Constitutive models for geomaterials are the basis of modern geotechnical engineering and geomechanics. When numerical methods are used to analyse geotechnical engineering problems, the description of the material behaviour of the relevant components is a key aspect. As predominantly natural materials, geomaterials are usually three-phase media consisting of solid components, water and air. Geomaterials are porous media whose solid phase is often granular. The resulting material behaviour is highly non-linear, characterised by permanent deformation and rate-dependent effects as well as contractance, dilatancy, hysteresis and anisotropy. The rheology of granular materials includes, depending on the density, stress state and loading process, behaviour patterns typically known from solid, liquid and gaseous materials.

Due to this complex behaviour, the possibility of large deformations and multiphysical couplings, numerical simulations with corresponding constitutive approaches also serve to better understand the mechanical behaviour of complex geotechnical structures with their manifold interactions.

At the Chair of Soil Mechanics of the TU Freiberg we use the methods of continuum mechanics and material theory to describe thermal, hydraulic and mechanical phenomena occurring in porous and granular geomaterials and to derive consistent constitutive models for small and large deformations. We pay special attention to inelastic effects such as viscoplasticity or damage, as well as to the combination of modern rheological approaches for granulates with the consideration of multiphysical interactions.

Via generic interfaces, the models find their way into various calculation programs, first and foremost the open-source simulation software OpenGeoSys (www.opengeosys.org). For this purpose, we use state-of-the-art methods of software engineering in order to create efficient code and to be able to capture even large-scale geotechnical applications with high accuracy.