurry shield tunneling under complex working condition

The dynamic discharge process of cuttings within the working chamber plays a pivotal role in ensuring both excavation efficiency and safety throughout the slurry shield tunneling cycle. Prior research has primarily concentrated on cuttings that are statically deposited at the base of the chamber, failing to reveal the mechanisms behind the dynamic evolution of clogging risks under complex working conditions. To address this gap, this paper incorporates actual engineering and establishes a computational model to represent the dynamic discharge of cuttings by employing the CFD-DEM approach. A systematic investigation was conducted to assess the impact of critical factors, including slurry velocity at the intake gate and scouring pipes (v_inlet1 and v_inlet2), cuttings diameter (d), slurry concentration (sc), and adhesion strength (γ), on the dynamic discharge behavior of cuttings. The results demonstrate that v_inlet1 has a markedly stronger effect on improving discharge performance during tunneling than v_inlet2. Cuttings with large d are more susceptible to inducing clogging. An increase in sc enhances both the kinetic energy of the cuttings and their ability to resist disturbances caused by the scouring pipes. The increase in γ not only suppresses the cuttings discharge, but also disrupts the stability of the process, making its transport behavior more unpredictable. These findings provide a scientific foundation for assessing the clogging risk and devising effective construction strategies.