Mechanism of Coal Burst and Prevention Practice in Deep Asymmetric Isolated Coal Pillar: A Case Study from YaoQiao Coal Mine

Table 6

Relation between positive velocity anomalies and coal burst risk level.

Coal burst risk index	Coal burst risk level	Positive velocity anomaly, An (%)
0	None	<5
1	Weak	5∼15
2	Middle	15∼25
3	Strong	>25