Analysis of Deformation and Degradation of Fouled Ballast: Experimental Testing and DEM Modeling
The deformation and degradation of fouled ballast have been examined by large-scale triaxial tests and discrete element modeling (DEM) to understand how clay fouling changes the shear strength and micromechanical aspects of ballast. Particle shape analysis using 3D aggregate imaging and a laser scanner is introduced to construct more realistic polyhedral discrete elements that will represent natural ballast particles. Shear stress-strain and volumetric changes of fresh and clay-fouled ballast are analyzed. Micromechanical analysis of the fouled ballast is carried out and the effects of fines are quantified by considering the changes of ballast breakage, particle connectivity number Cn, and the associated distribution of contact forces that could not be measured experimentally. These findings enable a more insightful understanding of the load-deformation of fouled ballast from a micromechanical perspective.