Thermal and thermomechanical model calculations

The TSS-test involving relevant repository conditions provides measurements which could be used for the validation of calculation models and of the constitutive relations of backfill and rock salt. The rise of the temperature, the closure of the drifts, followed by the compaction of the backfill and the resulting stresses in rock salt, are investigated numerically. Prior to the excavation of the test drifts, their thermomechanical responses were calculated using the constitutive models available at that time. As data from in situ measurement became available the comparison with numerical results was made. The pre-test calculations revealed a good correspondence of measured and calculated temperatures. However, with respect to thermomechanical calculations there are some discrepancies between numerical results and measurements. A further aim of this work was to explain the reason of these discrepancies. The numerical simulation was performed in two steps. The first step consisted in the thermal analysis. The FAST-BEST finite element code, specifically developed for studying the drift disposal, was used to calculate the temperature fields. The second step involved the thermomechanical analysis with the MAUS code which includes suitable material models for rock salt and crushed salt. (orig.)