Prediction of Rockburst Intensity Grade in Deep Underground Excavation Using Adaptive Boosting Classifier

Table 1

Grading criteria of rockburst intensity.

Rockburst grade	No rockburst (1)	Moderate rockburst (2)	Strong rockburst (3)	Violent rockburst (4)
σθ/σc	<0.3	0.3–0.5	0.5–0.7	>0.7
σc/σt	>40	26.7–40	14.5–26.7	<14.5
Wet	>5	3.5–5.0	2.0–3.5	<2.0

Note. σ_θ/σ_c = stress concentration factor; σ_c/σ_t = rock brittleness.