Stress-Strain Degradation Response of Railway Ballast Stabilized with Geosynthetics

Abstract

Large cyclic loading on ballasted railroad tracks is now inevitable owing to an increased demand for freight and public transport. This leads to a progressive deterioration and densification of railroad ballast and consequently to the loss of track geometry and differential settlement. Understanding these complex stress-strain and degradation mechanisms is essential to predict the desirable track maintenance cycle, as well as the design of new track. This paper presents the results of cyclic drained tests and numerical studies carried out on a segment of model railway track supported on geosynthetically reinforced railroad ballast bed. The relative performance and effectiveness of single- and dual-layer configurations of geosynthetic reinforcement was evaluated using a large-scale prismoidal triaxial chamber. Laboratory tests on unreinforced and reinforced railway track were simulated in a numerical model, and the results were then analyzed to better understand the distribution of displacements and stresses inside the railroad ballast layer. It was observed that in view of strain and breakage control, both the type of reinforcement and its layout played a vital role in improving the capacity of the track. These laboratory test findings were supported by the predictions from an advanced elastoplastic numerical analysis.