Vulnerability Analysis of Soft Caving Tunnel Support System and Surrounding Rock Optimal Control Technology Research

Table 1

Quality ranks of rock mass integrity influence and quantitative scores.

Structural surface spacing (m)	Structural features	RQD (%)	Quality rank	Scores
1∼2 groups, >1.0	Whole shape or thick-bedded	>70	Integrity	2
1∼2 groups, >0.8	Massive or thick-bedded	50≤𝑅≤70	Relatively Integrity	4
2∼3 groups, >0.6	Block or in fissures, thin-bedded	30≤𝑅<50	Medium	6
2∼3 groups, >0.4	Massive fissure, fracture-like	10≤𝑅<30	Relatively broken	8
3∼4 groups, 0.1∼0.4	Granular form	<10	Broken	10