Numerical investigation of pipeline transport characteristics of slurry shield under gravel stratum

•A fluid-particle two-phase flow model is established based on multiphase flow theory.•Simulation models were established based on CFD-DEM technology.•The rheological property of slurry is considered in this study.•The pipeline transport characteristics of slurry shield are obtained by numerical simulation.

In order to grasp the pipeline transport characteristics of slurry shield under gravel stratum, with a cross-river tunnel construction of Lanzhou metro as the research background, the numerical simulation method is adopted, and a slurry-stone two-phase flow model is established based on multiphase flow theory by considering the rheological properties of slurry. Besides, corresponding simulation models validated by experiment are established using CFD and DEM softwares, and the impacts of inlet slurry velocity, stone volumetric concentration and pipe inclination angle on pressure drop and transport capacity of the pipeline are investigated. The results show that stones are mainly distributed at the bottom of the pipeline for horizontal straight pipes. The pressure drop and transport capacity increase exponentially with the increase of inlet slurry velocity and stone volumetric concentration. For inclined straight pipes, the pressure drop of the pipeline increases slowly with the pipe inclination angle increasing from 0° to 60°, but increases rapidly when the pipe inclination angle increases from 60° to 90°; the transport capacity reduces slowly at first and then increases rapidly with the increase of pipe inclination angle, and the lowest value appears at 45-60°.