Finite element benchmarks for clays - The INTERCLAY II project

In the context of long-term disposal of radioactive waste, scoping calculations have shown that for commonly advocated disposal concepts, i.e. the incarceration of waste underground in suitable host media such as low permeability, low conductivity clays, the heat emission from high level waste canisters could induce temperature changes extending over several thousands of years with corresponding modifications in the stress regime. It is therefore necessary to demonstrate that the predictive modelling capability of clay behaviour is compatible with these time spans. The INTERCLAY exercise was designed with this requirement in mind. In 1989, a small-scale exercise was performed, in which three organisations independently analyzed two hypothetical problems. While the results were broadly in agreement, they were shown to be sensitive to both the constitutive model and the data used. As a result, INTER CLAY II was initiated, involving 11 organisations from various member states of the EC in a CEC-sponsored project investigating the numerical modelling of the long-term response of clays to geomechanical and thermal disturbances. This paper briefly describes the main results and presents some preliminary conclusions.