Research Article
An Evaluation Method of Rock Brittleness Based on the Prepeak Crack Initiation and Postpeak Stress Drop Characteristics
Table 1
Calculation results of the brittleness index for marble under different confining pressures.
| Confining pressure (MPa) | Peak strain | Crack initiation strain | Strain difference | Bi | Bii | BI | Qualitative analysis of the test curve | εc/% | εci/% | △ε=εc−εci | εci/△ε | S/S△ | Bi·Bii |
| 5 | 0.003980 | 0.001250 | 0.00273 | 0.46 | 0.33 | 0.152 | Brittleness | 15 | 0.007170 | 0.002170 | 0.00500 | 0.43 | 0.25 | 0.110 | Elasticity-plasticity | 25 | 0.007570 | 0.002440 | 0.00513 | 0.48 | 0.17 | 0.082 | Elasticity-plasticity | 35 | 0.011820 | 0.002730 | 0.00909 | 0.30 | 0.26 | 0.078 | Elasticity-plasticity |
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