Research Article.
A Method for Determining Feasibility of Mining Residual Coal above Out-Fashioned Goaf under Variable Load: A Case Study
Table 1
Stability determination methods of the upward mining of longwall goaf.
| Methods | Calculation formula and application condition |
| Rational analytical method [6, 7] | K > 6(single seam) K > 6.3(multiple seam) |
| Mathematical statistics method [8] | |
| The “three-zone” method [6, 9–13] | Caving zone 1: | Caving zone 2: | Fracture zone 1: | (here (a) strong and hard: c1 = 2.1, c2 = 16, c3 = 1.2, c4 = 2; (b) medium strong: c1 = 4.7, c2 = 19, c3 = 1.6, c4 = 3.6; (c) soft and weak: c1 = 6.2, c2 = 32, c3 = 3.1, c4 = 5) | Fracture zone 2: | (here m is the mining thickness and hi is the stratum thickness i) |
| The method of equilibrium surrounding rock [14–16] | | (here K1, M, and hp are, respectively, the bulking coefficient, mining thickness, and equilibrium surrounding rock thickness) |
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