Research Article
Overburden Migration and Failure Characteristics in Mining Shallow Buried Coal Seam with Thick Loose Layer
Table 2
Value of excavation disturbance parameter D.
| Project disturbance | D |
| The rock mass is excellent, controlled blasting or rock excavation by machine | 0 | The rock mass quality is poor, manual prying or mechanical excavation | 0 | The tunnel is located in the squeezing stratum and has floor heave without invert | 0.5 | The blasting quality of hard rock tunnel is poor, and the influence depth of loosening is 2-3 m | 0.8 | The damage of surrounding rock is common and the blasting quality is poor in small-scale slope excavation | 1.0 | The damage of surrounding rock is general and the blasting quality is good in small-scale slope excavation | 0.7 | Large-scale production blasting, serious disturbance, production blasting | 1.0 | Large-scale production blasting, serious disturbance, mechanical excavation | 0.7 |
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