Research Article
The Study on Large-Diameter Drilling Prevention Method of Rock Burst in the Xinxing Coal
Table 5
Three-level 65-story roof and floor features.
| | Roof and floor | Rock type | Thickness (m) | Lithology |
| | Roof | Old roof | Coarse sandstone | 19 | Hard | | Direct roof | Fine sandstone~siltstone | 35 | Gray~black gray | | Floor | Direct floor | Fine sandstone | 1.2 | Off-white hard, not obvious layering | | Old floor | Fine sandstone~siltstone | 6.8 | Off-white dense and hard |
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