NCG is uniquely placed to apply its expertise to the solution of transportation geotechnics problems, together with the strong history at Nottingham in pavement engineering with a portfolio of expertise held within:
- including constitutive and numerical modelling
- shakedown theory
- particle fracture
- laboratory testing
A large Railway Test Facility has been designed and commissioned for the repeated loading of full-sized sleepers embedded in ballast over subgrade. A variety 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. The Facility has recently been upgraded as part of the EPSRC Track 21 Project: Railway Track for the 21st Century, to study the effect of sleeper type, reinforcement, ballast type and the use of under-sleeper pads on performance.
A bespoke large triaxial system is used 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.