CFD–DEM modelling of the infiltration of non-spherical slurry particles in granular soils

The slurry filtration process at an excavation surface plays an important role in supporting pressure transmission, which is crucial to the stability of a tunnel face during slurry shield tunnelling. In this paper, a series of coupled computational fluid dynamics (CFD)–discrete element method (DEM) numerical simulations were carried out to model the slurry filtration column test. Oblate spheroids of varying aspect ratios were adopted to represent slurry particles. A simplified pitching torque model was implemented to better simulate the motion of slurry particles. The pressure distribution, void fraction, permeability and orientations of the particles were analysed as the aspect ratio was systematically changed. The pressure distribution, void fraction and the permeability within a stratum are highly dependent on the aspect ratio of the particles. Particles with larger aspect ratios tend to effectively seal infiltration channels and transfer slurry pressure to effective pressure, thereby helping to maintain stability at the tunnel face. This research study explores how particle shape impacts the slurry infiltration procedure and the microstructure of the filter cake.