The broad portfolio of expertise held within NCG, including constitutive and numerical modelling, micro-mechanics, shakedown theory, particle fracture and laboratory testing, together with the strong history at Nottingham in pavement engineering, means that NCG is uniquely placed to apply its expertise to the solution of transportation geotechnics problems.
A large Railway Test Facility has been designed and commissioned for the repeated loading of full-sized sleepers embedded in ballast over subgrade. A range of ballasts, including those reinforced with geogrids, are studied using it. Discrete element modelling is used to complement the research and provide insight into material behaviour.
A bespoke large triaxial system is now in use for testing ballasts under a range of stress conditions. The triaxial apparatus uses a double-cell arrangement for measuring volumetric strains.
Constitutive modelling has been applied to the repeated loading of pavements and used to develop an understanding of the mechanics of rutting. Laboratory wheel-tracking tests on model pavements have been used to gain data on the permanent deformation of pavements and railway foundations. The data obtained is used to validate a newly developed pavement design method based on the shakedown concept of plasticity theory.