Research article
Concept to proof long-term safety of abandoned salt mines by hydro-mechanical coupled simulations with FLAC3D and Ansys Fluent
Fabian Weber*, Heinz Konietzky
Deep Resources Engineering. 2025, 2(4): 100201. 
doi.org10.1016j.deepre.2025.100201.pdf
Abstract: Evaluation and prediction of the long-term behavior of abandoned mines have to consider complex interactions of different physical processes. The hydro-mechanical coupling plays an important role for potential short- and long-term environmental risks (e.g. surface subsidence, pollution of the biosphere, damage of the geological barrier, damage of groundwater regime). This work addresses challenges and key mechanisms in respect to long-term predictions for abandoned salt and potash mines and provides a general simulation concept. Exemplary, this concept is applied to a generic salt mine model characterized by hydro-mechanical coupling and visco-elasto as well as elasto-plastic material behavior. The concept considers time-depending rock mass and backfill material behavior. Long-lasting and large-scale fluid flow within solution-filled and backfilled cavities as well as a cavern due to creep induced convergence is simulated. A new coupling scheme between the numerical codes FLAC3D and Ansys Fluent is developed and employed for this purpose giving plausible and accurate results by efficient simulation duration. The presented workflow provides a step-by-step overview for assessing long-term safety of abandoned mines, starting with indication of main aspects determining the geomechanical and hydraulic processes followed by the exemplary model set-up, the choice of constitutive models, the simplification of the modelled mining process, the model calibration and the interpretation of the numerical results. Different model scenarios in respect to initial fluid saturation are simulated considering a partially saturated mine and a fully saturated mine, which leads to free fluid surface evolution up to the generation of excess of fluid pressure.
Highlights:
• Challenges and key mechanisms for long-term predictions for abandoned salt and potash mines are addressed.
• A general simulation concept is provided.
• Applying the concept to a generic salt mine model with hydro-mechanical coupling and visco-elasto-plastic materials.
• Long-lasting and large-scale convergence induced fluid flow within solution-filled and backfilled cavities and a cavern.
• A new coupling scheme between the numerical codes FLAC3D and Ansys Fluent is developed and employed for this purpose.
Keywords: Salt mines; Abandoned mines; Long-term prediction; Hydro-mechanical coupling; FLAC3D; Ansys Fluent; Salt mechanics; Numerical simulation; Continuum mechanics; Computational Fluid Dynamics
Cite: Weber, F.; Konietzky, H., Concept to proof long-term safety of abandoned salt mines by hydro-mechanical coupled simulations with FLAC3D and Ansys Fluent [J]. Deep Resources Engineering 2025, 2 (4): 100201. https://doi.org/10.1016/j.deepre.2025.100201
