Three‐dimensional hydromechanical modeling of internal erosion in dike‐on‐foundation

Abstract

Currently, numerical studies at the real scale of an entire engineering structure considering internal erosion are still rare. This paper presents a threedimensional (3D) numerical simulation of the effects of internal erosion within a linear dike located on a foundation. A two-dimensional (2D) finite element code has been extended to 3D in order to analyze the impact of internal erosion under more realistic hydromechanical conditions. The saturated soil has been considered as a mixture of four interacting constituents: soil skeleton, erodible fines, fluidized fine particles, and fluid. The detachment and transport of the fine particles have been modeled with a mass exchange model between the solid and the fluid phases. An elastoplastic constitutive model for sand-silt mixtures has been developed to monitor the effect of the evolution of both the porosity and the fines content induced by internal erosion upon the behavior of the soil skeleton. An unsaturated flow condition has been implemented into this coupled hydromechanical model to describe more accurately the seepage within the dike and the foundation. A stabilized finite element method was used to eliminate spurious numerical oscillations in solving the convectiondominated transport of fluidized particles. This numerical tool was then applied to a specific dike-on-foundation case subjected to internal erosion induced by a leakage located at the bottom of the foundation. Different failure modes were observed and analyzed for different boundary conditions, including the significant influence of the leakage cavity size and the elevation of the water level at the upstream and downstream sides of the dike. K E Y W O R D Scritical state, dike, fines content, granular media, internal erosion, stabilized finite element method

A coupled CFD‐DEM investigation of suffusion of gap graded soil: Coupling effect of confining pressure and fines content

“…34 Table 2 summarizes the properties of particles and fluid and numerical settings in the simulations. To achieve numerical stability for CFD and DEM domain, the Courant number, defined in Equation 13, should be below 0.2 and the time step for DEM domain should be determined by the method proposed by Cundall and Strack 40 as seen in Equation (14). where Δt f is the fluid timestep and Δl is the minimum fluid cell length.…”

“…Previous experimental and theoretical studies on suffusion have revealed that the erodibility of gap-graded soil is significantly influenced by confining pressure (p′) and fines content (F c ). [1][2][3][4][5][6][7][8][9][10][11][12][13][14] It was concluded from some studies that a higher confining F I G U R E 1 (A) Illustration of internal erosion and (B) schematic diagram of coarse grid DEM-CFD simulation approach adopted in this study pressure (p′) may help to prevent the occurrence of suffusion, due to the resulted increase in the interparticle contact force and particle connectivity. 8,9,15,16 Conversely, it was revealed from other studies that an increasing confining pressure could have intensified the suffusion (e.g., more fines loss) of a gap-graded soil.…”

“…It is indisputable that the significant changes of hydraulic and mechanical behavior of the soil induced by suffusion are the cause of many unfavorable evolutions, which may lead to failure. Previous experimental and theoretical studies on suffusion have revealed that the erodibility of gap‐graded soil is significantly influenced by confining pressure ( p ′) and fines content ( F c ) 1–14 . It was concluded from some studies that a higher confining pressure ( p ′) may help to prevent the occurrence of suffusion, due to the resulted increase in the interparticle contact force and particle connectivity 8,9,15,16 .…”

Soil‐structure interface modeling with the nonlinear incremental approach

“…The granular soils under deviatoric stress path experience particle breakage and their critical state line (CSL) in e ‐ σ n plane move toward the lower void ratio 35,36 . The CSL translation has been simulated differently in previous studies 2,37–42 . In the proposed interface constitutive model, the effect of particle breakage in interface area is taken into account by translating downward the CSL in the e ‐ σ n plane through the determination of the reference critical void ratio ( e ref ) using the approaches by Liu et al 43 as given in Equation (11).…”

Preconditioners for multiphase poromechanics with strong capillarity

“…Multiphase flow through porous, deformable media occurs in a variety of applications in science and engineering 1–4 . In geotechnical engineering, predicting the increase of soil saturation due to rainfall infiltration is key to accurate modeling of landslide triggering 5–12 .…”