The rapid discharge of cuttings from the air cushion chamber is crucial for the construction safety and excavation efficiency of the slurry shield, previous studies have mainly focused on the transport characteristics of cuttings in the slurry discharge pipe, while the complete process of cuttings entering the slurry discharge pipe from the air cushion chamber until its discharged is often overlooked. Based on the CFD-DEM (computational fluid dynamics-discrete element method) coupling calculation method and combined with the actual project, a numerical calculation model that can fully reflect the discharge of cuttings in the air cushion chamber was established. The discharged ratio of cuttings under different scouring pipes layouts (vertical distance h₁, horizontal distance h₂ and rotation angle β) was compared, and the sensitivity of different factors to the discharged ratio of cuttings was summarized. The results show that the discharged ratio of cuttings decreases with the increase of h₁, and increases with the increase of h₂ and β. The average sensitivity order of the three factors is h₁ (1.6) > h₂ (0.79) > β (0.61). Therefore, reducing the height of the scour pipes is the most effective measure to improve the cuttings discharged ratio in practical engineering. The research results can provide practical reference for optimizing the layout of scouring pipes and formulating relevant construction measures.