ABSTRACT
Despites these difficulties, long-term evolution of underground structures in salt formations has to be evaluated accurately because of their potential impacts on the safety of persons and property and the protection of the environment. The high number of accidental salt dissolution, initially protected against groundwater but becoming in contact with water through the access facilities (shafts, galleries), boreholes and fractures (Berest et al., 2004) show that long-term prediction of the stability of underground structures in salt is very difficult to guarantee. This may be paradoxical because some salt formations are used for definitive storage of radioactive or toxic chemical wastes. This choice is usually justified by the fact that virgin salt is almost tight to fluids (the typical value of permeability is 10-21 m2, 10-14 m/s, 10-9 Darcy). This is not the case for a damaged salt in the excavations nearby (several orders of magnitudes of permeability increase after Stormont et al., 1991).
