Intelligent Autofeedback and Safety Early-Warning for Underground Cavern Engineering during Construction Based on BP Neural Network and FEM

Table 1

The allowable deformation.

Rock type	Buried 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