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Deep glacial melt water erosion of sedimentary rock through tunnel valleys – numerical modelling in the presence of uncertainty

The lowlands of northern Germany and neighbouring countries have been subject to glaciation several times in the pleistocene. These glacial periods have left behind several erosional features, of which tunnel valleys are the deepest and most remarkable. The current consensus of the respective field of science is that those valleys are formed by the flow of melt water below the melting glacier.

Within the site selection procedure in Germany for a high-level nuclear waste (HLW) repository, a safety assessment for 1 million years has to be conducted. During this time span repeated glaciations are likely to occur in northern Europe, and therefore repeated glacial erosion is to be expected.

However, beyond the safe inclusion in the selected host rock of a HLW repository, a sufficient stability of the overlaying overburden horizons must be ensured.

To address the numerous uncertainties regarding the glacier melting process and the conditions of the sedimentary layers eroded by melt water transport, we have developed a combined modelling approach. This method comprises a three-dimensional deterministic numerical modelling of the tunnel valley genesis with FLAC3D and a multivariate probabilistic modelling with GoldSim to account for the remarkable uncertainties over 1 Ma. The approach allows to evaluate the resistance of different overburden stratigraphies against deep glacial erosion processes and therefore can be a valuable contribution to the site selection process.

The research project presented here is funded by BASE under the grant number FKZ 4721F10401.

Details

Author
Matthias Brandt1, Anton Carl-Dworschak2, Andreas Jockel2, Rene Kahnt3
Institutionen
1Insitut fuer Gebirgsmechanik, Germany; 2ERCOSPLAN Group, Erfurt, Germany; 3G.E.O.S. Ingenieurgesellschaft mbH, Freiberg, Germany
Veranstaltung
GeoSaxonia 2024
Datum
2024
DOI
10.48380/mhs3-s704