Keywords: excavation damage zone, damage model, thermo-mechanical analysis, generalized trapezoidal rule, coupled modeling, fem.

Deep geological repositories for radioactive waste are usually planned in crystalline rocks which are brittle and contain fractures of various scales. The fractures can create preferential paths for transport of water which may contain various chemical species or radionuclides. It is therefore essential to know how much of the substance would reach the rock mass in the event of an accident. If the engineering barrier is capable of containing any potential leakage of hazardous substances, the excavation damage zone is not a critical factor in the safety assessment. This contribution therefore focuses on a detailed analysis of the behaviour of a single borehole and its impact on the surrounding environment. For transport processes and related safety assessment of deep geological repositories is crucial to describe the amount of any transported species close to the rock mass. Results from such analysis will serve in detailed study of excavation damage zone. To provide an accurate description of the repository, the model must also include engineering barriers, which are usually made of bentonite. The behaviour of bentonite is highly complex, and a specialised material model must be used to describe it. All analyses are based on the finite element method. The nonlinear behaviour is solved with the help of the Newton's method and time integration is done by the generalized trapezoidal rule.

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