Modelling water uptake in highly compacted bentonite in environmental sealing barriers

Plans to close a German radioactive waste repository in rock salt include a s one alternative the construction of a 'Cross Section Closure (CSC)' seali ng barrier, The proposed material for the sealing barrier is highly compact ed bentonite. To investigate the swelling behaviour of a highly compacted b entonite, a large number of laboratory tests were performed. In addition, l arge scale model tests were carried out to demonstrate the development of a nearly homogeneous and isotropic swelling pressure. The results of the lar ge scale model tests were interpreted numerically based on the models for s tress-strain behaviour and water uptake which are implemented in the finite element computer codes FEST03 and HYDOPO. The investigations show good agr eement between the results of the model tests and the corresponding analyse s and show that the theoretical models are capable of describing the behavi our of sealing structures based on highly compacted bentonite.