Table 2.
Parameters used for the modeling of joint development in the Opalinus Clay, starting with a maximum burial depth of 2 km below the ground surface
| Parameter | Opalinus Clay | Unit |
|---|---|---|
| Maximum burial depth | 2,000 | m |
| Average density | 2.37a | g/cm3 |
| Fluid density | 1 | g/cm3 |
| Overpressure | 0 | MPa |
| Poisson’s ratio (ν) | 0.25a | |
| Applied tectonic stress | 0 | MPa |
| Cohesion (S0) | 3.6b | MPa |
| Coefficient of internal friction (μi) | 0.47b | |
| Tensile strength (T) | 1.8c | MPa |
| Coefficient of thermal expansion (α) | 19d | 10−6 K−1 |
| Young’s modulus (E) | 10.49a | GPa |
| Vertical stress at maximum depth | 46.5 | MPa |
| Fluid pressure at maximum depth | 19.62 | MPa |
| Geostatic stress ratio (ko) | 0.333 | |
| Vertical effective stress (σ′V) at maximum depth | 26.88 | MPa |
| Horizontal effective stress (σ′H= σ′Vko) at maximum depth | 8.95 | MPa |
Input parameters are in bold and output parameters are in italics. The geothermal gradient is assumed to be 30 K per km. The data are from the Mont Terri Rock Laboratory in Switzerland, where the structural history is different from the region of interest in Germany (see text). Data sources.
Schuster et al.112 (mean values from 9 samples).
Bossart,113 with the coefficient of internal friction based on an internal friction angle of 25°.
Jobmann et al.114 (mean values from 6 samples).
Jobmann and Polster.115 Maximum depth, overpressure and applied tectonic stress are starting point values used in the base case.