Research Article
Influence of Valleys Terrain on Pressure of Fully Mechanized Working Faces in Shallow Coal Seams
Table 2
Missing statistics of the main key stratum in the overlying strata of the No. 3 Panel from the Huojitu Coal Mine.
| Working face | Valley no. | Relative position of interface between bottom of key stratum and valley bottom (m) | Condition |
| 21304 | 1 | +22.36 | Missing | 2 | +27.13 | Missing | 3 | +26.11 | Missing |
| 21305 | 1 | +30.01 | Missing | 2 | +12.97 | Missing | 3 | +2.91 | Missing | 4 | ā2.87 | Not missing |
| 21306 | 1 | ā4.12 | Not missing | 2 | +5.01 | Missing |
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