Table 1.
Summary of rock strength properties, loosely correlated top-down to Fig. 3.
| Rock type | UCS (MPa) | Elastic modulus (GPa) | Poisson’s ratio | Internal friction angle (°) | Residual friction angle (°) |
|---|---|---|---|---|---|
| Dark gray shale | 85.3 | 16.7 | 0.15 | 24.00 | 56.0 |
| Black shale | 22.7 | ||||
| Shaley sandstone | 144.0 | 40.8 | 0.25 | 19.20 | 40.5 |
| Gray clay shale | 80.8 | 15.5 | 0.26 | 34.4 | |
| Limestone | 265.0 | 78.6 | 0.30 | 33.10 | |
| Claystone with calcareous nodules | 103.6 | 22.3 | 0.14 | 18.10 | 42.4 |
| Clay shale | 43.8 | 14.1 | 0.22 | 31.00 | 39.3 |
| Gray silty shale | 58.5 | 10.8 | 0.21 | 26.40 | 35.2 |
| Coalbed being mined | N/A | ||||
| Dark-gray shale with coal streaks | 59.0 | 9.4 | 0.28 | 7.65 | 54.7 |
| Dark-gray shale with sandstone streaks | 60.7 | 16.0 | 0.14 | 14.30 | 41.4 |