Dependency of material parameters on temperature or stress state in OGS
Geomaterials exhibit often temperature or stress dependent behaviour. This is especially the case for materials used in the context of the geological disposal of radioactive waste. Due to the heat produced by the heat-generating waste geomaterials in place are subject to temperature up to 200°C. This has an non negligible effect on their behaviour. For example, the water viscosity decrease with temperature following the equation:
\mu = \exp(A + \frac{B}{C+T})
with T
the temperature in Kelvin and A = -3.719
, B = 578.919
, C = -137.546
The thermal conductivity of crushed salt is a function of the temperature and of the porosity. The porosity in this case varies with the actual stress state in the material:
Thus the material parameters to use in simulation should be able to change according to the actual temperature and stress state in the model. This feature is unfortunately not available in OGS right now but it is strongly needed for simulations regarding the safety assessment of repository systems.