Optimization research on the layout of scouring pipes in the slurry shield based on CFD-DEM simulation

Slurry shield construction frequently encounters the risk of air cushion chamber clogging, which may cause pipeline damage at a minor level, or serious abnormal shutdown of the shield machine, resulting in serious negative impacts on construction safety and efficiency. Current studies primarily focus on the transport characteristics of cuttings in the discharge pipe, while the complete process from the air cushion chamber into the discharge pipe until discharge is often overlooked. The air cushion chamber is decisive in this process, fundamentally determining the discharge performance of cuttings. Therefore, the reasonable layout of scouring pipes within the chamber is particularly critical for alleviating the clogging risk. However, the current layout of scouring pipes lacks sufficient guidance, necessitating urgent optimization research. This paper establishes a model that more comprehensively reflects the process of cuttings discharge based on the CFD-DEM method and investigates the effects of scouring pipes layout on cuttings discharge performance. The results indicate that the cuttings discharge performance improves with the decrease in the layout height and rotation angle of the scouring pipes, as well as with the increase in the layout width and extension distance. Additionally, the layout scheme of scouring pipes with optimal discharge performance is determined based on the response surface method. These findings contribute to alleviating the risk of clogging in the air cushion chamber of the slurry shield.