Behavior of sand-contaminated ballast reinforced with geogrid under cyclic loading

Abstract

A ballasted railway track is contaminated when passes through sandy areas. Due to sand penetration into the ballast voids, mechanical behavior of tracks deteriorates. Despite the dynamic nature of the load in the railway system, mechanical behavior of ballast reinforced with geogrid and contaminated with sand under cyclic loading have not been investigated. To study the influence of geogrid on improvement of cyclic mechanical properties of contaminated ballast, extensive laboratory tests were performed in this research. To this end, a ballast box machine was used in order to model in-situ cyclic loads. The tests were carried out on ballast samples contaminated with various sand dosages and reinforced with different geogrids. The results indicate that sand materials make ballast aggregates move and slide easier, causing more ballast settlement. It was shown that by geogrid reinforcement, settlement decreases (up to 75%), degradation (breakage) of ballast reduces (up to 23%), and its stiffness increases (up to 50%). An innovative model was developed which takes into account sand content and geogrid reinforcement that provides the settlement of ballast. An effective method of geogrid reinforcement for obtaining the best performance of ballast under cyclic loading was derived.