Constitutive and Numerical Modeling
Constitutive modelling of geomaterials forms a central theme of research within the NCG. The research team not only derive and develop new models but also implement them into numerical methods for the solution of boundary value problems relevant to geotechnical engineering.
Theoretical modelling focuses on developing new models for geomaterials, applicable to clay, sand and other granular materials.
They are based on mathematical and physical formulations incorporating critical states, micro-mechanics and energy concepts. Models have been developed with realistic yield surfaces, incorporating both kinematic hardening and bounding surface plasticity.
Recent effort has been focused on the development of novel non-coaxial plasticity theories for modelling geomaterials under stress rotations. The use of non-coaxial models is found to be essential for accurate solutions of many soil-structure interaction problems.
The continuum models which have been developed have been applied using finite element methods (FEM) to soil-structure interaction problems and repeated loading of pavements. Discrete element modelling (DEM) is used to gain insight into particle micro-mechanics and investigate fundamental element behaviour in addition to complete boundary value problems. DEM involves the use of non-spherical particles and incorporates particle crushing. The models reveal useful information about particle mechanics for the development of continuum models. DEM is also used to model the behaviour of railway ballast. Finite element and finite difference modelling of rock mechanics problems complete the strong and internationally renowned theoretical modelling portfolio with the NCG.
Recently, DEM has been used to show with a simple crushing model, without the use of agglomerates, the micro mechanical origin of the fundamental compression law for granular materials.