Coupled DEM–LBM simulation of internal fluidisation induced by a leaking pipe

• Results agree with previous experimental findings qualitatively well.
• A radial flow distribution is identified before fluidisation.
• Fluidising pressure is derived by Ergun flow equation for a radial flow case.
• Numerically measured fluidising pressure matches the analytical solution well.
• An equivalent bed height is proposed to be proportional to fluidising pressure.

This paper presents a numerical study of soil fluidisation induced by local leakage from a buried pipe using the coupled discrete element and lattice Boltzmann approach (DEM–LBM). The behaviour of the system is studied using different flow rates and initial bed heights. The excess pore pressure distribution and the soil behaviour due to a localised leak are investigated and compared with previous experimental findings. The comparison indicates that DEM–LBM is capable of capturing the leakage–soil interaction at the particle scale. Moreover, as the flow distribution is found to be one-dimensional in the radial direction rather than one-dimensional in the vertical direction, an extension to the Ergun flow equation is derived and the numerically measured fluidising pressure shows good agreement with this analytical solution. In addition, as indicated by the numerical results and the derived analytical solution, the relationship between fluidising pressure and pipe buried depth as well as leak size is also established. The simulation results suggest that DEM–LBM is a promising tool to carry out further studies into the internal fluidisation phenomenon.

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