Evaluation of the properties of railway capping layer soil

A capping layer placed below the ballast protects the underlying weaker soils. Even thick capping layers fail to eliminate plastic deformation of tracks. This paper reports an economical method of evaluating the elastoplastic material properties using penetration tests on specimens contained in rigid test moulds, coupled with a finite element modelling based backcalculation approach. The material properties thus determined simulate the behaviour of capping layers under a track structure effectively as shown using full scale laboratory experiments. Sensitivity of the material parameters to the behaviour of the capping layer soil is also presented.