Research Article
Analysis and Application on Controlling Thick Hard Roof Caving with Deep-Hole Position Presplitting Blasting
Table 1
Characteristics of strata loading and caving intervals.
| | No | Lithology | Thickness (m) | qn = γh (KPa) | Loading (KPa) | Load strata | Uniaxial tensile strength (MPa) | Periodic caving interval (m) | Remark |
| | 9 | Fine sandstone | 15.0 | 378.0 | — | — | 5.63 | — | |
| | 8 | Sandy mudstone | 4.4 | 103.7 | q8 > (q9)8 = 9.6 | 8 | 3.42 | 8.6 | Loading stratum | | 7 | Coal | 0.4 | 5.4 | — | — | 2.65 | — | | 6 | Siltstone | 3.5 | 93.5 | (q6 + q7) > (q8)6 = 89.7 | 6–7 | 4.80 | 14.2 |
| | 5 | Gritstone | 14.2 | 379.2 | (q8)5 = 564.3 > (q9)5 = 511.6 | 5–8 | 2.59 | 33.7 | Hinged strata |
| | 4 | Fine sandstone | 4.2 | 105.8 | q4 > (q5)4 = 14.5 | 4 | 2.86 | 9.9 | Combined cantilever beam | | 3 | Medium sandstone | 13.7 | 405.1 | (q4)3 = 497.3 > (q5)3 = 464.5 | 3–4 | 6.05 | 18.8 | | 2 | Fine sandstone | 2.7 | 68.1 | q2>(q3)2 = 2.1 | 2 | 2.83 | 9.7 | | 1 | Sandy mudstone | 1.8 | 42.4 | q1 > (q2)1 = 21.3 | 1 | 3.42 | 5.9 |
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