Damage detection of longitudinal cracked concrete sleeper rested on sand-fouled ballast in desert areas: A roadmap for ballast and sleeper maintenance

This study investigates the dynamic behavior of ballasted railway tracks in arid environments, focusing on the combined effects of sand fouling and sleeper damage—two critical yet understudied issues caused by sand intrusion and rebar corrosion. An integrated experimental and numerical approach was employed. Experimental modal analysis was performed on a laboratory setup with both healthy and longitudinally cracked concrete sleepers resting on clean and fouled ballast. Subsequently, the results were used to develop and validate a three-dimensional finite element model. A comprehensive parametric study of over 100 cases analyzed three scenarios: undamaged sleeper on fouled ballast (GA), damaged sleeper on clean ballast (GB), and their combination (GC), considering various crack geometries and sand locations. The results show that severe sand fouling for GA reduced natural frequencies by up to 36% in rigid-body modes and 14% in the first bending mode, and led to a more sloped mode shape in rigid-body modes. A damaged sleeper in GB caused reductions of 30, 22, and 17% in the rigid body, first bending, and higher bending modes, respectively. The combined critical damage state presented the most severe serviceability challenge, with reductions of 46% (rigid body), 27% (first bending), and up to 19% (higher bending modes), along with amplified mode shape deflections. Based on the findings, the study proposes a viable method for damage identification and a novel maintenance framework that defines protective, corrective, and critical zones for ballasted railway tracks in desert regions.