Numerical investigation of internal erosion in granular soils : from micro to macro

Abstract

Internal erosion in sandy soils is a prevalent engineering hazard in which fine particles are transported and lost through the pore spaces of the soil skeleton under seepage flow, ultimately leading to soil deformation and structural failure. Given its multi-field, multi-phase, and multi-scale nature, internal erosion presents significant research challenges. To elucidate the micro- to macro-scale mechanisms governing erosion, this study systematically investigates particle migration behavior using a cross-scale approach, integrating Computational Fluid Dynamics-Discrete Element Method (CFD-DEM) and Finite Element Method (FEM). First, microscopic particle erosion mechanics are examined at the small-scale Representative Volume Element (RVE) level, accounting for the influence of soil stress anisotropy and fabric anisotropy. Building on these insights, the internal erosion processes and structural mechanical response of a water-soil-tunnel system are further investigated through a meso-scale CFD-DEM-FEM boundary value model, identifying key factors affecting system stability. Additionally, a novel erosion law is proposed based on CFD-DEM simulations, and a coupled seepage-erosion-mechanics numerical analysis method is developed within the framework of four-constituent medium theory. Finally, leveraging ABAQUS UEL subroutine development, this study enables large-scale numerical analysis of dam seepage erosion. By bridging discrete and continuum media and connecting microscopic particle behavior to macroscopic engineering responses, this research achieves a comprehensive cross-scale investigation of internal erosion, advancing both theoretical understanding and practical applications in geotechnical engineering.