Stress distribution in railway formation - A simulated study

To meet the growing traffic needs, Indian Railways is going for introduction of heavier axle load wagons. Almost all the existing formations on core routes were constructed many decades ago without any design consideration of soil strength. Due to phenomenal increase in axle loads, traffic and speed of trains in recent years, large lengths of existing formations are showing signs of distress/instability and these lengths are likely to increase further with introduction of heavier axle loads. Improvement in top layer of railway subgrade by providing suitably designed sub-ballast layer is essential to withstand higher stresses, however, laying of thick sub-ballast layer under running traffic is extremely difficult and costly preposition. Reinforcing the sub-ballast layer with geomaterials like geogrid is expected to give relief in its thickness by reducing subgrade stresses appreciably. The study of formation stresses on Full Scale Track Panel Testing Equipment at RDSO has enabled assessment of induced stresses inside the railway formation due to heavier axle load and effect of geogrid reinforcement in reducing the stresses.