Table 2 Roof and floor lithology and ratio.
From: Fracture propagation and water seepage behavior in overburden strata at Tunbao coal mine
Serial number | Top layer | Lithologic characters | Thickness of stratum/m | Elastic modulus | Poisson ratio | Tensile strength Pb-ten(MPa) | Angle of internal friction pb-fa(°) | Mass ratio River sand : gypsum : white powder : coal powder |
|---|---|---|---|---|---|---|---|---|
1 | main roof | siltstone | 35 | 9.7 | 0.23 | 4.66 | 36 | 8:3:7:0 |
2 | immediate roof | grit stone | 24 | 15.90 | 0.15 | 3.13 | 42 | 7:5:5:0 |
3 | coal | M4-5 coal | 10 | 6.9 | 0.27 | 1.33 | 42.6 | 26:1:5:16 |
4 | direct bottom | siltstone | 12 | 35 | 9.7 | 0.23 | 4.66 | 8:3:7:0 |
5 | Basic bottom | fine sandstone | 12 | 24.8 | 0.21 | 3.06 | 38.8 | 7:4:6:0 |
