ABSTRACT
This chapter discusses different types of geosynthetics available for geotechnical applications and their effectiveness in harsh railway environment. Geosynthetics is the collective term applied to thin, flexible sheets manufactured from synthetic materials which are used in conjunction with soils and aggregates to enhance soil properties. The reinforcement mechanism between geogrid and railway ballast is governed by the interlocking effect attributed to the ballast particles partially penetrating through the apertures in the geogrid. The reduction in settlement could be represented by means of a "settlement reduction factor", which can be defined as the ratio between the difference in the settlement of reinforced and unreinforced ballast. The coal fines can reduce the peak shear stresses of the reinforced and unreinforced ballast assemblies because they coat the surfaces of ballast grains, thus inhibiting inter-particle friction and reducing the shearing resistance at the geogrid–ballast interface.
