Research Article
Effect of the Initial Support of the Tunnel on the Characteristics of Rockburst: Case Study and Mechanism Analysis
Table 2
Composite stiffness of surrounding rock and support system in rockburst.
| | Hazards | Rockburst “12.17” | Rockburst “12.29” | Rockburst “01.14” | Rockburst “03.12” |
| | Time span | 2017/12/15-12/17 | 2017/12/26-12/29 | 2018/01/10-01/14 | 2018/03/08-03/12 | | Lithology | Gabbro with granulite interbedded, grade III | Granulite with gabbro interbedded, grade IV | Gabbro with granulite interbedded, grade III | Gabbro with granulite interbedded, grade III | | Support structure and parameter | Steel arch: spacing 80 cm. Anchor: 12 per steel arch. Shotcrete: thickness 20 cm. | Steel arch: spacing 80 cm. Anchor: 12 per steel arch. Shotcrete: thickness 20 cm. | Strengthened steel arch: spacing 70 cm. Anchor: 20 per steel arch. Shotcrete: thickness 20 cm. | Steel arch: spacing 60 cm. Anchor: 12 per steel arch. Shotcrete: thickness 20 cm. | | Stiffness score | 58.50 | 48.50 | 75.43 | 62.67 | | Stiffness (For these four rockbursts) | Weak stiffness | Weak stiffness | Strong stiffness | Strong stiffness |
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