Support design methods applied to excavations of the CIGEO waste repository : advices in numerical modelling
Résumé
In the framework of the design of the French nuclear waste repository called Cigéo, a two years collaborative work including French nuclear waste producers (EDF, CEA and AREVA) and the French National Radioactive Waste Management Agency (Andra) has been conducted in order to improve methods of modelling support for design of drift. Among a lot of identified issues, the main idea was to well take into account the real excavation steps and all elements of the support depending on the excavation/support method (tunnelling machine, road header, delayed in place casted support,…) in the modelling approach and identify the effect on the long term loading of the lining assuming creep of the rock mass. Calculations have been performed with the finite difference code FLAC using two different elasto-viscoplastic models (Kleine 2007, Souley et al 2011). The sensibility to various numerical parameters has been analysed as: mesh of support elements, interfaces between elements,…Supports taking into account compressible material have also been considered in the modelling with models for the Highly Deformable Elements. The paper sums up the main results of this fruitful collaboration and exhibits conclusions which could feed and help the project designer of Cigéo.