Numerical Study on Fluid Flow Characterization of the Souring System in a Large-Sized Slurry Shield

To solve frequent blockage of air cushion chamber during tunnel construction with the slurry shield, a slurry shield with a diameter of 15.76 m in a tunnel project crossing the Yellow River in Jinan City was taken as the research object. A three-dimensional CFD simulation model of the scouring system of the slurry shield was established to study the influence of the slurry circulation flow Q, the ratio φ of scouring flow to slurry circulation flow on the flow field characteristic, where the correctness of the simulation model was verified using PIV experiment. Additionally, orthogonal experimental design and numerical simulation were comprehensively applied to obtain the influence degree of each scouring pipeline on the flow performance and the optimal working mode. The results show that the increase of the flow Q and the ratio φ will improve the flow performance of the flow field at the bottom of the air cushion chamber and enhance the muck carrying capacity of the slurry. However, the increasing the flow Q would weaken the resisting muck settlement ability of slurry. And with the increase of the ratio φ, the resisting muck settlement ability of slurry initially increases till the vertex when φ = 20%, then decreases and finally becomes stable. Finally, considering the simulation results, it is suggested to control the slurry circulation flow Q between 2800 and 3000 m³/h, the scouring flow ratio φ between 30 and 40% and close the V5 pipeline or increase its installation angle.