Experimental Investigation of Mechanical Properties of Ballast Contaminated with Wet Sand Materials

Abstract

Considerable parts of worldwide railway networks cross deserts where there are frequent sandstorms, which cause contamination of ballast. One of the most important challenges for railway industries is the adverse effects of sand contamination on the mechanical properties of ballast that sometimes halt the operation of railways. Although the available studies have focused on dry sand contamination, the majority of the published reports indicate that wet sand contamination is a more important source of the problem. Due to rainwater infiltration, sands act as a lubricant in the ballast, which causes ballast aggregates to slide easily over each other, and therefore reduce the vertical stiffness and shear strengths of the ballast. To address this problem, the characteristics of railway ballast contaminated with wet sand will be investigated in this study through a comprehensive experimental investigation. Large-scale direct shear tests and plate load tests (PLTs) will be conducted on ballast samples contaminated with different percentages of sand and water content. New mathematical expressions will be derived that present ballast mechanical properties as a function of sand percentage and water content. Through the analysis of the obtained results, a new guideline will be developed for the effective maintenance of ballast in sandy areas.