The planned use of crushed salt as the backfill and sealing material for the final disposal of radioactive waste in rock salt is justified by the favorable crushed salt material properties. A prognostic long-term safety assessment requires sufficiently proved physical modeling that can only be met on the basis of suitable laboratory and field investigations. To reduce the currently existing uncertainties, triaxial long-term compaction tests TUC-V2 and TUC-V4 (KOMPASS II) were carried out.

As part of BARIK, a laboratory programme is used to generate a dataset for anisotropic material to verify and validate the developed constitutive model. Based on Freiberger gneis, basic tests and multi-stage triaxial compression tests were conducted, the latter to investigate a post-failure region. Hydromechanical coupled triaxial compression tests to observe micromechanical damage processes are in progress. This contribution provides an overview of the laboratory programme and first results.

For the deep geological disposal of high-level nuclear waste in rock salt formations, the safety concept includes the backfilling of open cavities with crushed salt. For the prognosis of the sealing function of the backfill for the safe containment of the nuclear waste, it is crucial to have a comprehensive process understanding of the crushed-salt compaction behavior. The KOMPASS projects were initiated to improve the scientific knowledge of using crushed salt as backfill material.

This contribution gives an overview of how the BARIK constitutive model was developed and tested. BARIK is an extended Hoek–Brown model for fractured crystalline rock that takes up to three fracture systems into account. It gives a numerical value to qualitative integrity criteria to show that the containment-providing rock zone in crystalline host rock is still intact. The BARIK model is a step forward in understanding and modeling the complex behavior of fractured crystalline hard rock.