Assessing clogging potential and optimizing driving parameter of slurry shield tunneling in clay stratum assisted with CFD-DEM modeling

This paper proposed a two-way coupled computational fluid dynamics (CFD) and discrete element method (DEM) approach to analyze the evolution of clogging in slurry shield tunneling quantitatively. The interactions between clay particles and slurry were considered by exchanging three interaction forces, including buoyancy force, pressure gradient force, and drag force. The CFD-DEM coupling approach was first benchmarked by comparing cutterhead torque and total thrust with field monitored data of a practical slurry shield tunnel project. The evolution process of the particle phase and the fluid phase over time was presented. The results indicated that fewer than 70% of the particles can be washed away in time by the circulating slurry. About 9% of the particles adhered to the submerged wall, resulting in increased cutterhead torque and thrust. Through parametric analysis, the influence of the shield driving parameters on the clay clogging behavior is further explored. The time history of cutterhead torque or thrust can be used as a criterion for judging whether clogging has occurred. Additionally, a new assessment method of clogging risk and an optimization strategy of driving parameters were proposed, which were intended to provide some guidance for similar projects.