A Dynamic Risk Assessment Method for Deep-Buried Tunnels Based on a Bayesian Network

Table 2

Allowable relative displacement (%).

Surrounding rock level	Tunnel depth (m)
	<50	50~300	>300
III	0.10~0.30	0.20~0.50	0.40~1.20
IV	0.15~0.50	0.40~1.20	0.80~2.00
V	0.20~0.80	0.60~1.60	1.00~3.00

The relative displacement value refers to the ratio of the measured displacement to the distance between two measuring points or the ratio of the measured value of the arch crown convergence to the height of the tunnel.