Research Article
Fractal Characteristics of Coal and Sandstone Failure under Different Unloading Confining Pressure Tests
Table 6
Mass fractions of fragments at different scales in the coal sample under different unloading rates.
| Scale (mm) | Unloading rate (MPa/s) | Coal | 0.02 | 0.05 | 0.08 | 0.11 | 0.14 |
| 0.3 ≥ d | 0.0219 | 0.0152 | 0.0154 | 0.0134 | 0.0097 | 0.6 ≥ d > 0.3 | 0.0523 | 0.0436 | 0.0342 | 0.0335 | 0.0327 | 1.18 ≥ d > 0.6 | 0.0717 | 0.0609 | 0.0544 | 0.0570 | 0.0570 | 2.36 ≥ d > 1.18 | 0.1029 | 0.0882 | 0.1017 | 0.0950 | 0.0970 | 4.75 ≥ d > 2.36 | 0.1408 | 0.1420 | 0.1228 | 0.1229 | 0.1248 | 9.5 ≥ d > 4.75 | 0.1703 | 0.1805 | 0.1671 | 0.1687 | 0.1673 | 13.2 ≥ d > 9.5 | 0.1956 | 0.2191 | 0.2255 | 0.2291 | 0.2267 | 19 ≥ d > 13.2 | 0.2445 | 0.2505 | 0.2789 | 0.2804 | 0.2848 |
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