Initial steps toward characterizing particle mobilization using pore-scale particle mobilization imaging experiments

This paper presents the preliminary results of an experimental study focused on investigating the fundamental mechanisms of particle-fluid interactions during soil erosion. Historically, researchers have focused primarily on how various soil properties (grain-size distribution, composition, plasticity) affect water-induced erosion. However, recent investigations suggested it is also important to consider permeating fluids other than pure water and how certain physicochemical properties of these fluids (pH, ionic strength, viscosity, composition and concentration of suspended solids) influence soil erosion behavior. The precise mechanisms of particle-fluid interactions and the role of these mechanisms in governing particle mobilization are not currently understood. In this study, pore-scale particle mobilization imaging experiments were utilized in an attempt to preliminarily characterize the mobilization process in terms of the hydraulic shear stress acting on individual particles. Tests were performed on ASTM 20-30 silica sand specimens formed within a custom-fabricated, acrylic, horizontally oriented flow cell that allowed for visual observation of the specimen. The particle mobilization process was captured using a high-definition CMOS camera and imaging system capable of acquiring clear images of individual particles at several hundred frames per second. To specifically focus on the capabilities of the test setup and avoid the inevitable complications associated with testing multiple permeating fluids, only distilled water was used as a permeating fluid. Preliminary results confirm the system's potential to characterize particle behaviors during mobilization.