The disposal of nuclear in so-called deep geotechnical repositories is one of the most challenging missions in current geosciences. An impermeable soil and rock barrier is needed to protect our natural resources against contamination from the sources of emission. Expansive clay materials are suited for the barrier due to their low hydraulic permeability and swelling capacity, which prevent a possible migration of contaminated water and even selfheal dangerous cracks in the buffer. In the design of repositories, numerical simulations help to predict the performance during the functionality period of the barrier estimated at 1 million years, but existing material models and simulation techniques are reaching their limits in predicting the coupled hydro-mechanical behavior due to complex boundary conditions. In my research, I am aiming to develop a new model based on an experimental campaign that investigates numerous combinations of hydro-mechanical loading paths, with special attention to the material’s loading history. The novel aspect of my proposed model is to consider the water bound by the swelling process as a separate phase with its own properties and hydro-mechanical contribution to the overall behavior. The material model will be implemented in an advanced in-house finite element software for coupled geotechnical simulations to model the holistic material behavior with less compromise and validate the experimental results.
In September 2021 I joined a workshop on Engineered Barrier Systems and Bentonite properties and applications, organized by Nagra, the Swiss National Cooperative for the Disposal of Radioactive Waste. The workshop took place in one of Nagra’s Underground Rock Laboratories located in the swiss alps just below the Grimsel Pass at an elevation of approx. 1700 m. As well as seeing Nagra's large-scale experiments in the rock laboratory, we were treated to a week of lectures and discussions by internationally recognised experts in the field of nuclear waste disposal. Both the participants and the speakers came from different disciplines, which made for a very open and fruitful exchange during the week-long workshop. The informal setting of the event made it very easy to make contacts, so that it was a great introductory event for me on the international level. I am grateful that I was able to realise this activity with the help of IRB funded by RUB Research School!