For the simulation of the hydraulic and mechanical behavior of rock salt as well as the hydraulic-mechanical interaction in the disturbed rock zone (DRZ) around sealing systems, the TUC coupling concept has been developed within the past years, which includes the mechanical material model Hou/Lux formulated with effective stresses, a flow equation using the Darcy flow model as well as several coupling models (e.g. permeability model, a-model, model for the determination of the hydraulic forces, strength model, damage model), describing the hydraulic and mechanical behavior of rock salt as well as the necessary interfaces and Interactions between the geomechanical and the geohydraulic field. An exemplary drift sealing construction is investigated according to this coupling concept. The numerical results of the calculations show some hydraulic and mechanical behavior of rock salt as well as some hydraulic-mechanical interactions, with details unknown so far.
Mining experience and phenomenological observations have shown first findings on the development of DRZ near drifts, shafts, boreholes and caverns in rock salt. In backfilled excavations, DRZ is usually of only minor importance for the long-term safety considerations regarding the geotechnical stability and the geohydraulic behavior. In the vicinity of sealing systems, however, it can reduce the functionality of such constructions or even render them Ineffective due to its relatively high permeability. The realistic detection, description and forecast of the geomechanical and the geohydraulic behavior of the rock salt in DRZ and the resulting interactions have over recent years gained Worldwide importance. Based on statements of the poroelesticity theory, e.g. Charlez (1991), and On the coupling concept following Cosenza & Ghoreychi (1996) for rock salt, the TUC coupling concept has been developed using the effective stresses as the basic unknowns, Hou (1999), Hou & Lux (2001), Xie (2002) and Lux et al. (2002).
The Hou/Lux material model, which describes the effects of the different deformation mechanisms mainly integrally, was developed based on the Lubby2 material model and on the fundamentals of continuum damage mechanics (Hou, 1997). Considering that in a saturated porous medium only those forces actually acting inside the rock matrix are responsible for the matrix deformation, the effective stresses instead of the total stresses have been introduced into the Hou/Lux material model, (Hou, 1999). Details can be found in Hou (1997, 2000), Hou & Lux (1998, 2002) and Lux & Hou (1999).
Although the mechanical and the hydraulic field are described by means of different models, they must be viewed jointly in case of a seepage flow due to the hydraulic-mechanical interactions. This requires a coupling concept, to bring together both fields in a plausible, mechanically and hydraulically compatible manner as well as in order to take account of the hydraulic-mechanical interactions. Details about the TUC coupling concept and about the coupling models can be found in Hou (1999), Hou & Lux (200 I), Xie (2002) and Lux et al. (2002).