The demonstration of the disposal of high-level radioactive waste in Belgium involves construction works to extend the current research infrastructure (at 223 m depth in a tertiary clay layer) with a second access shaft and a connecting gallery. These work give us a unique opportunity to extend our knowledge on the behaviour of clay at these depths, more specifically on the Excavation Disturbed Zone (EDZ) due to tunnelling works as this zone might affect the protective properties of the clay host formation. A research programme asesses the short-term hydro-mechanical disturbance caused by gallery excavation. This is performed by predictive modelling, field measurements (pressure and displacement), and a characterisation programme to determine the initial field conditions. The results of the first modelling exercises have allowed us to determine the optimal position and measurement range of the instruments. This paper presents both the first modelling and experimental results.
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