Numerical Simulation of Water-Silt Inrush Hazard of Fault Rock: A Three-Phase Flow Model

Fault rock is a typical hazardous material of water-silt inrush during the excavation in underground mines. To investigate hydraulic characteristics of fault rock during the water-silt inrush, a one-dimensional radial three-phase flow model of water-rock-silt was established in this study. In the proposed model, the mass conservation and continuity equations of the three-phase flow were obtained; the rock particle migration and the momentum conservation of the three-phase fluid migration were described by erosion constitutive equations and non-Darcy flow equations, respectively. The laboratory tests of porosity and the evolution of volume discharge rate were compared, and the accuracy of the proposed three-phase model was verified by the comparison results. From the test and numerical results, a high standard deviation of repeated results is observed in the case with high silt concentrations, and the erosion effect is inhibited by the silt flow. Last but not least, the temporal-spatial distribution of hydraulic properties is obtained by the numerical simulation: With the progress of the three-phase flow, rock particles near the fluid outlet are first fluidized and constantly migrate outward, resulting in an increase of the porosity and permeability in fault rock. Subsequently, water-conducting pathways are gradually formed inside the fault rock, and then more fluidized rock particles flow out. Finally, the fluidized rock particles have completely migrated, and the porosity and permeability tend to be stable with the more significant non-uniform spatial distribution.

Automated summary

A one-dimensional radial three-phase flow model of water-rock-silt was established to investigate the hydraulic characteristics of fault rock during water-silt inrush. The accuracy of the proposed model was verified through laboratory tests and the temporal-spatial distribution of hydraulic properties was obtained.