Abstract
In geotechnical engineering, the seepage phenomena, especially regarding the hydraulic heave, is one of the most dangerous failure mechanisms related to infrastructural stability. Hence, a fundamental understanding of this occurrence is important for the design and construction of water-retaining structures. In this study, a computational fluid dynamics (CFD) solver was developed and coupled with discrete element method (DEM) software to simulate the seepage failure process for the three phases of soil, water, and air. Specimens were constructed with two layers of gap-graded particles to give different permeability properties in the vertical direction. More significant heave failure was observed for the sample with higher permeability in the upper layer. Special attention was drawn to the particle-scale observations of the internal structure and drag force to study the erosion mechanism. The soil filled with air bubbles produced a higher drag force in the region below the retaining wall and showed a larger loss of fine particles than the saturated soil, particularly in the initial stages. The results indicate that the impact of air bubbles would accelerate the development of the heave or boiling phenomenon and influence the stability of the system at an early stage.
Highlights
Seepage failure is a phenomenon that occurs when the seepage pressure exceeds the dead load of a considered soil bulk
Tanaka and Verruijt [10] analyzed the seepage failure behind the sheet piles and found that the critical hydraulic gradient depended on the anisotropy of the permeability of the soil
Huang et al [23] investigated the migration of particles under hydraulic load using a computational fluid dynamics (CFD) discrete element method (DEM)
Summary
Seepage failure is a phenomenon that occurs when the seepage pressure exceeds the dead load of a considered soil bulk. Koltuk et al [20] simulated heave failure in stratified cohesionless soils using the finite element method (FEM) They found that a larger ratio of permeability between the upper layer and the base layer would result in a higher critical hydraulic gradient, and that the developed fluid flow had a great impact on the pore water pressure. Huang et al [23] investigated the migration of particles under hydraulic load using a computational fluid dynamics (CFD) discrete element method (DEM) They found that the erosion resistance of the filter decreased with the increase of the representative size ratio (D15 /d85 ). Zou et al [26] employed the CFD-DEM software to conduct simulations of the suffusion phenomenon with gap-graded sandy gravel They observed obvious redistribution of particles during suffusion, while a sharp reduction in the fine grain content occurred in the bottom layer under upward seepage.
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