Support Structures for Potential German Repository in Claystone and their Design by THMModelling - 23296

Claystone as potential host rock for radioactive waste repositories offers low permeability, high sorption capacity, and, in a certain way, self-sealing capacities. However, the mid to low strength and the complex hydro-mechanical material behavior place high demands on the excavation techniques and the support structures. A regular support structure is essential in order to guarantee stability of the galleries and, thus, operational safety. Further requirements can be deduced from long-term safety stipulations and the from the regulatory framework. For example, retrievability is a design criterion stipulated by German law. As a result, a unique and complex set of requirements will influence the design of the support systems for a future German repository in claystone. BGE Technology GmbH takes into account different directions when developing suitable support structures. On the one hand, numerical parametric studies have been performed to determine the most promising support structures in various geo-mechanical conditions. On the other hand, advanced hydro-mechanical material models are being used and extended to develop a basis for the numerical analysis and performance assessment of support systems in claystone. This paper gives an insight into these activities. (authors)