Enhancing Ballast Performance Using Geocell Confinement

A major issue in the enduring performance of embankments subjected to repeated loading is its progressive deformation and loss of strength over time. In particular, railroad ballast embankments are prone to a rapid loss of geometry under loading by heavy freight trains. This deterioration manifests itself with high rate of track geometry loss, costing many millions of dollars each year by requiring frequent maintenance that can disrupt train schedule. The objective of this work was to simulate repeated loading on a ballast embankment, exploring a promising methodology to slow the deterioration process. A series of 6 loading tests on idealized representations of railroad ballast embankments, unreinforced and reinforced with geocell were performed to study the impact of geocell on the strength and stability of confined ballast. Three test configurations (unreinforced, single-layer, double-layer) were used, each of which was loaded to failure under monotonic conditions, and separately loaded cyclically with stress amplitude of 140 kPa and 275kPa for unreinforced and reinforced configurations, respectively. Measurements show that the presence of geocell allowed for a significant increase in stiffness and strength while reducing permanent deformation implying that an optimized use of geocell reinforcement could lead to significant reduction in maintenance due to ballast degradation.