From 1985 to 2015 extensive instrumentation with geotechnical measuring instruments followed by long-term observation in the U1 investigation area and in the main tunnel. The U1 was extended to a rock laboratory, where the swellable mountain (claystone containing anhydrite) was artificially irrigated. Here, the stress changes and deformations at different expansion resistances were measured according to the resistance principle and the principle of flexible base support. The following measurement methods were used:

  • Sliding Micrometer
  • Extensometers
  • Pressure cells for radial and tangential clamping
  • Concrete extensometer
  • Steel extensometer
  • Distometer ISETH
  • Anchor load cells
  • Fine levelling
  • Curvo- /Deformeter
  • Porewater Pressure Transducers
  • Measuring Weirs

In addition, four double-load plate tests were carried out in the dome of the main tunnel.

Freudensteintunnel (rock lab)