Simulating the Hydraulic Heave Phenomenon with Multiphase Fluid Flows Using CFD-DEM

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.

Keywords

• seepage
• air bubbles
• stratified soils
• particle velocity
• internal structure
• drag force