Investigation into starting speed of stone in slurry shield circulation system

Abstract

Slurry circulating system is the core system for transporting excavated stone from the excavation interface, and the flow characteristics of stone in circulating pipeline is the key to determine whether stone can be transported smoothly. Based on Computational Fluid Dynamics-Discrete Element Method (CFD-DEM) coupling method, the movement model of stone in horizontal straight pipe of circulation system is established, and the influence of stone shape coefficient and equal volume particle size on stone starting speed is studied. The simulation results indicate that under the condition of equal volume particle size of stone is same, starting speed of stone with different shapes is ellipsoid > flat > nearly spherical; When the equal volume particle size of stone is 38.5, 42.5, 53.3, 56.2 and 58 mm, the starting speed of stone is 0.48, 1.06, 1.26, 2.36 and 4.7 m/ s respectively, which increases exponentially with the increase of equal volume particle size. The conclusions can be helpful for setting the working parameters of circulation system.