Abstract:
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Salt rocks are being considered as potential recipients for geologic disposal of
nuclear waste because of their favourable hydraulic and mechanical properties.
In essence, processes controlling the behaviour of salt rocks are similar to those
occurring in other media, except that they take place at unusually fast rates.
The high solubility of salt in water is one of the causes of these high rates. In
fact, creep deformation of wet salts takes place much faster than under dry
conditions. This can be explained by means of a mechanism of creep
deformation based on salt dissolution, molecular diffusion and precipitation at
the pore scale caused by stress concentration[...]. The complex behaviour of saline media requires new theoretical and
numerical developments. The study of the basic mechanisms has revealed that
coupling between thermal, hydraulic and mechanical problems may be required
in some cases. We have developed the governing equations for nonisothermal
multiphase flow of brine and gas in deformable saline media. These
include mass balance equations for the species in the system (salt, water and air), energy balance equation and stress equilibrium equation. Equilibrium
restrictions complete the theoretical formulation.
This paper presents a numerical formulation required for solving this
complex problem in a practical way. An example of its application is also
included. |