Numerical Evaluation on Dynamic Response of Existing Underlying Tunnel Induced by Blasting Excavation of a Subway Tunnel

Table 3

Relevant safety criteria for tunnel lining structures [32].

Structure type	Allowable safety peak particle velocity/cm/s
	1 d ≤ CA ≤ 3 d	3 d ≤ CA ≤ 7 d	7 d ≤ CA ≤ 28 d
Concrete	1.2	1.2~5.0	5.0~7.0
Shot concrete	5.0
Grouting	1	1.5	2~2.5
Bolts and anchor cables	1	1.5	5~7