Dynamic Effect in Capillary Pressure

What is it about?

Soil water retention curve (SWRC) as the constitutive relationship of hydro-mechanical coupling bridge of unsaturated soil has been experimentally investigated decades regarding impacts from dynamic effects in sandy soil and deformation in soft soil. However, due to inaccessibility of observation of microscale dynamic capillary behavior in geotechnical testing scale, most of the experimental methods can only provide the deviation between static SWRC and dynamic SWRC on drainage and imbibition. With the development of Computational Fluid Dynamic (CFD) simulation, several numerical methods so far can be utilized to investigate the soil water retention behavior in both micro- and macro-scale and upscaling between them, such as pore network model, Navier-Stokes integrated with Volume of Fluid and Level Set Method. Nevertheless, none of them provide a vision of interaction between fundamental fluid fractions in order to replicate the physical behavior of fluid tension from their mathematical expression. Compared to those CFD methods, Lattice Boltzmann Methods (LBM) is formulated on microscale for simulation of fluid dynamics. In addition to the interaction forces between fluid-fluid and fluid-solid phases, it fundamentally replicates the physical meaning of immiscible multiphase flow behavior in porous media. Therefore, LBM is selected to investigate the dynamic effect in soil water retention behavior in this study. The aim is to investigate the dynamic capillary pressure (soil suction in soil mechanics) varying with the saturation of each phase in a Representative Elementary Volume (REV) domain.

Featured Image

Photo by Maxim Tolchinskiy on Unsplash

Photo by Maxim Tolchinskiy on Unsplash

Why is it important?

Soil water retention curve (SWRC) as the constitutive relationship of hydro-mechanical coupling bridge of unsaturated soil has been experimentally investigated decades regarding impacts from dynamic effects in sandy soil and deformation in soft soil. However, due to inaccessibility of observation of microscale dynamic capillary behavior in geotechnical testing scale, most of the experimental methods can only provide the deviation between static SWRC and dynamic SWRC on drainage and imbibition. With the development of Computational Fluid Dynamic (CFD) simulation, several numerical methods so far can be utilized to investigate the soil water retention behavior in both micro- and macro-scale and upscaling between them, such as pore network model, Navier-Stokes integrated with Volume of Fluid and Level Set Method. Nevertheless, none of them provide a vision of interaction between fundamental fluid fractions in order to replicate the physical behavior of fluid tension from their mathematical expression. Compared to those CFD methods, Lattice Boltzmann Methods (LBM) is formulated on microscale for simulation of fluid dynamics. In addition to the interaction forces between fluid-fluid and fluid-solid phases, it fundamentally replicates the physical meaning of immiscible multiphase flow behavior in porous media. Therefore, LBM is selected to investigate the dynamic effect in soil water retention behavior in this study. The aim is to investigate the dynamic capillary pressure (soil suction in soil mechanics) varying with the saturation of each phase in a Representative Elementary Volume (REV) domain.

Perspectives